DISCOVERY OF AN EXTREMELY WIDE-ANGLE BIPOLAR OUTFLOW IN AFGL 5142

Energy Technology Data Exchange (ETDEWEB)

Liu, Tie; Kim, Kee-Tae; Lee, Chang-Won; Cho, Se-Hyung [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wu, Yuefang [Department of Astronomy, Peking University, Beijing 100871 (China); Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Li, Di [National Astronomical Observatories, Chinese Academy of Science, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Liu, Sheng-Yuan; Chen, Huei-Ru [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China); Tatematsu, Ken’ichi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Wang, Ke [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Lee, Jeong-Eun [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Qin, Sheng-Li [Department of Astronomy, Yunnan University, and Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming 650091 (China); Mardones, Diego, E-mail: liutiepku@gmail.com [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)

2016-06-10

Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle (∼180°) bipolar outflow (“EWBO”) in a cluster forming region AFGL 5142 from low-velocity emission of the HCN (3–2) and HCO{sup +} (3–2) lines. This bipolar outflow is along a north-west to south-east direction with a line of sight flow velocity of about 3 km s{sup −1} and is spatially connected to the high-velocity jet-like outflows. It seems to be a collection of low-velocity material entrained by the high-velocity outflows due to momentum feedback. The total ejected mass and mass loss rate due to both high-velocity jet-like outflows and the “EWBO” are ∼24.5 M {sub ⊙} and ∼1.7 × 10{sup −3} M {sub ⊙} yr{sup −1}, respectively. Global collapse of the clump is revealed by the “blue profile” in the HCO{sup +} (1–0) line. A hierarchical network of filaments was identified in NH{sub 3} (1, 1) emission. Clear velocity gradients of the order of 10 km s{sup −1} pc{sup −1} are found along filaments, indicating gas inflow along the filaments. The sum of the accretion rate along filaments and mass infall rate along the line of sight is ∼3.1 × 10{sup −3} M {sub ⊙} yr{sup −1}, which exceeds the total mass loss rate, indicating that the central cluster is probably still gaining mass. The central cluster is highly fragmented and 22 condensations are identified in 1.1 mm continuum emission. The fragmentation process seems to be determined by thermal pressure and turbulence. The magnetic field may not play an important role in fragmentation.

Quasar outflow energetics from broad absorption line variability

Science.gov (United States)

McGraw, S. M.; Shields, J. C.; Hamann, F. W.; Capellupo, D. M.; Herbst, H.

2018-03-01

Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in active galactic nucleus (AGN) feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71 BAL quasars with P V broad absorption. The presence of P V BALs indicates that other BALs like C IV are saturated, such that variability in those lines favours clouds crossing the line of sight. We use these constraints with measurements of BAL variability to estimate outflow locations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ) BAL variations from 10 quasars in our sample over rest-frame time-scales between ≤0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally ≲ 1-10 pc from the SMBH using the transverse-motion scenario, and ≲ 100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NH ≳ 1022 cm-2), yield outflow kinetic luminosities between ˜ 0.001 and 1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback.

Outflow and Accretion Physics in Active Galactic Nuclei

Science.gov (United States)

McGraw, Sean Michael

2016-09-01

This dissertation focuses on placing observational constraints on outflows and accretion disks in active galactic nuclei (AGN) for the purpose of better understanding the physics of super-massive black holes (SMBHs) and their evolution with the host galaxy over cosmic time. Quasar outflows and their importance in SMBH-host galaxy co-evolution can be further understood by analyzing broad absorption lines (BALs) in rest-frame UV spectra that trace a range of wind conditions. We quantify the properties of the flows by conducting BAL variability studies using multiple-epoch spectra acquired primarily from MDM Observatory and from the Sloan Digital Sky Survey. Iron low-ionization BALs (FeLoBALs) are a rare type of outflow that may represent a transient phase in galaxy evolution, and we analyze the variations in 12 FeLoBAL quasars with redshifts between 0.7 ≤ z ≤ 1.9 and rest frame timescales between ˜10 d to 7.6 yr. We investigate BAL variability in 71 quasar outflows that exhibit P V absorption, a tracer of high column density gas (i.e. NH ≥ 1022 cm -2), in order to quantify the energies and momenta of the flows. We also characterize the variability patterns of 26 quasars with mini-BALs, an interesting class of absorbers that may represent a distinct phase in the evolution of outflows. Low-luminosity AGN (LLAGN) are important objects to study since their prominence in the local Universe suggest a possible evolution from the quasar era, and their low radiative outputs likely indicate a distinct mode of accretion onto the SMBH. We probe the accretion conditions in the LLAGN NGC 4203 by estimating the SMBH mass, which is obtained by modeling the 2-dimensional velocity field of the nebular gas using spectra from the Hubble Space Telescope. We detect significant BAL and mini-BAL variability in a subset of quasars from each of our samples, with measured rest-frame variability time-scales from days to years and over multiple years on average. Variable wavelength

Quantitation of uveoscleral outflow in normotensive and glaucomatous Beagles by 3H-labeled dextran

International Nuclear Information System (INIS)

Barrie, K.P.; Gum, G.G.; Samuelson, D.A.; Gelatt, K.N.

1985-01-01

In uveoscleral outflow, aqueous humor leaves the anterior chamber and passes caudally through the trabecular meshwork and the sclerociliary cleft to enter the supraciliary and suprachoroidal spaces. The fluid is then absorbed by choroidal and scleral circulations. Using 3 H-labeled dextran, uveoscleral outflow was quantitated in normotensive and glaucomatous Beagles under general anesthesia. The intrascleral plexus was isolated and 3 H-labeled dextran was injected into the anterior chamber. Intrascleral plexus contents were sampled every 5 minutes over a 30- to 60-minute period. The eyes were enucleated, sectioned, and prepared for scintillation counting. Uveoscleral outflow accounted for 15% and 3% of the total aqueous humor outflow in the normotensive dogs and in the advanced glaucomatous dogs, respectively. In the advanced glaucomatous Beagle, conventional and uveoscleral outflow pathways were reduced and contributed to the etiopathogenesis of glaucoma

Modeling X-ray Absorbers in AGNs with MHD-Driven Accretion-Disk Winds

Science.gov (United States)

Fukumura, Keigo; Kazanas, D.; Shrader, C. R.; Tombesi, F.; Contopoulos, J.; Behar, E.

2013-04-01

We have proposed a systematic view of the observed X-ray absorbers, namely warm absorbers (WAs) in soft X-ray and highly-ionized ultra-fast outflows (UFOs), in the context of magnetically-driven accretion-disk wind models. While potentially complicated by variability and thermal instability in these energetic outflows, in this simplistic model we have calculated 2D kinematic field as well as density and ionization structure of the wind with density profile of 1/r corresponding to a constant column distribution per decade of ionization parameter. In particular we show semi-analytically that the inner layer of the disk-wind manifests itself as the strongly-ionized fast outflows while the outer layer is identified as the moderately-ionized absorbers. The computed characteristics of these two apparently distinct absorbers are consistent with X-ray data (i.e. a factor of ~100 difference in column and ionization parameters as well as low wind velocity vs. near-relativistic flow). With the predicted contour curves for these wind parameters one can constrain allowed regions for the presence of WAs and UFOs.The model further implies that the UFO's gas pressure is comparable to that of the observed radio jet in 3C111 suggesting that the magnetized disk-wind with density profile of 1/r is a viable agent to help sustain such a self-collimated jet at small radii.

A HIGH RESOLUTION VIEW OF THE WARM ABSORBER IN THE QUASAR MR 2251-178

Energy Technology Data Exchange (ETDEWEB)

Reeves, J. N.; Gofford, J.; Nardini, E. [Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire, ST5 5BG (United Kingdom); Porquet, D. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Braito, V. [INAF - Osservatorio Astronomico di Brera, Via Bianchi 46 I-23807 Merate (Italy); Turner, T. J. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Crenshaw, D. M. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, One Park Place South SE, Suite 700, Atlanta, GA 30303 (United States); Kraemer, S. B., E-mail: j.n.reeves@keele.ac.uk [Institute for Astrophysics and Computational Sciences, Department of Physics, The Catholic University of America, Washington, DC 20064 (United States)

2013-10-20

High resolution X-ray spectroscopy of the warm absorber in a nearby quasar, MR 2251-178 (z = 0.06398), is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating (HETG) and the XMM-Newton Reflection Grating Spectrometer, with net exposure times of approximately 400 ks each. A multitude of absorption lines from C to Fe are detected, revealing at least three warm absorbing components ranging in ionization parameter from log (ξ/erg cm s{sup –1}) = 1-3 with outflow velocities ∼< 500 km s{sup –1}. The lowest ionization absorber appears to vary between the Chandra and XMM-Newton observations, which implies a radial distance of between 9 and 17 pc from the black hole. Several broad soft X-ray emission lines are strongly detected, most notably from He-like oxygen, with FWHM velocity widths of up to 10,000 km s{sup –1}, consistent with an origin from broad-line region (BLR) clouds. In addition to the warm absorber, gas partially covering the line of sight to the quasar appears to be present, with a typical column density of N{sub H} = 10{sup 23} cm{sup –2}. We suggest that the partial covering absorber may arise from the same BLR clouds responsible for the broad soft X-ray emission lines. Finally, the presence of a highly ionized outflow in the iron K band from both the 2002 and 2011 Chandra HETG observations appears to be confirmed, which has an outflow velocity of –15600 ± 2400 km s{sup –1}. However, a partial covering origin for the iron K absorption cannot be excluded, resulting from low ionization material with little or no outflow velocity.

THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

Energy Technology Data Exchange (ETDEWEB)

O’Dell, C. R. [Department of Physics and Astronomy, Vanderbilt University, Box 1807-B, Nashville, TN 37235 (United States); Ferland, G. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Henney, W. J. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apartado Postal 3-72, 58090 Morelia, Michoacán, México (Mexico); Peimbert, M. [Instituto de Astronomia, Universidad Nacional Autónoma de México, Apdo, Postal 70-264, 04510 México D. F., México (Mexico); García-Díaz, Ma. T. [Instituto de Astronomia, Universidad Nacional Autónoma de México, Km 103 Carretera Tijuana-Ensenada, 22860 Ensenada, B.C., México (Mexico); Rubin, Robert H., E-mail: cr.odell@vanderbilt.edu [NASA/Ames Research Center, Moffett Field, CA 94035-0001 (United States)

2015-10-15

Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database.

THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

International Nuclear Information System (INIS)

O’Dell, C. R.; Ferland, G. J.; Henney, W. J.; Peimbert, M.; García-Díaz, Ma. T.; Rubin, Robert H.

2015-01-01

Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database

PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

Energy Technology Data Exchange (ETDEWEB)

Wang Ke; Wu Yuefang; Zhang Huawei [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zhang Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Li Huabai, E-mail: kwang@cfa.harvard.edu [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

2012-02-15

The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH{sub 3} (J,K) = (1,1), (2,2), (3,3) lines, as well as H{sub 2}O and class I CH{sub 3}OH masers. Multiple NH{sub 3} transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH{sub 3} (3,3) emission features are also found coincident with the outflows. A weak NH{sub 3} (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

International Nuclear Information System (INIS)

Wang Ke; Wu Yuefang; Zhang Huawei; Zhang Qizhou; Li Huabai

2012-01-01

The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH 3 (J,K) = (1,1), (2,2), (3,3) lines, as well as H 2 O and class I CH 3 OH masers. Multiple NH 3 transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH 3 (3,3) emission features are also found coincident with the outflows. A weak NH 3 (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

Galactic cluster winds in presence of a dark energy

Science.gov (United States)

Bisnovatyi-Kogan, G. S.; Merafina, M.

2013-10-01

We obtain a solution for the hydrodynamic outflow of the polytropic gas from the gravitating centre, in the presence of the uniform dark energy (DE). The antigravity of DE is enlightening the outflow and makes the outflow possible at smaller initial temperature, at the same density. The main property of the wind in the presence of DE is its unlimited acceleration after passing the critical point. In application of this solution to the winds from galaxy clusters, we suggest that collision of the strongly accelerated wind with another galaxy cluster, or with another galactic cluster wind, could lead to the formation of a highest energy cosmic rays.

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

International Nuclear Information System (INIS)

Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M.

2012-01-01

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W r (2796) ≥ 0.1 Å] and 35 spectroscopically confirmed non-absorbing galaxies [W r (2796) r (2796) r (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100° and 40°, respectively. We find that the probability of detecting outflows is ∼60%, implying that winds are more commonly observed.

MAGNETICALLY DRIVEN ACCRETION DISK WINDS AND ULTRA-FAST OUTFLOWS IN PG 1211+143

International Nuclear Information System (INIS)

Fukumura, Keigo; Tombesi, Francesco; Kazanas, Demosthenes; Shrader, Chris; Behar, Ehud; Contopoulos, Ioannis

2015-01-01

We present a study of X-ray ionization of MHD accretion-disk winds in an effort to constrain the physics underlying the highly ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption-line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an XMM-Newton/EPIC spectrum of the narrow-line Seyfert, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log (ξ c [erg cm s −1 ]) ≃ 5–6 and a column density on the order of N H ≃ 10 23 cm −2 outflowing at a characteristic velocity of v c /c ≃ 0.1–0.2 (where c is the speed of light). The best-fit model favors its radial location at r c ≃ 200 R o (R o is the black hole’s innermost stable circular orbit), with an inner wind truncation radius at R t ≃ 30 R o . The overall K-shell feature in the data is suggested to be dominated by Fe xxv with very little contribution from Fe xxvi and weakly ionized iron, which is in good agreement with a series of earlier analyses of the UFOs in various AGNs, including PG 1211+143

Ultra-Fast Outflows in Radio-Loud AGN: New Constraints on Jet-Disk Connection

Science.gov (United States)

Sambruna, Rita

There is strong observational and theoretical evidence that outflows/jets are coupled to accretion disks in black hole accreting systems, from Galactic to extragalactic sizes. While in radio-quiet AGN there is ample evidence for the presence of Ultra-Fast Outflows (UFOs) from the presence of blue-shifted absorption features in their 4-10~keV spectra, sub-relativistic winds are expected on theoretical basis in radio-loud AGN but have not been observed until now. Our recent Suzaku observations of 5 bright Broad- Line Radio Galaxies (BLRGs, the radio-loud counterparts of Seyferts) has started to change this picture. We found strong evidence for UFOs in 3 out of 5 BLRGs, with ionization parameters, column densities, and velocities of the absorber similar to Seyferts. Moreover, the outflows in BLRGs are likely to be energetically very significant: from the Suzaku data of the three sources, outflow masses similar to the accretion masses and kinetic energies of the wind similar to the X-ray luminosity and radio power of the jet are inferred. Clearly, UFOs in radio-loud AGN represent a new key ingredient to understand their central engines and in particular, the jet-disk linkage. Our discovery of UFOs in a handful of BLRGs raises the questions of how common disk winds are in radio-loud AGN, what the absorber physical and dynamical characteristics are, and what is the outflow role in broader picture of galaxy-black hole connection for radio sources, i.e., for large-scale feedback models. To address these and other issues, we propose to use archival XMM-Newton and Suzaku spectra to search for Ultra-Fast Outflows in a large number of radio sources. Over a period of two years, we will conduct a systematic, uniform analysis of the archival X-ray data, building on our extensive experience with a similar previous project for Seyferts, and using robust analysis and statistical methodologies. As an important side product, we will also obtain accurate, self- consistent measurements

Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

Science.gov (United States)

Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-01-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

Data-Model and Inter-Model Comparisons of the GEM Outflow Events Using the Space Weather Modeling Framework

Science.gov (United States)

Welling, D. T.; Eccles, J. V.; Barakat, A. R.; Kistler, L. M.; Haaland, S.; Schunk, R. W.; Chappell, C. R.

2015-12-01

Two storm periods were selected by the Geospace Environment Modeling Ionospheric Outflow focus group for community collaborative study because of its high magnetospheric activity and extensive data coverage: the September 27 - October 4, 2002 corotating interaction region event and the October 22 - 29 coronal mass ejection event. During both events, the FAST, Polar, Cluster, and other missions made key observations, creating prime periods for data-model comparison. The GEM community has come together to simulate this period using many different methods in order to evaluate models, compare results, and expand our knowledge of ionospheric outflow and its effects on global dynamics. This paper presents Space Weather Modeling Framework (SWMF) simulations of these important periods compared against observations from the Polar TIDE, Cluster CODIF and EFW instruments. Emphasis will be given to the second event. Density and velocity of oxygen and hydrogen throughout the lobes, plasma sheet, and inner magnetosphere will be the focus of these comparisons. For these simulations, the SWMF couples the multifluid version of BATS-R-US MHD to a variety of ionospheric outflow models of varying complexity. The simplest is outflow arising from constant MHD inner boundary conditions. Two first-principles-based models are also leveraged: the Polar Wind Outflow Model (PWOM), a fluid treatment of outflow dynamics, and the Generalized Polar Wind (GPW) model, which combines fluid and particle-in-cell approaches. Each model is capable of capturing a different set of energization mechanisms, yielding different outflow results. The data-model comparisons will illustrate how well each approach captures reality and which energization mechanisms are most important. Inter-model comparisons will illustrate how the different outflow specifications affect the magnetosphere. Specifically, it is found that the GPW provides increased heavy ion outflow over a broader spatial range than the alternative

Observations of the Evolution of Ion Outflow During a Sawtooth Event

Science.gov (United States)

Lund, E. J.; Nowrouzi, N.; Kistler, L. M.; Cai, X.; Frey, H. U.

2015-12-01

Sawtooth oscillations are one of several convection modes known to exist in the magnetosphere. Recent simulations have suggested that O+^+ ions transported from the high-latitude ionosphere to the magnetotail can drive sawtooth events. We present observational case studies of sawtooth events using data from FAST near the noon-midnight meridional plane, Cluster in the magnetotail, GOES and LANL energetic particle sensors at geosynchronous orbit, and ACE solar wind data to investigate the evolution of ion outflow during sawtooth events and the question of whether O+^+ outflow from one tooth helps to drive subsequent teeth. We find that oxygen enters the tail from the lobes after each tooth onset, the oxygen fraction in the magnetotail often increases after a tooth onset, and that the oxygen fraction of outflowing ions increases after a tooth event both in the cusp and on the nightside. However, a significant amount of low energy oxygen (≲1 keV) can end up in the dayside inner magnetosphere.

Effects of Energetic Ion Outflow on Magnetospheric Dynamics

Science.gov (United States)

Kistler, L. M.; Mouikis, C.; Lund, E. J.; Menz, A.; Nowrouzi, N.

2016-12-01

There are two dominant regions of energetic ion outflow: the nightside auroral region and the dayside cusp. Processes in these regions can accelerate ions up to keV energies. Outflow from the nightside has direct access to the plasma sheet, while outflow from the cusp is convected over the polar cap and into the lobes. The cusp population can enter the plasma sheet from the lobe, with higher energy ions entering further down the tail than lower energy ions. During storm times, the O+ enhanced plasma sheet population is convected into the inner magnetosphere. The plasma that does not get trapped in the inner magnetosphere convects to the magnetopause where reconnection is taking place. An enhanced O+ population can change the plasma mass density, which may have the effect of decreasing the reconnection rate. In addition O+ has a larger gyroradius than H+ at the same velocity or energy. Because of this, there are larger regions where the O+ is demagnetized, which can lead to larger acceleration because the O+ can move farther in the direction of the electric field. In this talk we will review results from Cluster, Van Allen Probes, and MMS, on how outflow from the two locations affects magnetospheric dynamics. We will discuss whether enhanced O+ from either population has an effect on the reconnection rate in the tail or at the magnetopause. We will discuss how the two populations impact the inner magnetosphere during storm times. And finally, we will discuss whether either population plays a role in triggering substorms, particularly during sawtooth events.

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W.; Nielsen, Nikole M., E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2012-11-20

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W{sub r} (2796) {>=} 0.1 A] and 35 spectroscopically confirmed non-absorbing galaxies [W{sub r} (2796) < 0.1 A] imaged with Hubble Space Telescope and Sloan Digital Sky Survey. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by W{sub r} (2796) < 0.1 A. We find that blue star-forming galaxies clearly drive the bimodality while red passive galaxies may exhibit an excess along their major axis. These results are consistent with galaxy evolution scenarios where star-forming galaxies accrete new gas, forming new stars and producing winds, while red galaxies exist passively due to reduced gas reservoirs. We further compute an azimuthal angle dependent Mg II absorption covering fraction, which is enhanced by as much as 20%-30% along the major and minor axes. The W{sub r} (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100 Degree-Sign and 40 Degree-Sign , respectively. We find that the probability of detecting outflows is {approx}60%, implying that winds are more commonly observed.

Massive Outflows Associated with ATLASGAL Clumps

Science.gov (United States)

Yang, A. Y.; Thompson, M. A.; Urquhart, J. S.; Tian, W. W.

2018-03-01

We have undertaken the largest survey for outflows within the Galactic plane using simultaneously observed {}13{CO} and {{{C}}}18{{O}} data. Out of a total of 919 ATLASGAL clumps, 325 have data suitable to identify outflows, and 225 (69% ± 3%) show high-velocity outflows. The clumps with detected outflows show significantly higher clump masses ({M}clump}), bolometric luminosities ({L}bol}), luminosity-to-mass ratios ({L}bol}/{M}clump}), and peak H2 column densities ({N}{{{H}}2}) compared to those without outflows. Outflow activity has been detected within the youngest quiescent clump (i.e., 70 μ {{m}} weak) in this sample, and we find that the outflow detection rate increases with {M}clump}, {L}bol}, {L}bol}/{M}clump}, and {N}{{{H}}2}, approaching 90% in some cases (UC H II regions = 93% ± 3%; masers = 86% ± 4%; HC H II regions = 100%). This high detection rate suggests that outflows are ubiquitous phenomena of massive star formation (MSF). The mean outflow mass entrainment rate implies a mean accretion rate of ∼ {10}-4 {M}ȯ {yr}}-1, in full agreement with the accretion rate predicted by theoretical models of MSF. Outflow properties are tightly correlated with {M}clump}, {L}bol}, and {L}bol}/{M}clump} and show the strongest relation with the bolometric clump luminosity. This suggests that outflows might be driven by the most massive and luminous source within the clump. The correlations are similar for both low-mass and high-mass outflows over 7 orders of magnitude, indicating that they may share a similar outflow mechanism. Outflow energy is comparable to the turbulent energy within the clump; however, we find no evidence that outflows increase the level of clump turbulence as the clumps evolve. This implies that the origin of turbulence within clumps is fixed before the onset of star formation.

Development and qualification of reference calculation schemes for absorbers in pressured water reactor

International Nuclear Information System (INIS)

Blanc-Tranchant, P.

2001-01-01

The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code APOLLO2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B4C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI4. They were then checked against experimental data measured during French experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

STAR CLUSTER FORMATION WITH STELLAR FEEDBACK AND LARGE-SCALE INFLOW

International Nuclear Information System (INIS)

Matzner, Christopher D.; Jumper, Peter H.

2015-01-01

During star cluster formation, ongoing mass accretion is resisted by stellar feedback in the form of protostellar outflows from the low-mass stars and photo-ionization and radiation pressure feedback from the massive stars. We model the evolution of cluster-forming regions during a phase in which both accretion and feedback are present and use these models to investigate how star cluster formation might terminate. Protostellar outflows are the strongest form of feedback in low-mass regions, but these cannot stop cluster formation if matter continues to flow in. In more massive clusters, radiation pressure and photo-ionization rapidly clear the cluster-forming gas when its column density is too small. We assess the rates of dynamical mass ejection and of evaporation, while accounting for the important effect of dust opacity on photo-ionization. Our models are consistent with the census of protostellar outflows in NGC 1333 and Serpens South and with the dust temperatures observed in regions of massive star formation. Comparing observations of massive cluster-forming regions against our model parameter space, and against our expectations for accretion-driven evolution, we infer that massive-star feedback is a likely cause of gas disruption in regions with velocity dispersions less than a few kilometers per second, but that more massive and more turbulent regions are too strongly bound for stellar feedback to be disruptive

Development and qualification of reference calculation schemes for absorbers in pressured water reactor; Elaboration et qualification de schemas de calcul de reference pour les absorbants dans les reacteurs a eau pressurisee

Energy Technology Data Exchange (ETDEWEB)

Blanc-Tranchant, P

2001-07-01

The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code APOLLO2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B4C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI4. They were then checked against experimental data measured during French experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

Studying the outflow-core interaction with ALMA Cycle 1 observations of the HH 46/47 molecular outflow

Science.gov (United States)

Zhang, Yichen; Arce, Hector G.; Mardones, Diego; Dunham, Michael; Garay, Guido; Noriega-Crespo, Alberto; Corder, Stuartt; Offner, Stella; Cabrit, Sylvie

2016-01-01

We present ALMA Cycle 1 observations of the HH 46/47 molecular outflow which is driven by a low-mass Class 0/I protostar. Previous ALMA Cycle 0 12CO observation showed outflow cavities produced by the entrainment of ambient gas by the protostellar jet and wide-angle wind. Here we present analysis of observation of 12CO, 13CO, C18O and other species using combined 12m array and ACA observations. The improved angular resolution and sensitivity allow us to detect details of the outflow structure. Specially, we see that the outflow cavity wall is composed of two or more layers of outflowing gas, which separately connect to different shocked regions along the outflow axis inside the cavity, suggesting the outflow cavity wall is composed of multiple shells entrained by a series of jet bow-shock events. The new 13CO and C18O data also allow us to trace relatively denser and slower outflow material than that traced by the 12CO. These species are only detected within about 1 to 2 km/s from the cloud velocity, tracing the outflow to lower velocities than what is possible using only the 12CO emission. Interestingly, the cavity wall of the red lobe appears at very low outflow velocities (as low as ~0.2 km/s). In addition, 13CO and C18O allow us to correct for the CO optical depth, allowing us to obtain more accurate estimates of the outflow mass, momentum and kinetic energy. Applying the optical depth correction significantly increases the previous mass estimate by a factor of 14. The outflow kinetic energy distribution shows that even though the red lobe is mainly entrained by jet bow-shocks, most of the outflow energy is being deposited into the cloud at the base of the outflow cavity rather than around the heads of the bow shocks. The estimated total mass, momentum, and energy of the outflow indicate that the outflow has the ability to disperse the parent core. We found possible evidence for a slowly moving rotating outflow in CS. Our 13CO and C18O observations also trace a

New Insights into AGN Mass Outflows: Detailed Study of the Spectral Properties of NGC 4151

Science.gov (United States)

Denes Couto, Jullianna

2017-08-01

Active Galactic Nuclei (AGNs) exist in a few percent of all massive galaxies. It is believed that AGNs are powered by accretion of matter onto a supermassive black hole (SMBH), generating in the process huge amounts of radiation that span the entire electromagnetic spectrum. In turn, this also triggers the so-called AGN Feedback phenomenon, by inducing the formation of accretion disk winds (or outflows) that accelerate highly ionized gas outwards and affect the intergalactic medium of the host galaxy, reducing star formation rates and preventing bulge growth. It has been suggested that a dominant component of mass outflows is observable in the X-rays, and there are a limited number of detailed studies of single objects for which the relation between outflows and power of the central engine can be determined directly. The Seyfert 1.5 galaxy NGC 4151 is a great study candidate, given its proximity (14.077 Mpc, z = 0.0033), X-ray brightness and orientation. Over the past decades, it has been the target of many single and multiwavelength observations, and its heavily absorbed X-ray spectrum and complex absorption features have been extensively stud- ied and characterized. I have investigated the relationship between the long term X-ray spectral variability in and its intrinsic absorption, by comparing our 2014 simultaneous ultraviolet/X-Ray observations taken with Hubble Space Telescope Imaging Spectrometer (STIS) Echelle and Chandra High Energy Transmission Grating Spectrometer (HETGS) with archival observations from Chandra, XMM-Newton and Suzaku. The observations were divided into "high" and "low" flux states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. The X-ray model consists of a broken powerlaw, neutral reflection and two dominant absorption components, a high and a low ionization component, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes

DETECTION OF OUTFLOWING AND EXTRAPLANAR GAS IN DISKS IN AN ASSEMBLING GALAXY CLUSTER AT z = 0.37

International Nuclear Information System (INIS)

Freeland, Emily; Tran, Kim-Vy H.; Irwin, Trevor; Giordano, Lea; Saintonge, Amélie; Gonzalez, Anthony H.; Zaritsky, Dennis; Just, Dennis

2011-01-01

We detect ionized gas characteristics indicative of winds in three disk-dominated galaxies that are members of a super-group at z = 0.37 that will merge to form a Coma-mass cluster. All three galaxies are IR luminous (L IR > 4 × 10 10 L ☉ , SFR > 8 M ☉ yr –1 ) and lie outside the X-ray cores of the galaxy groups. We find that the most IR-luminous galaxy has strong blueshifted and redshifted emission lines with velocities of ∼ ± 200 km s –1 and a third, blueshifted (∼900 km s –1 ) component. This galaxy's line widths (Hβ, [O III]λ5007, [N II], Hα) correspond to velocities of 100-1000 km s –1 . We detect extraplanar gas in two of the three galaxies with SFR >8 M ☉ yr –1 whose orientations are approximately edge-on and which have integral field unit (IFU) spaxels off the stellar disk. IFU maps reveal that the extraplanar gas extends to r h ∼ 10 kpc; [N II] and Hα line widths correspond to velocities of ∼200-400 km s –1 in the disk and decrease to ∼50-150 km s –1 above the disk. Multi-wavelength observations indicate that the emission is dominated by star formation. Including the most IR-luminous galaxy we find that 18% of supergroup members with SFR >8 M ☉ yr –1 show ionized gas characteristics indicative of outflows. This is a lower limit as showing that gas is outflowing in the remaining, moderately inclined, galaxies requires a non-trivial decoupling of contributions to the emission lines from rotational and turbulent motion. Ionized gas mass loss in these winds is ∼0.1 M ☉ yr –1 for each galaxy, although the winds are likely to entrain significantly larger amounts of mass in neutral and molecular gases.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

Energy Technology Data Exchange (ETDEWEB)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei, E-mail: gbmou@ustc.edu.cn [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026 (China)

2017-07-20

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

International Nuclear Information System (INIS)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei

2017-01-01

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

Science.gov (United States)

Mou, Guobin; Wang, Tinggui; Yang, Chenwei

2017-07-01

The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

Energy Technology Data Exchange (ETDEWEB)

Nilsson, H.; Waara, M.; Arvelius, S.; Yamauchi, M.; Lundin, R. [Inst. of Space Physics, Kiruna (Sweden); Marghitu, O. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); Inst. for Space Sciences, Bucharest (Romania); Bouhram, M. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); CETP-CNRS, Saint-Maur (France); Hobara, Y. [Inst. of Space Physics, Kiruna (Sweden); Univ. of Sheffield, Sheffield (United Kingdom); Reme, H.; Sauvaud, J.A.; Dandouras, I. [Centre d' Etude Spatiale des Rayonnements, Toulouse (France); Balogh, A. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom); Kistler, L.M. [Univ. of New Hampshire, Durham (United States); Klecker, B. [Max-Planck-Inst. fuer Extraterrestriche Physik, Garching (Germany); Carlson, C.W. [Space Science Lab., Univ. of California, Berkeley (United States); Bavassano-Cattaneo, M.B. [Ist. di Fisica dello Spazio Interplanetario, Roma (Italy); Korth, A. [Max-Planck-Inst. fuer Sonnensystemforschung, Katlenburg-Lindau (Germany)

2006-07-01

The results of a statistical study of oxygen ion outflow using cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H{sup +}) and oxygen ions (O{sup +}) from 3 years (2001-2003) of spring orbits (January to May) have been used. The altitudes covered were mainly in the range 5-12 R{sub E} geocentric distance. It was found that O{sup +} is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O{sup +} parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O{sup +} parallel bulk velocities in excess of 60 km s{sup -1} were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O{sup +} the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H{sup +} and O{sup +} was found to typically be close to the same throughout the observation interval when the H{sup +} bulk velocity was calculated for all pitch-angles. When the H{sup +} bulk velocity was calculated for upward moving particles only the H{sup +} parallel bulk velocity was typically higher than that of O{sup +}. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O{sup +} ions dominates. The thermal velocity of O{sup +} was always well below that of H{sup +}. Thus perpendicular energization that is more effective for O{sup +} takes place, but this is not enough to explain the close to similar parallel velocities. Further parallel acceleration must occur. The results presented constrain the models of perpendicular heating and parallel

Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

Directory of Open Access Journals (Sweden)

H. Nilsson

2006-05-01

Full Text Available The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H+ and oxygen ions (O+ from 3 years (2001-2003 of spring orbits (January to May have been used. The altitudes covered were mainly in the range 5–12 RE geocentric distance. It was found that O+ is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O+ parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O+ parallel bulk velocities in excess of 60 km s-1 were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O+ the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H+ and O+ was found to typically be close to the same throughout the observation interval when the H+ bulk velocity was calculated for all pitch-angles. When the H+ bulk velocity was calculated for upward moving particles only the H+ parallel bulk velocity was typically higher than that of O+. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O+ ions dominates. The thermal velocity of O+ was always well below that of H+. Thus perpendicular energization that is more effective for O+ takes place, but this is not enough to explain the close to similar parallel velocities. Further parallel acceleration must occur. The results presented constrain the models of perpendicular heating and parallel acceleration. In particular centrifugal acceleration of the outflowing ions, which may

Molecular outflows in protostellar evolution

International Nuclear Information System (INIS)

Fukui, Y.; Iwata, T.; Mizuno, A.; Ogawa, H.; Kawabata, K.; Sugitani, K.

1989-01-01

Molecular outflow is an energetic mass-ejection phenomenon associated with very early stage of stellar evolution. The large kinetic energy involved in the phenomenon indicates that outflow may play an essential role in the process of star formation, particularly by extracting angular momentum. Most of the previous searches have been strongly biased toward optical or near-infrared signposts of star formation. They are not able, therefore, to provide the complete database necessary for a statistical study of the evolutionary status of molecular outflow. To overcome this difficulty, it is of vital importance to make an unbiased search of single molecular clouds for molecular outflows; here we report the final result of such a survey of the Lynds 1641 dark cloud. We show that molecular outflows are characterized by a total luminosity significantly greater than that of T Tauri stars. This indicates that molecular outflow corresponds to the main accretion phase of protostellar evolution, in which the luminosity excess is due to the gravitational energy released by dynamical mass accretion onto the protostellar core. (author)

Elaboration and qualification of a reference calculation routes for the absorbers in the PWR reactors; Elaboration et qualification des schemas de calcul de reference pour les absorbants dans les reacteurs a eau pressurisee

Energy Technology Data Exchange (ETDEWEB)

Blanc-Tranchant, P

1999-11-01

The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code Apollo 2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B{sub 4}C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI14. They were then checked against experimental data measured during french experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

Elaboration and qualification of a reference calculation routes for the absorbers in the PWR reactors

International Nuclear Information System (INIS)

Blanc-Tranchant, P.

1999-11-01

The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code Apollo 2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B 4 C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI14. They were then checked against experimental data measured during french experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

Supernova-driven outflows and chemical evolution of dwarf spheroidal galaxies.

Science.gov (United States)

Qian, Yong-Zhong; Wasserburg, G J

2012-03-27

We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized systems with their stars undergoing slow internal evolution. For a wide variety of infall histories of unprocessed baryonic matter to feed star formation, most of the observed MDs can be well described by our model. The key requirement is that the fraction of the gas mass lost by supernova-driven outflows is close to unity. This model also predicts a relationship between the total stellar mass and the mean metallicity for dSphs in accord with properties of their dark matter halos. The model further predicts as a natural consequence that the abundance ratios [E/Fe] for elements such as O, Mg, and Si decrease for stellar populations at the higher end of the [Fe/H] range in a dSph. We show that, for infall rates far below the net rate of gas loss to star formation and outflows, the MD in our model is very sharply peaked at one [Fe/H] value, similar to what is observed in most globular clusters. This result suggests that globular clusters may be end members of the same family as dSphs.

EVIDENCE FOR ULTRA-FAST OUTFLOWS IN RADIO-QUIET ACTIVE GALACTIC NUCLEI. II. DETAILED PHOTOIONIZATION MODELING OF Fe K-SHELL ABSORPTION LINES

International Nuclear Information System (INIS)

Tombesi, F.; Cappi, M.; Dadina, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.

2011-01-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s –1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ∼10,000 km s –1 (∼0.03c) up to ∼100,000 km s –1 (∼0.3c), with a peak and mean value of ∼42,000 km s –1 (∼0.14c). The ionization parameter is very high and in the range log ξ ∼ 3-6 erg s –1 cm, with a mean value of log ξ ∼ 4.2 erg s –1 cm. The associated column densities are also large, in the range N H ∼ 10 22 -10 24 cm –2 , with a mean value of N H ∼ 10 23 cm –2 . We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected

The use of staggered scheme and an absorbing buffer zone for computational aeroacoustics

Science.gov (United States)

Nark, Douglas M.

1995-01-01

Various problems from those proposed for the Computational Aeroacoustics (CAA) workshop were studied using second and fourth order staggered spatial discretizations in conjunction with fourth order Runge-Kutta time integration. In addition, an absorbing buffer zone was used at the outflow boundaries. Promising results were obtained and provide a basis for application of these techniques to a wider variety of problems.

Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study

Directory of Open Access Journals (Sweden)

H. Nilsson

2006-05-01

Full Text Available The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H⁺ and oxygen ions (O⁺ from 3 years (2001-2003 of spring orbits (January to May have been used. The altitudes covered were mainly in the range 5–12 R_E geocentric distance. It was found that O⁺ is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O⁺ parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O⁺ parallel bulk velocities in excess of 60 km s^-1 were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O⁺ the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H⁺ and O⁺ was found to typically be close to the same throughout the observation interval when the H⁺ bulk velocity was calculated for all pitch-angles. When the H⁺ bulk velocity was calculated for upward moving particles only the H⁺ parallel bulk velocity was typically higher than that of O⁺. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O⁺ ions dominates. The thermal velocity of O⁺ was always well below that of H⁺. Thus perpendicular energization that is more effective for O⁺ takes place, but this is not enough to explain the close to similar parallel velocities. Further

SPITZER OBSERVATIONS OF BOW SHOCKS AND OUTFLOWS IN RCW 38

Energy Technology Data Exchange (ETDEWEB)

Winston, E. [ESA-ESTEC (SRE-SA), Keplerlaan 1, 2201 AZ Noordwijk ZH (Netherlands); Wolk, S. J.; Bourke, T. L.; Spitzbart, B. [Harvard Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Megeath, S. T. [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Ave., Toledo, OH 43606 (United States); Gutermuth, R., E-mail: ewinston@rssd.esa.int [Five Colleges Astronomy Department, Smith College, Northampton, MA 01027 (United States)

2012-01-10

We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at Infrared Array Camera (IRAC) wavelengths, the fifth is only visible at 24 {mu}m. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS 2, have caused an outflow to the northeast and southwest of the central subcluster. The southern lobe of hot ionized gas is detected in X-rays; shocked gas and heated dust from the shock front are detected with Spitzer at 4.5 and 24 {mu}m. The northern outflow may have initiated the present generation of star formation, based on the filamentary distribution of the protostars in the central subcluster. Further, the bow-shock driving star, YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are identified within this pillar at near- to mid-IR wavelengths. We also report on IRAC 3.6 and 5.8 {mu}m observations of the cluster DBS2003-124, northeast of RCW 38, where 33 candidate young stellar objects (YSOs) are identified. One star associated with the cluster drives a parsec-scale jet. Two Herbig-Haro objects associated with the jet are visible at IRAC and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. The jet extends over a distance of {approx}3 pc. Assuming a velocity of 100 km s{sup -1} for the jet material gives an age of 3 Multiplication-Sign 10{sup 4} yr, indicating that the star (and cluster) are likely to be very young, with a similar or possibly younger age than RCW 38, and that star formation is ongoing in the extended RCW 38 region.

SPITZER OBSERVATIONS OF BOW SHOCKS AND OUTFLOWS IN RCW 38

International Nuclear Information System (INIS)

Winston, E.; Wolk, S. J.; Bourke, T. L.; Spitzbart, B.; Megeath, S. T.; Gutermuth, R.

2012-01-01

We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at Infrared Array Camera (IRAC) wavelengths, the fifth is only visible at 24 μm. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS 2, have caused an outflow to the northeast and southwest of the central subcluster. The southern lobe of hot ionized gas is detected in X-rays; shocked gas and heated dust from the shock front are detected with Spitzer at 4.5 and 24 μm. The northern outflow may have initiated the present generation of star formation, based on the filamentary distribution of the protostars in the central subcluster. Further, the bow-shock driving star, YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are identified within this pillar at near- to mid-IR wavelengths. We also report on IRAC 3.6 and 5.8 μm observations of the cluster DBS2003-124, northeast of RCW 38, where 33 candidate young stellar objects (YSOs) are identified. One star associated with the cluster drives a parsec-scale jet. Two Herbig-Haro objects associated with the jet are visible at IRAC and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. The jet extends over a distance of ∼3 pc. Assuming a velocity of 100 km s –1 for the jet material gives an age of 3 × 10 4 yr, indicating that the star (and cluster) are likely to be very young, with a similar or possibly younger age than RCW 38, and that star formation is ongoing in the extended RCW 38 region.

Large-Scale Star Formation-Driven Outflows at 13D-HST Survey

Science.gov (United States)

Lundgren, Britt; Brammer, G.; Van Dokkum, P. G.; Bezanson, R.; Franx, M.; Fumagalli, M.; Momcheva, I. G.; Nelson, E.; Skelton, R.; Wake, D.; Whitaker, K. E.; da Cunha, E.; Erb, D.; Fan, X.; Kriek, M.; Labbe, I.; Marchesini, D.; Patel, S.; Rix, H.; Schmidt, K.; van der Wel, A.

2013-01-01

We present evidence of large-scale outflows from three low-mass star-forming galaxies observed at z=1.24, z=1.35 and z=1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W>0.8A) MgII absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the H-alpha emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well-exceeds 0.1 solar mass / yr / kpc^2, the typical threshold for starburst galaxies in the local Universe. From a small but complete parallel census of the 0.650.8A MgII covering fraction of star-forming galaxies at 10.4A MgII absorbing gas around star-forming galaxies may evolve from 2 to the present, consistent with recent observations of an increasing collimation of star formation-driven outflows with time from 3.

Molecular outflows driven by low-mass protostars. I. Correcting for underestimates when measuring outflow masses and dynamical properties

Energy Technology Data Exchange (ETDEWEB)

Dunham, Michael M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States); Arce, Héctor G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Mardones, Diego [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Lee, Jeong-Eun [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of); Matthews, Brenda C. [National Research Council of Canada, Herzberg Astronomy and Astrophysics, 5071 W. Saanich Road, Victoria, BC V9E 2E7 (Canada); Stutz, Amelia M. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Williams, Jonathan P., E-mail: mdunham@cfa.harvard.edu [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

2014-03-01

We present a survey of 28 molecular outflows driven by low-mass protostars, all of which are sufficiently isolated spatially and/or kinematically to fully separate into individual outflows. Using a combination of new and archival data from several single-dish telescopes, 17 outflows are mapped in {sup 12}CO (2-1) and 17 are mapped in {sup 12}CO (3-2), with 6 mapped in both transitions. For each outflow, we calculate and tabulate the mass (M {sub flow}), momentum (P {sub flow}), kinetic energy (E {sub flow}), mechanical luminosity (L {sub flow}), and force (F {sub flow}) assuming optically thin emission in LTE at an excitation temperature, T {sub ex}, of 50 K. We show that all of the calculated properties are underestimated when calculated under these assumptions. Taken together, the effects of opacity, outflow emission at low velocities confused with ambient cloud emission, and emission below the sensitivities of the observations increase outflow masses and dynamical properties by an order of magnitude, on average, and factors of 50-90 in the most extreme cases. Different (and non-uniform) excitation temperatures, inclination effects, and dissociation of molecular gas will all work to further increase outflow properties. Molecular outflows are thus almost certainly more massive and energetic than commonly reported. Additionally, outflow properties are lower, on average, by almost an order of magnitude when calculated from the {sup 12}CO (3-2) maps compared to the {sup 12}CO (2-1) maps, even after accounting for different opacities, map sensitivities, and possible excitation temperature variations. It has recently been argued in the literature that the {sup 12}CO (3-2) line is subthermally excited in outflows, and our results support this finding.

Outflow Kinematics Manifested by the Hα Line: Gas Outflows in Type 2 AGNs. IV

Energy Technology Data Exchange (ETDEWEB)

Kang, Daeun; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

2017-08-20

Energetic ionized gas outflows driven by active galactic nuclei (AGNs) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow-line region, [O iii] λ 5007 has been utilized in a number of studies showing nonvirial kinematic properties due to AGN outflows. In this paper, we statistically investigate whether the H α emission line is influenced by AGN-driven outflows by measuring the kinematic properties based on the H α line profile and comparing them with those of [O iii]. Using the spatially integrated spectra of ∼37,000 Type 2 AGNs at z < 0.3 selected from the Sloan Digital Sky Survey DR7, we find a nonlinear correlation between H α velocity dispersion and stellar velocity dispersion that reveals the presence of the nongravitational component, especially for AGNs with a wing component in H α . The large H α velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on hydrogen gas, while relatively smaller kinematic properties compared to those of [O iii] imply that the observed outflow effect on the H α line is weaker than the case of [O iii].

Large-Scale Outflows in Seyfert Galaxies

Science.gov (United States)

Colbert, E. J. M.; Baum, S. A.

1995-12-01

\\catcode`\\@=11 \\ialign{m @th#1hfil ##hfil \\crcr#2\\crcr\\sim\\crcr}}} \\catcode`\\@=12 Highly collimated outflows extend out to Mpc scales in many radio-loud active galaxies. In Seyfert galaxies, which are radio-quiet, the outflows extend out to kpc scales and do not appear to be as highly collimated. In order to study the nature of large-scale (>~1 kpc) outflows in Seyferts, we have conducted optical, radio and X-ray surveys of a distance-limited sample of 22 edge-on Seyfert galaxies. Results of the optical emission-line imaging and spectroscopic survey imply that large-scale outflows are present in >~{{1} /{4}} of all Seyferts. The radio (VLA) and X-ray (ROSAT) surveys show that large-scale radio and X-ray emission is present at about the same frequency. Kinetic luminosities of the outflows in Seyferts are comparable to those in starburst-driven superwinds. Large-scale radio sources in Seyferts appear diffuse, but do not resemble radio halos found in some edge-on starburst galaxies (e.g. M82). We discuss the feasibility of the outflows being powered by the active nucleus (e.g. a jet) or a circumnuclear starburst.

Measurement of Outflow Facility Using iPerfusion.

Directory of Open Access Journals (Sweden)

Joseph M Sherwood

Full Text Available Elevated intraocular pressure (IOP is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied

GALAXY OUTFLOWS WITHOUT SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Sur, Sharanya [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore 560034 (India); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 876004, Tempe-85287 (United States); Ostriker, Eve C., E-mail: sharanya.sur@iiap.res.in, E-mail: sharanya.sur@asu.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2016-02-10

High surface density, rapidly star-forming galaxies are observed to have ≈50–100 km s{sup −1} line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s{sup −1}, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M{sub ⊙} yr{sup −1} kpc{sup −2}. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

Outflows, dusty cores, and a burst of star formation in the North America and Pelican nebulae

Energy Technology Data Exchange (ETDEWEB)

Bally, John [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Ginsburg, Adam [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Munchen (Germany); Probst, Ron [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Reipurth, Bo [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii at Manoa, 640 North A' ohoku Place, Hilo, HI 96720 (United States); Shirley, Yancy L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Stringfellow, Guy S., E-mail: John.Bally@colorado.edu, E-mail: aginsburg@eso.org, E-mail: probst@noao.edu, E-mail: reipurth@ifa.hawaii.edu, E-mail: yshirley@as.arizona.edu, E-mail: Guy.Stringfellow@colorado.edu [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309 (United States)

2014-12-01

We present observations of near-infrared 2.12 μm molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000/IC 5070/W80 H II region are among the most active sites of ongoing star formation in the solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionization front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80°. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The 'Gulf of Mexico', located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen objects (MHOs), Herbig-Haro (HH) objects, and over 300 young stellar objects (YSOs), indicating a recent burst of star formation. The largest outflow detected thus far in the North America and Pelican Nebula complex, the 1.6 parsec long MHO 3417 flow, emerges from a 500 M {sub ☉} BGPS clump and may be powered by a forming massive star. Several prominent outflows such as MHO 3427 appear to be powered by highly embedded YSOs only visible at λ > 70 μm. An 'activity index' formed by dividing the number of shocks by the mass of the cloud containing their source stars is used to estimate the relative evolutionary states of Bolocam clumps. Outflows can be used as indicators of the evolutionary state of clumps detected in millimeter and submillimeter dust continuum surveys.

Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy.

Science.gov (United States)

Geach, J E; Hickox, R C; Diamond-Stanic, A M; Krips, M; Rudnick, G H; Tremonti, C A; Sell, P H; Coil, A L; Moustakas, J

2014-12-04

Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and have typical scales of less than a kiloparsec. In at least some cases, input from active galactic nuclei is dynamically important, so pure stellar feedback (the momentum return into the interstellar medium) has been considered incapable of rapidly terminating star formation on galactic scales. Molecular gas has been detected outside the galactic plane of the archetypal starburst galaxy M82 (refs 4 and 5), but so far there has been no evidence that starbursts can propel substantial quantities of cold molecular gas to the same galactocentric radius (about 10 kiloparsecs) as the warmer gas that has been traced by metal ion absorbers in the circumgalactic medium. Here we report observations of molecular gas in a compact (effective radius 100 parsecs) massive starburst galaxy at redshift 0.7, which is known to drive a fast outflow of ionized gas. We find that 35 per cent of the total molecular gas extends approximately 10 kiloparsecs, and one-third of this extended gas has a velocity of up to 1,000 kilometres per second. The kinetic energy associated with this high-velocity component is consistent with the momentum flux available from stellar radiation pressure. This demonstrates that nuclear bursts of star formation are capable of ejecting large amounts of cold gas from the central regions of galaxies, thereby strongly affecting their evolution by truncating star formation and redistributing matter.

Molecular Outflows: Explosive versus Protostellar

Energy Technology Data Exchange (ETDEWEB)

Zapata, Luis A.; Rodríguez, Luis F.; Palau, Aina; Loinard, Laurent [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Schmid-Burgk, Johannes [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany)

2017-02-10

With the recent recognition of a second, distinctive class of molecular outflows, namely the explosive ones not directly connected to the accretion–ejection process in star formation, a juxtaposition of the morphological and kinematic properties of both classes is warranted. By applying the same method used in Zapata et al., and using {sup 12}CO( J = 2-1) archival data from the Submillimeter Array, we contrast two well-known explosive objects, Orion KL and DR21, to HH 211 and DG Tau B, two flows representative of classical low-mass protostellar outflows. At the moment, there are only two well-established cases of explosive outflows, but with the full availability of ALMA we expect that more examples will be found in the near future. The main results are the largely different spatial distributions of the explosive flows, consisting of numerous narrow straight filament-like ejections with different orientations and in almost an isotropic configuration, the redshifted with respect to the blueshifted components of the flows (maximally separated in protostellar, largely overlapping in explosive outflows), the very-well-defined Hubble flow-like increase of velocity with distance from the origin in the explosive filaments versus the mostly non-organized CO velocity field in protostellar objects, and huge inequalities in mass, momentum, and energy of the two classes, at least for the case of low-mass flows. Finally, all the molecular filaments in the explosive outflows point back to approximately a central position (i.e., the place where its “exciting source” was located), contrary to the bulk of the molecular material within the protostellar outflows.

The energetics of AGN radiation pressure-driven outflows

Science.gov (United States)

Ishibashi, W.; Fabian, A. C.; Maiolino, R.

2018-05-01

The increasing observational evidence of galactic outflows is considered as a sign of active galactic nucleus (AGN) feedback in action. However, the physical mechanism responsible for driving the observed outflows remains unclear, and whether it is due to momentum, energy, or radiation is still a matter of debate. The observed outflow energetics, in particular the large measured values of the momentum ratio (\\dot{p}/(L/c) ˜ 10) and energy ratio (\\dot{E}_k/L ˜ 0.05), seems to favour the energy-driving mechanism; and most observational works have focused their comparison with wind energy-driven models. Here, we show that AGN radiation pressure on dust can adequately reproduce the observed outflow energetics (mass outflow rate, momentum flux, and kinetic power), as well as the scalings with luminosity, provided that the effects of radiation trapping are properly taken into account. In particular, we predict a sublinear scaling for the mass outflow rate (\\dot{M} ∝ L^{1/2}) and a superlinear scaling for the kinetic power (\\dot{E}_k ∝ L^{3/2}), in agreement with the observational scaling relations reported in the most recent compilation of AGN outflow data. We conclude that AGN radiative feedback can account for the global outflow energetics, at least equally well as the wind energy-driving mechanism, and therefore both physical models should be considered in the interpretation of future AGN outflow observations.

Physical Conditions in Ultra-fast Outflows in AGN

Science.gov (United States)

Kraemer, S. B.; Tombesi, F.; Bottorff, M. C.

2018-01-01

XMM-Newton and Suzaku spectra of Active Galactic Nuclei (AGN) have revealed highly ionized gas, in the form of absorption lines from H-like and He-like Fe. Some of these absorbers, ultra-fast outflows (UFOs), have radial velocities of up to 0.25c. We have undertaken a detailed photoionization study of high-ionization Fe absorbers, both UFOs and non-UFOs, in a sample of AGN observed by XMM-Newton. We find that the heating and cooling processes in UFOs are Compton-dominated, unlike the non-UFOs. Both types are characterized by force multipliers on the order of unity, which suggest that they cannot be radiatively accelerated in sub-Eddington AGN, unless they were much less ionized at their point of origin. However, such highly ionized gas can be accelerated via a magneto-hydrodynamic (MHD) wind. We explore this possibility by applying a cold MHD flow model to the UFO in the well-studied Seyfert galaxy, NGC 4151. We find that the UFO can be accelerated along magnetic streamlines anchored in the accretion disk. In the process, we have been able to constrain the magnetic field strength and the magnetic pressure in the UFO and have determined that the system is not in magnetic/gravitational equipartition. Open questions include the variability of the UFOs and the apparent lack of non-UFOs in UFO sources.

Clustering at high redshifts

International Nuclear Information System (INIS)

Shaver, P.A.

1986-01-01

Evidence for clustering of and with high-redshift QSOs is discussed. QSOs of different redshifts show no clustering, but QSOs of similar redshifts appear to be clustered on a scale comparable to that of galaxies at the present epoch. In addition, spectroscopic studies of close pairs of QSOs indicate that QSOs are surrounded by a relatively high density of absorbing matter, possibly clusters of galaxies

PROTOSTELLAR OUTFLOWS IN L1340

Energy Technology Data Exchange (ETDEWEB)

Walawender, Josh [W. M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Wolf-Chase, Grace [Astronomy Department, Adler Planetarium, 1300 South Lake Shore Drive, Chicago, IL 60605 (United States); Smutko, Michael [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); OLinger-Luscusk, JoAnn [California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Moriarty-Schieven, Gerald, E-mail: jmwalawender@keck.hawaii.edu [National Research Council—Herzberg Astronomy and Astrophysics, 5017 West Saanich Road, Victoria, BC, V9E 2E7 (Canada)

2016-12-01

We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H{sub 2} 2.122 μ m near-infrared line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, and L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes into 12 distinct outflows and identify candidate source stars for each. We examine the properties ( A {sub V}, T {sub bol}, and L {sub bol}) of the source protostars and compare them to the properties of the general population of Class 0/I and flat spectral energy distribution protostars and find that there is an indication, albeit at low statistical significance, that the outflow-driving protostars are drawn from a population with lower A {sub V}, higher L {sub bol}, and lower T {sub bol} than the general population of protostars.

AGN outflows as neutrino sources: an observational test

Science.gov (United States)

Padovani, P.; Turcati, A.; Resconi, E.

2018-04-01

We test the recently proposed idea that outflows associated with Active Galactic Nuclei (AGN) could be neutrino emitters in two complementary ways. First, we cross-correlate a list of 94 "bona fide" AGN outflows with the most complete and updated repository of IceCube neutrinos currently publicly available, assembled by us for this purpose. It turns out that AGN with outflows matched to an IceCube neutrino have outflow and kinetic energy rates, and bolometric powers larger than those of AGN with outflows not matched to neutrinos. Second, we carry out a statistical analysis on a catalogue of [O III] λ5007 line profiles using a sample of 23,264 AGN at z values (˜6 and 18 per cent respectively, pre-trial) for relatively high velocities and luminosities. Our results are consistent with a scenario where AGN outflows are neutrino emitters but at present do not provide a significant signal. This can be tested with better statistics and source stacking. A predominant role of AGN outflows in explaining the IceCube data appears in any case to be ruled out.

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2006-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2008-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Molecular outflows in the L1641 region of Orion

International Nuclear Information System (INIS)

Morgan, J.A.

1990-01-01

Little is known about the interaction between molecular outflows associated with young stellar objects and the parent molecular cloud that produced them. This is because molecular outflows are a recently discovered phenomenon and, so, have not had their global properties studied in great detail and molecular clouds were not mapped to sufficiently high spatial resolution to resolve the interaction. The interaction between molecular outflows and the L1641 molecular cloud is addressed by both identifying and mapping all the molecular outflows as well as the detailed structure of the cloud. Candidate molecular outflows were found from single point 12-CO observations of young stellar objects identified from the IRAS survey data. The candidate sources were then mapped to confirm their molecular outflow nature. From these maps, molecular outflow characteristics such as their morphology, orientation, and energetics were determined. In addition, the Orion molecular cloud was mapped to compare directly with the molecular outflows. The molecular outflows identified were found to have rising infrared spectra, radio continuum emission that suggests a stellar wind or optically thick H II region, and molecular line strengths that indicate that they are embedded within a very dense environment. The lack of an optical counterpart for many molecular outflows suggests that they occur at the earliest stages of stellar evolution. The lack of an optical counterpart for many molecular outflows suggest that they occur at the earliest stages of stellar evolution. The orientations of the molecular outflows appear to lie in no preferred direction and they have shapes that indicate that the molecular cloud is responsible for determining their direction and collimation

Studies of Quasar Outflows

Science.gov (United States)

Arav, Nahum

2002-01-01

The main aim of this research program is to determine the ionization equilibrium and abundances in quasar outflows. Especially in the broad absorption line QSO PG 0946+301. We find that the outflow's metalicity is consistent with being solar, while the abundance ratio of phosphorus to other metals is at least ten times solar. These findings are based on diagnostics that are not sensitive to saturation and partial covering effects in the BALs (Broad Adsorption Lines), which considerably weakened previous claims for enhanced metalicity. Ample evidence for these effects is seen in the spectrum.

Knowledge Outflows from Foreign Subsidiaries

DEFF Research Database (Denmark)

Perri, Alessandra; Andersson, Ulf

This paper analyzes the MNC subsidiaries’ trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we find...... the value of the subsidiary’s knowledge stock is very high, the need for knowledge protection restrains reciprocity mechanisms in knowledge exchanges, thus reducing the extent of knowledge outflows to the host location. This study contributes to the literature on the firm-level antecedents of FDI...... that subsidiaries that extensively draw on external knowledge sources are also more likely to generate knowledge outflows to local firms. We argue that this may be explained by the subsidiaries’ willingness to build the trust that facilitates the establishment of reciprocal knowledge linkages. However, when...

Large-scale Star-formation-driven Outflows at 1 3D-HST Survey

Science.gov (United States)

Lundgren, Britt F.; Brammer, Gabriel; van Dokkum, Pieter; Bezanson, Rachel; Franx, Marijn; Fumagalli, Mattia; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Wake, David; Whitaker, Katherine; da Cunha, Elizabete; Erb, Dawn K.; Fan, Xiaohui; Kriek, Mariska; Labbé, Ivo; Marchesini, Danilo; Patel, Shannon; Rix, Hans Walter; Schmidt, Kasper; van der Wel, Arjen

2012-11-01

We present evidence of large-scale outflows from three low-mass (log(M */M ⊙) ~ 9.75) star-forming (SFR > 4 M ⊙ yr-1) galaxies observed at z = 1.24, z = 1.35, and z = 1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W λ2796 r >~ 0.8 Å) Mg II absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the Hα emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well exceeds 0.1 M ⊙ yr-1 kpc-2, the typical threshold for starburst galaxies in the local universe. From a small but complete parallel census of the 0.65 0.8 Å Mg II covering fraction of star-forming galaxies at 1 0.4 Å Mg II absorbing gas around star-forming galaxies may evolve from z ~ 2 to the present, consistent with recent observations of an increasing collimation of star-formation-driven outflows with time from z ~ 3.

Cumulative neutrino background from quasar-driven outflows

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiawei; Loeb, Abraham, E-mail: xiawei.wang@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-12-01

Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic γ-ray background data and derive a cumulative neutrino background of ∼ 10{sup −7} GeV cm{sup −2} s{sup −1} sr{sup −1} at neutrino energies E {sub ν} ∼> 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters. The link between the γ-ray and neutrino emission from quasar outflows can be used to constrain the high-energy physics of strong shocks at cosmological distances.

Negative and Positive Outflow-Feedback in Nearby (U)LIRGs

Energy Technology Data Exchange (ETDEWEB)

Cazzoli, Sara, E-mail: sara@iaa.es [Instituto de Astrofisica de Andalucia (CSIC), Granada (Spain)

2017-12-15

The starburst-AGN coexistence in local (U)LIRGs makes these galaxies excellent laboratories for the study of stellar and AGN outflows and feedback. Outflows regulate star formation and AGN activity, redistributing gas, dust and metals over large scales in the interstellar and intergalactic media (negative feedback) being also considered to be able to undergo vigorous star formation (positive feedback). In this contribution, I will summarize the results from a search for outflows in a sample of nearby 38 local (U)LIRG systems observed with VIMOS/VLT integral field unit. For two galaxies of the sample I will detail the outflow properties and discuss the observational evidence for negative and positive outflow-feedback. The assessment of both negative and positive feedback effects represent a novel approach toward a comprehensive understanding of the impact of outflow feedback in the galaxy evolution.

Compact binary merger and kilonova: outflows from remnant disc

Science.gov (United States)

Yi, Tuan; Gu, Wei-Min; Liu, Tong; Kumar, Rajiv; Mu, Hui-Jun; Song, Cui-Ying

2018-05-01

Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around 10-3 ˜ 10-1 M⊙ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around 1040 ˜ 1041 erg s-1. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).

Character and dynamics of the Red Sea and Persian Gulf outflows

Science.gov (United States)

Bower, Amy S.; Hunt, Heather D.; Price, James F.

2000-03-01

Historical hydrographic data and a numerical plume model are used to investigate the initial transformation, dynamics, and spreading pathways of Red Sea and Persian Gulf outflow waters where they enter the Indian Ocean. The annual mean transport of these outflows is relatively small (outflows in that they flow over very shallow sills (depth Red Sea outflow exhibits strong seasonal variability in transport. The four main results of this study are as follows. First, on the basis of observed temperature-salinity (T-S) characteristics of the outflow source and product waters we estimate that the Red Sea and Persian Gulf outflows are diluted by factors of ˜2.5 and 4, respectively, as they descend from sill depth to their depth of neutral buoyancy. The high-dilution factor for the Persian Gulf outflow results from the combined effects of large initial density difference between the outflow source water and oceanic water and low outflow transport. Second, the combination of low latitude and low outflow transport (and associated low outflow thickness) results in Ekman numbers for both outflows that are O(1). This indicates that they should be thought of as frictional density currents modified by rotation rather than geostrophic density currents modified by friction. Third, different mixing histories along the two channels that direct Red Sea outflow water into the open ocean result in product waters with significantly different densities, which probably contributes to the multilayered structure of the Red Sea product waters. In both outflows, seasonal variations in source water and oceanic properties have some effect on the T-S of the product waters, but they have only a minor impact on equilibrium depth. Fourth, product waters from both outflows are advected away from the sill region in narrow boundary currents, at least during part of the year. At other times, the product water appears more in isolated patches.

Cerebral venous outflow and cerebrospinal fluid dynamics

Directory of Open Access Journals (Sweden)

Clive B. Beggs

2014-12-01

Full Text Available In this review, the impact of restricted cerebral venous outflow on the biomechanics of the intracranial fluid system is investigated. The cerebral venous drainage system is often viewed simply as a series of collecting vessels channeling blood back to the heart. However there is growing evidence that it plays an important role in regulating the intracranial fluid system. In particular, there appears to be a link between increased cerebrospinal fluid (CSF pulsatility in the Aqueduct of Sylvius and constricted venous outflow. Constricted venous outflow also appears to inhibit absorption of CSF into the superior sagittal sinus. The compliance of the cortical bridging veins appears to be critical to the behaviour of the intracranial fluid system, with abnormalities at this location implicated in normal pressure hydrocephalus. The compliance associated with these vessels appears to be functional in nature and dependent on the free egress of blood out of the cranium via the extracranial venous drainage pathways. Because constricted venous outflow appears to be linked with increased aqueductal CSF pulsatility, it suggests that inhibited venous blood outflow may be altering the compliance of the cortical bridging veins.

ALMA OBSERVATIONS OF THE HH 46/47 MOLECULAR OUTFLOW

International Nuclear Information System (INIS)

Arce, Héctor G.; Mardones, Diego; Garay, Guido; Corder, Stuartt A.; Noriega-Crespo, Alberto; Raga, Alejandro C.

2013-01-01

The morphology, kinematics, and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29 point mosaic, covering the two lobes at an angular resolution of about 3'', detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model describes the observed structures in the position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a collimated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show gradients where the velocity increases toward the outflow axis, inconsistent with outflow rotation. Additionally, we find evidence for the existence of a small outflow driven by a binary companion

Relativistic Outflows from ADAFs

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Becker, Peter; Subramanian, Prasad; Kazanas, Demosthenes

2001-04-01

Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter, and are therefore gravitationally bound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a seudo - Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self - similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Our self - similar model may therefore help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approachs the unique form dot M ∝ r^1/2, with an associated density variation given by ρ ∝ r-1. This density variation agrees with that implied by the dependence of the X-ray hard time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the results of our self-similar model need to be confirmed in the future by incorporating a detailed physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk.

Density diagnostics of ionized outflows in active galacitc nuclei

Science.gov (United States)

Mao, J.; Kaastra, J.; Mehdipour, M.; Raassen, T.; Gu, L.

2017-10-01

Ionized outflows in Active Galactic Nuclei are thought to influence their nuclear and local galactic environment. However, the distance of outflows with respect to the central engine is poorly constrained, which limits our understanding of the kinetic power by the outflows. Therefore, the impact of AGN outflows on their host galaxies is uncertain. Given the density of the outflows, their distance can be immediately obtained by the definition of the ionization parameter. Here we carry out a theoretical study of density diagnostics of AGN outflows using absorption lines from metastable levels in Be-like to F-like ions. With the new self-consistent photoionization model (PION) in the SPEX code, we are able to calculate ground and metastable level populations. This enable us to determine under what physical conditions these levels are significantly populated. We then identify characteristic transitions from these metastable levels in the X-ray band. Firm detections of absorption lines from such metastable levels are challenging for current grating instruments. The next generation of spectrometers like X-IFU onboard Athena will certainly identify the presence/absence of these density- sensitive absorption lines, thus tightly constraining the location and the kinetic power of AGN outflows.

Characterization of molecular outflows in the substellar domain

International Nuclear Information System (INIS)

Phan-Bao, Ngoc; Dang-Duc, Cuong; Lee, Chin-Fei; Ho, Paul T. P.; Li, Di

2014-01-01

We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J = 2 → 1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M J , which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36°. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9 × 10 –6 M ☉ to 2.9 × 10 –5 M ☉ and an outflow mass-loss rate from 2.7 × 10 –9 M ☉ yr –1 to 4.1 × 10 –8 M ☉ yr –1 . These values are comparable to those we have observed in the young brown dwarf ISO-Oph 102 of 60 M J in ρ Ophiuchi and the very low-mass star MHO 5 of 90 M J in Taurus. Our results suggest that the outflow process in very low-mass objects is episodic with a duration of a few thousand years and the outflow rate of active episodes does not significantly change for different stages of the formation process of very low-mass objects. This may provide us with important implications that clarify the formation process of brown dwarfs.

DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU

International Nuclear Information System (INIS)

Tombesi, F.; Sambruna, R. M.; Mushotzky, R. F.; Reeves, J. N.; Gofford, J.; Braito, V.; Ballo, L.; Cappi, M.

2010-01-01

We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v ≅ 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ ≅ 4-5.6 erg s -1 cm and column densities of N H ≅ 10 22 -10 23 cm -2 . These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ∼0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

The Mass Outflow Rate of the Milky Way

Science.gov (United States)

Fox, Andrew

2017-08-01

The balance between gaseous inflow and outflow regulates star formation in spiral galaxies. This paradigm can be tested in the Milky Way, but whereas the star formation rate and inflow rate have both been measured, the outflow rate has not. We propose an archival COS program to determine the Galactic outflow rate in cool gas ( 10^4 K) by surveying UV absorption line high-velocity clouds (HVCs). This project will make use of the newly updated Hubble Spectroscopic Legacy Archive, which contains a uniformly reduced sample of 233 COS G130M spectra of background AGN. The outflow rate will be determined by (1) searching for redshifted HVCs; (2) modeling the clouds with photoionization simulations to determine their masses and physical properties; (3) combining the cloud masses with their velocities and distances. We will measure how the outflow is distributed spatially across the sky, calculate its mass loading factor, and compare the line profiles to synthetic spectra extracted from new hydrodynamic simulations. The distribution of HVC velocities will inform us what fraction of the outflowing clouds will escape the halo and what fraction will circulate back to the disk, to better understand how and where gas enters and exits the Milky Way.

GALAXY CLUSTERS IN THE LINE OF SIGHT TO BACKGROUND QUASARS. III. MULTI-OBJECT SPECTROSCOPY

International Nuclear Information System (INIS)

Andrews, H.; Barrientos, L. F.; Padilla, N.; Lacerna, I.; López, S.; Lira, P.; Maureira, M. J.; Gilbank, D. G.; Ellingson, E.; Gladders, M. D.; Yee, H. K. C.

2013-01-01

We present Gemini/GMOS-S multi-object spectroscopy of 31 galaxy cluster candidates at redshifts between 0.2 and 1.0 and centered on QSO sight lines taken from López et al. The targets were selected based on the presence of an intervening Mg II absorption system at a similar redshift to that of a galaxy cluster candidate lying at a projected distance 71 -1 Mpc from the QSO sight line (a p hotometric hit ) . The absorption systems span rest-frame equivalent widths between 0.015 and 2.028 Å. Our aim was three-fold: (1) to identify the absorbing galaxies and determine their impact parameters, (2) to confirm the galaxy cluster candidates in the vicinity of each quasar sightline, and (3) to determine whether the absorbing galaxies reside in galaxy clusters. In this way, we are able to characterize the absorption systems associated with cluster members. Our main findings are as follows. (1) We identified 10 out of 24 absorbing galaxies with redshifts between 0.2509 ≤ z gal ≤ 1.0955, up to an impact parameter of 142 h 71 -1 kpc and a maximum velocity difference of 280 km s –1 . (2) We spectroscopically confirmed 20 out of 31 cluster/group candidates, with most of the confirmed clusters/groups at z –1 from galaxy clusters/groups, in addition to two new ones related to galaxy group environments. These numbers imply efficiencies of 71% in finding such systems with MOS spectroscopy. This is a remarkable result since we defined a photometric hit as those cluster-absorber pairs having a redshift difference Δz = 0.1. The general population of our confirmed absorbing galaxies have luminosities L B ∼L B * and mean rest-frame colors (R c – z') typical of S cd galaxies. From this sample, absorbing cluster galaxies hosting weak absorbers are consistent with lower star formation activity than the rest, which produce strong absorption and agree with typical Mg II absorbing galaxies found in the literature. Our spectroscopic confirmations lend support to the selection of

THE ROLE OF COSMIC-RAY PRESSURE IN ACCELERATING GALACTIC OUTFLOWS

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Simpson, Christine M.; Pakmor, Rüdiger; Pfrommer, Christoph; Springel, Volker [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Marinacci, Federico [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Glover, Simon C. O. [Zentrum für Astronomie der Universität Heidelberg, ITA, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Clark, Paul C. [School of Physics and Astronomy, Queen’s Buildings, The Parade, Cardiff University, Cardiff CF24 3AA (United Kingdom); Smith, Rowan J., E-mail: Christine.Simpson@h-its.org [Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

2016-08-20

We study the formation of galactic outflows from supernova (SN) explosions with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.

Formation and spatial distribution of hypervelocity stars in AGN outflows

Science.gov (United States)

Wang, Xiawei; Loeb, Abraham

2018-05-01

We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy

Science.gov (United States)

Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Kriss, Gerard A.; Young, Andrew J.; Hardcastle, Martin J.; Chakravorty, Susmita; Fang, Taotao; Neilsen, Joseph; Rahoui, Farid; Smith, Randall K.

2018-02-01

We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately ‑17,300 km s‑1 (outflow redshift z out ∼ ‑0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ ∼ 2.9 {erg} {{{s}}}-1 {cm} and column density {log}{N}{{H}}∼ 21.5 {{cm}}-2. This corresponds to a stable region of the absorber’s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately ‑16,980 km s‑1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.

Characterization of molecular outflows in the substellar domain

Energy Technology Data Exchange (ETDEWEB)

Phan-Bao, Ngoc; Dang-Duc, Cuong [Department of Physics, International University-Vietnam National University HCM, Block 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City (Viet Nam); Lee, Chin-Fei; Ho, Paul T. P. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Di, E-mail: pbngoc@hcmiu.edu.vn, E-mail: pbngoc@asiaa.sinica.edu.tw [National Astronomical Observatories, Chinese Academy of Science, Chaoyang District Datun Rd A20, Beijing (China)

2014-11-01

We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J = 2 → 1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M {sub J}, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36°. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9 × 10{sup –6} M {sub ☉} to 2.9 × 10{sup –5} M {sub ☉} and an outflow mass-loss rate from 2.7 × 10{sup –9} M {sub ☉} yr{sup –1} to 4.1 × 10{sup –8} M {sub ☉} yr{sup –1}. These values are comparable to those we have observed in the young brown dwarf ISO-Oph 102 of 60 M {sub J} in ρ Ophiuchi and the very low-mass star MHO 5 of 90 M {sub J} in Taurus. Our results suggest that the outflow process in very low-mass objects is episodic with a duration of a few thousand years and the outflow rate of active episodes does not significantly change for different stages of the formation process of very low-mass objects. This may provide us with important implications that clarify the formation process of brown dwarfs.

PROTOSTELLAR OUTFLOW EVOLUTION IN TURBULENT ENVIRONMENTS

International Nuclear Information System (INIS)

Cunningham, Andrew J.; Frank, Adam; Carroll, Jonathan; Blackman, Eric G.; Quillen, Alice C.

2009-01-01

The link between turbulence in star-forming environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows, we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers'-type turbulence and produces a driving scale length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star-forming environments. In the last section, we contrast our work and its conclusions with previous studies which claim that jets cannot be the source of turbulence.

Wind influence on a coastal buoyant outflow

Science.gov (United States)

Whitney, Michael M.; Garvine, Richard W.

2005-03-01

This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ Wind events, however, overwhelm the buoyancy-driven flow (∣Ws∣ > 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

Diffusion escape through a cluster of small absorbing windows

Energy Technology Data Exchange (ETDEWEB)

Holcman, D [Department of Mathematics, Weizmann Institute of Science, Rehovot 76100 (Israel); Schuss, Z [Department of Mathematics, Tel-Aviv University, Tel-Aviv 69978 (Israel)

2008-04-18

We study the first eigenvalue of the Laplace equation in a bounded domain in R{sup d} (d=2,3) with mixed Neumann-Dirichlet (Zaremba) boundary conditions. The Neumann condition is imposed on most of the boundary and the Dirichlet boundary consists of a cluster of small windows. When the windows are well separated the first eigenvalue is asymptotically the sum of eigenvalues of mixed problems with a single Dirichlet window. However, when two or more Dirichlet windows cluster tightly together they interact nonlinearly. We compare our asymptotic approximation of the eigenvalue to the escape rate of simulated Brownian particles through the small windows.

Outflow and hot dust emission in broad absorption line quasars

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shaohua; Zhou, Hongyan [Polar Research Institute of China, 451 Jinqiao Road, Shanghai 200136 (China); Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng [Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhang, Kai, E-mail: zhangshaohua@pric.gov.cn, E-mail: whywang@mail.ustc.edu.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

2014-05-01

We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

Active galactic nucleus outflows in galaxy discs

Science.gov (United States)

Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

2018-05-01

Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

The combined effect of AGN and supernovae feedback in launching massive molecular outflows in high-redshift galaxies

Science.gov (United States)

Biernacki, Pawel; Teyssier, Romain

2018-04-01

We have recently improved our model of active galactic nucleus (AGN) by attaching the supermassive black hole (SMBH) to a massive nuclear star cluster (NSC). Here, we study the effects of this new model in massive, gas-rich galaxies with several simulations of different feedback recipes with the hydrodynamics code RAMSES. These simulations are compared to a reference simulation without any feedback, in which the cooling halo gas is quickly consumed in a burst of star formation. In the presence of strong supernovae (SN) feedback, we observe the formation of a galactic fountain that regulates star formation over a longer period, but without halting it. If only AGN feedback is considered, as soon as the SMBH reaches a critical mass, strong outflows of hot gas are launched and prevent the cooling halo gas from reaching the disc, thus efficiently halting star formation, leading to the so-called `quenching'. If both feedback mechanisms act in tandem, we observe a non-linear coupling, in the sense that the dense gas in the supernovae-powered galactic fountain is propelled by the hot outflow powered by the AGN at much larger radii than without AGN. We argue that these particular outflows are able to unbind dense gas from the galactic halo, thanks to the combined effect of SN and AGN feedback. We speculate that this mechanism occurs at the end of the fast growing phase of SMBH, and is at the origin of the dense molecular outflows observed in many massive high-redshift galaxies.

OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

International Nuclear Information System (INIS)

Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan; Zhang, Kai; Zhang, Shaohua

2013-01-01

Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus

The Simbol-X Perspective on the Physics of Quasar Outflows

Science.gov (United States)

Giustini, M.; Cappi, M.; Vignali, C.; Palumbo, G. G. C.; Fiore, F.; Malaguti, G.

2009-05-01

There is increasing evidence that quasar outflows may play a key role in providing the feedback between AGN/QSOs and their surrounding (and feeding) media, in regulating the central supermassive black hole growth and the galaxy formation and, on larger scales, in shaping the growth of cosmic structures (see e.g. [1]). X-ray observations of quasar outflows are crucial to probe their innermost parts and assess the global energetics entrained in the outflow by studying its most extreme (in terms of velocity, ionization state, mass outflow rate) phases. Simbol-X-with its high effective area in the Fe K energy band and above-will allow the detection and the characterization of powerful outflows in bright, nearby AGN and notably also in moderately faint AGN, thus shedding light on feedback processes in these objects.

ALMA Studies of the Disk-Jet-Outflow Connection

Science.gov (United States)

Dougados, Catherine; Louvet, F.; Mardones, D.; Cabrit, S.

2017-06-01

I will describe in this contribution recent results obtained with ALMA on the origin of the disk/jet/outflow connexion in T Tauri stars. I will first present ALMA observations of the disk associated with the jet source Th 28, which question previous jet rotation measurements in this source and the implications drawn from them. I will then discuss Cycle 2 ALMA observations of the disk and small scale CO outflow associated with the prototypical edge-on HH 30 source. The unprecedented angular resolution of this dataset brings new constraints on the origin of the CO outflows in young stars.

Alignment between Protostellar Outflows and Filamentary Structure

Energy Technology Data Exchange (ETDEWEB)

Stephens, Ian W.; Dunham, Michael M.; Myers, Philip C.; Pokhrel, Riwaj; Sadavoy, Sarah I.; Lee, Katherine I.; Goodman, Alyssa A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States); Vorobyov, Eduard I. [Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vienna, A-1060 (Austria); Tobin, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Pineda, Jaime E. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Offner, Stella S. R. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Kristensen, Lars E. [Centre for Star and Planet Formation, Niels Bohr Institute and Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K (Denmark); Jørgensen, Jes K. [Niels Bohr Institute and Center for Star and Planet Formation, Copenhagen University, DK-1350 Copenhagen K. (Denmark); Bourke, Tyler L. [SKA Organization, Jodrell Bank Observatory, Lower Withington, Macclesfield, Cheshire SK11 9DL (United Kingdom); Arce, Héctor G. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Plunkett, Adele L., E-mail: ian.stephens@cfa.harvard.edu [European Southern Observatory, Av. Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile)

2017-09-01

We present new Submillimeter Array (SMA) observations of CO(2–1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orientation of the local filaments as derived from Herschel observations. We find that the relative angles between outflows and filaments are inconsistent with purely parallel or purely perpendicular distributions. Instead, the observed distribution of outflow-filament angles are more consistent with either randomly aligned angles or a mix of projected parallel and perpendicular angles. A mix of parallel and perpendicular angles requires perpendicular alignment to be more common by a factor of ∼3. Our results show that the observed distributions probably hold regardless of the protostar’s multiplicity, age, or the host core’s opacity. These observations indicate that the angular momentum axis of a protostar may be independent of the large-scale structure. We discuss the significance of independent protostellar rotation axes in the general picture of filament-based star formation.

Misalignment of Magnetic Fields and Outflows in Protostellar Cores

OpenAIRE

Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erika; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.

2013-01-01

We present results of λ1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with ~2."5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotati...

Explosive Outflows from Forming Massive Stars

OpenAIRE

Bally, J.; Ginsburg, A.; Kasliwal, M. M.

2016-01-01

AO imaging of the near IR [Fe ii] and H_2 lines and ALMA CO J = 2 − 1 data confirms the explosive nature of the BN/KL outflow in Orion. N-body interactions in compact groups may be responsible for the production of powerful, explosive protostellar outflows and luminous infrared flares. The Orion event may have been triggered by a protostellar merger. First results of a search for Orion-like events in 200 nearby galaxies with the SPitzer InfraRed Intensive Transients Survey (SPIRITS) are brief...

Simulation of California's Major Reservoirs Outflow Using Data Mining Technique

Science.gov (United States)

Yang, T.; Gao, X.; Sorooshian, S.

2014-12-01

The reservoir's outflow is controlled by reservoir operators, which is different from the upstream inflow. The outflow is more important than the reservoir's inflow for the downstream water users. In order to simulate the complicated reservoir operation and extract the outflow decision making patterns for California's 12 major reservoirs, we build a data-driven, computer-based ("artificial intelligent") reservoir decision making tool, using decision regression and classification tree approach. This is a well-developed statistical and graphical modeling methodology in the field of data mining. A shuffled cross validation approach is also employed to extract the outflow decision making patterns and rules based on the selected decision variables (inflow amount, precipitation, timing, water type year etc.). To show the accuracy of the model, a verification study is carried out comparing the model-generated outflow decisions ("artificial intelligent" decisions) with that made by reservoir operators (human decisions). The simulation results show that the machine-generated outflow decisions are very similar to the real reservoir operators' decisions. This conclusion is based on statistical evaluations using the Nash-Sutcliffe test. The proposed model is able to detect the most influential variables and their weights when the reservoir operators make an outflow decision. While the proposed approach was firstly applied and tested on California's 12 major reservoirs, the method is universally adaptable to other reservoir systems.

TESTING THE POSSIBLE INTRINSIC ORIGIN OF THE EXCESS VERY STRONG Mg II ABSORBERS ALONG GAMMA-RAY BURST LINES-OF-SIGHT

International Nuclear Information System (INIS)

Cucchiara, A.; Jones, T.; Charlton, J. C.; Fox, D. B.; Einsig, D.; Narayanan, A.

2009-01-01

The startling discovery by Prochter et al. that the frequency of very strong (W r (2796)>1 A) Mg II absorbers along gamma-ray burst (GRB) lines of sight ([dN/dz] GRB = 0.90) is more than three times the frequency along quasar lines of sight ([dN/dz] QSO = 0.24), over similar redshift ranges, has yet to be understood. In particular, explanations appealing to dust antibias in quasar samples, partial covering of the quasar sources, and gravitational-lensing amplification of the GRBs have all been carefully examined and found wanting. We therefore reconsider the possibility that the excess of very strong Mg II absorbers toward GRBs is intrinsic either to the GRBs themselves or to their immediate environment, and associated with bulk outflows with velocities as large as v max ∼ 0.3c. In order to examine this hypothesis, we accumulate a sample of 27 W r (2796)>1 A absorption systems found toward 81 quasars, and compare their properties to those of 8 W r (2796) > 1 A absorption systems found toward six GRBs; all systems have been observed at high spectral resolution (R = 45, 000) using the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. We make multiple comparisons of the absorber properties across the two populations, testing for differences in metallicity, ionization state, abundance patterns, dust abundance, kinematics, and phase structure. We find no significant differences between the two absorber populations using any of these metrics, implying that, if the excess of absorbers along GRB lines of sight are indeed intrinsic, they must be produced by a process which has strong similarities to the processes yielding strong Mg II systems associated with intervening galaxies. Although this may seem a priori unlikely, given the high outflow velocities required for any intrinsic model, we note that the same conclusion was reached, recently, with respect to the narrow absorption line systems seen in some quasars.

Two separate outflows in the dual supermassive black hole system NGC 6240.

Science.gov (United States)

Müller-Sánchez, F; Nevin, R; Comerford, J M; Davies, R I; Privon, G C; Treister, E

2018-04-01

Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content 1-3 . Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows 4-6 , it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown 7-9 . Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O III] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O III] cone, respectively. Their combined mass outflow is comparable to the star formation rate 10 , suggesting that negative feedback on star formation is occurring.

How Do Inflows and Outflows from Galaxies Create Their Inner Circumgalactic Medium?

Science.gov (United States)

Bowen, David

2017-08-01

We propose using COS to observe 7 QSO sightlines within half a virial radius each of two galaxies in order to probe their circumgalactic mediums (CGMs) along multiple sightlines. Results from higher redshift QSO absorption line surveys suggest that this is the region where most metal line absorbing gas clouds reside, but their origin remains controversial. The two spiral galaxies studied in this proposal are NGC 4565 (the Needle Galaxy) which is highly inclined (i=86 degrees), and NGC 3184, which has a very low inclination (i=9 degrees). Their orientation makes them ideal targets for looking for kinematic and metallicity signatures from outflows along the minor axis, or inflows into the disk along the major axis. For both galaxies, we will measure how HI and metal line column densities change globally with radius, and how the ionzation structure of the absorbers varies with position. We predict that the HI column densities we detect will be similar to the Lyman Limit, or partial-Lyman Limit systems, and that we will be able to measure the gas metallicity in these clouds. These measurements can be used to infer whether the absorbing gas is flowing into the galaxy from the IGM (where the metallicity is lower than in the galaxy) or out of the galaxy (which should be metal enriched). Given that LLS and pLLS have been shown to have a bimodal distribution in their metallicity, we will see which of the two regimes the gas in our galaxies belong to, and even whether the bimodality can be seen in a single galaxy towards different sightlines.

Cosmic ray driven outflows in an ultraluminous galaxy

Science.gov (United States)

Fujita, Akimi; Mac Low, Mordecai-Mark

2018-06-01

In models of galaxy formation, feedback driven both by supernova (SN) and active galactic nucleus is not efficient enough to quench star formation in massive galaxies. Models of smaller galaxies have suggested that cosmic rays (CRs) play a major role in expelling material from the star-forming regions by diffusing SN energy to the lower density outskirts. We therefore run gas dynamical simulations of galactic outflows from a galaxy contained in a halo with 5 × 1012 M⊙ that resembles a local ultraluminous galaxy, including both SN thermal energy and a treatment of CRs using the same diffusion approximation as Salem & Bryan. We find that CR pressure drives a low-density bubble beyond the edge of the shell swept up by thermal pressure, but the main bubble driven by SN thermal pressure overtakes it later, which creates a large-scale biconical outflow. CRs diffusing into the disc are unable to entrain its gas in the outflows, yielding a mass-loading rate of only ˜ 0.1 per cent with varied CR diffusion coefficients. We find no significant difference in mass-loading rates in SN-driven outflows with or without CR pressure. Our simulations strongly suggest that it is hard to drive a heavily mass-loaded outflow with CRs from a massive halo potential, although more distributed star formation could lead to a different result.

THE ORION FINGERS: NEAR-IR SPECTRAL IMAGING OF AN EXPLOSIVE OUTFLOW

Energy Technology Data Exchange (ETDEWEB)

Youngblood, Allison; Bally, John [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Ginsburg, Adam, E-mail: allison.youngblood@colorado.edu [ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)

2016-06-01

We present near-IR (1.1–2.4 μ m) position–position–velocity cubes of the 500 year old Orion BN/KL explosive outflow with spatial resolution 1″ and spectral resolution 86 km s{sup −1}. We construct integrated intensity maps free of continuum sources of 15 H{sub 2} and [Fe ii] lines while preserving kinematic information of individual outflow features. Included in the detected H{sub 2} lines are the 1-0 S(1) and 1-0 Q(3) transitions, allowing extinction measurements across the outflow. Additionally, we present dereddened flux ratios for over two dozen outflow features to allow for the characterization of the true excitation conditions of the BN/KL outflow. All of the ratios show the dominance of the shock excitation of the H{sub 2} emission, although some features exhibit signs of fluorescent excitation from stellar radiation or J-type shocks. We also detect tracers of the PDR/ionization front north of the Trapezium stars in [O i] and [Fe ii] and analyze other observed outflows not associated with the BN/KL outflow.

MULTIPLE FAST MOLECULAR OUTFLOWS IN THE PRE-PLANETARY NEBULA CRL 618

Energy Technology Data Exchange (ETDEWEB)

Lee, Chin-Fei; Huang, Po-Sheng [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Sahai, Raghvendra [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States); Sánchez Contreras, Carmen [Astrobiology Center (CSIC-INTA), ESAC Campus, E-28691 Villanueva de la Canada, Madrid (Spain); Tay, Jeremy Jian Hao [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

2013-11-01

CRL 618 is a well-studied pre-planetary nebula. It has multiple highly collimated optical lobes, fast molecular outflows along the optical lobes, and an extended molecular envelope that consists of a dense torus in the equator and a tenuous round halo. Here we present our observations of this source in CO J = 3-2 and HCN J = 4-3 obtained with the Submillimeter Array at up to ∼0.''3 resolutions. We spatially resolve the fast molecular outflow region previously detected in CO near the central star and find it to be composed of multiple outflows that have similar dynamical ages and are oriented along the different optical lobes. We also detect fast molecular outflows further away from the central star near the tips of the extended optical lobes and a pair of equatorial outflows inside the dense torus. We find that two episodes of bullet ejections in different directions are needed, one producing the fast molecular outflows near the central star and one producing the fast molecular outflows near the tips of the extended optical lobes. One possibility to launch these bullets is a magneto-rotational explosion of the stellar envelope.

Integrity of neutron-absorbing components of LWR fuel systems

International Nuclear Information System (INIS)

Bailey, W.J.; Berting, F.M.

1991-03-01

A study of the integrity and behavior of neutron-absorbing components of light-water (LWR) fuel systems was performed by Pacific Northwest Laboratory (PNL) and sponsored by the US Department of Energy (DOE). The components studies include control blades (cruciforms) for boiling-water reactors (BWRs) and rod cluster control assemblies for pressurized-water reactors (PWRs). The results of this study can be useful for understanding the degradation of neutron-absorbing components and for waste management planning and repository design. The report includes examples of the types of degradation, damage, or failures that have been encountered. Conclusions and recommendations are listed. 84 refs

Light absorbing organic aerosols (brown carbon) over the tropical Indian Ocean: impact of biomass burning emissions

International Nuclear Information System (INIS)

Srinivas, Bikkina; Sarin, M M

2013-01-01

The first field measurements of light absorbing water-soluble organic carbon (WSOC), referred as brown carbon (BrC), have been made in the marine atmospheric boundary layer (MABL) during the continental outflow to the Bay of Bengal (BoB) and the Arabian Sea (ARS). The absorption signal measured at 365 nm in aqueous extracts of aerosols shows a systematic linear increase with WSOC concentration, suggesting a significant contribution from BrC to the absorption properties of organic aerosols. The mass absorption coefficient (b abs ) of BrC shows an inverse hyperbolic relation with wavelength (from ∼300 to 700 nm), providing an estimate of the Angstrom exponent (α P , range: 3–19; Av: 9 ± 3). The mass absorption efficiency of brown carbon (σ abs−BrC ) in the MABL varies from 0.17 to 0.72 m 2  g −1 (Av: 0.45 ± 0.14 m 2  g −1 ). The α P and σ abs−BrC over the BoB are quite similar to that studied from a sampling site in the Indo-Gangetic Plain (IGP), suggesting the dominant impact of organic aerosols associated with the continental outflow. A comparison of the mass absorption efficiency of BrC and elemental carbon (EC) brings to focus the significant role of light absorbing organic aerosols (from biomass burning emissions) in atmospheric radiative forcing over oceanic regions located downwind of the pollution sources. (letter)

The Resolved Outflow from 3C 48

Science.gov (United States)

Shih, Hsin-Yi; Stockton, Alan

2014-10-01

We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the

MASS OUTFLOW IN THE SEYFERT 1 GALAXY NGC 5548

International Nuclear Information System (INIS)

Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Kaastra, J. S.; Arav, N.; Gabel, J. R.; Korista, K. T.

2009-01-01

We present a study of the intrinsic UV absorption and emission lines in an historically low-state spectrum of the Seyfert 1 galaxy NGC 5548, which we obtained in 2004 February at high spatial and spectral resolution with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. We isolate a component of emission with a width of 680 km s -1 that arises from an 'intermediate-line region' (ILR), similar to that we discovered in NGC 4151, at a distance of ∼1 pc from the central continuum source. From a detailed analysis of the five intrinsic absorption components in NGC 5548 and their behavior over a span of eight years, we present evidence that most of the UV absorbers only partially cover the ILR and do not cover an extended region of UV continuum emission, most likely from hot stars in the circumnuclear region. We also find that four of the UV absorbers are at much greater distances (greater than 70 pc) than the ILR, and none have sufficient N V or C IV column densities to be the ILR in absorption. At least a portion of the UV absorption component 3, at a radial velocity of -530 km s -1 , is likely responsible for most of the X-ray absorption, at a distance less than 7 pc from the central source. The fact that we see the ILR in absorption in NGC 4151 and not in NGC 5548 suggests that the ILR is located at a relatively large polar angle (∼45 deg.) with respect to the narrow-line region outflow axis.

Evolution of the outflow activity of protostars

International Nuclear Information System (INIS)

Bontemps, Sylvain

1996-01-01

After a first part describing the formation of low-mass stars (sites of stellar formation, protostellar evolution) and matter outflows from young objects (molecular flows and their origin, optical and radio jets, outflow mechanisms), this research thesis discusses the evolution of molecular flows by reprinting a published article (Evolution of outflow activity around low-mass embedded young stellar objects), and by outlining some remaining issues (differences between clouds of stellar formation, morphological evolution of molecular flows). The author then discusses the continuous radio centimetre emission: origin, systematic search for Class 0 objects by using the VLA (Very Large Array radio interferometer), presentation of a new Class 0 protostar (HH24MMS). The author reports the study of H_2 emission in the infrared: generalities on protostellar shocks, infrared jet by HH24MMS, H_2 emission at 10 microns by using the ISOCAM camera [fr

Computer Study of Cluster Mechanism of Anti-greenhouse Effect

OpenAIRE

A. Galashev

2009-01-01

Absorption spectra of infra-red (IR) radiation of the disperse water medium absorbing the most important greenhouse gases: CO2 , N2O , CH4 , C2H2 , C2H6 have been calculated by the molecular dynamics method. Loss of the absorbing ability at the formation of clusters due to a reduction of the number of centers interacting with IR radiation, results in an anti-greenhouse effect. Absorption of O3 molecules by the (H2O)50 cluster is investigated at its interaction with Cl- io...

Mass outflow in the nearby proto-planetary system, Beta Pictoris

International Nuclear Information System (INIS)

Bruhweiler, F.C.; Grady, C.A.; Kondo, Yoji

1991-01-01

Previous spectral studies of circumstallar dust around the nearby, candidate proto-planetary system, Beta Pictoris, has detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the Beta Pictoris system. IUE high-dispersion spectra are presented which show, in addition to infall, the presence of mass outflow, with a maximum observed outflow velocity of -60 km/s, and a corresponding instantaneous outflow rate of 1.1 x 10 to the -14th solar mass/yr, or 1.1 x 10 to the -11th Jupiter mass/yr. This mass outflow rate and terminal velocity are comparable to the magnitudes of mass infall rates and terminal velocities observed from late 1986 through early 1988. The implications of these observations on our understanding of the mechanisms producing infall from the surrounding circumstellar disk are discussed, as are the implications for our understanding of the evolutionary status of the Beta Pic system. 23 refs

THE TURBULENT ORIGIN OF OUTFLOW AND SPIN MISALIGNMENT IN MULTIPLE STAR SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Offner, Stella S. R.; Lee, Katherine I.; Arce, Héctor G.; Fielding, Drummond B. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Dunham, Michael M., E-mail: soffner@astro.umass.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2016-08-10

The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momentum. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce {sup 12}CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. The CO-identified outflows exhibit a similar random distribution and are also statistically consistent with the observed distribution of molecular outflows. We conclude that the observed misalignment provides a clear signature of binary formation via turbulent fragmentation. The persistence of misaligned outflows and stellar spins following dynamical evolution may provide a signature of binary origins for more evolved multiple star systems.

THE TURBULENT ORIGIN OF OUTFLOW AND SPIN MISALIGNMENT IN MULTIPLE STAR SYSTEMS

International Nuclear Information System (INIS)

Offner, Stella S. R.; Lee, Katherine I.; Arce, Héctor G.; Fielding, Drummond B.; Dunham, Michael M.

2016-01-01

The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momentum. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce 12 CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. The CO-identified outflows exhibit a similar random distribution and are also statistically consistent with the observed distribution of molecular outflows. We conclude that the observed misalignment provides a clear signature of binary formation via turbulent fragmentation. The persistence of misaligned outflows and stellar spins following dynamical evolution may provide a signature of binary origins for more evolved multiple star systems.

A SEARCH FOR 95 GHz CLASS I METHANOL MASERS IN MOLECULAR OUTFLOWS

Energy Technology Data Exchange (ETDEWEB)

Gan, Cong-Gui; Chen, Xi; Shen, Zhi-Qiang [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan RD, Shanghai 200030 (China); Xu, Ye; Ju, Bing-Gang, E-mail: cggan@shao.ac.cn [Key Laboratory of Radio Astronomy, Chinese Academy of Sciences (China)

2013-01-20

We have observed a sample of 288 molecular outflow sources including 123 high-mass and 165 low-mass sources in order to search for class I methanol masers at the 95 GHz transition and to investigate the relationship between outflow characteristics and class I methanol maser emission with the Purple Mountain Observatory 13.7 m radio telescope. Our survey detected 62 sources with 95 GHz methanol masers above a 3{sigma} detection limit, which includes 47 high-mass sources and 15 low-mass sources. Therefore, the detection rate is 38% for high-mass outflow sources and 9% for low-mass outflow sources, suggesting that class I methanol masers are relatively easily excited in high-mass sources. There are 37 newly detected 95 GHz methanol masers (including 27 high-mass and 10 low-mass sources), 19 of which are newly identified (i.e., first identification) class I methanol masers (including 13 high-mass and 6 low-mass sources). A statistical analysis of the distributions of maser detections with the outflow parameters reveals that the maser detection efficiency increases with the outflow properties (e.g., mass, momentum, kinetic energy, mechanical luminosity of outflows, etc.). Systematic investigations of the relationships between the intrinsic luminosity of methanol masers and the outflow properties (including mass, momentum, kinetic energy, bolometric luminosity, and mass-loss rate of the central stellar sources) indicate a positive correlation. This further supports the theory that class I methanol masers are collisionally pumped and associated with shocks when outflows interact with the surrounding ambient medium.

How to detect trap cluster systems?

International Nuclear Information System (INIS)

Mandowski, Arkadiusz

2008-01-01

Spatially correlated traps and recombination centres (trap-recombination centre pairs and larger clusters) are responsible for many anomalous phenomena that are difficult to explain in the framework of both classical models, i.e. model of localized transitions (LT) and the simple trap model (STM), even with a number of discrete energy levels. However, these 'anomalous' effects may provide a good platform for identifying trap cluster systems. This paper considers selected cluster-type effects, mainly relating to an anomalous dependence of TL on absorbed dose in the system of isolated clusters (ICs). Some consequences for interacting cluster (IAC) systems, involving both localized and delocalized transitions occurring simultaneously, are also discussed

AGN feedback in action? - outflows and star formation in type 2 AGNs

Science.gov (United States)

Woo, Jong-Hak

2017-01-01

We present the statistical constraints on the ionized gas outflows and their connection to star formation, using a large sample of ~110,000 AGNs and star-forming galaxies at z dispersion of star forming galaxies can be entirely accounted by the gravitational potential of host galaxies, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. Second, the distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the outflows are AGN-driven. Third, the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. Interestingly, we find that the specific star formation of non-outflow AGNs is much lower than that of strong outflow AGNs, while the star formation rate of strong outflow AGNs is comparable to that of star forming galaxies. We interpret this trend as a delayed AGN feedback as it takes dynamical time for the outflows to suppress star formation in galactic scales.

A young bipolar outflow from IRAS 15398-3359

Science.gov (United States)

Bjerkeli, P.; Jørgensen, J. K.; Brinch, C.

2016-03-01

Context. Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry as well as the kinematical information, allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. Aims: We aim to determine the spatial distribution of different species that are of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim to determine the nature of the infalling and outflowing gas in the system. We also aim to determine the physical properties of the outflow. Methods: Maps from the Submillimeter Array (SMA) reveal the spatial distribution of the gaseous emission towards IRAS 15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ are detected and shown to trace the motions of the outflow. For CO, the circumstellar envelope and the surrounding cloud also have a profound impact on the observed line profiles. N2H+ is detected in the outflow, but is suppressed towards the central region, perhaps because of the competing reaction between CO and H3+ in the densest regions as well as the destruction of N2H+ by CO. N2D+ is detected in a ridge south-west of the protostellar condensation and is not associated with the outflow. The morphology and kinematics of the CO emission suggests that the source is younger than ~1000 years. The mass, momentum, momentum rate, mechanical luminosity, kinetic energy, and mass-loss rate are also all estimated to be low. A full 3D radiative transfer model of the system can explain all the kinematical and morphological features in the system.

Multiple monopolar outflows driven by massive protostars in IRAS 18162-2048

Energy Technology Data Exchange (ETDEWEB)

Fernández-López, M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Girart, J. M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain); Curiel, S.; Fonfría, J. P. [Instituto de Astronomía, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-264, 04510 México, DF (Mexico); Zapata, L. A. [Centro de Radioastronomía y Astrofísica, UNAM, Apartado Postal 3-72, Morelia, Michoacán 58089 (Mexico); Qiu, K., E-mail: manferna@illinois.edu, E-mail: girart@ieec.cat [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

2013-11-20

In this article, we present Combined Array for Research in Millimeter-wave Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 μm observations toward the high-mass star-forming region IRAS 18162-2048, which is the core of the HH 80/81/80N system. Molecular emission from HCN, HCO{sup +}, and SiO traces two molecular outflows (the so-called northeast and northwest outflows). These outflows have their origin in a region close to the position of MM2, a millimeter source known to harbor two protostars. For the first time we estimate the physical characteristics of these molecular outflows, which are similar to those of 10{sup 3}-5 × 10{sup 3} L {sub ☉} protostars, and suggest that MM2 harbors high-mass protostars. High-angular resolution CO observations show an additional outflow due southeast. Also for the first time, we identify its driving source, MM2(E), and see evidence of precession. All three outflows have a monopolar appearance, but we link the NW and SE lobes, and explain their asymmetric shape as being a consequence of possible deflection.

Fusion process of Lennard-Jones clusters: global minima and magic numbers formation

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2004-01-01

We present a new theoretical framework for modeling the fusion process of Lennard–Jones (LJ) clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing paths up to the cluster size of 150 atoms...

Variations of surface ozone at Ieodo Ocean Research Station in the East China Sea and the influence of Asian outflows

Science.gov (United States)

Han, J.; Shin, B.; Lee, M.; Hwang, G.; Kim, J.; Shim, J.; Lee, G.; Shim, C.

2015-11-01

Ieodo Ocean Research Station (IORS), a research tower (~ 40 m a.s.l.) for atmospheric and oceanographic observations, is located in the East China Sea (32.07° N, 125.10° E). The IORS is almost equidistant from South Korea, China, and Japan and, therefore, it is an ideal place to observe Asian outflows without local emission effects. The seasonal variation of ozone was distinct, with a minimum in August (37 ppbv) and two peaks in April and October (62 ppbv), and was largely affected by the seasonal wind pattern over east Asia. At IORS, six types of air masses were distinguished with different levels of O3 concentrations by the cluster analysis of backward trajectories. Marine air masses from the Pacific Ocean represent a relatively clean background air with a lowest ozone level of 32 ppbv, which was most frequently observed in summer (July-August). In spring (March-April) and winter (December-February), the influence of Chinese outflows was dominant with higher ozone concentrations of 62 and 49 ppbv, respectively. This study confirms that the influence of Chinese outflows was the main factor determining O3 levels at IORS and its extent was dependent on meteorological state, particularly at a long-term scale.

Superposed epoch analysis of O+ auroral outflow during sawtooth events and substorms

Science.gov (United States)

Nowrouzi, N.; Kistler, L. M.; Lund, E. J.; Cai, X.

2017-12-01

Sawtooth events are repeated injection of energetic particles at geosynchronous orbit. Studies have shown that 94% of sawtooth events occurred during magnetic storm times. The main factor that causes a sawtooth event is still an open question. Simulations have suggested that heavy ions like O+ may play a role in triggering the injections. One of the sources of the O+ in the Earth's magnetosphere is the nightside aurora. O+ ions coming from the nightside auroral region have direct access to the near-earth magnetotail. A model (Brambles et al. 2013) for interplanetary coronal mass ejection driven sawtooth events found that nightside O+ outflow caused the subsequent teeth of the sawtooth event through a feedback mechanism. This work is a superposed epoch analysis to test whether the observed auroral outflow supports this model. Using FAST spacecraft data from 1997-2007, we examine the auroral O+ outflow as a function of time relative to an injection onset. Then we determine whether the profile of outflow flux of O+ during sawtooth events is different from the outflow observed during isolated substorms. The auroral region boundaries are estimated using the method of (Andersson et al. 2004). Subsequently the O+ outflow flux inside these boundaries are calculated and binned as a function of superposed epoch time for substorms and sawtooth "teeth". In this way, we will determine if sawtooth events do in fact have greater O+ outflow, and if that outflow is predominantly from the nightside, as suggested by the model results.

Dissecting the Butterfly: Dual Outflows in the Dual AGN NGC 6240

Science.gov (United States)

Mueller Sanchez, Francisco; Comerford, Julie; Nevin, Rebecca; Davies, Richard; Treister, Ezequiel; Privon, George

2018-01-01

Current theories of galaxy evolution invoke some kind of feedback (from the stars or the supermassive black hole) to explain the properties of galaxies. However, numerical simulations and observations have not been able to evaluate the real impact of feedback in galaxies. This is largely because most studies have focused on studying stellar feedback or AGN feedback alone, instead of considering the combined effect of both. In fact, this is an unexplored territory for observations due to the difficulty of separating the contribution from the two sources.In this contribution I present the discovery of a dual outflow of different species of gas in the prototypical merging galaxy NGC 6240 using HST imaging, long-slit and integral-eld spectroscopy: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. The AGN outflow extends up to 4 kpc along a position angle of 56 degrees, has a conical shape with an opening angle of 52 degrees and a maximum line-of-sight velocity of 350 km/s. The WFC3 images also reveal a bubble of Halpha emission in the northwest, which has no counterpart in [O III], consistent with a scenario in which the starburst is ionizing and driving outflowing winds which inflate the bubble at an expansion velocity of 380 km/s. Assuming a spherical geometry for the starburst-driven bubble and a conical geometry for the AGN-driven outflow, we estimate mass outflow rates of 26 Msun/yr and 62 Msun/yr, respectively. We conclude that the AGN contribution to the evolution of the merger remnant and the formation of outflowing winds is signicant in the central 5 kpc of NGC 6240.

On the evolution of globular clusters and the origin of galactic halo stars

International Nuclear Information System (INIS)

Surdin, V.G.

1978-01-01

Evolution of globular clusters of galactic halo is considered. It is shown that evolution of massive globular clusters with a greater degree of probability takes place under the effect of dynamic friction, which brings about the cluster fall on the center of galactic and their destruction by tidal forces. Evolution of small massive cluster takes place under the effect of dissipation. All the other reasons, causing the destruction of globular clusters (gravitational tidal forces, mutual cluster collision, outflow of gas from red gigant atmospheres, the change of the radius of the cluster orbit at the expense of the change of the galaxy mass inside the cluster orbit) play a secondary role. The whole mass of the stars lost by globular clusters does not exceed 10 7 M sun. It is concluded that the origin of the star population of galactic halo field can not be explained by destruction of already formed only astral globular clusters

An X-Ray/SDSS Sample: Observational Characterization of The Outflowing Gas

Science.gov (United States)

Perna, Michele; Brusa, M.; Lanzuisi, G.; Mignoli, M.

2016-10-01

Powerful ionised AGN-driven outflows, commonly detected both locally and at high redshift, are invoked to contribute to the co-evolution of SMBH and galaxies through feedback phenomena. Our recent works (Brusa+2015; 2016; Perna+2015a,b) have shown that the XMM-COSMOS targets with evidence of outflows collected so far ( 10 sources) appear to be associated with low X-ray kbol corrections (Lbol /LX ˜ 18), in spite of their spread in obscuration, in the locations on the SFR-Mstar diagram, in their radio emission. A higher statistical significance is required to validate a connection between outflow phenomena and a X-ray loudness. Moreover, in order to validate their binding nature to the galaxy fate, it is crucial to correctly determine the outflow energetics. This requires time consuming integral field spectroscopic (IFS) observations, which are, at present, mostly limited to high luminosity objectsThe study of SDSS data offers a complementary strategy to IFS efforts. I will present physical and demographic characterization of the AGN-galaxy system during the feedback phase obtained studying a sample of 500 X-ray/SDSS AGNs, at zdispersion) and X-ray properties (intrinsic X-ray luminosity, obscuration and X-ray kbol correction), to determine what drives ionised winds. Several diagnostic line ratios have been used to infer the physical properties of the ionised outflowing gas. The knowledge of these properties can reduce the actual uncertainties in the outflow energetics by a factor of ten, pointing to improve our understanding of the AGN outflow phenomenon and its impact on galaxy evolution.

LARGE-SCALE STAR-FORMATION-DRIVEN OUTFLOWS AT 1 < z < 2 IN THE 3D-HST SURVEY

International Nuclear Information System (INIS)

Lundgren, Britt F.; Van Dokkum, Pieter; Bezanson, Rachel; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Wake, David; Whitaker, Katherine; Brammer, Gabriel; Franx, Marijn; Fumagalli, Mattia; Labbé, Ivo; Patel, Shannon; Da Cunha, Elizabete; Rix, Hans Walter; Schmidt, Kasper; Erb, Dawn K.; Fan Xiaohui; Kriek, Mariska; Marchesini, Danilo

2012-01-01

We present evidence of large-scale outflows from three low-mass (log(M * /M ☉ ) ∼ 9.75) star-forming (SFR > 4 M ☉ yr –1 ) galaxies observed at z = 1.24, z = 1.35, and z = 1.75 in the 3D-HST Survey. Each of these galaxies is located within a projected physical distance of 60 kpc around the sight line to the quasar SDSS J123622.93+621526.6, which exhibits well-separated strong (W λ2796 r ∼> 0.8 Å) Mg II absorption systems matching precisely to the redshifts of the three galaxies. We derive the star formation surface densities from the Hα emission in the WFC3 G141 grism observations for the galaxies and find that in each case the star formation surface density well exceeds 0.1 M ☉ yr –1 kpc –2 , the typical threshold for starburst galaxies in the local universe. From a small but complete parallel census of the 0.65 140 ∼ r > 0.8 Å Mg II covering fraction of star-forming galaxies at 1 r > 0.4 Å Mg II absorbing gas around star-forming galaxies may evolve from z ∼ 2 to the present, consistent with recent observations of an increasing collimation of star-formation-driven outflows with time from z ∼ 3.

Low-energy ion outflow modulated by the solar wind energy input

Science.gov (United States)

Li, Kun; Wei, Yong; Andre, Mats; Eriksson, Anders; Haaland, Stein; Kronberg, Elena; Nilsson, Hans; Maes, Lukas

2017-04-01

Due to the spacecraft charging issue, it has been difficult to measure low-energy ions of ionospheric origin in the magnetosphere. A recent study taking advantage of the spacecraft electric potential has found that the previously 'hidden' low-energy ions is dominant in the magnetosphere. This comprehensive dataset of low-energy ions allows us to study the relationship between the ionospheric outflow and energy input from the solar wind (ɛ). In this study, we discuss the ratios of the solar wind energy input to the energy of the ionospheric outflow. We show that the ɛ controls the ionospheric outflow when the ɛ is high, while the ionospheric outflow does not systematically change with the ɛ when the ɛ is low.

Cluster growing process and a sequence of magic numbers

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2003-01-01

demonstrate that in this way all known global minimum structures of the Lennard-Jones (LJ) clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence for the clusters of noble gas atoms......We present a new theoretical framework for modeling the cluster growing process. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system, and absorbing its energy at each step, we find cluster growing paths up to the cluster sizes of more than 100 atoms. We...

Transport pathways for Asian pollution outflow over the Pacific: Interannual and seasonal variations

Science.gov (United States)

Liu, Hongyu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

2003-10-01

The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (pollution signal. Spring 2001 (La Niña) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

Plasma Outflows: Known Knowns, Known Unknowns, and The Unknown

Science.gov (United States)

Moore, T. E.

2012-01-01

A brief summary is given of i) what we know from observing ionospheric outflows and ii) how outflow parameterizations are being used in global simulations to evaluate their effects on magnetospheric dynamics. Then, a list of unanswered questions and issues to be resolved is given, followed by a description of the known future mission plans expressed in the Heliophysics Roadmap, such as Origin of Near-Earth Plasmas (ONEP), and Ion-Neutral Coupling in the Atmosphere (INCA). Finally, a set of requirements for definitive plasma outflow observations are identified, along with possible methods for fulfilling them in future missions. Since results of the current Heliophysics Decadal Survey are expected soon, it is hoped that future plans can be summarized and discussed without speculation at the GEM 2012 meeting.

The outflow speed of the coma of Halley's comet

International Nuclear Information System (INIS)

Combi, M.R.

1989-01-01

Data concerning the outflow speed of the coma of Comet Halley are studied in relation to a generalization of the coupled pure-gas-dynamic/Monte Carlo model of Combi and Smyth (1988) to include the dusty-gas dynamics of the inner coma. Measurements made by the Giotto neutral-gas spectrometer, IR water observations from the Kuiper Airborne Observatory, and Doppler radio line profiles of HCN and OH are used to examine the radial dependence of the outflow speed, the asymmetry in the outflow speed, and the overall heliocentric distance dependence of the Doppler profiles, respectively. The results suggest that the model makes it possible to understand the gross long-term behavior and radial structure of the dynamics of the cometary coma. 23 refs

Determinants of Foreign Direct Investments Outflow From a Developing Country: the Case of Turkey

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Gokhan Onder

2013-09-01

Full Text Available Foreign direct investments (FDI outflows of Turkey have remarkably been raising over the last decade. This rapid increase brings about the need for questioning the determinants of FDI outflows. The aim of this paper is to estimate the factors affecting outflow FDI from Turkey from 2002 to 2011 by using Prais-Winsten regression analysis. According to estimation results, population, infrastructure, percapita gross domestic product of the host country, and home country exports to the host country are the factors having positive effects on outflow FDI. We found, on the other hand, that the annual inflation rate of the host country, its tax rate collected from commercial profit, and its distance from Turkey have a negative relation with investment outflows. Moreover our results show that while investment outflows to developed countries are in the form of horizontal investments, investment outflows to developing countries are in the form of vertical investments.

CLASSICAL T TAURI-LIKE OUTFLOW ACTIVITY IN THE BROWN DWARF MASS REGIME

International Nuclear Information System (INIS)

Whelan, E. T.; Ray, T. P.; Podio, L.; Bacciotti, F.; Randich, S.

2009-01-01

Over the last number of years, spectroscopic studies have strongly supported the assertion that protostellar accretion and outflow activity persist to the lowest masses. Indeed, previous to this work, the existence of three brown dwarf (BD) outflows had been confirmed by us. In this paper, we present the results of our latest investigation of BD outflow activity and report on the discovery of two new outflows. Observations to date have concentrated on studying the forbidden emission line (FEL) regions of young BDs and in all cases data have been collected using the UV-Visual Echelle Spectrometer (UVES) on the ESO Very Large Telescope. Offsets in the FEL regions are recovered using spectro-astrometry. Here, ISO-Oph 32 is shown to drive a blueshifted outflow with a radial velocity of 10-20 km s -1 and spectro-astrometric analysis constrains the position angle of this outflow to 240 0 ± 7 0 . The BD candidate, ISO-ChaI 217 is found to have a bipolar outflow bright in several key forbidden lines (V RAD = -20 km s -1 , +40 km s -1 ) and with a P.A. of 193 0 -209 0 . A striking feature of the ISO-ChaI 217 outflow is the strong asymmetry between the red- and blueshifted lobes. This asymmetry is revealed in the relative brightness of the two lobes (redshifted lobe is brighter), the factor of 2 difference in radial velocity (the redshifted lobe is faster) and the difference in the electron density (again higher in the red lobe). Such asymmetries are common in jets from low-mass protostars and the observation of a marked asymmetry at such a low mass ( sun ) supports the idea that BD outflow activity is scaled down from low-mass protostellar activity. Also note that although asymmetries are unexceptional, it is uncommon for the redshifted lobe to be the brightest as some obscuration by the accretion disk is assumed. This phenomenon has only been observed in one other source, the classical T Tauri (CTTS) star RW Aur. The physical mechanism responsible for the brightening of

Unveiling the molecular bipolar outflow of the peculiar red supergiant VY Canis Majoris

Science.gov (United States)

Shinnaga, Hiroko; Claussen, Mark J.; Lim, Jeremy; Dinh-van-Trung; Tsuboi, Masato

2003-04-01

We carried out polarimetric spectral-line imaging of the molecular outflow of the peculiar red supergiant VY Canis Majoris in SiO J=1-0 line in the ground vibrational state, which contains highly linearly-polarized velocity components, using the Very Large Array. We succeeded in unveiling the highly linearly polarized bipolar outflow for the first time at subarcsecond spatial resolution. The results clearly show that the direction of linear polarization of the brightest maser components is parallel to the outflow axis. The results strongly suggest that the linear polarization of the SiO maser is closely related to the outflow phenomena of the star. Furthermore, the results indicate that the linear polarization observed in the optical and infrared also occur due to the outflow phenomena.

BAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns

Science.gov (United States)

Shimizu, T. Taro; Davies, Richard I.; Koss, Michael; Ricci, Claudio; Lamperti, Isabella; Oh, Kyuseok; Schawinski, Kevin; Trakhtenbrot, Benny; Burtscher, Leonard; Genzel, Reinhard; Lin, Ming-yi; Lutz, Dieter; Rosario, David; Sturm, Eckhard; Tacconi, Linda

2018-04-01

We explore the relationship between X-ray absorption and optical obscuration within the BAT AGN Spectroscopic Survey (BASS), which has been collecting and analyzing the optical and X-ray spectra for 641 hard X-ray selected (E > 14 keV) active galactic nuclei (AGNs). We use the deviation from a linear broad Hα-to-X-ray relationship as an estimate of the maximum optical obscuration toward the broad line region (BLR) and compare the A V to the hydrogen column densities ({N}{{H}}) found through systematic modeling of their X-ray spectra. We find that the inferred columns implied by A V toward the BLR are often orders of magnitude less than the columns measured toward the X-ray emitting region, indicating a small-scale origin for the X-ray absorbing gas. After removing 30% of Sy 1.9s that potentially have been misclassified due to outflows, we find that 86% (164/190) of the Type 1 population (Sy 1–1.9) are X-ray unabsorbed as expected based on a single obscuring structure. However, 14% (26/190), of which 70% (18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting that the BLR itself is providing extra obscuration toward the X-ray corona. The fraction of X-ray absorbed Type 1 AGNs remains relatively constant with AGN luminosity and Eddington ratio, indicating a stable BLR covering fraction.

UNRAVELLING THE COMPLEX STRUCTURE OF AGN-DRIVEN OUTFLOWS. II. PHOTOIONIZATION AND ENERGETICS

Energy Technology Data Exchange (ETDEWEB)

Karouzos, Marios; Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Department of Astronomy and Center for Galaxy EVolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

2016-12-20

Outflows have been shown to be prevalent in galaxies hosting luminous active galactic nuclei (AGNs); they present a physically plausible way to couple the AGN energy output with the interstellar medium of their hosts. Despite their prevalence, accurate characterization of these outflows has been challenging. In the second of a series of papers, we use Gemini Multi-Object Spectrograph integral field unit (IFU) data of six local ( z  < 0.1) and moderate-luminosity Type 2 AGNs to study the ionization properties and energetics of AGN-driven outflows. We find strong evidence connecting the extreme kinematics of the ionized gas to the AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as virial motions or rotation, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that 30 to 90% of the total mass and kinetic energy of the outflow is contained within the central kpc of the galaxy. The spatially integrated mass and kinetic energy of the gas entrained in the outflow correlate well with the AGN bolometric luminosity and results in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of galaxy-scale negative feedback.

Multi-phase outflows as probes of AGN accretion history

Science.gov (United States)

Nardini, Emanuele; Zubovas, Kastytis

2018-05-01

Powerful outflows with a broad range of properties (such as velocity, ionization, radial scale and mass loss rate) represent a key feature of active galactic nuclei (AGN), even more so since they have been simultaneously revealed also in individual objects. Here we revisit in a simple analytical framework the recent remarkable cases of two ultraluminous infrared quasars, IRAS F11119+3257 and Mrk 231, which allow us to investigate the physical connection between multi-phase AGN outflows across the ladder of distance from the central supermassive black hole (SMBH). We argue that any major deviations from the standard outflow propagation models might encode unique information on the past SMBH accretion history, and briefly discuss how this could help address some controversial aspects of the current picture of AGN feedback.

ON THE ORIGIN OF THE MOLECULAR OUTFLOWS IN IRAS 16293–2422

Energy Technology Data Exchange (ETDEWEB)

Girart, Josep M.; Palau, Aina; Torrelles, José M. [Institut de Ciències de l' Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5p 2, E-08193 Bellaterra, Catalonia (Spain); Estalella, Robert [Departament d' Astronomia i Meteorologia, Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès, Universitat de Barcelona, E-08028 Barcelona, Catalonia (Spain); Rao, Ramprasad, E-mail: girart@ice.cat [Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720 (United States)

2014-01-01

We present CO 3-2, SiO 8-7, C{sup 34}S 7-6, and 878 μm dust continuum subarcsecond angular resolution observations with the Submillimeter Array (SMA) toward the IRAS 16293–2422 (I16293) multiple low-mass protostellar system. The C{sup 34}S emission traces the 878 μm dust continuum well, and in addition clearly shows a smooth velocity gradient along the major axis of component I16293A. CO shows emission at moderate high velocities arising from two bipolar outflows, which appear to be perpendicular with respect to each other. The high sensitivity and higher angular resolution of these observations allows us to pinpoint well the origin of these two outflows at the center of component I16293A. Interestingly, the most compact outflow appears to point toward I16293B. Our data show that the previously reported monopolar blueshifted CO outflow associated with component I16293B seems to be part of the compact outflow arising from component I16293A. In addition, the SiO emission is also tracing this compact outflow: on the one hand, the SiO emission appears to have a jet-like morphology along the southern redshifted lobe; on the other hand, the SiO emission associated with the blueshifted northern lobe traces a well-defined arc on the border of component I16293B facing I16293A. The blueshifted CO lobe of the compact outflow splits into two lobes around the position of this SiO arc. All these results lead us to propose that the compact outflow from component I16293A is impacting on the circumstellar gas around component I16293B, possibly being diverged as a consequence of the interaction.

DIVERSE PROTOSTELLAR EVOLUTIONARY STATES IN THE YOUNG CLUSTER AFGL961

International Nuclear Information System (INIS)

Williams, Jonathan P.; Mann, Rita K.; Beaumont, Christopher N.; Swift, Jonathan J.; Adams, Joseph D.; Hora, Joe; Kassis, Marc; Lada, Elizabeth A.; Roman-Zuniga, Carlos G.

2009-01-01

We present arcsecond resolution mid-infrared and millimeter observations of the center of the young stellar cluster AFGL961 in the Rosette molecular cloud. Within 0.2 pc of each other, we find an early B star embedded in a dense core, a neighboring star of similar luminosity with no millimeter counterpart, a protostar that has cleared out a cavity in the circumcluster envelope, and two massive, dense cores with no infrared counterparts. An outflow emanates from one of these cores, indicating a deeply embedded protostar, but the other is starless, bound, and appears to be collapsing. The diversity of states implies either that protostellar evolution is faster in clusters than in isolation or that clusters form via quasi-static rather than dynamic collapse. The existence of a pre-stellar core at the cluster center shows that some star formation continues after and in close proximity to massive, ionizing stars.

The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility

Directory of Open Access Journals (Sweden)

Vassilios P Kozobolis

2010-08-01

Full Text Available Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, Stavrenia C Koukoula, Georgios LabirisDepartment of Ophthalmology and Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, GreecePurpose: To develop, characterize, and validate a prototype digital aqueous humor outflow tonographer (DAHOM.Material and methods: The DAHOM was developed, characterized, and validated in three phases. Phase 1 involved construction of the sensor. This was broadly based on the fundamental design of a typical Schiotz tonographer with a series of improvements, including corneal indentation, which was converted to an electrical signal via a linear variable differential transducer, an analog signal which was converted to digital via ADC circuitry, and digital data acquisition and processing which was made possible by a serial port interface. Phase 2 comprised development of software for automated assessment of the outflow facility. Automated outflow facility assessment incorporated a series of fundamental improvements in comparison with traditional techniques, including software-based filtering of ripple noise and extreme variations, rigidity impact analysis, and evaluation of the impact of patient age, central corneal thickness, and ocular axial length. Phase 3 comprised characterization and validation of DAHOM, for which we developed an experimental setup using porcine cadaver eyes. DAHOM’s repeatability was evaluated by means of Cronbach’s alpha and intraclass correlation coefficient. The level of agreement with a standard Schiotz tonographer was evaluated by means of paired t-tests and Bland-Altman analysis in human eyes.Results: The experimental setup provided the necessary data for the characterization of DAHOM. A fourth order polynomial equation provided excellent fit (R square >0.999. DAHOM demonstrated high repeatability (Cronbach’s alpha ≥0.997; intraclass correlation coefficient ≥0.987 and an adequate level of

The impact of remittances outflows on the economy of Poland

OpenAIRE

LASTOVETSKA ROKSOLANA ORESTIVNA

2015-01-01

The impact of remittances outflows on the economy of Poland is analyzed in the article. Based on historical data the vector autoregression model (VAR) was built to examine the effects of the sharp rise in the volume of remittances outflows. The model results are presented for the next macroeconomic indicators: GDP, inflation, interest rate and exchange rate.

Investigation of conspicuous infrared star cluster and star-forming region RCW 38 IR Cluster

International Nuclear Information System (INIS)

Gyulbudaghian, A.L.; May, J.

2008-01-01

An infrared star cluster RCW 38 IR Cluster, which is also a massive star-forming region, is investigated. The results of observations with SEST (Cerro is Silla, Chile) telescope on 2.6-mm 12 CO spectral line and with SIMBA on 1.2-mm continuum are given. The 12 CO observations revealed the existence of several molecular clouds, two of which (clouds I and 2) are connected with the object RCW 38 IR Cluster. Cloud 1 is a massive cloud, which has a depression in which the investigated object is embedded. It is not excluded that the depression was formed by the wind and/or emission from the young bright stars belonging to the star cluster. Rotation of cloud 2, around the axis having SE-NW direction, with an angular velocity ω 4.6 · 10 -14 s -1 is also found. A red-shifted outflow with velocity ∼+5.6 km/s, in the SE direction and perpendicular to the elongation of cloud 2 has been also found. The investigated cluster is associated with an IR point source IRAS 08573-4718, which has IR colours typical for a, non-evolved embedded (in the cloud) stellar object. The cluster is also connected with a water maser. The SIMBA image shoves the existence of a central bright condensation, coinciding with the cluster itself, and two extensions. One of these extensions (the one with SW-NE direction) coincides, both in place and shape, with cloud 2, so that it is not excluded the possibility that this extension might be also rotating like cloud 2. In the vicinity of these extensions there are condensations resembling HH objects

Generation of shockwave and vortex structures at the outflow of a boiling water jet

Science.gov (United States)

Alekseev, M. V.; Lezhnin, S. I.; Pribaturin, N. A.; Sorokin, A. L.

2014-12-01

Results of numerical simulation for shock waves and generation of vortex structures during unsteady outflow of boiling liquid jet are presented. The features of evolution of shock waves and vortex structures formation during unsteady outflow of boiling water are compared with corresponding structures during unsteady gas outflow.

[Surgical treatment of congenital obstruction of the left ventricular outflow tract].

Science.gov (United States)

Biocina, B; Sutlić, Z; Husedinović, I; Letica, D; Sokolić, J

1993-01-01

This report presents the classification and all types of left ventricular outflow tract obstructions. The possibilities of operative therapies are surveyed as well. Results of surgical treatment in 34 patients with obstruction to left ventricular outflow are shown. The majority of patients underwent operation under extracorporeal circulation (84.4%), while the rest were operated by means of the inflow occlusion technique (14.7%). The obtained results were compared with those from the literature. The importance of echocardiographic evaluation of location of the left ventricular outflow tract obstruction and the appropriate choice of a surgical technique according to the patient's age are emphasized.

Silo outflow of soft frictionless spheres

Science.gov (United States)

Ashour, Ahmed; Trittel, Torsten; Börzsönyi, Tamás; Stannarius, Ralf

2017-12-01

Outflow of granular materials from silos is a remarkably complex physical phenomenon that has been extensively studied with simple objects like monodisperse hard disks in two dimensions (2D) and hard spheres in 2D and 3D. For those materials, empirical equations were found that describe the discharge characteristics. Softness adds qualitatively new features to the dynamics and to the character of the flow. We report a study of the outflow of soft, practically frictionless hydrogel spheres from a quasi-2D bin. Prominent features are intermittent clogs, peculiar flow fields in the container, and a pronounced dependence of the flow rate and clogging statistics on the container fill height. The latter is a consequence of the ineffectiveness of Janssen's law: the pressure at the bottom of a bin containing hydrogel spheres grows linearly with the fill height.

Another piece of the puzzle: The fast H I outflow in Mrk 231

Science.gov (United States)

Morganti, Raffaella; Veilleux, Sylvain; Oosterloo, Tom; Teng, Stacy H.; Rupke, David

2016-09-01

We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast H I 21 cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow H I absorption blueshifted ~1300 km s-1 with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15 × 1018Tspin cm-2. We derive the Tspin to lie in the range 400-2000 K and the corresponding H I densities are nHI ~ 10-100 cm-3. Our results complement previous findings and confirm the multiphase nature of the outflow in Mrk 231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the H I outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by Na I and molecular gas in this source. Our results suggest that an H I component is present in fast outflows regardless of the acceleration mechanism (wind vs. jet driven) and that it must be connected with common properties of the pre-interaction gas involved. Considering the observed similarity of their column densities, the H I outflow likely represents the inner part of the broad wind identified on larger scales in atomic Na I. The mass outflow rate of the H I outflow (between 8 and 18 M⊙ yr-1) does not appear to be as large as that observed in molecular gas, partly owing to the smaller sizes of the outflowing region sampled by the H I absorption. These characteristics are commonly seen in other cases of outflows driven by the active galactic nucleus (AGN) suggesting that the H I may represent a short intermediate phase in the rapid cooling of the gas. The results further confirm H I as a good tracer for AGN-driven outflows not only in powerful radio sources. We also obtained deeper continuum

CORONAL MASS EJECTION INDUCED OUTFLOWS OBSERVED WITH HINODE/EIS

International Nuclear Information System (INIS)

Jin, M.; Ding, M. D.; Chen, P. F.; Fang, C.; Imada, S.

2009-01-01

We investigate the outflows associated with two halo coronal mass ejections (CMEs) that occurred on 2006 December 13 and 14 in NOAA 10930, using the Hinode/EIS observations. Each CME was accompanied by an EIT wave and coronal dimmings. Dopplergrams in the dimming regions are obtained from the spectra of seven EIS lines. The results show that strong outflows are visible in the dimming regions during the CME eruption at different heights from the lower transition region to the corona. It is found that the velocity is positively correlated with the photospheric magnetic field, as well as the magnitude of the dimming. We estimate the mass loss based on height-dependent EUV dimmings and find it to be smaller than the CME mass derived from white-light observations. The mass difference is attributed partly to the uncertain atmospheric model, and partly to the transition region outflows, which refill the coronal dimmings.

A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

Energy Technology Data Exchange (ETDEWEB)

Schwarz, Kamber R.; Shirley, Yancy L. [Steward Observatory, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Dunham, Michael M. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

2012-10-01

We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; L{sub int} {<=} 0.1 L{sub Sun }). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D < 400 pc) star-forming regions. Each object was observed in {sup 12}CO and {sup 13}CO J = 2 {yields} 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

International Nuclear Information System (INIS)

Schwarz, Kamber R.; Shirley, Yancy L.; Dunham, Michael M.

2012-01-01

We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; L int ≤ 0.1 L ☉ ). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D 12 CO and 13 CO J = 2 → 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

Interaction of intense ultrashort pulse lasers with clusters

International Nuclear Information System (INIS)

Petrov, G. M.; Davis, J.

2008-01-01

The dynamics of clusters composed of different material irradiated by a high-intensity ultrashort pulse laser was studied using a fully relativistic three-dimensional molecular dynamics model. Key parameters of the cluster evolution such as particle positions, energy absorption, and cluster explosion were simulated. By a direct comparison of these parameters for clusters of equal initial radius but made of different material (deuterium, neon, argon, and xenon), the main stages and attributes of cluster evolution were elucidated. The simulations showed that clusters made of different material act alike, especially those of heavy elements. Clusters made of heavy elements (neon, argon, and xenon) differentiate from clusters made of light elements (deuterium) by the magnitude of the absorbed energy per cluster and the final mean energy of exploding ions. What most distinguishes clusters composed of different material is the amount of emitted radiation and its spectral range

Incision of the Jezero Crater Outflow Channel by Fluvial Sediment Transport

Science.gov (United States)

Holo, S.; Kite, E. S.

2017-12-01

Jezero crater, the top candidate landing site for the Mars 2020 rover, once possessed a lake that over-spilled and eroded a large outflow channel into the Eastern rim. The Western deltaic sediments that would be the primary science target of the rover record a history of lake level, which is modulated by the inflow and outflow channels. While formative discharges for the Western delta exist ( 500 m3/s), little work has been done to see if these flows are the same responsible for outflow channel incision. Other models of the Jezero outflow channel incision assume that a single rapid flood (incision timescales of weeks), with unknown initial hydraulic head and no discharge into the lake (e.g. from the inflow channels or the subsurface), incised an open channel with discharge modulated by flow over a weir. We present an alternate model where, due to an instability at the threshold of sediment motion, the incision of the outflow channel occurs in concert with lake filling. In particular, we assume a simplified lake-channel-valley system geometry and that the channel is hydraulically connected to the filling/draining crater lake. Bed load sediment transport and water discharge through the channel are quantified using the Meyer-Peter and Mueller relation and Manning's law respectively. Mass is conserved for both water and sediment as the lake level rises/falls and the channel incises. This model does not resolve backwater effects or concavity in the alluvial system, but it does capture the non-linear feedbacks between lake draining, erosion rate, channel flow rate, and slope relaxation. We identify controls on incision of the outflow channel and estimate the time scale of outflow channel formation through a simple dynamical model. We find that the observed 300m of channel erosion can be reproduced in decades to centuries of progressive bed load as the delta forming flows fill the lake. This corresponds to time scales on the order of or smaller than the time scale

Shock absorber

International Nuclear Information System (INIS)

Housman, J.J.

1978-01-01

A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

The HST-pNFL program: Mapping the Fluorescent Emission of Galactic Outflows

Science.gov (United States)

Heckman, Timothy

2017-08-01

Galactic outflows associated with star formation are believed to play a crucial role in the evolution of galaxies and the IGM. Most of our knowledge about outflows has come from down-the-barrel UV absorption spectroscopy of star-forming galaxies. However, absorption-line data alone provide only indirect information about the radial structure of the gas flows, which introduces large systematic uncertainties in some of the most important quantities, such as the outflow rate, the mass loading factor, and the momentum, metal, and energy fluxes. Recent spectroscopic observations of star-forming galaxies with large (projected physical) apertures have revealed non-resonant (fluorescent) emission in the UV, e.g., FeII* and SiII*, that can be naturally produced by spatially extended emission from the same outflowing material traced in absorption. Encouraged by the most recent observations of FeII* emission by the SDSS-IV/eBOSS survey (Zhu et al. 2015), we propose a pilot program to use narrow-band filter UVIS F280N images to map the extended FeII* 2626 and 2613 fluorescent emission in a carefully-chosen sample of 4 starburst galaxies at z=0.065, and COS G130M to obtain down-the- barrel spectra for SiII absorption and SiII* emission. This HST pilot program can provide unique information about the spatial structure of galactic outflows and can potentially lead to a revolution in our understanding of outflow physics and its impact on galaxies and the IGM.

Ionized Gas Outflows from the MAGNUM Survey: NGC 1365 and NGC 4945

Energy Technology Data Exchange (ETDEWEB)

Venturi, Giacomo; Marconi, Alessandro [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino (Italy); Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Mingozzi, Matilde [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Carniani, Stefano [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge (United Kingdom); Kavli Institute for Cosmology, University of Cambridge, Cambridge (United Kingdom); Cresci, Giovanni [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Risaliti, Guido [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino (Italy); Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Mannucci, Filippo, E-mail: gventuri@arcetri.astro.it [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy)

2017-11-24

AGN feedback, acting through strong outflows accelerated in the nuclear region of AGN hosts, is invoked as a key ingredient for galaxy evolution by many models to explain the observed BH-galaxy scaling relations. Recently, some direct observational evidence of radiative mode feedback in action has been finally found in quasars at z >1.5. However, it is not possible to study outflows in quasars at those redshifts on small scales (≲100 pc), as spatial information is limited by angular resolution. This is instead feasible in nearby active galaxies, which are ideal laboratories to explore outflow structure and properties, as well as the effects of AGN on their host galaxies. In this proceeding we present preliminary results from the MAGNUM survey, which comprises nearby Seyfert galaxies observed with the integral field spectrograph VLT/MUSE. We focus on two sources, NGC 1365 and NGC 4945, that exhibit double conical outflows extending on distances >1 kpc. We disentangle the dominant contributions to ionization of the various gas components observed in the central ~5.3 kpc of NGC 1365. An attempt to infer outflow 3D structure in NGC 4945 is made via simple kinematic modeling, suggesting a hollow cone geometry.

Brain Circuitry Supporting Multi-Organ Autonomic Outflow in Response to Nausea.

Science.gov (United States)

Sclocco, Roberta; Kim, Jieun; Garcia, Ronald G; Sheehan, James D; Beissner, Florian; Bianchi, Anna M; Cerutti, Sergio; Kuo, Braden; Barbieri, Riccardo; Napadow, Vitaly

2016-02-01

While autonomic outflow is an important co-factor of nausea physiology, central control of this outflow is poorly understood. We evaluated sympathetic (skin conductance level) and cardiovagal (high-frequency heart rate variability) modulation, collected synchronously with functional MRI (fMRI) data during nauseogenic visual stimulation aimed to induce vection in susceptible individuals. Autonomic data guided analysis of neuroimaging data, using a stimulus-based (analysis windows set by visual stimulation protocol) and percept-based (windows set by subjects' ratings) approach. Increased sympathetic and decreased parasympathetic modulation was associated with robust and anti-correlated brain activity in response to nausea. Specifically, greater autonomic response was associated with reduced fMRI signal in brain regions such as the insula, suggesting an inhibitory relationship with premotor brainstem nuclei. Interestingly, some sympathetic/parasympathetic specificity was noted. Activity in default mode network and visual motion areas was anti-correlated with parasympathetic outflow at peak nausea. In contrast, lateral prefrontal cortical activity was anti-correlated with sympathetic outflow during recovery, soon after cessation of nauseogenic stimulation. These results suggest divergent central autonomic control for sympathetic and parasympathetic response to nausea. Autonomic outflow and the central autonomic network underlying ANS response to nausea may be an important determinant of overall nausea intensity and, ultimately, a potential therapeutic target. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Extreme Gaseous Outflows in Radio-Loud Narrow-Line Seyfert 1 Galaxies

Science.gov (United States)

Komossa, S.; Xu, D. W.; Wagner, A. Y.

2018-04-01

We present four radio-loud NLS1 galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km/s, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km/s. An ionization stratification (higher line shift at higher ionization potential) implies that we see a large-scale outflow rather than single, localized jet-cloud interactions. Similarly, the paucity of zero-velocity [OIII]λ5007 emitting gas implies the absence of a second narrow-line region (NLR) component at rest, and therefore a large part of the high-ionization NLR is affected by the outflow. Given the radio loudness of these NLS1 galaxies, the observations are consistent with a pole on view onto their central engines, so that the effects of polar outflows are maximized. In addition, a very efficient driving mechanism is required, to reach the high observed velocities. We explore implications from recent hydrodynamic simulations of the interaction between fast winds or jets with the large-scale NLR. Overall, the best agreement with observations (and especially the high outflow speeds of the [NeV] emitting gas) can be reached if the NLS1 galaxies are relatively young sources with lifetimes not much exceeding 1 Myr. These systems represent sites of strong feedback at NLR scales at work, well below redshift one.

Radio Jets as Driving Mechanism of Fast Outflows: The HI View

NARCIS (Netherlands)

Morganti, Raffaella; Maccagni, Filippo; Oosterloo, Tom; Schulz, Robert; Santoro, Francesco

2017-01-01

The complex and multi-phase nature of gas outflows is one of the properties highlighted by the work in recent years on AGN-driven outflows. In particular, the cold gas is found to play a more important role than previously expected. Surprisingly, HI has been shown to be a good tracer of fast

Misalignment of outflow axes in the proto-multiple systems in Perseus

DEFF Research Database (Denmark)

Lee, Katherine I.; Dunham, Michael M.; Myers, Philip C.

2016-01-01

We investigate the alignment between outflow axes in nine of the youngest binary/multiple systems in the Perseus Molecular Cloud. These systems have typical member spacing larger than 1000 au. For outflow identification, we use 12CO(2-1) and 12CO(3-2) data from a large survey with the Submillimet...

Magnetic Topology and Ion Outflow in Mars' Magnetotail

Science.gov (United States)

Mitchell, D. L.; Xu, S.; McFadden, J. P.; Hara, T.; Luhmann, J. G.; Mazelle, C. X.; Andersson, L.; DiBraccio, G. A.; Connerney, J. E. P.

2017-12-01

Planetary ion outflow down the Martian magnetotail could be an important atmospheric loss mechanism. This process depends on magnetic connectivity to the day-side ionosphere and on acceleration of ions to escape velocity. The Mars Atmosphere and Volatile Evolution (MAVEN) mission has obtained comprehensive ion, electron, and magnetic field data in Mars' magnetotail. The spacecraft is in a 75°-inclination, elliptical orbit that samples altitudes from 150 to 6200 km. As the orbit precesses, it sweeps through the tail at a variety of altitudes in this range. Data from the Solar Wind Electron Analyzer (SWEA) and Magnetometer (MAG) are used to determine the magnetic field topology in the tail at high cadence (every 2-4 seconds), and in particular whether field lines are open, closed, or draped, and if open whether they have access to the day-side or night-side ionosphere. Simultaneous observations by the Supra-Thermal and Thermal Ion Composition (STATIC) instrument and the Langmuir Probe and Waves (LPW) experiment are used to measure the density, composition, and velocity of planetary plasma on these field lines. We find that magnetic topology in the tail is complex and variable, and is influenced by the IMF polarity and the orientation of Mars' crustal magnetic fields with respect to the Sun. We find that planetary ion outflow occurs on both open and draped field lines. On open field lines, outflow tends to occur parallel to the field line, with colder, denser, and slower outflow on field lines connected to the day-side ionosphere (Fig. 1). On these same field lines (after correction for the spacecraft potential) a shift in the position of the He-II photoelectron feature indicates a 1-Volt parallel electric potential directed away from the planet. Except for H+ and occasionally O+, this potential is insufficient by itself to accelerate planetary ions to escape velocity. Outflow is warmer, less dense, and faster moving on draped field lines. In this case, the ion bulk

A POPULATION OF WEAK METAL-LINE ABSORBERS SURROUNDING THE MILKY WAY

International Nuclear Information System (INIS)

Richter, Philipp; Charlton, Jane C.; Fangano, Alessio P. M.; Bekhti, Nadya Ben; Masiero, Joseph R.

2009-01-01

intergalactic medium and satellite galaxies, galactic fountains, and outflows. We speculate that this absorber population represents the local analog of weak Mg II systems that are commonly observed in the circumgalactic environment of low- and high-redshift galaxies.

Ultrafast outflows disappear in high-radiation fields

Science.gov (United States)

Pinto, C.; Alston, W.; Parker, M. L.; Fabian, A. C.; Gallo, L. C.; Buisson, D. J. K.; Walton, D. J.; Kara, E.; Jiang, J.; Lohfink, A.; Reynolds, C. S.

2018-05-01

Ultrafast outflows (UFOs) are the most extreme winds launched by active galactic nuclei (AGN) due to their mildly relativistic speeds (˜0.1-0.3c) and are thought to significantly contribute to galactic evolution via AGN feedback. Their nature and launching mechanism are however not well understood. Recently, we have discovered the presence of a variable UFO in the narrow-line Seyfert 1 IRAS 13224-3809. The UFO varies in response to the brightness of the source. In this work we perform flux-resolved X-ray spectroscopy to study the variability of the UFO and found that the ionization parameter is correlated with the luminosity. In the brightest states the gas is almost completely ionized by the powerful radiation field and the UFO is hardly detected. This agrees with our recent results obtained with principal component analysis. We might have found the tip of the iceberg: the high ionization of the outflowing gas may explain why it is commonly difficult to detect UFOs in AGN and possibly suggest that we may underestimate their actual feedback. We have also found a tentative correlation between the outflow velocity and the luminosity, which is expected from theoretical predictions of radiation-pressure-driven winds. This trend is rather marginal due to the Fe XXV-XXVI degeneracy. Further work is needed to break such degeneracy through time-resolved spectroscopy.

Shock absorbing structure

International Nuclear Information System (INIS)

Kojima, Naoki; Matsushita, Kazuo.

1992-01-01

Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

An absorbing phase transition from a structured active particle phase

Energy Technology Data Exchange (ETDEWEB)

Lopez, Cristobal [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain); Ramos, Francisco [Departamento de Electromagnetismo y Fisica de la Materia and Instituto de Fisica Teorica y Computacional Carlos I, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Hernandez-GarcIa, Emilio [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain)

2007-02-14

In this work we study the absorbing state phase transition of a recently introduced model for interacting particles with neighbourhood-dependent reproduction rates. The novelty of the transition is that as soon as the active phase is reached by increasing a control parameter a periodically arranged structure of particle clusters appears. A numerical study in one and two dimensions shows that the system falls into the directed percolation universality class.

Champagne flutes and brandy snifters: modelling protostellar outflow-cloud chemical interfaces

Science.gov (United States)

Rollins, R. P.; Rawlings, J. M. C.; Williams, D. A.; Redman, M. P.

2014-10-01

A rich variety of molecular species has now been observed towards hot cores in star-forming regions and in the interstellar medium. An increasing body of evidence from millimetre interferometers suggests that many of these form at the interfaces between protostellar outflows and their natal molecular clouds. However, current models have remained unable to explain the origin of the observational bias towards wide-angled `brandy snifter' shaped outflows over narrower `champagne flute' shapes in carbon monoxide imaging. Furthermore, these wide-angled systems exhibit unusually high abundances of the molecular ion HCO+. We present results from a chemodynamic model of such regions where a rich chemistry arises naturally as a result of turbulent mixing between cold, dense molecular gas and the hot, ionized outflow material. The injecta drives a rich and rapid ion-neutral chemistry in qualitative and quantitative agreement with the observations. The observational bias towards wide-angled outflows is explained naturally by the geometry-dependent ion injection rate causing rapid dissociation of CO in the younger systems.

The Lack of Chemical Equilibrium does not Preclude the Use of the Classical Nucleation Theory in Circumstellar Outflows

Science.gov (United States)

Paquette, John A.; Nuth, Joseph A., III

2011-01-01

Classical nucleation theory has been used in models of dust nucleation in circumstellar outflows around oxygen-rich asymptotic giant branch stars. One objection to the application of classical nucleation theory (CNT) to astrophysical systems of this sort is that an equilibrium distribution of clusters (assumed by CNT) is unlikely to exist in such conditions due to a low collision rate of condensable species. A model of silicate grain nucleation and growth was modified to evaluate the effect of a nucleation flux orders of magnitUde below the equilibrium value. The results show that a lack of chemical equilibrium has only a small effect on the ultimate grain distribution.

A young bipolar outflow from IRAS 15398-3359

DEFF Research Database (Denmark)

Bjerkeli, Per; Jørgensen, Jes Kristian; Brinch, Christian

2016-01-01

emission towards IRAS 15398-3359. The lineradiative transfer code LIME is used to construct a full 3D model of thesystem taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ aredetected and shown to trace the motions of the outflow. For CO, thecircumstellar envelope...... and the surrounding cloud also have a profoundimpact on the observed line profiles. N2H+ isdetected in the outflow, but is suppressed towards the central region,perhaps because of the competing reaction between CO andH3+ in the densest regions as well as thedestruction of N2H+ by CO.N2D+ is detected in a ridge south...

X-ray evidence for ultra-fast outflows in AGNs

Science.gov (United States)

Tombesi, Francesco; Sambruna, Rita; Braito, Valentina; Reeves, James; Reynolds, Christopher; Cappi, Massimo

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 radio galaxies observed with XMM-Newton and Suzaku. We assessed the global detection significance of the absorption lines and performed a detailed photo-ionization modeling. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1} and the associated mechanical power is high, in the range ˜10^{43}--10^{45} erg/s. Therefore, UFOs are capable to provide a significant contribution to the AGN cosmological feedback and their study can provide important clues on the connection between accretion disks, winds and jets.

Financial Crisis, Capital Outflows, and Policy Responses: Examples from East Asia

Science.gov (United States)

Rajan, Ramkishen S.

2007-01-01

Financial crises seem to have become the norm rather than the exception since 1992. The author examines the impact of a crisis of confidence and resultant capital outflows from a small and open economy and the possible policy options in response to such outflows, using simple tools and definitions that will be familiar to any money and banking or…

THE SINS/zC-SINF SURVEY of z {approx} 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES

Energy Technology Data Exchange (ETDEWEB)

Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Foerster-Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr.1, D-85748 Garching (Germany); Griffin, Kristen Shapiro [Space Sciences Research Group, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Mancini, Chiara; Renzini, Alvio [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, Padova, I-35122 (Italy); Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich, CH-8093 (Switzerland); Bouche, Nicolas [Institut de Recherche en Astrophysique et Planetologie (IRAP), Universite de Toulouse, UPS-OMP, IRAP, 14, avenue Edouard Berlin, F-31400 Toulouse (France); Burkert, Andreas [Department fuer Physik, Universitaets-Sternwarte Ludwig-Maximilians-Universitaet (USM), Scheinerstr. 1, Muenchen, D-81679 (Germany); Cresci, Giovanni [Istituto Nazionale di AstrofisicaOsservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Genel, Shy [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hicks, Erin K. S. [Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580 (United States); Naab, Thorsten, E-mail: sfnewman@berkeley.edu [Max-Planck Institute for Astrophysics, Karl Schwarzschildstrasse 1, D-85748 Garching (Germany); and others

2012-12-10

Using SINFONI H{alpha}, [N II], and [S II] AO data of 27 z {approx} 2 star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, we explore the dependence of outflow strength (via the broad flux fraction) on various galaxy parameters. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius ({approx}a few kpc). Decomposition of the [S II] doublet into broad and narrow components suggests that this outflowing gas probably has a density of {approx}10-100 cm{sup -3}, less than that of the star-forming gas (600 cm{sup -3}). There is a strong correlation of the H{alpha} broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 M{sub Sun} yr{sup -1} kpc{sup -2}. Above this threshold, we find that SFGs with log m{sub *} > 10 have similar or perhaps greater wind mass-loading factors ({eta} = M-dot{sub out}/SFR) and faster outflow velocities than lower mass SFGs, suggesting that the majority of outflowing gas at z {approx} 2 may derive from high-mass SFGs. The mass-loading factor is also correlated with the star formation rate (SFR), galaxy size, and inclination, such that smaller, more star-forming, and face-on galaxies launch more powerful outflows. We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk.

Delayed or No Feedback? Gas Outflows in Type 2 AGNs. III

Energy Technology Data Exchange (ETDEWEB)

Woo, Jong-Hak; Son, Donghoon; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr, E-mail: hjbae@galaxy.yonsei.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

2017-04-20

We present gas kinematics based on the [O iii] λ 5007 line and their connection to galaxy gravitational potential, active galactic nucleus (AGN) energetics, and star formation, using a large sample of ∼110,000 AGNs and star-forming (SF) galaxies at z < 0.3. Gas and stellar velocity dispersions are comparable to each other in SF galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. In contrast, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. The [O iii] velocity–velocity dispersion (VVD) diagram dramatically expands toward high values as a function of AGN luminosity, implying that the outflows are AGN-driven, while SF galaxies do not show such a trend. We find that the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [O iii] profile. AGNs with strong outflow signatures show on average similar specific star formation rates (sSFRs) to those of star-forming galaxies. In contrast, AGNs with weak or no outflows have an order of magnitude lower sSFRs, suggesting that AGNs with current strong outflows do now show any negative AGN feedback and that it may take dynamical time to impact on star formation over galactic scales.

Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics

Science.gov (United States)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

2012-05-01

Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ˜0.0003-0.03 pc (˜ 102-104rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ˜0.01 and 1 M⊙ yr-1, corresponding to >rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log? 42.6-44.6 erg s-1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies.

Ionized Gas Outflows from the MAGNUM Survey: NGC 1365 and NGC 4945

Directory of Open Access Journals (Sweden)

Giacomo Venturi

2017-11-01

Full Text Available AGN feedback, acting through strong outflows accelerated in the nuclear region of AGN hosts, is invoked as a key ingredient for galaxy evolution by many models to explain the observed BH-galaxy scaling relations. Recently, some direct observational evidence of radiative mode feedback in action has been finally found in quasars at z >1.5. However, it is not possible to study outflows in quasars at those redshifts on small scales (≲100 pc, as spatial information is limited by angular resolution. This is instead feasible in nearby active galaxies, which are ideal laboratories to explore outflow structure and properties, as well as the effects of AGN on their host galaxies. In this proceeding we present preliminary results from the MAGNUM survey, which comprises nearby Seyfert galaxies observed with the integral field spectrograph VLT/MUSE. We focus on two sources, NGC 1365 and NGC 4945, that exhibit double conical outflows extending on distances >1 kpc. We disentangle the dominant contributions to ionization of the various gas components observed in the central ~5.3 kpc of NGC 1365. An attempt to infer outflow 3D structure in NGC 4945 is made via simple kinematic modeling, suggesting a hollow cone geometry.

Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel

Science.gov (United States)

Veilleux, S.; Melendez, M.; Sturm, E.; Garcia-Carpio, J.; Fischer, J.; Gonzalez-Alfonso, E.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.;

The dependence of galactic outflows on the properties and orientation of zCOSMOS galaxies at z ∼ 1

International Nuclear Information System (INIS)

Bordoloi, R.; Lilly, S. J.; Hardmeier, E.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Fevre, O. Le; Garilli, B.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Zamorani, G.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Caputi, K.; Cucciati, O.; De la Torre, S.; De Ravel, L.; Iovino, A.

2014-01-01

We present an analysis of cool outflowing gas around galaxies, traced by Mg II absorption lines in the coadded spectra of a sample of 486 zCOSMOS galaxies at 1 ≤ z ≤ 1.5. These galaxies span a range of stellar masses (9.45 ≤ log 10 [M * /M ☉ ] ≤ 10.7) and star formation rates (0.14 ≤ log 10 [SFR/M ☉ yr –1 ] ≤ 2.35). We identify the cool outflowing component in the Mg II absorption and find that the equivalent width of the outflowing component increases with stellar mass. The outflow equivalent width also increases steadily with the increasing star formation rate of the galaxies. At similar stellar masses, the blue galaxies exhibit a significantly higher outflow equivalent width as compared to red galaxies. The outflow equivalent width shows strong correlation with the star formation surface density (Σ SFR ) of the sample. For the disk galaxies, the outflow equivalent width is higher for the face-on systems as compared to the edge-on ones, indicating that for the disk galaxies, the outflowing gas is primarily bipolar in geometry. Galaxies typically exhibit outflow velocities ranging from –150 km s –1 ∼–200 km s –1 and, on average, the face-on galaxies exhibit higher outflow velocity as compared to the edge-on ones. Galaxies with irregular morphologies exhibit outflow equivalent width as well as outflow velocities comparable to face on disk galaxies. These galaxies exhibit mass outflow rates >5-7 M ☉ yr –1 and a mass loading factor (η = M-dot out /SFR) comparable to the star formation rates of the galaxies.

FEATURES OF OUTFLOW OF INTRAOCULAR LIQUID AFTER AN EKSIMERLAZER SKLEREKTOMY (PILOT STUDY

Directory of Open Access Journals (Sweden)

E. A. Korchuganova

2017-01-01

Full Text Available Modern approaches to surgical glaucoma treatment is based on the safe and effective methods. In recent years, great attention is paid to the techniques of stimulating uveoscleral path outtake aqueous humor from the eye. Uveoscleral space in the extended outflow pathways is dominant and constitutes about 72%. Sclera is a field of the greatest interest, as the end stages of the outflow of aqueous humor via the uveoscleral path. The aim of the study was to investigate the influence of excimer laser sclerectomy on the drainage function of the eye and development of a mathematical model based on the permeability of the sclera of the amount of laser ablation at a defined area of laser exposure and the level of IOP. Studies were conducted on 12 human cadaver eyes isolated person. The domestic excimer laser “MicroScan Vizum” with a wavelength of 193нм (0,193 µm was used for the thinning of sclera. In the experiment used a special computer program provided ablation of scleral tissue, the scleral bed forming a rectangular shape with a size 7,0x5,0 mm. the Depth of influence started from 100 microns to 600 microns in increments of 50 µn. The exposure was carried out at a constant perfusion pressure of 25 mm Hg After each impact was measured of the coefficient ease the outflow. A correlation was established between the factor and effective features, i.e., between the excimer laser deep sclerectomy (µm and ratio of lightness outflow (mm3/min/mm Hg.St. Thinning of the sclera leads to an improvement of its permeability and increasing the coefficient ease the outflow. A mathematical model, allowing to achieve the desired ratio of lightness outflow experiment by excimer laser sclerectomy was developed. The mathematical model has the form of the regression equation.The sclera is a promising object for further developments in the surgical treatment of glaucoma. Laser ablation of the sclera leads to an improvement of outflow via the uveoscleral path and

The Gaseous Environments of Quasars: Outflows, Feedback & Cold Mode Accretion

Science.gov (United States)

Chen, Chen; Hamann, Fred

2018-06-01

The early stages of massive galaxy evolution can involve galaxy-scale outflows driven by a starburst or a central quasar and cold-mode accretion (infall) that adds to the mass buildup in the galaxies. I will describe three related studies that use quasar absorption lines to measure outflows, infall, and the general gaseous environments of quasars across a range of spatial scales. The three studies are: 1) High-resolution spectroscopy with Keck-HIRES and VLT-UVES to study associated absorption lines (AALs) that have redshifts greater than the emission redshifts indicating infall and/or rich multi-component AAL complexes that might be interstellar clouds in the host galaxies that have been shredded and dispersed by a fast unseen quasar-driven wind. The data provide strong constraints on the gas kinematics, spatial structure, column densities, metallicities, and energetics. 2) A complete inventory of high-velocity CIV 1548,1550 mini-BAL outflows in quasars using high-resolution high signal-to-noise spectra in the public VLT-UVES and Keck-HIRES archives. This sensitive mini-BAL survey fills an important niche between previous work on narrow absorption lines (NALs) and the much-studied broad absorption lines (BALs) to build a more complete picture of quasar outflows. I will report of the mini-BAL statistics, the diversity of lines detected, and some tests for correlations with the quasar properties. We find, for example, that mini-BALs at v > 4000 km/s in at least 10% of 511 quasars studied, including 1% at v > 0.1 c. Finally, 3) Use the much larger database of NALs measured in 262,449 BOSS quasars by York et al. (in prep.) to study their potential relationships to the quasars and, specifically, their origins in quasar outflows. This involves primarily comparisons of the incidence and properties of NALs at different velocity shifts to other measured properties of the quasars such as BAL outflows, emission line characteristics, radio-loudness, and red colors. We find

The effect of outflowing water coolant with supercritical parameters on a barrier

Directory of Open Access Journals (Sweden)

Alekseev Maksim

2017-01-01

Full Text Available The outflow of supercritical coolant with different initial parameters and its impact on the barrier have been numerically simulated. Spatial and axial distributions of pressure and steam quality are presented. The force acting on the barrier at different parameters of the outflow has been calculated.

Absorbing Property of Multi-layered Short Carbon Fiber Absorbing Coating

OpenAIRE

Liu, Zhaohui; Tao, Rui; Ban, Guodong; Luo, Ping

2018-01-01

The radar absorbing coating was prepared with short carbon fiber asabsorbent and waterborne polyurethane (WPU) as matrix resin. The coating’s absorbing property was tested with vectornetwork analyzer, using aramid honeycomb as air layer which was matched withcarbon fiber coating. The results demonstrate that the single-layered carbonfiber absorbing coating presented relatively poor absorbing property when thelayer was thin, and the performance was slightly improved after the matched airlayer ...

Quenching star formation with quasar outflows launched by trapped IR radiation

Science.gov (United States)

Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

2018-06-01

We present cosmological radiation-hydrodynamic simulations, performed with the code RAMSES-RT, of radiatively-driven outflows in a massive quasar host halo at z = 6. Our simulations include both single- and multi-scattered radiation pressure on dust from a quasar and are compared against simulations performed with thermal feedback. For radiation pressure-driving, we show that there is a critical quasar luminosity above which a galactic outflow is launched, set by the equilibrium of gravitational and radiation forces. While this critical luminosity is unrealistically high in the single-scattering limit for plausible black hole masses, it is in line with a ≈ 3 × 10^9 M_⊙ black hole accreting at its Eddington limit, if infrared (IR) multi-scattering radiation pressure is included. The outflows are fast (v ≳ 1000 km s^{-1}) and strongly mass-loaded with peak mass outflow rates ≈ 10^3 - 10^4 M_⊙ yr^{-1}, but short-lived (star formation in the bulge. We hence argue that radiation pressure-driven feedback may be an important ingredient in regulating star formation in compact starbursts, especially during the quasar's `obscured' phase.

Long-Term Results of Stent Placement in Patients with Outflow Block After Living-Donor-Liver Transplantation

Energy Technology Data Exchange (ETDEWEB)

Fujimori, Masashi, E-mail: fujimorim@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Department of Radiology (Japan); Yamakado, Koichiro, E-mail: yamakado47@gmail.com; Takaki, Haruyuki, E-mail: takaki-h@clin.medic.mie-u.ac.jp [Hyogo College of Medicine, Department of Radiology (Japan); Nakatsuka, Atsuhiro, E-mail: nakatuka@clin.medic.mie-u.ac.jp; Uraki, Junji, E-mail: junji@clin.medic.mie-u.ac.jp; Yamanaka, Takashi, E-mail: t-yama@clin.medic.mie-u.ac.jp; Hasegawa, Takaaki, E-mail: hasegawat@clin.medic.mie-u.ac.jp; Sugino, Yuichi, E-mail: ysugino23@clin.medic.mie-u.ac.jp; Nakajima, Ken, E-mail: k-nakajima@clin.medic.mie-u.ac.jp; Matsushita, Naritaka, E-mail: n-matsushita@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Department of Radiology (Japan); Mizuno, Shugo, E-mail: mizunos@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Hepatobiliary Pancreatic and Transplant Surgery (Japan); Sakuma, Hajime, E-mail: sakuma.mie@gmail.com [Mie University School of Medicine, Department of Radiology (Japan); Isaji, Shuji, E-mail: isaji-s@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Hepatobiliary Pancreatic and Transplant Surgery (Japan)

2016-04-15

PurposeTo evaluate long-term results of stent placement retrospectively in patients with outflow block after living-donor-liver transplantation (LDLT).Materials and MethodsFor this institutional review board approved retrospective study conducted during 2002–2012, stents were placed in outflow veins in 15 patients (11.3 %, 15/133) (12 men; 3 female) in whom outflow block developed after LDLT. Their mean age was 52.3 years ± 15.3 (SD) (range, 4–69 years). Venous stenosis with a pressure gradient ≥5 mmHg (outflow block) was observed in the inferior vena cava in seven patients, hepatic vein in seven patients, and both in one patient. Technical success, change in a pressure gradient and clinical manifestations, and complications were evaluated. Overall survival of 15 patients undergoing outflow block stenting was compared with that of 116 patients without outflow block after LDLT.ResultsStents were placed across the outflow block veins without complications, lowering the pressure gradient ≤ 3 mmHg in all patients (100 %, 15/15). Clinical manifestations improved in 11 patients (73.3 %, 11/15), and all were discharged from the hospital. However, they did not improve in the other 4 patients (26.7 %, 4/15) who died in the hospital 1.0–3.7 months after stenting (mean, 2.0 ± 1.2 months). No significant difference in 5-year survival rates was found between patients with and without outflow block after LDLT (61.1 vs. 72.2 %, p = .405).ConclusionStenting is a feasible, safe, and useful therapeutic option to resolve outflow block following LDLT, providing equal survival to that of patients without outflow block.

Reconstructing Global-scale Ionospheric Outflow With a Satellite Constellation

Science.gov (United States)

Liemohn, M. W.; Welling, D. T.; Jahn, J. M.; Valek, P. W.; Elliott, H. A.; Ilie, R.; Khazanov, G. V.; Glocer, A.; Ganushkina, N. Y.; Zou, S.

2017-12-01

The question of how many satellites it would take to accurately map the spatial distribution of ionospheric outflow is addressed in this study. Given an outflow spatial map, this image is then reconstructed from a limited number virtual satellite pass extractions from the original values. An assessment is conducted of the goodness of fit as a function of number of satellites in the reconstruction, placement of the satellite trajectories relative to the polar cap and auroral oval, season and universal time (i.e., dipole tilt relative to the Sun), geomagnetic activity level, and interpolation technique. It is found that the accuracy of the reconstructions increases sharply from one to a few satellites, but then improves only marginally with additional spacecraft beyond 4. Increased dwell time of the satellite trajectories in the auroral zone improves the reconstruction, therefore a high-but-not-exactly-polar orbit is most effective for this task. Local time coverage is also an important factor, shifting the auroral zone to different locations relative to the virtual satellite orbit paths. The expansion and contraction of the polar cap and auroral zone with geomagnetic activity influences the coverage of the key outflow regions, with different optimal orbit configurations for each level of activity. Finally, it is found that reconstructing each magnetic latitude band individually produces a better fit to the original image than 2-D image reconstruction method (e.g., triangulation). A high-latitude, high-altitude constellation mission concept is presented that achieves acceptably accurate outflow reconstructions.

The outflows accelerated by the magnetic fields and radiation force of accretion disks

Energy Technology Data Exchange (ETDEWEB)

Cao, Xinwu, E-mail: cxw@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 (China)

2014-03-01

The inner region of a luminous accretion disk is radiation-pressure-dominated. We estimate the surface temperature of a radiation-pressure-dominated accretion disk, Θ=c{sub s}{sup 2}/r{sup 2}Ω{sub K}{sup 2}≪(H/r){sup 2}, which is significantly lower than that of a gas-pressure-dominated disk, Θ ∼ (H/r){sup 2}. This means that the outflow can be launched magnetically from the photosphere of the radiation-pressure-dominated disk only if the effective potential barrier along the magnetic field line is extremely shallow or no potential barrier is present. For the latter case, the slow sonic point in the outflow will probably be in the disk, which leads to a slow circular dense flow above the disk. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that the relativistic jets are related to hot plasma in some X-ray binaries and active galactic nuclei. We investigate the outflows accelerated from the hot corona above the disk by the magnetic field and radiation force of the accretion disk. We find that with the help of the radiation force, the mass loss rate in the outflow is high, which leads to a slow outflow. This may be why the jets in radio-loud narrow-line Seyfert galaxies are in general mildly relativistic compared with those in blazars.

Atmospheric outflow of nutrients to the Bay of Bengal: Impact of anthropogenic sources..

Digital Repository Service at National Institute of Oceanography (India)

Srinivas, B.; Sarin, M.M.; Sarma, V.V.S.S.

outflow show pronounced temporal variability. The inorganic nitrogen (NH4 + -N: ~90% of NInorg) dominates the total soluble nitrogen (NTot). Although the contribution of organic nitrogen is not significant, the mass ratio of NOrg/NTotin the outflow varied...

X-ray evidence for ultra-fast outflows in Seyfert galaxies

Science.gov (United States)

Tombesi, Francesco; Braito, Valentina; Reeves, James; Cappi, Massimo; Dadina, Mauro

2012-07-01

X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts observed with XMM-Newton. Similar results are also obtained from a Suzaku analysis of 5 radio galaxies. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1}. The associated mechanical power is also high, in the range ˜10^{43}--10^{45} erg/s, which indicates that UFOs are capable to provide a significant contribution to the AGN cosmological feedback.

A Massive X-ray Outflow From The Quasar PDS 456

Science.gov (United States)

Reeves, J. N.; O'Brien, P. T.; Ward, M. J.

2003-01-01

We report on XMM-Newton spectroscopic observations of the luminous, radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, which can be attributed to a series of blue-shifted K-shell absorption edges due to highly ionized iron. The higher resolution soft X-ray grating RGS spectrum exhibits a broad absorption line feature near 1 keV, which can be modeled by a blend of L-shell transitions from highly ionized iron (Fe XVII - XXIV). An extreme outflow velocity of approx. 50000 km/s is required to model the K and L shell iron absorption present in the XMM-Newton data. Overall, a large column density (N(sub H) = 5 x 10(exp 23)/sq cm) of highly ionized gas (log xi = 2.5) is required in PDS 456. A large mass outflow rate of approx. 10 solar mass/year (assuming a conservative outflow covering factor of 0.1 steradian) is derived, which is of the same order as the overall mass accretion rate in PDS 456. This represents a substantial fraction (approx. 10%) of the quasar energy budget, whilst the large column and outflow velocity place PDS 456 towards the extreme end of the broad absorption line quasar population.

Energetic molecular outflow near AFGL 961: millimeter-wave and infrared observations

International Nuclear Information System (INIS)

Lada, C.J.; Gautier, T.N. III

1982-01-01

We report detailed millimeter-wave and near-infrared spectroscopy of the dynamically active region around the infrared source AFGL 961, near the Rosette nebula. Millimeter-wave 12 CO observations are used to study the high-velocity molecular flow around AFGL 961. These observations show that the high-velocity flow has a maximum extent of at least 6' or 2.9 pc at the distance of AFGL 961. The flow is found to be anisotropic, with redshifted high-velocity emission considerably more extended than blueshifted high-velocity emission. However, the flow does not appear to be as highly collimated as some other sources of high-velocity bipolar outflow. We also find the emission profiles to be asymmetric in velocity such that the integrated intensity of the redshifted high-velocity emission is on average 2.5 times greater than that of the blueshifted emission. The mass of the gas involved in the flow is determined to be approximately 19 M/sub sun/, and the kinetic energy of this gas is estimated to be about 8 x 10 46 ergs. These observations are interpreted as evidence that an energetic bipolar outflow of molecular gas is occurring near AFGL 961. The momentum of the outflowing molecular gas is large, and it is shown that this places strong constraints on possible physical mechanisms which may be driving the outflow. The near-infrared spectrum of AFGL 961 from 1.4-2.4 μm was obtained in order to study the conditions immediately around the infrared source which may be driving the molecular outflow

Soft X-ray Emission from Large-Scale Galactic Outflows in Seyfert Galaxies

Science.gov (United States)

Colbert, E. J. M.; Baum, S.; O'Dea, C.; Veilleux, S.

1998-01-01

Kiloparsec-scale soft X-ray nebulae extend along the galaxy minor axes in several Seyfert galaxies, including NGC 2992, NGC 4388 and NGC 5506. In these three galaxies, the extended X-ray emission observed in ROSAT HRI images has 0.2-2.4 keV X-ray luminosities of 0.4-3.5 x 10(40) erg s(-1) . The X-ray nebulae are roughly co-spatial with the large-scale radio emission, suggesting that both are produced by large-scale galactic outflows. Assuming pressure balance between the radio and X-ray plasmas, the X-ray filling factor is >~ 10(4) times as large as the radio plasma filling factor, suggesting that large-scale outflows in Seyfert galaxies are predominantly winds of thermal X-ray emitting gas. We favor an interpretation in which large-scale outflows originate as AGN-driven jets that entrain and heat gas on kpc scales as they make their way out of the galaxy. AGN- and starburst-driven winds are also possible explanations if the winds are oriented along the rotation axis of the galaxy disk. Since large-scale outflows are present in at least 50 percent of Seyfert galaxies, the soft X-ray emission from the outflowing gas may, in many cases, explain the ``soft excess" X-ray feature observed below 2 keV in X-ray spectra of many Seyfert 2 galaxies.

Spectroscopic Observations of the Outflowing Wind in the Lensed Quasar SDSS J1001+5027

Science.gov (United States)

Misawa, Toru; Inada, Naohisa; Oguri, Masamune; Charlton, Jane C.; Eracleous, Michael; Koyamada, Suzuka; Itoh, Daisuke

2018-02-01

We performed spectroscopic observations of the small-separation lensed quasar SDSS J1001+5027, whose images have an angular separation θ =2\\buildrel{\\prime\\prime}\\over{.} 86, and placed constraints on the physical properties of gas clouds in the vicinity of the quasar (i.e., in the outflowing wind launched from the accretion disk). The two cylinders of sight to the two lensed images go through the same region of the outflowing wind and they become fully separated with no overlap at a very large distance from the source (∼330 pc). We discovered a clear difference in the profile of the C IV broad absorption line (BAL) detected in the two lensed images in two observing epochs. Because the kinematic components in the BAL profile do not vary in concert, the observed variations cannot be reproduced by a simple change of ionization state. If the variability is due to gas motion around the background source (i.e., the continuum source), the corresponding rotational velocity is {v}rot} ≥ 18,000 km s‑1, and their distance from the source is r≤slant 0.06 pc assuming Keplerian motion. Among three Mg II and three C IV NAL systems that we detected in the spectra, only the Mg II system at {z}abs} = 0.8716 shows a hint of variability in its Mg I profile on a rest-frame timescale of {{Δ }}{t}rest} ≤slant 191 days and an obvious velocity shear between the sightlines whose physical separation is ∼7 kpc. We interpret this as the result of motion of a cosmologically intervening absorber, perhaps located in a foreground galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Large sea ice outflow into the Nares Strait in 2007

DEFF Research Database (Denmark)

Kwok, R.; Pedersen, L.T.; Gudmandsen, Preben

2010-01-01

Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea...... at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin...... ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 x 10(3) km(2) and 254 km(3) are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents similar to 10% of our estimates of the mean ice export...

Fluid outflows from Venus impact craters - Analysis from Magellan data

Science.gov (United States)

Asimow, Paul D.; Wood, John A.

1992-01-01

Many impact craters on Venus have unusual outflow features originating in or under the continuous ejecta blankets and continuing downhill into the surrounding terrain. These features clearly resulted from flow of low-viscosity fluids, but the identity of those fluids is not clear. In particular, it should not be assumed a priori that the fluid is an impact melt. A number of candidate processes by which impact events might generate the observed features are considered, and predictions are made concerning the rheological character of flows produce by each mechanism. A sample of outflows was analyzed using Magellan images and a model of unconstrained Bingham plastic flow on inclined planes, leading to estimates of viscosity and yield strength for the flow materials. It is argued that at least two different mechanisms have produced outflows on Venus: an erosive, channel-forming process and a depositional process. The erosive fluid is probably an impact melt, but the depositional fluid may consist of fluidized solid debris, vaporized material, and/or melt.

Geometry of anisotropic CO outflows

International Nuclear Information System (INIS)

Liseau, R.; Sandell, G.; Helsinki Univ., Observatory, Finland)

1986-01-01

A simple geometrical model for the space motions of the bipolar high-velocity CO outflows in regions of recent, active star formation is proposed. It is assumed that the velocity field of the neutral gas component can be represented by large-scale uniform motions. From observations of the spatial distribution and from the characteristics of the line shape of the high-velocity molecular gas emission the geometry of the line-emitting regions can be inferred, i.e., the direction in space and the collimating angle of the flow. The model has been applied to regions where a check on presently obtained results is provided by independent optical determinations of the motions of Herbig-Haro objects associated with the CO flows. These two methods are in good agreement and, furthermore, the results obtained provide convincingly strong evidence for the physical association of CO outflows and Herbig-Haro objects. This also supports the common view that a young stellar central source is responsible for the active phenomena observed in its environmental neighborhood. It is noteworthy that within the framework of the model the determination of the flow geometry of the high-velocity gas from CO measurements is independent of the distance to the source and, furthermore, can be done at relatively low spatial resolution. 32 references

Rapid growth of black holes accompanied with hot or warm outflows exposed to anisotropic super-Eddington radiation

Science.gov (United States)

Takeo, Eishun; Inayoshi, Kohei; Ohsuga, Ken; Takahashi, Hiroyuki R.; Mineshige, Shin

2018-05-01

We perform two-dimensional radiation hydrodynamical simulations of accretion flows on to a black hole (BH) with a mass of 103 ≤ MBH/ M⊙ ≲ 106 in order to study rapid growth of BHs in the early Universe. For spherically symmetric flows, hyper-Eddington accretion from outside the Bondi radius can occur unimpeded by radiation feedback when MBH ≳ 104 M⊙(n∞/105 cm - 3) - 1(T∞/104 K)3/2, where the density and temperature of ambient gas are initially set to n∞ = 105 cm-3 and T∞ = 104 K. Here, we study accretion flows exposed to anisotropic radiation from a nuclear accretion disc with a luminosity higher than the Eddington value (LEdd) due to collimation towards the bipolar directions. We find that, unlike the spherically symmetric case, even less massive BHs with MBH ionized regions expand towards the poles producing hot outflows with T ˜ 105 K. For more massive BHs with MBH ≳ 5 × 105 M⊙, intense inflows of neutral gas through the equator totally cover the central radiating region due to the non-radial gas motions. Because of efficient recombination by hydrogen, the entire flow settles in neutral and warm gas with T ≃ 8000 K. The BH is fed at a rate of ˜5 × 104LEdd/c2 (a half of the inflow rate from the Bondi radius). Moreover, radiation momentum absorbed by neutral hydrogen produces warm outflows towards the bipolar directions at ˜ 10 per cent of the BH feeding rate and with a velocity several times higher than the escaping value.

Method of absorbing UF6 from gaseous mixtures in alkamine absorbents

International Nuclear Information System (INIS)

Lafferty, R.H.; Smiley, S.H.; Radimer, K.J.

1976-01-01

A method is described for recovering UF 6 from gaseous mixtures by absorption in a liquid. The liquid absorbent must have a relatively low viscosity and at least one component of the absorbent is an alkamine having less than 3 carbon atoms bonded to the amino nitrogen, less than 2 of the carbon atoms other than those bonded to the amino nitrogen are free of the hydroxy radical and precipitate the absorbed uranium from the absorbent. At least one component of the absorbent is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2

Discrete potentials guided radiofrequency ablation for idiopathic outflow tract ventricular arrhythmias.

Science.gov (United States)

Liu, Enzhao; Xu, Gang; Liu, Tong; Ye, Lan; Zhang, Qitong; Zhao, Yanshu; Li, Guangping

2015-03-01

Discrete potentials (DPs) have been recorded and targeted as the site of ablation of the outflow tract arrhythmias. The aim of the present study was to investigate the significance of DPs with respect to mapping and ablation for idiopathic outflow tract premature ventricular contractions (PVCs) or ventricular tachycardias (VTs). Seventeen consecutive patients with idiopathic right or left ventricular outflow tract PVCs/VTs who underwent radiofrequency catheter ablation were included. Intracardiac electrograms during the mapping and ablation were analysed. During sinus rhythm, sharp high-frequency DPs that displayed double or multiple components were recorded following or buried in the local ventricular electrograms in all of the 17 patients, peak amplitude 0.51 ± 0.21 mV. The same potential was recorded prior to the local ventricular potential of the PVCs/VTs. Spontaneous reversal of the relationship of the DPs to the local ventricular electrogram during the arrhythmias was noted. The DPs were related to a region of low voltage showed by intracardiac high-density contact mapping. At the sites with DPs, lower unipolar and bipolar ventricular voltage of sinus beats were noted compared with the adjacent regions without DPs (unipolar: 6.1 ± 1.8 vs. 8.3 ± 2.3 mV, P Discrete potentials were not present in seven controls. Discrete potentials and related low-voltage regions were common in idiopathic outflow tract ventricular arrhythmias. Discrete potential- and substrate-guided ablation strategy will help to reduce the recurrence of idiopathic outflow tract arrhythmias. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Turbulent mixing layers in supersonic protostellar outflows, with application to DG Tauri

Science.gov (United States)

White, M. C.; Bicknell, G. V.; Sutherland, R. S.; Salmeron, R.; McGregor, P. J.

2016-01-01

Turbulent entrainment processes may play an important role in the outflows from young stellar objects at all stages of their evolution. In particular, lateral entrainment of ambient material by high-velocity, well-collimated protostellar jets may be the cause of the multiple emission-line velocity components observed in the microjet-scale outflows driven by classical T Tauri stars. Intermediate-velocity outflow components may be emitted by a turbulent, shock-excited mixing layer along the boundaries of the jet. We present a formalism for describing such a mixing layer based on Reynolds decomposition of quantities measuring fundamental properties of the gas. In this model, the molecular wind from large disc radii provides a continual supply of material for entrainment. We calculate the total stress profile in the mixing layer, which allows us to estimate the dissipation of turbulent energy, and hence the luminosity of the layer. We utilize MAPPINGS IV shock models to determine the fraction of total emission that occurs in [Fe II] 1.644 μm line emission in order to facilitate comparison to previous observations of the young stellar object DG Tauri. Our model accurately estimates the luminosity and changes in mass outflow rate of the intermediate-velocity component of the DG Tau approaching outflow. Therefore, we propose that this component represents a turbulent mixing layer surrounding the well-collimated jet in this object. Finally, we compare and contrast our model to previous work in the field.

GAS OUTFLOWS IN SEYFERT GALAXIES: EFFECTS OF STAR FORMATION VERSUS AGN FEEDBACK

Energy Technology Data Exchange (ETDEWEB)

Melioli, C.; Pino, E. M. de Gouveia Dal, E-mail: claudio.melioli@iag.usp.br, E-mail: dalpino@iag.usp.br [Department of Astronomy (IAG-USP), University of Sao Paulo (Brazil)

2015-10-20

Large-scale, weakly collimated outflows are very common in galaxies with large infrared luminosities. In complex systems in particular, where intense star formation (SF) coexists with an active galactic nucleus (AGN), it is not clear yet from observations whether the SF, the AGN, or both are driving these outflows. Accreting supermassive black holes are expected to influence their host galaxies through kinetic and radiative feedback processes, but in a Seyfert galaxy, where the energy emitted in the nuclear region is comparable to that of the body of the galaxy, it is possible that stellar activity is also playing a key role in these processes. In order to achieve a better understanding of the mechanisms driving the gas evolution especially at the nuclear regions of these galaxies, we have performed high-resolution three-dimensional hydrodynamical simulations with radiative cooling considering the feedback from both SF regions, including supernova (Type I and II) explosions and an AGN jet emerging from the central region of the active spiral galaxy. We computed the gas mass lost by the system, separating the role of each of these injection energy sources on the galaxy evolution, and found that at scales within 1 kpc an outflow can be generally established considering intense nuclear SF only. The jet alone is unable to drive a massive gas outflow, although it can sporadically drag and accelerate clumps of the underlying outflow to very high velocities.

Atmospheric transport and outflow of polycyclic aromatic hydrocarbons from China

Energy Technology Data Exchange (ETDEWEB)

Chang Lang; Shu Tao; Wenxin Liu; Yanxu Zhang; Staci Simonich [Peking University, Beijing (China). Laboratory for Earth Surface Processes, College of Environmental Sciences

2008-07-15

A potential receptor influence function (PRIF) model, based on air mass forward trajectory calculations, was applied to simulate the atmospheric transport and outflow of polycyclic aromatic hydrocarbons (PAHs) emitted from China. With a 10 day atmospheric transport time, most neighboring countries and regions, as well as remote regions, were influenced by PAH emissions from China. Of the total annual PAH emission of 114 Gg, 92.7% remained within the boundary of mainland China. The geographic distribution of PRIFs within China was similar to the geographic distribution of the source regions, with high values in the North China Plain, Sichuan Basin, Shanxi, and Guizhou province. The Tarim basin and Sichuan basin had unfavorable meteorological conditions for PAH outflow. Of the PAH outflow from China (8092 tons or 7.1% of the total annual PAH emission), approximately 69.9% (5655 tons) reached no further than the offshore environment of mainland China and the South China Sea. Approximate 227, 71, 746, and 131 tons PAHs reached North Korea, South Korea, Russia-Mongolia region, and Japan, respectively, 2-4 days after the emission. Only 1.4 tons PAHs reached North America after more than 9 days. Interannual variation in the eastward PAH outflow was positively correlated to cold episodes of El Nino/Southern Oscillation. However, trans-Pacific atmospheric transport of PAHs from China was correlated to Pacific North America index (PNA) which is associated with the strength and position of westerly winds. 38 refs., 4 figs.

VY Canis Majoris: Observational Studies of the Outflow

Science.gov (United States)

Harwit, M.

2001-12-01

A number of recent studies carried out with the Infrared Space Observatory, ISO, and the Submillimeter Wave Astronomy Satellite, SWAS, provide new information on the chemical composition of the dust and the geometry of the outflow. With ISO, we have obtained a near-, mid-, and far-infrared spectrum of VY CMa that shows the strong preponderance of amorphous, as contrasted to crystalline, silicates. The sharp spectral slope in the near-infrared suggests the presence also of iron grains. While an excellent theoretical fit to the data is obtained, we emphasize that this is far from unique. A resolution of ambiguities will require a self-consistent model that considers not only radiative transfer, but also plausible elemental abundances, laboratory studies of chemical condensation sequences, and gas dynamics. With SWAS we have obtained a high-resolution spectrum of the 557GHz ground state transition of ortho-water. The spectral profile enables us to rule out a number of outflow geometries proposed in the literature. With ISO we also obtained the intensities and velocity structure of several other spectral lines of water. Most of these lines must be optically thick but effectively thin, a circumstance that permits us to make use of recent gas-dynamic models to locate the radial position in the outflow where individual lines are emitted.

A RING/DISK/OUTFLOW SYSTEM ASSOCIATED WITH W51 NORTH: A VERY MASSIVE STAR IN THE MAKING

International Nuclear Information System (INIS)

Zapata, Luis A.; Schilke, Peter; Menten, Karl; Ho, Paul T. P.; Rodriguez, Luis F.; Palau, Aina; Garrod, Robin T.

2009-01-01

Sensitive and high angular resolution (∼0.''4) SO 2 [22 2,20 → 22 1,21 ] and SiO[5 → 4] line and 1.3 and 7 mm continuum observations made with the Submillimeter Array (SMA) and the Very Large Array (VLA) toward the young massive cluster W51 IRS2 are presented. We report the presence of a large (of about 3000 AU) and massive (40 M sun ) dusty circumstellar disk and a hot gas molecular ring around a high-mass protostar or a compact small stellar system associated with W51 North. The simultaneous observations of the silicon monoxide molecule, an outflow gas tracer, further revealed a massive (200 M sun ) and collimated (∼14 0 ) outflow nearly perpendicular to the dusty and molecular structures suggesting thus the presence of a single very massive protostar with a bolometric luminosity on the order of 10 5 L sun . A molecular hybrid local thermodynamic equilibrium model of a Keplerian and infalling disk with an inner cavity and a central stellar mass of more than 60 M sun agrees well with the SO 2 [22 2,20 → 22 1,21 ] line observations. Finally, these results suggest that mechanisms, such as mergers of low- and intermediate-mass stars, might not be necessary for forming very massive stars.

Ammonia toroid aligned perpendicular to the HH 1 and HH 2 bipolar outflow

International Nuclear Information System (INIS)

Torrelles, J.M.; Canto, J.; Rodriguez, L.F.; Ho, P.T.P.; Moran, J.M.; Universidad Nacional Autonoma de Mexico, Mexico City)

1985-01-01

The ammonia emission from the region containing the Herbig-Haro objects 1 and 2, which mark the presence of a bipolar outflow, was mapped. The ammonia observations delineate an elongated structure aligned perpendicular to the bipolar outflow. This ammonia condensation is centered between HH 1 and HH 2 and coincides with the recently discovered central radio continuum source. This continuum source has no optical counterpart. The ammonia spectrum at the position of the continuum source shows a remarkable splitting. Based on the orientation of the bipolar outflow, which is known to be oriented nearly perpendicular to the line of sight, and on theoretical considerations, it is concluded that the ammonia source is part of a toroid, viewed edge-on, in slow expansion driven by the wind pressure of the central source. This toroid may be the focusing mechanism for the bipolar outflow. Searches for ammonia condensations in the vicinity of other HH objects may help localize the energy sources of these systems. 26 references

Infall and outflow motions towards a sample of massive star-forming regions from the RMS survey

Science.gov (United States)

Cunningham, N.; Lumsden, S. L.; Moore, T. J. T.; Maud, L. T.; Mendigutía, I.

2018-06-01

We present the results of an outflow and infall survey towards a distance-limited sample of 31 massive star-forming regions drawn from the Red MSX source (RMS) survey. The presence of young, active outflows is identified from SiO (8-7) emission and the infall dynamics are explored using HCO+/H13CO+ (4-3) emission. We investigate if the infall and outflow parameters vary with source properties, exploring whether regions hosting potentially young active outflows show similarities or differences with regions harbouring more evolved, possibly momentum-driven, `fossil' outflows. SiO emission is detected towards approximately 46 per cent of the sources. When considering sources with and without an SiO detection (i.e. potentially active and fossil outflows, respectively), only the 12CO outflow velocity shows a significant difference between samples, indicating SiO is more prevalent towards sources with higher outflow velocities. Furthermore, we find the SiO luminosity increases as a function of the Herschel 70 μm to WISE 22 μm flux ratio, suggesting the production of SiO is prevalent in younger, more embedded regions. Similarly, we find tentative evidence that sources with an SiO detection have a smaller bolometric luminosity-to-mass ratio, indicating SiO (8-7) emission is associated with potentially younger regions. We do not find a prevalence towards sources displaying signatures of infall in our sample. However, the higher energy HCO+ transitions may not be the best suited tracer of infall at this spatial resolution in these regions.

From bipolar to quadrupolar - The collimation processes of the Cepheus A outflow

Science.gov (United States)

Torrelles, Jose M.; Verdes-Montenegro, Lourdes; Ho, Paul T. P.; Rodriguez, Luis F.; Canto, Jorge

1993-01-01

Results of new K-band observations of the (1, 1) and (2, 2) ammonia lines toward Cepheus A are reported. The lines are mapped with approximately 2 arcsec of angular resolution and 0.3 km/s of velocity resolution. A sensitivity of 10 mJy has been achieved. The observations reveal details of the spatial and kinematics structure of the ambient high-density gas. It is suggested that the interstellar high-density gas is diverting and redirecting the outflow in the sense that the quadrupolar structure of the molecular outflow is produced by the interaction with the ammonia condensationss, with Cep A-1 and Cep A-3 splitting in two halves, respectively the blue- and redshifted lobes of an east-west bipolar molecular outflow.

Fading AGN Candidates: AGN Histories and Outflow Signatures

International Nuclear Information System (INIS)

Keel, William C.; Maksym, W. Peter; Lintott, Chris J.; Bennert, Vardha N.; Scott, Bryan; Showley, Charles; Flatland, Kelsi; Chojnowski, S. Drew; Moiseev, Alexei; Smirnova, Aleksandrina; Schawinski, Kevin; Sartori, Lia F.; Urry, C. Megan; Pancoast, Anna; Schirmer, Mischa

2017-01-01

We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q ion derived from photoionization balance in the brightest pixels in H α at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2×10 4 yr before the direct view of the nucleus. The e -folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission

Fading AGN Candidates: AGN Histories and Outflow Signatures

Energy Technology Data Exchange (ETDEWEB)

Keel, William C.; Maksym, W. Peter [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Lintott, Chris J. [Astrophysics, Oxford University and Adler Planetarium, 1300 S. Lakeshore Drive, Chicago, IL 60605 (United States); Bennert, Vardha N.; Scott, Bryan; Showley, Charles; Flatland, Kelsi [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Chojnowski, S. Drew [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Moiseev, Alexei; Smirnova, Aleksandrina [Special Astrophysical Observatory, Russian Academy of Sciences, Nizhny Arkhyz, 369167 (Russian Federation); Schawinski, Kevin; Sartori, Lia F. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Straße 27, CH-8093 Zurich (Switzerland); Urry, C. Megan [Department of Physics, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Pancoast, Anna [Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Schirmer, Mischa, E-mail: wkeel@ua.edu [Gemini Observatory, La Serena (Chile)

2017-02-01

We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q {sub ion} derived from photoionization balance in the brightest pixels in H α at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q {sub ion} values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2×10{sup 4} yr before the direct view of the nucleus. The e -folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and

Hot Accretion onto Black Holes with Outflow

Directory of Open Access Journals (Sweden)

Park Myeong-Gu

2018-01-01

Full Text Available Classic Bondi accretion flow can be generalized to rotating viscous accretion flow. Study of hot accretion flow onto black holes show that its physical charateristics change from Bondi-like for small gas angular momentum to disk-like for Keperian gas angular momentum. Especially, the mass accretion rate divided by the Bondi accretion rate is proportional to the viscosity parameter alpha and inversely proportional to the gas angular momentum divided by the Keplerian angular momentum at the Bondi radius for gas angular momentum comparable to the Keplerian value. The possible presence of outflow will increase the mass inflow rate at the Bondi radius but decrease the mass accretion rate across the black hole horizon by many orders of magnitude. This implies that the growth history of supermassive black holes and their coevolution with host galaxies will be dramatically changed when the accreted gas has angular momentum or develops an outflow.

MHOs toward HMOs: A Search for Molecular Hydrogen Emission-Line Objects toward High-mass Outflows

Energy Technology Data Exchange (ETDEWEB)

Wolf-Chase, Grace [Astronomy Department Adler Planetarium 1300 S. Lake Shore Drive Chicago, IL 60605 (United States); Arvidsson, Kim [Trull School of Sciences and Mathematics Schreiner University 2100 Memorial Blvd. Kerrville, TX 78028 (United States); Smutko, Michael, E-mail: gwolfchase@adlerplanetarium.org [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), and Dept. of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States)

2017-07-20

We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H{sub 2} 2.12 μ m/H{sub 2} 2.25 μ m flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ∼1.5–3, while the vast majority of MHOs display flux ratios typical of C-type shocks (∼6–20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (∼3–4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.

Cloud Formation and Water Transport on Mars after Major Outflow Events

Science.gov (United States)

Santiago, D. L.; Colaprete, A.; Kreslavsky, M.; Kahre, M. A.; Asphaug, E.

2012-01-01

The triggering of a robust water cycle on Mars might have been caused by the gigantic flooding events evidenced by outflow channels. We use the Ames Mars General Circulation Model (MGCM) to test this hypothesis, studying how these presumably abrupt eruptions of water might have affected the climate of Mars in the past. We model where the water ultimately went as part of a transient atmospheric water cycle, to answer questions including: (1) Can sudden introductions of large amounts of water on the Martian surface lead to a new equilibrated water cycle? (2) What are the roles of water vapor and water ice clouds to sudden changes in the water cycle on Mars? (3) How are radiative feedbacks involved with this? (4) What is the ultimate fate of the outflow water? (5) Can we tie certain geological features to outflow water redistributed by the atmosphere?

Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs: III - Location and Energetics

Science.gov (United States)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

2012-01-01

Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval approx.0.0003-0.03pc (approx.10(exp 2)-10(exp 4)tau(sub s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between approx.0.01- 1 Stellar Mass/y, corresponding to approx. or >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are logE(sub K) approx. or = 42.6-44.6 erg/s. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN r.osmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies .

Kinetic modeling of auroral ion outflows observed by the VISIONS sounding rocket

Science.gov (United States)

Albarran, R. M.; Zettergren, M. D.

2017-12-01

The VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of the ion outflow below 1000km. Energetic ion data from the VISIONS polar cap boundary crossing show evidence of an ion "pressure cooker" effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes. VISIONS was also instrumented with an energetic neutral atom (ENA) detector which measured neutral particles ( 50-100 eV energy) presumably produced by charge-exchange with the energized outflowing ions. Hence, inferences about ion outflow may be made via remotely-sensing measurements of ENAs. This investigation focuses on modeling energetic outflowing ion distributions observed by VISIONS using a kinetic model. This kinetic model traces large numbers of individual particles, using a guiding-center approximation, in order to allow calculation of ion distribution functions and moments. For the present study we include mirror and parallel electric field forces, and a source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution characterizing the initial phase-space conditions for multiple particle trajectories. This project serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis methods for future sounding rocket and satellite missions.

Classifying Aerosols Based on Fuzzy Clustering and Their Optical and Microphysical Properties Study in Beijing, China

Directory of Open Access Journals (Sweden)

Wenhao Zhang

2017-01-01

Full Text Available Classification of Beijing aerosol is carried out based on clustering optical properties obtained from three Aerosol Robotic Network (AERONET sites. The fuzzy c-mean (FCM clustering algorithm is used to classify fourteen-year (2001–2014 observations, totally of 6,732 records, into six aerosol types. They are identified as fine particle nonabsorbing, two kinds of fine particle moderately absorbing (fine-MA1 and fine-MA2, fine particle highly absorbing, polluted dust, and desert dust aerosol. These aerosol types exhibit obvious optical characteristics difference. While five of them show similarities with aerosol types identified elsewhere, the polluted dust aerosol has no comparable prototype. Then the membership degree, a significant parameter provided by fuzzy clustering, is used to analyze internal variation of optical properties of each aerosol type. Finally, temporal variations of aerosol types are investigated. The dominant aerosol types are polluted dust and desert dust in spring, fine particle nonabsorbing aerosol in summer, and fine particle highly absorbing aerosol in winter. The fine particle moderately absorbing aerosol occurs during the whole year. Optical properties of the six types can also be used for radiative forcing estimation and satellite aerosol retrieval. Additionally, methodology of this study can be applied to identify aerosol types on a global scale.

SPECTROSCOPIC OBSERVATIONS OF CONTINUOUS OUTFLOWS AND PROPAGATING WAVES FROM NOAA 10942 WITH EXTREME ULTRAVIOLET IMAGING SPECTROMETER/HINODE

International Nuclear Information System (INIS)

Nishizuka, N.; Hara, H.

2011-01-01

We focused on 'sit-and-stare' observations of an outflow region at the edge of active region NOAA 10942 on 2007 February 20 obtained by the Extreme ultraviolet Imaging Spectrometer on board Hinode. We analyzed the data above the base of the outflow and found both continuous outflows and waves, which propagate from the base of the outflow. The spectra at the base of the outflow and at higher locations show different properties. The line profiles show blue-side asymmetry at the base of the outflow where nonthermal broadening becomes large because of fast upflows generated by heating events. On the other hand, at higher locations line profiles are symmetric and the intensity disturbances vary in phase with the velocity disturbances. The correlations between the intensity and velocity disturbances become noticeable at higher locations, so this indicates evidence of (at least locally) upward propagating slow-mode waves along the outflow. We also found a transient oscillation of different period in the wavelet spectrum. This indicates that a different wave is additionally observed during a limited period. High cadence spectroscopic observations revealed intermittent signatures of nonthermal velocities. Each of them seems to correspond to the base of the propagating disturbances. Furthermore, a jet was captured by the sit-and-stare observations across the slit. The similarity of line profiles of the outflow and the jet may indicate that the flows and waves originate in unresolved explosive events in the lower atmosphere of the corona.

Physical Processes for Driving Ionospheric Outflows in Global Simulations

Science.gov (United States)

Moore, Thomas Earle; Strangeway, Robert J.

2009-01-01

We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective.

Characterizing the origin and impact of the most extreme molecular outflows in the nearby universe

Science.gov (United States)

Gowardhan, Avani; Riechers, Dominik A.; Spoon, Henrik; Farrah, Duncan

2018-01-01

Observations over the last decade have revealed that feedback in the form of molecular gas outflows is ubiquitous in local ultra luminous infrared galaxies (ULIRGs). Such outflows can clear the nuclear environments of gas and dust, quench star formation and active galactic nuclei (AGN) growth, and they are a key step in the evolution of dust-obscured AGN to optically luminous quasars. We here present multi-spectral line observations of feedback in the two most powerful molecular gas outflows in the local universe. We spatially resolve the outflows to determine their kinematics and structure and find that they can drive out the molecular gas and quench star formation within ~ few Myr. Applying mid-IR diagnostics to constrain the relative contributions of AGN and nuclear starburst activity, we find that starburst activity plays a significant role in driving the outflow. We discuss the implications for future studies of feedback in the local universe and obscured AGN at high redshift, which is a key target population for JWST and ALMA over the next decade.

Inferring Polar Ion Outflows from Topside Ionograms

Science.gov (United States)

Sojka, J. J.; Rice, D. D.; Eccles, V.; Schunk, R. W.; David, M.; Benson, R. F.; James, H. G.

2017-12-01

The high-latitude topside ionosphere is dominated by O+ ions from the F-region peak around 300 km to over 1000 km altitude. The O+ profile shape provides information on the thermal structure, field aligned plasma dynamics, and outflows into the magnetosphere. Topside electron density profiles (EDP) are either obtained from topside sounders or Incoherent Scatter Radars. There is a large archive of topside sounder ionograms and hand scaled EDPs from the Alouette and ISIS satellites between 1962 and 1990. Recent NASA data enhancement efforts have augmented these EDP archives by producing digital topside ionograms both from the 7-track analog telemetry tapes and from 35 mm topside film ionograms. Rice et al [2017] in their 35 mm ionogram recovery emphasized high latitude ionograms taken during disturbed conditions. The figure below contrasts ISIS-II EDPs extracted from 35 mm films before and during a major storm (Dst -200nT) on 9 April 1972 (left panel: quiet period before the storm; right panel: during the peak of the storm). Both satellite passes used for these EDPs were centered on the Resolute Bay location that in 1972 was close to the magnetic pole. They begin at auroral latitudes around 2100 MLT and end on the dayside around 0900MLT. We will present results of how ionospheric models replicate both the quiet and disturbed conditions shown in the figure. Three types of models will be contrasted: an empirical ionosphere (IRI), a physics based ionospheric model (TDIM), and a fluid-based polar-wind model (PW). During the storm pass, when it is expected that substantial heating is present, the ISIS-II topside EDPs provide severe constraints on the usage of these models. These constraints enable estimates of the outflow fluxes as well as the heating that has occurred. The comparisons with the empirical model establish how well the pre-storm topside is modeled and identifies the challenges as the storm magnitude increases. The physics-based TDIM does have storm drivers

Dysregulated endocardial TGFβ signaling and mesenchymal transformation result in heart outflow tract septation failure.

Science.gov (United States)

Ma, Mancheong; Li, Peng; Shen, Hua; Estrada, Kristine D; Xu, Jian; Kumar, S Ram; Sucov, Henry M

2016-01-01

Heart outflow tract septation in mouse embryos carrying mutations in retinoic acid receptor genes fails with complete penetrance. In this mutant background, ectopic TGFβ signaling in the distal outflow tract is responsible for septation failure, but it was uncertain what tissue was responsive to ectopic TGFβ and why this response interfered with septation. By combining RAR gene mutation with tissue-specific Cre drivers and a conditional type II TGFβ receptor (Tgfbr2) allele, we determined that ectopic activation of TGFβ signaling in the endocardium is responsible for septation defects. Ectopic TGFβ signaling results in ectopic mesenchymal transformation of the endocardium and thereby in improperly constituted distal OFT cushions. Our analysis highlights the interactions between myocardium, endocardium, and neural crest cells in outflow tract morphogenesis, and demonstrates the requirement for proper TGFβ signaling in outflow tract cushion organization and septation. Copyright © 2015. Published by Elsevier Inc.

Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

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H. Nakajima

2006-01-01

Full Text Available Centrifuge modeling of one-step outflow tests were carried out using a 2-m radius geotechnical centrifuge, and the cumulative outflow and transient pore water pressure were measured during the tests at multiple gravity levels. Based on the scaling laws of centrifuge modeling, the measurements generally showed reasonable agreement with prototype data calculated from forward simulations with input parameters determined from standard laboratory tests. The parameter optimizations were examined for three different combinations of input data sets using the test measurements. Within the gravity level examined in this study up to 40g, the optimized unsaturated parameters compared well when accurate pore water pressure measurements were included along with cumulative outflow as input data. With its capability to implement variety of instrumentations under well controlled initial and boundary conditions and to shorten testing time, the centrifuge modeling technique is attractive as an alternative experimental method that provides more freedom to set inverse problem conditions for the parameter estimation.

Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

Science.gov (United States)

Nakajima, H.; Stadler, A. T.

2006-10-01

Centrifuge modeling of one-step outflow tests were carried out using a 2-m radius geotechnical centrifuge, and the cumulative outflow and transient pore water pressure were measured during the tests at multiple gravity levels. Based on the scaling laws of centrifuge modeling, the measurements generally showed reasonable agreement with prototype data calculated from forward simulations with input parameters determined from standard laboratory tests. The parameter optimizations were examined for three different combinations of input data sets using the test measurements. Within the gravity level examined in this study up to 40g, the optimized unsaturated parameters compared well when accurate pore water pressure measurements were included along with cumulative outflow as input data. With its capability to implement variety of instrumentations under well controlled initial and boundary conditions and to shorten testing time, the centrifuge modeling technique is attractive as an alternative experimental method that provides more freedom to set inverse problem conditions for the parameter estimation.

Coastal circulations driven by river outflow in a variable-density 1.5-layer model

Digital Repository Service at National Institute of Oceanography (India)

McCreary, J.P.; Zhang, S.; Shetye, S.R.

A variable-density, 1.5-layer model is used to investigate the dynamics of the fresher-water plumes generated by river outflow. Solutions are found in a north-south channel, and the transport M sub(tau) and salinity S sub(tau) of the outflow...

SPATIALLY RESOLVED OBSERVATIONS OF THE BIPOLAR OPTICAL OUTFLOW FROM THE BROWN DWARF 2MASS J12073347–3932540

International Nuclear Information System (INIS)

Whelan, E. T.; Ray, T. P.; Comeron, F.; Bacciotti, F.; Kavanagh, P. J.

2012-01-01

Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M JUP BD 2MASS J12073347–3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [O I]λ6300 emission line. Follow-up observations consisting of spectra and [S II], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow position angle (P.A.) at ∼65°. The [O I]λ6300 emission line region is spatially resolved and the outflow is detected in the [S II] images. The detection is firstly in the form of an elongation of the point-spread function (PSF) along the direction of the outflow P.A. Four faint knot-like features (labeled A-D) are also observed to the southwest of 2MASS J12073347–3932540 along the same P.A. suggested by the spectra and the elongation in the PSF. Interestingly, D, the feature furthest from the source, is bow shaped with the apex pointing away from 2MASS J12073347–3932540. A color-color analysis allows us to conclude that at least feature D is part of the outflow under investigation while A is likely a star or galaxy. Follow-up observations are needed to confirm the origin of B and C. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.

First-principles studies on graphene-supported transition metal clusters

International Nuclear Information System (INIS)

Sahoo, Sanjubala; Khanna, Shiv N.; Gruner, Markus E.; Entel, Peter

2014-01-01

Theoretical studies on the structure, stability, and magnetic properties of icosahedral TM 13 (TM = Fe, Co, Ni) clusters, deposited on pristine (defect free) and defective graphene sheet as well as graphene flakes, have been carried out within a gradient corrected density functional framework. The defects considered in our study include a carbon vacancy for the graphene sheet and a five-membered and a seven-membered ring structures for graphene flakes (finite graphene chunks). It is observed that the presence of defect in the substrate has a profound influence on the electronic structure and magnetic properties of graphene-transition metal complexes, thereby increasing the binding strength of the TM cluster on to the graphene substrate. Among TM 13 clusters, Co 13 is absorbed relatively more strongly on pristine and defective graphene as compared to Fe 13 and Ni 13 clusters. The adsorbed clusters show reduced magnetic moment compared to the free clusters

Aperiodic-metamaterial-based absorber

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Quanlong Yang

2017-09-01

Full Text Available The periodic-metamaterial-based perfect absorber has been studied broadly. Conversely, if the unit cell in the metamaterial-based absorber is arranged aperiodically (aperiodic-metamaterial-based absorber, how does it perform? Inspired by this, here we present a systematic study of the aperiodic-metamaterial-based absorber. By investigating the response of metamaterial absorbers based on periodic, Fibonacci, Thue-Morse, and quasicrystal lattices, we found that aperiodic-metamaterial-based absorbers could display similar absorption behaviors as the periodic one in one hand. However, their absorption behaviors show different tendency depending on the thicknesses of the spacer. Further studies on the angle and polarization dependence of the absorption behavior are also presented.

Herbig-haro objects and mid-infrared outflows in the VELA C molecular cloud

International Nuclear Information System (INIS)

Zhang, Miaomiao; Wang, Hongchi; Henning, Thomas

2014-01-01

We have performed a deep [S II] λλ6717/6731 wide field Herbig-Haro (HH) object survey toward the Vela C molecular cloud with a sky coverage of about 2 deg 2 . In total, 18 new HH objects, HH 1090-1107, are discovered and the two previously known HH objects, HH 73-74, are also detected in our [S II] images. We also present an investigation of mid-infrared outflows in the Vela C molecular cloud using the Wide-field Infrared Survey Explorer images taken from AllWISE data release. Using the method suggested by Zhang and Wang, 11 extended green objects (EGOs) are identified to be the mid-infrared outflows, including 6 new mid-infrared outflows that have not been detected previously at other wavelengths and 5 mid-infrared counterparts of the HH objects detected in this work. Using the AllWISE Source Catalog and the source classification scheme suggested by Koenig et al., we have identified 56 young stellar object (YSO) candidates in the Vela C molecular cloud. The possible driving sources of the HH objects and EGOs are discussed based on the morphology of HH objects and EGOs and the locations of HH objects, EGOs and YSO candidates. Finally we associate 12 HH objects and 5 EGOs with 10 YSOs and YSO candidates. The median length of the outflows in Vela C is 0.35 pc and the outflows seem to be oriented randomly.

Absorbing rods for nuclear fast neutron reactor absorbing assembly

International Nuclear Information System (INIS)

Aji, M.; Ballagny, A.; Haze, R.

1986-01-01

The invention proposes a neutron absorber rod for neutron absorber assembly of a fast neutron reactor. The assembly comprises a bundle of vertical rods, each one comprising a stack of pellets made of a neutron absorber material contained in a long metallic casing with a certain radial play with regard to this casing; this casing includes traps for splinters from the pellets which may appear during reactor operation, at the level of contact between adjacent pellets. The present invention prevents the casing from rupture involved by the disintegration of the pellets producing pieces of boron carbide of high hardness [fr

Outflows from black hole hyperaccretion systems: short and long-short gamma-ray bursts and `quasi-supernovae'

Science.gov (United States)

Song, Cui-Ying; Liu, Tong; Li, Ang

2018-06-01

The detections of some long gamma-ray bursts (LGRBs) relevant to mergers of neutron star (NS)-NS or black hole (BH)-NS, as well as some short gamma-ray bursts (SGRBs) probably produced by collapsars, muddle the boundary of two categories of gamma-ray bursts (GRBs). In both cases, a plausible candidate of central engine is a BH surrounded by a hyperaccretion disc with strong outflows, launching relativistic jets driven by Blandford-Znajek mechanism. In the framework of compact binary mergers, we test the applicability of the BH hyperaccretion inflow-outflow model on powering observed GRBs. We find that, for a low outflow ratio, ˜ 50 per cent, post-merger hyperaccretion processes could power not only all SGRBs but also most of LGRBs. Some LGRBs might originate from merger events in the BH hyperaccretion scenario, at least on the energy requirement. Moreover, kilonovae might be produced by neutron-rich outflows, and their luminosities and time-scales significantly depend on the outflow strengths. GRBs and their associated kilonovae are competitive with each other on the disc mass and total energy budgets. The stronger the outflow, the more similar the characteristics of kilonovae to supernovae (SNe). This kind of `nova' might be called `quasi-SN'.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

Science.gov (United States)

Rodriguez, J Alexis P; Kargel, Jeffrey S; Baker, Victor R; Gulick, Virginia C; Berman, Daniel C; Fairén, Alberto G; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

2015-09-08

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

Relativistic Outflows from Advection-dominated Accretion Disks around Black Holes

Science.gov (United States)

Becker, Peter A.; Subramanian, Prasad; Kazanas, Demosthenes

2001-05-01

Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter and are therefore gravitationally unbound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a pseudo-Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self-similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Hence, our self-similar solution may help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approaches the unique form M~r1/2, with an associated density variation given by ρ~r-1. This density variation agrees with that implied by the dependence of the hard X-ray time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the predictions made using our self-similar solution need to be confirmed in the future using a detailed model that includes a physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk.

Methods for absorbing neutrons

Science.gov (United States)

Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

2012-07-24

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

PROPER MOTIONS OF YOUNG STELLAR OUTFLOWS IN THE MID-INFRARED WITH SPITZER (IRAC). I. THE NGC 1333 REGION

International Nuclear Information System (INIS)

Raga, A. C.; Noriega-Crespo, A.; Carey, S. J.; Arce, H. G.

2013-01-01

We use two 4.5 μm Spitzer (IRAC) maps of the NGC 1333 region taken over a ∼7 yr interval to determine proper motions of its associated outflows. This is a first successful attempt at obtaining proper motions of stellars' outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8, and 10, we find proper motions of ∼9-13 km s –1 , which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of eight outflows, ranging from ∼10 to 100 km s –1 . The derived proper motions show that out of these eight outflows, three have tangential velocities ≤20 km s –1 . This result shows that a large fraction of the observed outflows have low intrinsic velocities and that the low proper motions are not merely a projection effect.

Bipolar molecular outflows: T Tauri stars and Herbig-Haro objects

International Nuclear Information System (INIS)

Choe, S.U.

1984-01-01

The relations of Herbig-Haro objects to the observed bipolar molecular outflows with T Tauri stars are studied. An evaporation disk model is proposed to obtain the shape of the disk where gas evaporates and to explain the collimation of the central T Tauri wind. In this case the collimation angle is about 10 0 . The collimated T Tauri wind making a form of de Laval nozzle viscously interacts with the surrounding medium. This interaction enhances the second collimation (about 40 0 ) of the resulting flow, mixing stellar and disk winds with external molecular gas. These viscous outflows are observed in the bipolar molecular outflow of the T Tauri stars. It is also proposed in the model that a Kelvin-Helmholtz instability in the throat of the de Laval nozzle produces clumps, which can be accelerated by the ram pressure of the collimated wind up to the wind speed. The clumps eventually pass through a shock in the outlfow, which results from its encounter with the ambient cloud. The clumps are then moving faster than the surrounding flow. These clumps are identified with Herbig-Haro objects

Low-energy irradiation effects of gas cluster ion beams

International Nuclear Information System (INIS)

Houzumi, Shingo; Takeshima, Keigo; Mochiji, Kozo; Toyoda, Noriaki; Yamada, Isao

2007-01-01

A cluster-ion irradiation system with cluster-size selection has been developed to study the effects of the cluster size for surface processes using cluster ions. A permanent magnet with a magnetic field of 1.2 T is installed for size separation of large cluster ions. Trace formations at HOPG surface by the irradiation with size-selected Ar-cluster ions under acceleration energy of 30 keV were investigated by a scanning tunneling microscopy. Generation behavior of the crater-like traces is strongly affected by the number of constituent atoms (cluster size) of the irradiating cluster ion. When the incident cluster ion is composed of 100-3000 atoms, crater-like traces are observed on the irradiated surfaces. In contrast, such traces are not observed at all with the irradiation of the cluster-ions composed of over 5000 atoms. Such the behavior is discussed on the basis of the kinetic energy per constituent atom of the cluster ion. To study GCIB irradiation effects against macromolecule, GCIB was irradiated on DNA molecules absorbed on graphite surface. By the GCIB irradiation, much more DNA molecules was sputtered away as compared with the monomer-ion irradiation. (author)

Understanding satellite-based monthly-to-seasonal reservoir outflow estimation as a function of hydrologic controls

Science.gov (United States)

Bonnema, Matthew; Sikder, Safat; Miao, Yabin; Chen, Xiaodong; Hossain, Faisal; Ara Pervin, Ismat; Mahbubur Rahman, S. M.; Lee, Hyongki

2016-05-01

Growing population and increased demand for water is causing an increase in dam and reservoir construction in developing nations. When rivers cross international boundaries, the downstream stakeholders often have little knowledge of upstream reservoir operation practices. Satellite remote sensing in the form of radar altimetry and multisensor precipitation products can be used as a practical way to provide downstream stakeholders with the fundamentally elusive upstream information on reservoir outflow needed to make important and proactive water management decisions. This study uses a mass balance approach of three hydrologic controls to estimate reservoir outflow from satellite data at monthly and annual time scales: precipitation-induced inflow, evaporation, and reservoir storage change. Furthermore, this study explores the importance of each of these hydrologic controls to the accuracy of outflow estimation. The hydrologic controls found to be unimportant could potentially be neglected from similar future studies. Two reservoirs were examined in contrasting regions of the world, the Hungry Horse Reservoir in a mountainous region in northwest U.S. and the Kaptai Reservoir in a low-lying, forested region of Bangladesh. It was found that this mass balance method estimated the annual outflow of both reservoirs with reasonable skill. The estimation of monthly outflow from both reservoirs was however less accurate. The Kaptai basin exhibited a shift in basin behavior resulting in variable accuracy across the 9 year study period. Monthly outflow estimation from Hungry Horse Reservoir was compounded by snow accumulation and melt processes, reflected by relatively low accuracy in summer and fall, when snow processes control runoff. Furthermore, it was found that the important hydrologic controls for reservoir outflow estimation at the monthly time scale differs between the two reservoirs, with precipitation-induced inflow being the most important control for the Kaptai

Investigations of Short-Timescale Outflow Variability in Quasars of the Sloan Digital Sky Survey

Science.gov (United States)

Hemler, Zachary; Grier, Catherine; Brandt, William; Hall, Patrick; Schneider, Donald; Shen, Yue; Fernandez-Trincado, Jose; SDSS-RM Collaboration

2018-01-01

Quasar outflows are hypothesized to regulate the growth of a quasar's host galaxy and the supermassive black hole (SMBH) itself. Thus, understanding the physics of these outflows is imperative to understanding galactic evolution. The physical properties of these outflows, such as density, radial distance from the SMBH, and kinetic energy can be investigated by measuring both the strength and shape variability of broad absorption lines (BALs) in quasar spectra. However, the accuracy of physical properties calculated using BAL variability methods is limited by the time resolution of the observations. Recent spectral data from the Sloan Digital Sky Survey Reverberation Mapping program (SDSS-RM) provides a novel opportunity to investigate the short-term BAL variability of many quasars at many epochs. The SDSS-RM program took many epochs of spectra for a large sample of quasars over a period of several years, many of which exhibit BALs. The median rest-frame time resolution of these observations is roughly 2 days, in contrast to previous large-sample studies, which typically have time spacing on the order of hundred of days. We are using the SDSS-RM dataset to conduct a BAL variability study that will further constrain outflow properties and provide significant insights into the variability mechanisms of quasar outflows. We are searching for variability in BALs on timescales of less than 2 days among our sample of 22 quasars and determining whether this behavior is common among quasars. We are also investigating the general short-term (less than 10 days) variability characteristics of the entire sample. We will present preliminary results from this study and the possible implications to our understanding of quasar outflows.

DIRECT IMAGING OF A COMPACT MOLECULAR OUTFLOW FROM A VERY LOW LUMINOSITY OBJECT: L1521F-IRS

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Satoko [Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Ohashi, Nagayoshi [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Bourke, Tyler L., E-mail: satoko.takahashi@nao.ac.jp [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-09-01

Studying the physical conditions of very low luminosity objects (VeLLOs; L{sub bol} < 0.1 L{sub Sun }) is important for understanding the earliest evolutionary stage of protostars and brown dwarfs. We report interferometric observations of the VeLLO L1521F-IRS, in {sup 12}CO (2-1) line emission and the 1.3 mm continuum emission, using the Submillimeter Array. With the {sup 12}CO (2-1) high-resolution observations, we have spatially resolved a compact but poorly collimated molecular outflow associated with L1521F-IRS for the first time. The blueshifted and redshifted lobes are aligned along the east and west side of L1521F-IRS with a lobe size of Almost-Equal-To 1000 AU. The estimated outflow mass, maximum outflow velocity, and outflow force are (9.0-80) Multiplication-Sign 10{sup -4} M{sub Sun }, 7.2 km s{sup -1}, and (7.4-66) Multiplication-Sign 10{sup -7} M{sub Sun} km s{sup -1} yr{sup -1}, respectively. The estimated outflow parameters such as size, mass, and momentum rate are similar to values derived for other VeLLOs, and are located at the lower end of values compared to previously studied outflows associated with low- to high-mass star-forming regions. Low-velocity less collimated (1.5 km s{sup -1}/1200 AU) and higher-velocity compact (4.0 km s{sup -1}/920 AU) outflow components are suggested by the data. These velocity structures are not consistent with those expected in the jet-driven or wind-driven outflow models, perhaps suggesting a remnant outflow from the first hydrostatic core as well as an undeveloped outflow from the protostar. Detection of an infrared source and compact millimeter continuum emission suggests the presence of the protostar, while its low bolometric luminosity (0.034-0.07 L{sub Sun }) and small outflow suggests that L1521F is in the earliest protostellar stage (<10{sup 4} yr) and contains a substellar mass object. The bolometric (or internal) luminosity of L1521F-IRS suggests that the current mass accretion rate is an order of

ERUPTIVE VARIABLE STARS AND OUTFLOWS IN SERPENS NW

Energy Technology Data Exchange (ETDEWEB)

Hodapp, Klaus W. [Institute for Astronomy, University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720 (United States); Chini, Rolf; Watermann, Ramon; Lemke, Roland, E-mail: hodapp@ifa.hawaii.edu [Ruhr Universitaet Bochum, Astronomisches Institut, Universitaetsstrasse 150, D-44801 Bochum (Germany)

2012-01-01

We study the outflow activity, photometric variability, and morphology of three very young stellar objects in the Serpens NW star-forming region: OO Serpentis, EC 37 (V370 Ser), and EC 53 (V371 Ser). High spatial resolution Keck/NIRC2 laser guide star adaptive optics images obtained in 2007 and 2009 in broadband K and in a narrowband filter centered on the 1-0 S(1) emission line of H{sub 2} allow us to identify the outflows from all three objects. We also present new, seeing-limited data on the photometric evolution of the OO Ser reflection nebula and re-analyze previously published data. We find that OO Ser declined in brightness from its outburst peak in 1995 to about 2003, but that this decline has recently stopped and actually reversed itself in some areas of the reflection nebula. The morphology and proper motions of the shock fronts MHO 2218 near EC 37 suggest that they all originate in EC 37 and that this is an outflow seen nearly along its axis. We identify an H{sub 2} jet emerging from the cometary nebula EC 53. The star illuminating EC 53 is periodically variable with a period of 543 days and has a close-by, non-variable companion at a projected distance of 92 AU. We argue that the periodic variability is the result of accretion instabilities triggered by another very close, not directly observable, binary companion and that EC 53 can be understood in the model of a multiple system developing into a hierarchical configuration.

Manipulation of Microbubble Clusters Using Focused Ultrasound

Science.gov (United States)

Matsuzaki, Hironobu; Osaki, Taichi; Kawaguchi, Kei; Unga, Johan; Ichiyanagi, Mitsuhisa; Azuma, Takashi; Suzuki, Ryo; Maruyama, Kazuo; Takagi, Shu

2017-11-01

In recent years, microbubbles (MBs) are expected to be utilized for the ultrasound drug delivery system (DDS). For the MB-DDS, it is important to establish a method of controlling bubbles and bubble clusters using ultrasound field. The objective of this study is to clarify behaviors of bubble clusters with various physical conditions. MBs in the ultrasound field are subjected to the primary Bjerknes force. The force traps MBs at the focal region of the focused ultrasound field. The trapped MBs form a bubble cluster at the region. A bubble cluster continues growing with absorbing surrounding bubbles until it reaches a maximum size beyond which it disappears from the focal region. In the present study, two kinds of MBs are used for the experiment. One is Sonazoid with average diameter of 2.6 um and resonant frequency of 5 MHz. The other is developed by Teikyo Univ., with average diameter of 1.5 um and presumed resonant frequency of 4 MHz. The bubble cluster's behaviors are analyzed using the high-speed camera. Sonazoid clusters have larger critical size than the other in every frequency, and its cluster size is inversely proportional to the ultrasound frequency, while Teikyo-bubble clusters have different tendency. These results are discussed in the presentation.

Human cerebral venous outflow pathway depends on posture and central venous pressure

DEFF Research Database (Denmark)

Gisolf, J; van Lieshout, J J; van Heusden, K

2004-01-01

and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest......Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture...... and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position...

Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

Energy Technology Data Exchange (ETDEWEB)

Cheng, Yang; Xu, Yonggang, E-mail: xuyonggang221@163.com; Cai, Jun; Yuan, Liming; Zhang, Deyuan

2015-09-01

Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz.

The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

Science.gov (United States)

Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

2012-12-01

It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric

Flow splitting in numerical simulations of oceanic dense-water outflows

Science.gov (United States)

Marques, Gustavo M.; Wells, Mathew G.; Padman, Laurie; Özgökmen, Tamay M.

2017-05-01

Flow splitting occurs when part of a gravity current becomes neutrally buoyant and separates from the bottom-trapped plume as an interflow. This phenomenon has been previously observed in laboratory experiments, small-scale water bodies (e.g., lakes) and numerical studies of small-scale systems. Here, the potential for flow splitting in oceanic gravity currents is investigated using high-resolution (Δx = Δz = 5 m) two-dimensional numerical simulations of gravity flows into linearly stratified environments. The model is configured to solve the non-hydrostatic Boussinesq equations without rotation. A set of experiments is conducted by varying the initial buoyancy number B0 =Q0N3 /g‧2 (where Q0 is the volume flux of the dense water flow per unit width, N is the ambient stratification and g‧ is the reduced gravity), the bottom slope (α) and the turbulent Prandtl number (Pr). Regardless of α or Pr, when B0 ≤ 0.002 the outflow always reaches the deep ocean forming an underflow. Similarly, when B0 ≥ 0.13 the outflow always equilibrates at intermediate depths, forming an interflow. However, when B0 ∼ 0.016, flow splitting always occurs when Pr ≥ 10, while interflows always occur for Pr = 1. An important characteristic of simulations that result in flow splitting is the development of Holmboe-like interfacial instabilities and flow transition from a supercritical condition, where the Froude number (Fr) is greater than one, to a slower and more uniform subcritical condition (Fr internal hydraulic jump and consequent mixing enhancement. Although our experiments do not take into account three-dimensionality and rotation, which are likely to influence mixing and the transition between flow regimes, a comparison between our results and oceanic observations suggests that flow splitting may occur in dense-water outflows with weak ambient stratification, such as Antarctic outflows.

Outflows in the narrow-line region of bright Seyfert galaxies - I. GMOS-IFU data

Science.gov (United States)

Freitas, I. C.; Riffel, R. A.; Storchi-Bergmann, T.; Elvis, M.; Robinson, A.; Crenshaw, D. M.; Nagar, N. M.; Lena, D.; Schmitt, H. R.; Kraemer, S. B.

2018-05-01

We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies - Mrk 6, Mrk 79, Mrk 348, Mrk 607, and Mrk 1058 - obtained from observations with the Gemini Multi-Object Spectrograph Integral Field Unit on the Gemini North Telescope. The data cover the inner 3.5 arcsec × 5.0 arcsec - corresponding to physical scales in the range 0.6 × 0.9-1.5 × 2.2 kpc2 - at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300-7100 Å and velocity resolution of ≈90 km s-1. The gas excitation is Seyfert like everywhere but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association with the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centred at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk 348 and Mrk 79, while in Mrk 1058 only the blueshifted part is clearly observed, while in cases of Mrk 6 and Mrk 607, the geometry of the outflow needs further constraints from modelling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.

GEOMETRIC AND KINEMATIC STRUCTURE OF THE OUTFLOW/ENVELOPE SYSTEM OF L1527 REVEALED BY SUBARCSECOND-RESOLUTION OBSERVATION OF CS

Energy Technology Data Exchange (ETDEWEB)

Oya, Yoko; López-Sepulcre, Ana; Watanabe, Yoshimasa; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sakai, Nami [The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198 (Japan); Lefloch, Bertrand; Ceccarelli, Cecilia, E-mail: oya@taurus.phys.s.u-tokyo.ac.jp [Universite Grenoble Alpes, IPAG, F-38000 Grenoble (France)

2015-10-10

Subarcsecond-resolution images of the rotational line emissions of CS and c-C{sub 3}H{sub 2} obtained toward the low-mass protostar IRAS 04368+2557 in L1527 with the Atacama Large Millimeter/submillimeter Array are investigated to constrain the orientation of the outflow/envelope system. The distribution of CS consists of an envelope component extending from north to south and a faint butterfly shaped outflow component. The kinematic structure of the envelope is well reproduced by a simple ballistic model of an infalling rotating envelope. Although the envelope has a nearly edge-on configuration, we find that the western side of the envelope faces the observer. This configuration is opposite to the direction of the large-scale (∼10{sup 4} AU) outflow suggested previously from the {sup 12}CO (J = 3–2) observation, and to the morphology of infrared reflection near the protostar (∼200 AU). The latter discrepancy could originate from high extinction by the outflow cavity of the western side, or may indicate that the outflow axis is not parallel to the rotation axis of the envelope. Position–velocity diagrams show the accelerated outflow cavity wall, and its kinematic structure in the 2000 AU scale is explained by a standard parabolic model with the inclination angle derived from the analysis of the envelope. The different orientation of the outflow between the small and large scale implies a possibility of precession of the outflow axis. The shape and the velocity of the outflow in the vicinity of the protostar are compared with those of other protostars.

FEATURES OF OUTFLOW OF INTRAOCULAR LIQUID AFTER AN EKSIMERLAZER SKLEREKTOMY (PILOT STUDY)

OpenAIRE

E. A. Korchuganova; O. A. Rumyantseva; S. B. Gudkova

2017-01-01

Modern approaches to surgical glaucoma treatment is based on the safe and effective methods. In recent years, great attention is paid to the techniques of stimulating uveoscleral path outtake aqueous humor from the eye. Uveoscleral space in the extended outflow pathways is dominant and constitutes about 72%. Sclera is a field of the greatest interest, as the end stages of the outflow of aqueous humor via the uveoscleral path. The aim of the study was to investigate the influence of excimer la...

Absorbant materials

International Nuclear Information System (INIS)

Quetier, Monique.

1978-11-01

Absorbants play a very important part in the nuclear industry. They serve for the control, shut-down and neutron shielding of reactors and increase the capacity of spent fuel storage pools and of special transport containers. This paper surveys the usual absorbant materials, means of obtainment, their essential characteristics relating to their use and their behaviour under neutron irradiation [fr

The Upshear Environment-Outflow Interface of a Sheared, Rapidly Intensifying Tropical Cyclone

Science.gov (United States)

Ryglicki, D.; Doyle, J. D.; Jin, Y.; Hodyss, D.; Viner, K.

2017-12-01

An idealized, simulated tropical cyclone (TC) which undergoes rapid intensification in moderate vertical wind shear is shown to exhibit structural similarities to observed TCs of this class. Due to a complex vortex tilt evolution, enhanced convection causes enhanced outflow from the TC which subsequently serves to block and to divert environmental flow around the TC. This allows for the TC to come back into vertical alignment and undergo rapid intensification. A trajectory analysis indicates that blocking is limited to a narrow range of heights, indicating that the vertical profile of environmental winds is a key factor for permitting this evolution. Satellite observations indicate the presence of upper-level arcs extending upshear beyond the TC. Synthetic satellite imagery of the simulated TC indicates this is the termination of the outflow. Using a Helmholtz decomposition, it is found that the divergent component of the outflow extends 1000 km upshear into the environment, potentially explaining the 1000-km clearing seen in satellite observations.

Efficient coupling of high intensity short laser pulses into snow clusters

Science.gov (United States)

Palchan, T.; Pecker, S.; Henis, Z.; Eisenmann, S.; Zigler, A.

2007-01-01

Measurements of energy absorption of high intensity laser pulses in snow clusters are reported. Targets consisting of sapphire coated with snow nanoparticles were found to absorb more than 95% of the incident light compared to 50% absorption in flat sapphire targets.

A 3D view of the outflow in the Orion Molecular Cloud 1 (OMC-1)

DEFF Research Database (Denmark)

Nissen, H.D.; Cunningham, N.J.; Sherson, Maiken Gustafsson

2012-01-01

and proper motion data for near-IR emission of molecular hydrogen to obtain the first 3-dimensional (3D) structure of the OMC-1 outflow. Our work illustrates a new diagnostic tool for studies of star formation that will be exploited in the near future with the advent of high spatial resolution spectro...... Observatory, the Anglo-Australian Observatory and the Subaru Telescope. These data give the 3D velocity of ejecta yielding a 3D reconstruction of the outflows. This allows one to view the material from different vantage points in space giving considerable insight into the geometry. Our analysis indicates......The fast outflow emerging from a region associated with massive star formation in the Orion Molecular Cloud 1 (OMC-1), located behind the Orion Nebula, appears to have been set in motion by an explosive event. Here we study the structure and dynamics of outflows in OMC-1. We combine radial velocity...

Differential Canalograms Detect Outflow Changes from Trabecular Micro-Bypass Stents and Ab Interno Trabeculectomy.

Science.gov (United States)

Parikh, Hardik A; Loewen, Ralitsa T; Roy, Pritha; Schuman, Joel S; Lathrop, Kira L; Loewen, Nils A

2016-11-04

Recently introduced microincisional glaucoma surgeries that enhance conventional outflow offer a favorable risk profile over traditional surgeries, but can be unpredictable. Two paramount challenges are the lack of an adequate training model for angle surgeries and the absence of an intraoperative quantification of surgical success. To address both, we developed an ex vivo training system and a differential, quantitative canalography method that uses slope-adjusted fluorescence intensities of two different chromophores to avoid quenching. We assessed outflow enhancement by trabecular micro-bypass (TMB) implantation or by ab interno trabeculectomy (AIT). In this porcine model, TMB resulted in an insignificant (p > 0.05) outflow increase of 13 ± 5%, 14 ± 8%, 9 ± 3%, and 24 ± 9% in the inferonasal, superonasal, superotemporal, and inferotemporal quadrant, respectively. AIT caused a 100 ± 50% (p = 0.002), 75 ± 28% (p = 0.002), 19 ± 8%, and 40 ± 21% increase in those quadrants. The direct gonioscopy and tactile feedback provided a surgical experience that was very similar to that in human patients. Despite the more narrow and discontinuous circumferential drainage elements in the pig with potential for underperformance or partial stent obstruction, unequivocal patterns of focal outflow enhancement by TMB were seen in this training model. AIT achieved extensive access to outflow pathways beyond the surgical site itself.

Absorber for terahertz radiation management

Science.gov (United States)

Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

2015-12-08

A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

Low-redshift Lyman limit systems as diagnostics of cosmological inflows and outflows

Science.gov (United States)

Hafen, Zachary; Faucher-Giguère, Claude-André; Anglés-Alcázar, Daniel; Kereš, Dušan; Feldmann, Robert; Chan, T. K.; Quataert, Eliot; Murray, Norman; Hopkins, Philip F.

2017-08-01

We use cosmological hydrodynamic simulations with stellar feedback from the FIRE (Feedback In Realistic Environments) project to study the physical nature of Lyman limit systems (LLSs) at z ≤ 1. At these low redshifts, LLSs are closely associated with dense gas structures surrounding galaxies, such as galactic winds, dwarf satellites and cool inflows from the intergalactic medium. Our analysis is based on 14 zoom-in simulations covering the halo mass range Mh ≈ 109-1013 M⊙ at z = 0, which we convolve with the dark matter halo mass function to produce cosmological statistics. We find that the majority of cosmologically selected LLSs are associated with haloes in the mass range 1010 ≲ Mh ≲ 1012 M⊙. The incidence and H I column density distribution of simulated absorbers with columns in the range 10^{16.2} ≤ N_{H I} ≤ 2× 10^{20} cm-2 are consistent with observations. High-velocity outflows (with radial velocity exceeding the halo circular velocity by a factor of ≳ 2) tend to have higher metallicities ([X/H] ˜ -0.5) while very low metallicity ([X/H] standard deviation) [X/H] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies, but consistent with LLSs arising from haloes with a broad range of masses and metallicities.

The near-infrared outflow and cavity of the proto-brown dwarf candidate ISO-Oph 200

Science.gov (United States)

Whelan, E. T.; Riaz, B.; Rouzé, B.

2018-03-01

In this Letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A 0.''5 blue-shifted outflow is detected in both H2 and [Fe II] lines at Vsys = (–35 ± 2) km s-1 and Vsys = (–51 ± 5) km s-1 respectively. In addition, slower ( ±10 km s-1) H2 emission is detected out to <5.''4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H2 emission is tracing a cavity. The source extinction is estimated at Av = 18 ± 1 mag and the outflow extinction at Av = 9 ± 0.4 mag. The H2 outflow temperature is calculated to be 1422 ± 255 K and the electron density of the [Fe II] outflow is measured at 10 000 cm-3. Furthermore, the mass outflow rate is estimated at Ṁout [H2] = 3.8 × 10-10 M⊙ yr-1 and Ṁout[Fe II] = 1 × 10-8 M⊙ yr-1. Ṁout[Fe II] takes a Fe depletion of 88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μm and [P II] 1.188 μm lines. Using the Paβ and Brγ lines and a range in stellar mass and radius Ṁacc is calculated to be (3–10) × 10-8 M⊙ yr-/1. Comparing these rates puts the jet efficiency in line with predictions of magneto-centrifugal models of jet launching in low mass protostars. This is a further case of a brown dwarf outflow exhibiting analogous properties to protostellar jets. Based on Observations collected with SINFONI at the Very Large Telescope on Cerro Paranal (Chile), operated by the European Southern Observatory (ESO). Program ID: 097.C-0732(A).

LOW-ALTITUDE RECONNECTION INFLOW-OUTFLOW OBSERVATIONS DURING A 2010 NOVEMBER 3 SOLAR ERUPTION

Energy Technology Data Exchange (ETDEWEB)

Savage, Sabrina L.; Holman, Gordon; Su, Yang [NASA/Goddard Space Flight Center, Oak Ridge Associated Universities, 8800 Greenbelt Road, Code 671, Greenbelt, MD 20771 (United States); Reeves, Katharine K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS 58, Cambridge, MA 02138 (United States); Seaton, Daniel B. [Royal Observatory of Belgium-SIDC, Avenue Circulaire 3, B-1180 Brussels (Belgium); McKenzie, David E. [Department of Physics, Montana State University, P.O. Box 173840, Bozeman, MT 59717-3840 (United States)

2012-07-20

For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion-an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from {approx}150 to 690 km s{sup -1} with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the Alfvenic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal light curve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be {approx}10{sup 2} km s{sup -1} with outflow speeds ranging from {approx}10{sup 2} to 10{sup 3} km s{sup -1}-indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could possibly either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops-presumably exiting the reconnection site.

LOW-ALTITUDE RECONNECTION INFLOW-OUTFLOW OBSERVATIONS DURING A 2010 NOVEMBER 3 SOLAR ERUPTION

International Nuclear Information System (INIS)

Savage, Sabrina L.; Holman, Gordon; Su, Yang; Reeves, Katharine K.; Seaton, Daniel B.; McKenzie, David E.

2012-01-01

For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion—an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from ∼150 to 690 km s –1 with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfvén speeds, we estimate the Alfvénic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal light curve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be ∼10 2 km s –1 with outflow speeds ranging from ∼10 2 to 10 3 km s –1 —indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could possibly either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops—presumably exiting the reconnection site.

Effect of clear cutting on snow accumulation and water outflow at Fraser, Colorado

Directory of Open Access Journals (Sweden)

C. A. Troendle

1997-01-01

Full Text Available This paper compares of snowpack accumulation and ablation, evapotranspiration, and water outflow from clearcut and forested plots within a high elevation (2900 m mixed conifer forest at the Fraser Experimental Forest near Fraser, Colorado, USA. Also presented is a method for defining contributing area where outflow is measured from unbounded plots. Plots were monitored from 1980 to 1990 and again in 1993. The clearcut plot was harvested in late 1984. Evapotranspiration (ET of the forested plot at zero discharge (ETo was estimated at 426 mm while the ET was 500 mm at the mean precipitation of 596 mm. ET was dependent on precipitation with about 28% of precipitation input in excess of 426 mm contributing to increased ET, while the remainder contributed to increased outflow. During the six monitored post-harvest years, Peak Water Equivalent of the snowpack averaged 36% higher on the cut plot than on the control, and the mean discharge increased from 85 mm to 356 mm. Area estimates were obtained from the slopes of the regression of outflow on precipitation inputs. Hydrologic parameters corresponded closely to those previously determined at Fraser Experimental Forest using other methods, lending credence to the validity of the area estimates.

ON THE HEATING EFFICIENCY DERIVED FROM OBSERVATIONS OF YOUNG SUPER STAR CLUSTERS IN M82

International Nuclear Information System (INIS)

Silich, Sergiy; Tenorio-Tagle, Guillermo; Torres-Campos, Ana; Munoz-Tunon, Casiana; Monreal-Ibero, Ana; Melo, Veronica

2009-01-01

Here, we discuss the mechanical feedback that massive stellar clusters provide to the interstellar medium of their host galaxy. We apply an analytic theory developed in a previous study for M82-A1 to a sample of 10 clusters located in the central zone of the starburst galaxy M82, all surrounded by compact and dense H II regions. We claim that the only way that such H II regions can survive around the selected clusters, is if they are embedded into a high-pressure ISM and if the majority of their mechanical energy is lost within the star cluster volume via strong radiative cooling. The latter implies that these clusters have a low heating efficiency, η, and evolve in the bimodal hydrodynamic regime. In this regime, the shock-heated plasma in the central zones of a cluster becomes thermally unstable, loses its pressure and is accumulated there, whereas the matter injected by supernovae and stellar winds outside this volume forms a high-velocity outflow-the star cluster wind. We calculated the heating efficiency for each of the selected clusters and found that in all cases it does not exceed 10%. Such low heating efficiency values imply a low mechanical energy output and the impact that the selected clusters provide to the ISM of M82 is thus much smaller than what one would expect using stellar cluster synthetic models.

Acromegaly-induced cardiomyopathy with dobutamine-induced outflow tract obstruction.

Science.gov (United States)

Abdelsalam, Mahmoud A; Nippoldt, Todd B; Geske, Jeffrey B

2016-03-09

A 50-year-old man with a history of acromegaly was referred for preoperative cardiac evaluation preceding trans-sphenoidal resection of a pituitary macroadenoma. Dobutamine stress echocardiography was negative for myocardial ischaemia. Resting left ventricular (LV) LV ejection fraction (LVEF) was 64% and there was hypertrophy of ventricular septum (18 mm) without resting LV outflow tract obstruction. With 40 µg/kg/min of dobutamine, the LVEF became hyperdynamic at 80%, and there was a maximal instantaneous LV outflow tract gradient of 77 mm Hg. There was no delayed myocardial enhancement on cardiac MRI and the pattern of hypertrophy was concentric. Acromegaly-induced cardiomyopathy can mimic hypertrophic cardiomyopathy in the setting of dobutamine provocation. Because cardiomyopathy is an important cause of mortality in acromegaly, diagnosis and appropriate management are critical to improve survival. 2016 BMJ Publishing Group Ltd.

Atmospheric pollutant outflow from southern Asia: a review

Science.gov (United States)

Lawrence, M. G.; Lelieveld, J.

2010-11-01

Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern Asian atmospheric pollutant outflow and its large scale effects. An outlook

Recognition and treatment of outflow tract stenosis during and after endovascular exclusion for abdominal aortic aneurysm

International Nuclear Information System (INIS)

Lu Qingsheng; Jing Zaiping; Zhao Zhiqing; Bao Junmin; Zhao Jun; Feng Xiang; Feng Rui; Huang Sheng

2003-01-01

Objective: To study the cognition and treatment of outflow tract stenosis in and after endovascular exclusion for abdominal aortic aneurysm. Methods: From Mar 1997 to Oct 2002, in 136 patients undergoing abdominal aortic aneurysm endovascular exclusion, 8 patients had outflow tract stenosis during the operation, and 3 patients had outflow tract stenosis after operation. The stenosis of 5 patients occurred at the crotch of the graft-stent. PTA was done in 7 patients and stents were placed in stenotic segment in 2 patients. 2 patients were treated with crossover operation. Results: Following up 1 month to 2 years, all patients have no lower limbs ischemia. Conclusions: The diagnosis of outflow tract stenosis during and after abdominal endovascular exclusion for aortic aneurysm must be in time. The treatment should be according to the different causes of stenosis

Further studies of the role of dense molecular clouds around outflow sources

International Nuclear Information System (INIS)

Verdes-Montenegro, L.; Torrelles, J.M.; Rodriguez, L.F.; Anglada, G.; Lopez, R.

1989-01-01

The (J,K) = (1,1) and (2,2) ammonia inversion transitions toward six regions with active star formation and evidence of gas outflows have been observed. Ammonia emission has been detected and mapped in five of these regions: AFGL 5142, AFGL 5157, AFGL 6366S, HHL 73, and S140N. NH3 (2,2) emission was detected toward the peak of the NH3 (1,1) core of AFGL 5157 and S140N. A rotational temperature of T(R) (2,2;1,1) = about 16 K was estimated for the two regions. Two new H2O masers of intense emission, S(nu) greater or equal 40 Jy, were detected toward the ammonia cores of AFGL 5142 and AFGL 5157. It is clear that the dense NH3 gas is closely associated with the star formation activities, since the ammonia cores in all peak close to the centers of activity. In particular, the AFGL 5157 ammonia condensation coincides with the geometrical center of a bipolar molecular outflow, suggesting that the exciting source is embedded in the ammonia core. In contrast, the molecular outflow in the AFGL 6366S region is located at the southeast edge of the NH3 condensation, suggesting that the exciting source is outside the ammonia core and that the morphology of the outflow may be influenced by the interaction with the dense ambient gas. 52 refs

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

Energy Technology Data Exchange (ETDEWEB)

Chan, Chi-Ho [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.

Foreshock-like density cavity in the outflow region of magnetotail reconnection

Directory of Open Access Journals (Sweden)

C. L. Cai

2009-08-01

Full Text Available During Cluster spacecraft crossing of the magnetotail, a novel density depleted cavity in association with magnetic compressions in the outflow region of reconnection was observed. It contains intense reflected field-aligned particles, which are produced by a generation mechanism similar to that of the terrestrial foreshock, and hence manifests a foreshock-like morphology. In this cavity, reflected field-aligned proton beams were observed and simultaneously the feature of magnetic-mirror loss-cone proton distributions were found. Magnetic field fluctuations, especially quasi-monochromatic oscillations, were recorded. Both the leading egde and the ULF wave boundary of the ion foreshock are identified from the time sequence of proton and magnetic field observations. Just upstream of the leading egde of the ion foreshock, reflected field-aligned electrons were detected, whose distribution has a narrow bump-on-tail pattern. However, close to the shock front, reflected electrons with a broad bump-on-tail pattern was measured. These two different manifestations of reflected electrons reveal the differences in their microscopic physics of the reflecting process. Moreover, a part of incident ions was further accelerated in the cavity due to trans-time magnetic pumping which provides another possible mechanism in the multi-step acceleration processes in reconnection.

Self-interstitial atom clusters as obstacles to glide of 1/3{11-bar 00} edge dislocations in α-zirconium

International Nuclear Information System (INIS)

Voskoboynikov, R.E.; Osetsky, Yu.N.; Bacon, D.J.

2005-01-01

Atomic-scale details of interaction of a 1/3 {11-bar 00} edge dislocation with clusters of self-interstitial atoms (SIAs) in α-zirconium has been studied by computer simulation. Four typical clusters are considered. A triangular cluster of five SIAs lying within a basal plane bisected by the dislocation glide plane is not absorbed by the dislocation but acts as a moderately strong obstacle. A 3-D SIA cluster lying across the glide plane is completely absorbed by the dislocation by creation of super-jogs, and is a weak obstacle. Interaction of the dislocation with glissile SIA loops with perfect Burgers vector inclined at 60 deg. to the dislocation glide plane shows that the process depends on the vector orientation. Defects of the two orientations are strong obstacles, and one, which initially forms a sessile segment on the dislocation line, is particularly so

Aggregation and composition effects on absorption and scattering properties of dye-sensitized anatase TiO{sub 2} particle clusters

Energy Technology Data Exchange (ETDEWEB)

Vargas, William E. [Centro de Investigacion en Ciencia e Ingenieria de Materiales and Escuela de Fisica, Universidad de Costa Rica, 2060 San Jose (Costa Rica)], E-mail: vargasc@cariari.ucr.ac.cr

2008-06-15

A transition matrix approach is used to compute the scattering and absorption cross sections, as well as phase functions, asymmetry factors and forward scattering ratios, of clusters of spherical particles. In order to approach the local structure and composition of the nanosized active layer of photoelectrochemical solar cells, some clusters consist of homogeneous non-absorbing anatase spherical pigments, others have anatase particles coated with a monolayer of absorbing dye molecules, and others can consist of both uncoated and dye-coated anatase particles. Orientation average values of the volumetric scattering and absorption cross sections are computed in terms of the size of the spherical particles in the clusters and their number. The degree of scattering and absorption when considering dye-coated anatase particles in the clusters is characterized. The effect of dependent scattering on the average angular distribution of the scattered radiation is also considered.

Dependence of Ca outflow and depression of frog myocardium contraction on ryodipine concentration.

Science.gov (United States)

Narusevicius, E; Gendviliene, V; Macianskiene, R; Hmelj-Dunai, G; Velena, A; Duburs, G

1988-02-01

The effect of ryodipine on calcium outflow from tissues, on contraction force, the duration of action potentials and the relaxation phase time-constant in the contraction cycles of myocardial strips was studied using frog heart preparations. It was found that calcium outflow (delta Ca) as a function on ryodipine concentration can be represented as: (formula; see text) A linear correlation exists between Ca2+, contraction blocking and the shortening of the action potential in the presence of various ryodipine concentrations. Ryodipine (10(-5) mol/l) decreased the relaxation time-constant by about 20% as compared to controls. It was concluded that calcium outflow from myocardial tissues in response to ryodipine is due to blockade of calcium entry into the cells and their output through the Na+--Ca2+ exchange system. Frog heart myocardial contractions are essentially under the control of calcium entry through sarcolemmal calcium channels.

NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G.; Cooke, Jeff [Swinburne University of Technology, Victoria 3122 (Australia); Martin, Crystal L.; Ho, Stephanie H. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane [CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP) de Toulouse, 14 Avenue E. Belin, F-31400 Toulouse (France); Churchill, Christopher W.; Klimek, Elizabeth, E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2014-09-01

We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

Better Than Nothing: A Rational Approach for Minimizing the Impact of Outflow Strategy on Cerebrovascular Simulations.

Science.gov (United States)

Chnafa, C; Brina, O; Pereira, V M; Steinman, D A

2018-02-01

Computational fluid dynamics simulations of neurovascular diseases are impacted by various modeling assumptions and uncertainties, including outlet boundary conditions. Many studies of intracranial aneurysms, for example, assume zero pressure at all outlets, often the default ("do-nothing") strategy, with no physiological basis. Others divide outflow according to the outlet diameters cubed, nominally based on the more physiological Murray's law but still susceptible to subjective choices about the segmented model extent. Here we demonstrate the limitations and impact of these outflow strategies, against a novel "splitting" method introduced here. With our method, the segmented lumen is split into its constituent bifurcations, where flow divisions are estimated locally using a power law. Together these provide the global outflow rate boundary conditions. The impact of outflow strategy on flow rates was tested for 70 cases of MCA aneurysm with 0D simulations. The impact on hemodynamic indices used for rupture status assessment was tested for 10 cases with 3D simulations. Differences in flow rates among the various strategies were up to 70%, with a non-negligible impact on average and oscillatory wall shear stresses in some cases. Murray-law and splitting methods gave flow rates closest to physiological values reported in the literature; however, only the splitting method was insensitive to arbitrary truncation of the model extent. Cerebrovascular simulations can depend strongly on the outflow strategy. The default zero-pressure method should be avoided in favor of Murray-law or splitting methods, the latter being released as an open-source tool to encourage the standardization of outflow strategies. © 2018 by American Journal of Neuroradiology.

Sub-arcsecond imaging of Arp 299-A at 150 MHz with LOFAR: Evidence for a starburst-driven outflow

Science.gov (United States)

Ramírez-Olivencia, N.; Varenius, E.; Pérez-Torres, M.; Alberdi, A.; Pérez, E.; Alonso-Herrero, A.; Deller, A.; Herrero-Illana, R.; Moldón, J.; Barcos-Muñoz, L.; Martí-Vidal, I.

2018-03-01

We report on the first sub-arcsecond (0.44 × 0.41 arcsec2) angular resolution image at 150 MHz of the A-nucleus in the luminous infrared galaxy Arp 299, from International Low Frequency Array (LOFAR) Telescope observations. The most remarkable finding is that of an intriguing two-sided, filamentary structure emanating from the A-nucleus, which we interpret as an outflow that extends up to at least 14 arcsec from the A-nucleus in the N-S direction ( ≈5 kpc deprojected size) and accounts for almost 40% of the extended emission of the entire galaxy system. We also discuss HST/NICMOS [FeII] 1.64 μm and H2 2.12 μm images of Arp 299-A, which show similar features to those unveiled by our 150 MHz LOFAR observations, providing strong morphological support for the outflow scenario. Finally, we discuss unpublished Na I D spectra that confirm the outflow nature of this structure. From energetic arguments, we rule out the low-luminosity active galactic nucleus in Arp 299-A as a driver for the outflow. On the contrary, the powerful, compact starburst in the central regions of Arp 299-A provides plenty of mechanical energy to sustain an outflow, and we conclude that the intense supernova (SN) activity in the nuclear region of Arp 299-A is driving the observed outflow. We estimate that the starburst wind can support a mass-outflow rate in the range (11-63 M⊙ yr-1) at speeds of up to 370-890 km s-1, and is relatively young, with an estimated kinematic age of 3-7 Myr. Those results open an avenue to the use of low-frequency (150 MHz), sub-arcsecond imaging with LOFAR to detect outflows in the central regions of local luminous infrared galaxies.

PROBING THE EXTREME REALM OF ACTIVE GALACTIC NUCLEUS FEEDBACK IN THE MASSIVE GALAXY CLUSTER, RX J1532.9+3021

Energy Technology Data Exchange (ETDEWEB)

Hlavacek-Larrondo, J.; Allen, S. W.; Canning, R. E. A.; Werner, N.; Ehlert, S.; Von der Linden, A. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Taylor, G. B.; Grimes, C. K. [Department of Physics and Astronomy, University of New-Mexico, Albuquerque, NM 87131 (United States); Fabian, A. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Sanders, J. S., E-mail: juliehl@stanford.edu [Max-Planck-Institut fur extraterrestrische Physik (MPE), Giessenbachstrasse, D-85748 Garching (Germany)

2013-11-10

We present a detailed Chandra, XMM-Newton, Very Large Array (VLA) and Hubble Space Telescope analysis of one of the strongest cool core clusters known, RX J1532.9+3021 (z = 0.3613). Using new, deep 90 ks Chandra observations, we confirm the presence of a western X-ray cavity or bubble, and report on a newly discovered eastern X-ray cavity. The total mechanical power associated with these active galactic nucleus (AGN) driven outflows is (22 ± 9) × 10{sup 44} erg s{sup –1}, and is sufficient to offset the cooling, indicating that AGN feedback still provides a viable solution to the cooling flow problem even in the strongest cool core clusters. Based on the distribution of the optical filaments, as well as a jet-like structure seen in the 325 MHz VLA radio map, we suggest that the cluster harbors older outflows along the north to south direction. The jet of the central AGN is therefore either precessing or sloshing-induced motions have caused the outflows to change directions. There are also hints of an X-ray depression to the north aligned with the 325 MHz jet-like structure, which might represent the highest redshift ghost cavity discovered to date. We further find evidence of a cold front (r ≈ 65 kpc) that coincides with the outermost edge of the western X-ray cavity and the edge of the radio mini-halo. The common location of the cold front with the edge of the radio mini-halo supports the idea that the latter originates from electrons being reaccelerated due to sloshing-induced turbulence. Alternatively, its coexistence with the edge of the X-ray cavity may be due to cool gas being dragged out by the outburst. We confirm that the central AGN is highly sub-Eddington and conclude that a >10{sup 10} M{sub ☉} or a rapidly spinning black hole is favored to explain both the radiative-inefficiency of the AGN and the powerful X-ray cavities.

Unicameral bone cyst: radiographic assessment of venous outflow by cystography as a prognostic index.

Science.gov (United States)

Ramirez, Ana; Abril, Juan Carlos; Touza, Alberto

2012-11-01

The aim of this study was to determine the benefits of cystography in the management of a simple bone cyst, its implication in the final result of the treatment after corticoid intracystic injections, and the presence of secondary effects. We retrospectively reviewed 42 patients diagnosed with a simple bone cyst. Cystography was performed before the corticoid injection. The presence or absence of loculation intracyst and the existence and number of venous outflows were determined. According to the venous drainage, cysts were classified as type 0 when a venous outflow did not exist and as type 1 when there was a rapid venous outflow (unicameral bone cyst with absent loculation in 16 cases (37.3%), whereas the lesion showed multiloculation in 26 cases (62.7%). There was no statistical difference between loculation intracyst (present or absent) and the final outcomes of the 42 cysts treated with a steroid injection (P=0.9). Cystography showed a negative venogram in 10 cases (23.8%), whereas the cysts showed a rapid venous outflow in 32 cases (76.2%). On the basis of Neer's classification, all patients with a negative venogram achieved complete healing of the cyst. Patients with a rapid venous outflow achieved complete healing in 14 cases (Neer I). In two patients, the healing was incomplete at the end of the follow-up period (Neer IV). In most cases (21 cysts), healing was partial (Neer II). Five patients showed a recurrence after initial healing of the cyst (Neer III) (P<0.05). The number or the size of veins did not affect healing of a bone cyst (P=0.6). Two patients with a rapid venous outflow showed a generalized hypertrichosis after the first injection of corticosteroids. Sex and age at the initiation of the first injection were not significant factors of healing (P=0.4). The average follow-up time was 59 months (24-60 months). Cystography provides morphological and functional information of simple bone cyst. It is a useful test before the administration of

Advection-dominated Inflow/Outflows from Evaporating Accretion Disks.

Science.gov (United States)

Turolla; Dullemond

2000-03-01

In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture, the ADAF fills the central cavity evacuated by the SSD and extends beyond the transition radius into a coronal region. We find that, because of global angular momentum conservation, a significant fraction of the hot gas flows away from the black hole, forming a transsonic wind, unless the injection rate depends only weakly on radius (if r2sigma&d2;~r-xi, xiBernoulli number of the inflowing gas is negative if the transition radius is less, similar100 Schwarzschild radii, so matter falling into the hole is gravitationally bound. The ratio of inflowing to outflowing mass is approximately 1/2, so in these solutions the accretion rate is of the same order as in standard ADAFs and much larger than in advection-dominated inflow/outflow models. The possible relevance of evaporation-fed solutions to accretion flows in black hole X-ray binaries is briefly discussed.

The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow

Science.gov (United States)

Feruglio, C.; Fiore, F.; Carniani, S.; Piconcelli, E.; Zappacosta, L.; Bongiorno, A.; Cicone, C.; Maiolino, R.; Marconi, A.; Menci, N.; Puccetti, S.; Veilleux, S.

2015-11-01

Mrk 231 is a nearby ultra-luminous IR galaxy exhibiting a kpc-scale, multi-phase AGN-driven outflow. This galaxy represents the best target to investigate in detail the morphology and energetics of powerful outflows, as well as their still poorly-understood expansion mechanism and impact on the host galaxy. In this work, we present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO(2-1) and (3-2) observations obtained with the IRAM/PdBI. In addition, we analyze archival deep Chandra and NuSTAR X-ray observations. We use this unprecedented combination of multi-wavelength data sets to constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular CO(2-1) outflow has a size of 1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to 1 kpc, thus implying that the density of the outflowing material must decrease from the nucleus outwards as r-2. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to 1 kpc, thus implying a limit on its age of 1 Myr. Mapping the mass and energy rates of the molecular outflow yields dot {M} OF = [500-1000] M⊙ yr-1 and Ėkin,OF = [7-10] × 1043 erg s-1. The total kinetic energy of the outflow is Ekin,OF is of the same order of the total energy of the molecular disk, Edisk. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity -20 000 km s-1, dot {M}UFO = [0.3-2.1] M⊙ yr-1, and momentum load dot {P}UFO/ dot {P}rad = [0.2-1.6]. We find Ėkin,UFO Ėkin,OF as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO

Molecular Outflow and Feedback in an Obscured Quasar at z˜1.5 Revealed by ALMA

Science.gov (United States)

Brusa, Marcella

2017-11-01

We imaged with ALMA and ARGOS/LUCI the molecular gas and the dust and stellar continuum in XID2028, an obscured QSO at z=1.593, where the presence of a massive outflow in the ionized gas component traced by the [O III]5007 emission has been resolved up to 10 kpc. This target does represent a unique test case to study QSO 'feedback in action' at the peak epoch of AGN- galaxy coevolution. The QSO has been detected both in the CO(5-4) transition and in the 1.3mm continuum, with emissions confined in the central ( consumption conditions in XID2028, possibly due to feedback effects on the host galaxy. Finally, we observe an asymmetric profile of the CO(5-4) line, which suggests the presence of high velocity gas up to 700 km/s. An image of the blueshfited and redshifted CO wings provides the first detection of a spatially resolved, galaxy-scale molecular outflow at high-z, extended in opposite directions with the approaching component spatially coincident with the ionised gas outflow. The resolved, molecular outflow appear to be cospatial with the component observed int the ionised gas. XID2028 therefore represents the first example of molecular and ionised kpc scales outflows at high-z.

Outflow monitoring of a pneumatic ventricular assist device using external pressure sensors.

Science.gov (United States)

Kang, Seong Min; Her, Keun; Choi, Seong Wook

2016-08-25

In this study, a new algorithm was developed for estimating the pump outflow of a pneumatic ventricular assist device (p-VAD). The pump outflow estimation algorithm was derived from the ideal gas equation and determined the change in blood-sac volume of a p-VAD using two external pressure sensors. Based on in vitro experiments, the algorithm was revised to consider the effects of structural compliance caused by volume changes in an implanted unit, an air driveline, and the pressure difference between the sensors and the implanted unit. In animal experiments, p-VADs were connected to the left ventricles and the descending aorta of three calves (70-100 kg). Their outflows were estimated using the new algorithm and compared to the results obtained using an ultrasonic blood flow meter (UBF) (TS-410, Transonic Systems Inc., Ithaca, NY, USA). The estimated and measured values had a Pearson's correlation coefficient of 0.864. The pressure sensors were installed at the external controller and connected to the air driveline on the same side as the external actuator, which made the sensors easy to manage.

The response of relativistic outflowing gas to the inner accretion disk of a black hole.

Science.gov (United States)

Parker, Michael L; Pinto, Ciro; Fabian, Andrew C; Lohfink, Anne; Buisson, Douglas J K; Alston, William N; Kara, Erin; Cackett, Edward M; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C; Garcia, Javier; Harrison, Fiona A; King, Ashley L; Middleton, Matthew J; Miller, Jon M; Miniutti, Giovanni; Reynolds, Christopher S; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J; Wilkins, Daniel R; Zoghbi, Abderahmen

2017-03-01

The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different

Primary cardiac tumor presenting as left ventricular outflow tract obstruction and complex arrhythmia.

Science.gov (United States)

Fries, R; Achen, S; O'Brien, M T; Jackson, N D; Gordon, S

2017-10-01

An adult female mixed breed dog presented for recurrent collapsing episodes over several weeks. Holter evaluation revealed periods of sinus arrest and echocardiography identified a soft tissue mass with subsequent severe dynamic obstruction of the left ventricular outflow tract. The patient was euthanized five days after presentation for severe dyspnea. Necropsy revealed an irregular mass circumferentially lining the left ventricular outflow tract as well as multiple myocardial metastases. The final diagnosis was an undifferentiated pleomorphic endocardial sarcoma. Published by Elsevier B.V.

Cellular automaton model in the fundamental diagram approach reproducing the synchronized outflow of wide moving jams

International Nuclear Information System (INIS)

Tian, Jun-fang; Yuan, Zhen-zhou; Jia, Bin; Fan, Hong-qiang; Wang, Tao

2012-01-01

Velocity effect and critical velocity are incorporated into the average space gap cellular automaton model [J.F. Tian, et al., Phys. A 391 (2012) 3129], which was able to reproduce many spatiotemporal dynamics reported by the three-phase theory except the synchronized outflow of wide moving jams. The physics of traffic breakdown has been explained. Various congested patterns induced by the on-ramp are reproduced. It is shown that the occurrence of synchronized outflow, free outflow of wide moving jams is closely related with drivers time delay in acceleration at the downstream jam front and the critical velocity, respectively. -- Highlights: ► Velocity effect is added into average space gap cellular automaton model. ► The physics of traffic breakdown has been explained. ► The probabilistic nature of traffic breakdown is simulated. ► Various congested patterns induced by the on-ramp are reproduced. ► The occurrence of synchronized outflow of jams depends on drivers time delay.

Molecular Gas toward the Gemini OB1 Molecular Cloud Complex. II. CO Outflow Candidates with Possible WISE Associations

Science.gov (United States)

Li, Yingjie; Li, Fa-Cheng; Xu, Ye; Wang, Chen; Du, Xin-Yu; Yang, Wenjin; Yang, Ji

2018-03-01

We present a large-scale survey of CO outflows in the Gem OB1 molecular cloud complex and its surroundings, using the Purple Mountain Observatory Delingha 13.7 m telescope. A total of 198 outflow candidates were identified over a large area (∼58.5 square degrees), of which 193 are newly detected. Approximately 68% (134/198) are associated with the Gem OB1 molecular cloud complex, including clouds GGMC 1, GGMC 2, BFS 52, GGMC 3, and GGMC 4. Other regions studied are: the Local arm (Local Lynds, West Front), Swallow, Horn, and Remote cloud. Outflow candidates in GGMC 1, BFS 52, and Swallow are mainly located at ring-like or filamentary structures. To avoid excessive uncertainty in distant regions (≳3.8 kpc), we only estimated the physical parameters for clouds in the Gem OB1 molecular cloud complex and in the Local arm. In those clouds, the total kinetic energy and the energy injection rate of the identified outflow candidates are ≲1% and ≲3% of the turbulent energy and the turbulent dissipation rate of each cloud, indicating that the identified outflow candidates cannot provide enough energy to balance turbulence of their host cloud at the scale of the entire cloud (several to dozens of parsecs). The gravitational binding energy of each cloud is ≳135 times the total kinetic energy of the identified outflow candidates within the corresponding cloud, indicating that the identified outflow candidates cannot cause major disruptions to the integrity of their host cloud at the scale of the entire cloud.

The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

Science.gov (United States)

Gallo, L. C.; Fabian, A. C.

2013-07-01

In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

Hydraulic shock absorbers

International Nuclear Information System (INIS)

Thatcher, G.; Davidson, D. F.

1984-01-01

A hydraulic shock absorber of the dash pot kind for use with electrically conducting liquid such as sodium, has magnet means for electro magnetically braking a stream of liquid discharged from the cylinder. The shock absorber finds use in a liquid metal cooled nuclear reactor for arresting control rods

Reflection measurements of microwave absorbers

Science.gov (United States)

Baker, Dirk E.; van der Neut, Cornelis A.

1988-12-01

A swept-frequency interferometer is described for making rapid, real-time assessments of localized inhomogeneities in planar microwave absorber panels. An aperture-matched exponential horn is used to reduce residual reflections in the system to about -37 dB. This residual reflection is adequate for making comparative measurements on planar absorber panels whose reflectivities usually fall in the -15 to -25 dB range. Reflectivity measurements on a variety of planar absorber panels show that multilayer Jaumann absorbers have the greatest inhomogeneity, while honeycomb absorbers generally have excellent homogeneity within a sheet and from sheet to sheet. The test setup is also used to measure the center frequencies of resonant absorbers. With directional couplers and aperture-matched exponential horns, the technique can be easily applied in the standard 2 to 40 GHz waveguide bands.

ALMA OBSERVATIONS OF THE OUTFLOW FROM SOURCE I IN THE ORION-KL REGION

Energy Technology Data Exchange (ETDEWEB)

Zapata, Luis A.; Rodriguez, Luis F.; Loinard, Laurent [Centro de Radioastronomia y Astrofisica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacan (Mexico); Schmid-Burgk, Johannes; Menten, Karl M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Curiel, Salvador [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ap. 70-264, 04510 DF (Mexico)

2012-07-20

In this Letter, we present sensitive millimeter SiO (J = 5-4; {nu} = 0) line observations of the outflow arising from the enigmatic object Orion Source I made with the Atacama Large Millimeter/Submillimeter Array (ALMA). The observations reveal that at scales of a few thousand AU, the outflow has a marked 'butterfly' morphology along a northeast-southwest axis. However, contrary to what is found in the SiO and H{sub 2}O maser observations at scales of tens of AU, the blueshifted radial velocities of the moving gas are found to the northwest, while the redshifted velocities are in the southeast. The ALMA observations are complemented with SiO (J = 8-7; {nu} = 0) maps (with a similar spatial resolution) obtained with the Submillimeter Array. These observations also show a similar morphology and velocity structure in this outflow. We discuss some possibilities to explain these differences at small and large scales across the flow.

Systemic Embolization from an Unusual Intracardiac Mass in the Left Ventricular Outflow Tract

Directory of Open Access Journals (Sweden)

Kelechukwu U. Okoro

2017-01-01

Full Text Available Endocarditis can affect any endocardial surface; in the vast majority of cases, the cardiac valves are involved. It is exceedingly rare to develop infective endocarditis on the endocardium of the left ventricular outflow tract due to the high velocity of blood that traverses this area. Herein, we present a rare case of left ventricular outflow tract endocarditis that likely occurred secondary to damage to the aortic valve leaflets (from healed prior aortic valve endocarditis causing a high velocity aortic valve regurgitant jet that impinged upon the interventricular septum which damaged the endocardium and resulted in a fibrotic “jet lesion.” This fibrous jet lesion served as a nidus for bacterial proliferation and vegetation formation. The high shear stress (due to high blood flow velocity through the left ventricular outflow tract likely promoted the multiple embolic events observed in this case. Our patient was successfully treated with aortic valve replacement, vegetation resection, and antibiotics.

Human cerebral venous outflow pathway depends on posture and central venous pressure

DEFF Research Database (Denmark)

Gisolf, J; van Lieshout, J J; van Heusden, K

2004-01-01

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture...... and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R(2) = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway...

Understanding the strong intervening O VI absorber at zabs ˜ 0.93 towards PG1206+459

Science.gov (United States)

Rosenwasser, B.; Muzahid, S.; Charlton, J. C.; Kacprzak, G. G.; Wakker, B. P.; Churchill, C. W.

2018-05-01

We have obtained new observations of the partial Lyman limit absorber at zabs=0.93 towards quasar PG 1206+459, and revisit its chemical and physical conditions. The absorber, with N({H I})˜ 10^{17.0} cm-2 and absorption lines spread over ≳1000 km s-1 in velocity, is one of the strongest known O VI absorbers at \\log N({{O VI}})= 15.54 ± 0.17. Our analysis makes use of the previously known low- (e.g. Mg II), intermediate- (e.g. Si IV), and high-ionization (e.g. C IV, N V, Ne VIII) metal lines along with new Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) observations that cover O VI and an HST/ACS image of the quasar field. Consistent with previous studies, we find that the absorber has a multiphase structure. The low-ionization phase arises from gas with a density of \\log (n_H/cm^{-3})˜ -2.5 and a solar to supersolar metallicity. The high-ionization phase stems from gas with a significantly lower density, i.e. \\log (n_H/cm^{-3}) ˜ -3.8, and a near-solar to solar metallicity. The high-ionization phase accounts for all of the absorption seen in C IV, N V, and O VI. We find the the detected Ne VIII, reported by Tripp et al. (2011), is best explained as originating in a stand-alone collisionally ionized phase at T˜ 10^{5.85} K, except in one component in which both O VI and Ne VIII can be produced via photoionization. We demonstrate that such strong O VI absorption can easily arise from photoionization at z ≳ 1, but that, due to the decreasing extragalactic UV background radiation, only collisional ionization can produce large O VI features at z ˜ 0. The azimuthal angle of ˜88° of the disc of the nearest (68 kpc) luminous (1.3L*) galaxy at zgal = 0.9289, which shows signatures of recent merger, suggests that the bulk of the absorption arises from metal enriched outflows.

Atmospheric pollutant outflow from southern Asia: a review

Directory of Open Access Journals (Sweden)

M. G. Lawrence

2010-11-01

Full Text Available Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ, located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern Asian atmospheric pollutant outflow and its large scale

Corrosion resistant neutron absorbing coatings

Science.gov (United States)

Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

2012-05-29

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE

International Nuclear Information System (INIS)

Brooks, David H.; Warren, Harry P.

2011-01-01

One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed outflows from the edges of active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that the outflows reach velocities of 50 km s -1 with spectral line asymmetries approaching 200 km s -1 . It has been suggested that these outflows may lie on open field lines that connect to the heliosphere, and that they could potentially be a significant source of the slow speed solar wind. A direct link has been difficult to establish, however. We use EIS measurements of spectral line intensities that are sensitive to changes in the relative abundance of Si and S as a result of the first ionization potential (FIP) effect, to measure the chemical composition in the outflow regions of AR 10978 over a 5 day period in 2007 December. We find that Si is always enhanced over S by a factor of 3-4. This is generally consistent with the enhancement factor of low FIP elements measured in situ in the slow solar wind by non-spectroscopic methods. Plasma with a slow wind-like composition was therefore flowing from the edge of the AR for at least 5 days. Furthermore, on December 10 and 11, when the outflow from the western side was favorably oriented in the Earth direction, the Si/S ratio was found to match the value measured a few days later by the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer. These results provide strong observational evidence for a direct connection between the solar wind, and the coronal plasma in the outflow regions.

GGD 37: AN EXTREME PROTOSTELLAR OUTFLOW

International Nuclear Information System (INIS)

Green, J. D.; Watson, D. M.; Forrest, W. J.; Kim, K. H.; Bergin, E.; Maret, S.; Melnick, G.; Tolls, V.; Sonnentrucker, P.; Sargent, B. A.; Raines, S. N.

2011-01-01

We present the first Spitzer-IRS spectral maps of the Herbig-Haro flow GGD 37 detected in lines of [Ne III], [O IV], [Ar III], and [Ne V]. The detection of extended [O IV] (55 eV) and some extended emission in [Ne V] (97 eV) indicates a shock temperature in excess of 100,000 K, in agreement with X-ray observations, and a shock speed in excess of 200 km s -1 . The presence of an extended photoionization or collisional ionization region indicates that GGD 37 is a highly unusual protostellar outflow.

The three-dimensional properties and energetics of radio-jet-driven outflows

Energy Technology Data Exchange (ETDEWEB)

Shih, Hsin-Yi; Stockton, Alan, E-mail: hsshih@ifa.hawaii.edu, E-mail: stockton@ifa.hawaii.edu [Institute for Astronomy, University of Hawai' i 2680 Woodlawn Dr, Honolulu, HI 96822 (United States)

2014-05-01

Extended emission-line regions (EELRs), found around radio-loud sources, are likely outflows driven by one form of powerful active galactic nucleus (AGN) feedback mechanism. We seek to constrain the three-dimensional gas properties and the outflow energetics of the EELRs in this study. We used an integral field unit to observe EELRs around two samples of radio-loud AGNs with similar radio properties, but different orientations: a sample of quasars and a sample of radio galaxies. A morphological comparison suggests a scenario where the three-dimensional EELR gas distribution follows rough biconical shapes with wide opening angles. The average extent of the EELRs is ∼18.5 kpc. The estimated average mass of the EELRs, with reasonable assumptions for gas densities, is ∼3 × 10{sup 8} M {sub ☉}, and the average mass outflow rate is ∼30 M {sub ☉} yr{sup –1}. The EELRs around quasars and radio galaxies share similar kinematic properties. Both samples have velocity structures that display a range of complexities, they do not appear to correlate with the jet orientations, and both span a similar range of velocity dispersions. Around 30% of the detected EELRs show large-scale rotational motions, which may have originated from recent mergers involving gas-rich disk galaxies.

PWR burnable absorber evaluation

International Nuclear Information System (INIS)

Cacciapouti, R.J.; Weader, R.J.; Malone, J.P.

1995-01-01

The purpose of the study was to evaluate the relative neurotic efficiency and fuel cycle cost benefits of PWR burnable absorbers. Establishment of reference low-leakage equilibrium in-core fuel management plans for 12-, 18- and 24-month cycles. Review of the fuel management impact of the integral fuel burnable absorber (IFBA), erbium and gadolinium. Calculation of the U 3 O 8 , UF 6 , SWU, fuel fabrication, and burnable absorber requirements for the defined fuel management plans. Estimation of fuel cycle costs of each fuel management plan at spot market and long-term market fuel prices. Estimation of the comparative savings of the different burnable absorbers in dollar equivalent per kgU of fabricated fuel. (author)

Modeling the outflow of liquid with initial supercritical parameters using the relaxation model for condensation

Directory of Open Access Journals (Sweden)

Lezhnin Sergey

2017-01-01

Full Text Available The two-temperature model of the outflow from a vessel with initial supercritical parameters of medium has been realized. The model uses thermodynamic non-equilibrium relaxation approach to describe phase transitions. Based on a new asymptotic model for computing the relaxation time, the outflow of water with supercritical initial pressure and super- and subcritical temperatures has been calculated.

Source attribution of light-absorbing impurities in seasonal snow across northern China

Science.gov (United States)

Zhang, R.; Hegg, D. A.; Huang, J.; Fu, Q.

2013-01-01

Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of light-absorbing impurities (LAI), including all particles that absorb light in the 650-700 nm wavelength interval. The LAI, together with 14 other analytes, are used as input to a positive matrix factorization (PMF) receptor model to explore the sources of the LAI in the snow. The PMF analysis for the LAI sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured snow light absorption: a soil dust source, an industrial pollution source, and a biomass and biofuels burning source. Soil dust was the main source of the LAI, accounting for ~ 53% of the LAI on average.

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping

2016-05-18

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping; Wu, Ying; Lai, Yun

2016-01-01

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Feynman Integrals with Absorbing Boundaries

OpenAIRE

Marchewka, A.; Schuss, Z.

1997-01-01

We propose a formulation of an absorbing boundary for a quantum particle. The formulation is based on a Feynman-type integral over trajectories that are confined to the non-absorbing region. Trajectories that reach the absorbing wall are discounted from the population of the surviving trajectories with a certain weighting factor. Under the assumption that absorbed trajectories do not interfere with the surviving trajectories, we obtain a time dependent absorption law. Two examples are worked ...

MULTIPLE OUTFLOWS IN THE GIANT ERUPTION OF A MASSIVE STAR

Energy Technology Data Exchange (ETDEWEB)

Humphreys, Roberta M.; Gordon, Michael S.; Jones, Terry J. [Minnesota Institute for Astrophysics, 116 Church St. SE, University of Minnesota, Minneapolis, MN 55455 (United States); Martin, John C., E-mail: roberta@umn.edu [University of Illinois Springfield, Springfield, IL 62703 (United States)

2016-08-01

The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of ≈−14 mag. It was quickly realized that it was not a true supernova, but another example of a nonterminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow velocities of −400, −1100, and −1600 km s{sup −1}. Multiple outflows have been observed in only a few other objects. In this paper we describe the evolution of the spectrum and the P Cygni profiles for 3 months past maximum, the post-maximum formation of a cool, dense wind, and the identification of a possible progenitor. One of the possible progenitors is an infrared source. Its pre-eruption spectral energy distribution suggests a bolometric luminosity of −8.3 mag and a dust temperature of 780 K. If it is the progenitor, it is above the AGB limit, unlike the intermediate-luminosity red transients. The three P Cygni profiles could be due to ejecta from the current eruption, the wind of the progenitor, or previous mass-loss events. We suggest that they were all formed as part of the same high-mass-loss event and are due to material ejected at different velocities or energies. We also suggest that multiple outflows during giant eruptions may be more common than reported.

Figuring Out Gas and Galaxies in Enzo (FOGGIE): Simulating effects of feedback on galactic outflows

Science.gov (United States)

Morris, Melissa Elizabeth; Corlies, Lauren; Peeples, Molly; Tumlinson, Jason; O'Shea, Brian; Smith, Britton

2018-01-01

The circumgalactic medium (CGM) is the region beyond the galactic disk in which gas is accreted through pristine inflows from the intergalactic medium and expelled from the galaxy by stellar feedback in large outflows that can then be recycled back onto the disk. These gas cycles connect the galactic disk with its cosmic environment, making the CGM a vital component of galaxy evolution. However, the CGM is primarily observed in absorption, which can be difficult to interpret. In this study, we use high resolution cosmological hydrodynamic simulations of a Milky Way mass halo evolved with the code Enzo to aid the interpretation of these observations. In our simulations, we vary feedback strength and observe the effect it has on galactic outflows and the evolution of the galaxy’s CGM. We compare the star formation rate of the galaxy with the velocity flux and mass outflow rate as a function of height above the plane of the galaxy in order to measure the strength of the outflows and how far they extend outside of the galaxy.This work was supported by The Space Astronomy Summer Program at STScI and NSF grant AST-1517908.

Modification history of the Harmakhis Vallis outflow channel, Mars, based on CTX-scale photogeologic mapping and crater count dating

Science.gov (United States)

Kukkonen, S.; Kostama, V.-P.

2018-01-01

Harmakhis Vallis is one of the four major outflow channel systems (Dao, Niger, Harmakhis, and Reull Valles) that cut the eastern rim region of the Hellas basin, the largest well-preserved impact structure on Mars. The structure of Harmakhis Vallis and the volume of its head depression, as well as earlier dating studies of the region, suggest that the outflow channel formed in the Hesperian period by collapsing when a large amount of subsurface fluid was released. Thus Harmakhis Vallis, as well as the other nearby outflow channels, represents a significant stage of the fluvial activity in the regional history. On the other hand, the outflow channel lies in the Martian mid-latitude zone, where there are several geomorphologic indicators of past and possibly also contemporary ground ice. The floor of Harmakhis also displays evidence of a later-stage ice-related activity, as the outflow channel has been covered by lineated valley fill deposits and debris apron material. The eastern rim region of the Hellas impact basin has been the subject of numerous geologic mapping studies at various scales and based on different imaging data sets. However, Harmakhis Vallis itself has received less attention and the studies on the outflow channel have focused only on limited parts of the outflow channel or on separated different geologic events. In this work, the Harmakhis Vallis floor is mapped and dated from the head depression to the beginning of the terminus based on the Mars Reconnaissance Orbiter's ConTeXt camera images (CTX; ∼ 6 m/pixel). Our results show that Harmakhis Vallis has been modified by several processes after its formation. Age determinations on the small uncovered parts of the outflow channel, which possibly represent the original floor of Harmakhis, imply that Harmakhis may have experienced fluvial activity only 780-850 ( ± 400-600) Ma ago. The discovered terrace structure instead shows that the on-surface activity of the outflow channel has been periodic

Dancoff factors of unit cells in cluster geometry with partial absorption of neutrons; Fatores de Dancoff de celulas unitarias em geometria cluster com absorcao parcial de neutrons

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Leticia Jenisch

2011-01-15

In its classical formulation, the Dancoff factor for a perfectly absorbing fuel rod is defined as the relative reduction in the incurrent of resonance neutrons into the rod in the presence of neighboring rods, as compared to the incurrent into a single fuel rod immersed in an infinite moderator. Alternatively, this factor can be viewed as the probability that a neutron emerging from the surface of a fuel rod will enter another fuel rod without any collision in the moderator or cladding. For perfectly absorbing fuel these definitions are equivalent. In the last years, several works appeared in literature reporting improvements in the calculation of Dancoff factors, using both the classical and the collision probability definitions. In this work, we step further reporting Dancoff factors for perfectly absorbing (Black) and partially absorbing (Grey) fuel rods calculated by the collision probability method, in cluster cells with square outer boundaries. In order to validate the results, comparisons are made with the equivalent cylindricalized cell in hypothetical test cases. The calculation is performed considering specularly reflecting boundary conditions, for the square lattice, and diffusive reflecting boundary conditions, for the cylindrical geometry. The results show the expected asymptotic behavior of the solution with increasing cell sizes. In addition, Dancoff factors are computed for the Canadian cells CANDU-37 and CANFLEX by the Monte Carlo and Direct methods. Finally, the effective multiplication factors, k{sub eff}, for these cells (cluster cell with square outer boundaries and the equivalent cylindricalized cell) are also computed, and the differences reported for the cases using the perfect and partial absorption assumptions. (author)

Radiative effects of absorbing aerosols over northeastern India: Observations and model simulations

Science.gov (United States)

Gogoi, Mukunda M.; Babu, S. Suresh; Moorthy, K. Krishna; Bhuyan, Pradip Kumar; Pathak, Binita; Subba, Tamanna; Chutia, Lakhima; Kundu, Shyam Sundar; Bharali, Chandrakala; Borgohain, Arup; Guha, Anirban; De, Barin Kumar; Singh, Brajamani; Chin, Mian

2017-01-01

Multiyear measurements of spectral properties of aerosol absorption are examined over four geographically distinct locations of northeastern India. Results indicated significant spatiotemporal variation in aerosol absorption coefficients (σabs) with highest values in winter and lowest in monsoon. The western parts of the region, close to the outflow of Indo-Gangetic Plains, showed higher values of σabs and black carbon (BC) concentration—mostly associated with fossil fuel combustion. But, the eastern parts showed higher contributions from biomass-burning aerosols, as much as 20-25% to the total aerosol absorption, conspicuously during premonsoon season. This is attributed to a large number of burning activities over the Southeast Asian region, as depicted from Moderate Resolution Imaging Spectroradiometer fire count maps, whose spatial extent and magnitude peaks during March/April. The nearly consistent high values of aerosol index (AI) and layer height from Ozone Monitoring Instrument indicate the presence of absorbing aerosols in the upper atmosphere. The observed seasonality has been captured fairly well by Goddard Chemistry Aerosol Radiation and Transport (GOCART) as well as Weather Research and Forecasting-Chemistry (WRF-Chem) model simulations. The ratio of column-integrated optical depths due to particulate organic matter and BC from GOCART showed good coincidence with satellite-based observations, indicating the increased vertical dispersion of absorbing aerosols, probably by the additional local convection due to higher fire radiative power caused by the intense biomass-burning activities. In the WRF-Chem though underperformed by different magnitude in winter, the values are closer or overestimated near the burnt areas. Atmospheric forcing due to BC was highest ( 30 Wm-2) over the western part associated with the fossil fuel combustion.

Visible light broadband perfect absorbers

Energy Technology Data Exchange (ETDEWEB)

Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

2016-03-15

The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

Superwind Outflow in Seyfert Galaxies? : Optical Observations of an Edge-On Sample

Science.gov (United States)

Colbert, E.; Gallimore, J.; Baum, S.; O'Dea, C.; Lehnert, M.

1994-12-01

Large-scale galactic winds (superwinds) are commonly found flowing out of the nuclear region of ultraluminous infrared and powerful starburst galaxies. Stellar winds and supernovae from the nuclear starburst are thought to provide the energy to drive these superwinds. The outflowing gas escapes along the rotation axis, sweeping up and shock-heating clouds in the halo, which produces optical line emission, X-rays and radio synchrotron emission. These features can most easily be studied in edge-on systems, so that the wind emission is not confused by that from the disk. Diffuse radio emission has been found (Baum et al. 1993, ApJ, 419, 553) to extend out to kpc-scales in a number of edge-on Seyfert galaxies. We have therefore launched a systematic search for superwind outflows in Seyferts. We present here narrow-band optical images and optical spectra for a sample of edge-on Seyferts. These data have been used to estimate the frequency of occurence of superwinds. Approximately half of the sample objects show evidence for extended emission-line regions which are preferentially oriented perpendicular to the galaxy disk. It is possible that these emission-line regions may be energized by a superwind outflow from a circumnuclear starburst, although there may also be a contribution from the AGN itself. A goal of this work is to find a diagnostic that can be used to distinguish between large-scale outflows that are driven by starbursts and those that are driven by an AGN. The presence of starburst-driven superwinds in Seyferts, if established, would have important implications for the connection between starburst galaxies and AGN.

The Associated Absorption Features in Quasar Spectra of the Sloan Digital Sky Survey. I. Mg II Absorption Doublets

Science.gov (United States)

Chen, Zhi-Fu; Huang, Wei-Rong; Pang, Ting-Ting; Huang, Hong-Yan; Pan, Da-Sheng; Yao, Min; Nong, Wei-Jing; Lu, Mei-Mei

2018-03-01

Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II λλ2796, 2803 narrow absorption doublets in the spectra data around Mg II λ2798 emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299 ≤ z abs ≤ 2.5663. We find that a velocity offset of υ r 6000 km s‑1. If associated Mg II absorbers are defined by υ r present at least one associated Mg II system with {W}{{r}}λ 2796≥slant 0.2 \\mathringA . The fraction of associated Mg II systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The υ r distribution of the outflow Mg II absorbers is peaked at 1023 km s‑1, which is smaller than the corresponding value of the outflow C IV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by υ r > ‑3000 km s‑1 differs from that of absorbers constrained by υ r > 2000 km s‑1. Absorbers limited by υ r > 2000 km s‑1 and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger υ r . The distributions of equivalent widths, and the ratio of {W}rλ 2796/{W}rλ 2803, are the same for associated and intervening systems, and independent of quasar luminosity.

Circumstellar Disks and Outflows in Turbulent Molecular Cloud Cores: Possible Formation Mechanism for Misaligned Systems

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Tomoaki [Faculty of Sustainability Studies, Hosei University, Fujimi, Chiyoda-ku, Tokyo 102-8160 (Japan); Machida, Masahiro N. [Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Inutsuka, Shu-ichiro, E-mail: matsu@hosei.ac.jp [Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan)

2017-04-10

We investigate the formation of circumstellar disks and outflows subsequent to the collapse of molecular cloud cores with the magnetic field and turbulence. Numerical simulations are performed by using an adaptive mesh refinement to follow the evolution up to ∼1000 years after the formation of a protostar. In the simulations, circumstellar disks are formed around the protostars; those in magnetized models are considerably smaller than those in nonmagnetized models, but their size increases with time. The models with stronger magnetic fields tend to produce smaller disks. During evolution in the magnetized models, the mass ratios of a disk to a protostar is approximately constant at ∼1%–10%. The circumstellar disks are aligned according to their angular momentum, and the outflows accelerate along the magnetic field on the 10–100 au scale; this produces a disk that is misaligned with the outflow. The outflows are classified into two types: a magnetocentrifugal wind and a spiral flow. In the latter, because of the geometry, the axis of rotation is misaligned with the magnetic field. The magnetic field has an internal structure in the cloud cores, which also causes misalignment between the outflows and the magnetic field on the scale of the cloud core. The distribution of the angular momentum vectors in a core also has a non-monotonic internal structure. This should create a time-dependent accretion of angular momenta onto the circumstellar disk. Therefore, the circumstellar disks are expected to change their orientation as well as their sizes in the long-term evolutions.

Misalignment of magnetic fields and outflows in protostellar cores

NARCIS (Netherlands)

Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erica; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.; Looney, Leslie W.; Matthews, Brenda C.; Mundy, Lee; Pillai, Thushara; Pound, Marc W.; Stephens, Ian W.; Tobin, John J.; Vaillancourt, John E.; Volgenau, N. H.; Wright, Melvyn C. H.

2013-01-01

We present results of lambda 1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with similar to 2 ''.5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of similar to 1000 AU are not tightly aligned with outflows from the

Standing Shocks around Black Holes and Estimation of Outflow ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

Abstract. We self-consistently obtain shock locations in an accretion flow by using an analytical method. One can obtain the spectral properties, quasi-periodic oscillation frequencies and the outflow rates when the inflow parameters are known. Since temperature of the CENBOL decides the spectral states of the black hole, ...

Seasonal changes and driving forces of inflow and outflow through the Bohai Strait

Science.gov (United States)

Zhang, Zhixin; Qiao, Fangli; Guo, Jingsong; Guo, Binghuo

2018-02-01

This work focuses on analyzing seasonal variation of inflow and outflow through the Bohai Strait that greatly affect the marine environment in the Bohai Sea, using observational data including sea bed mounted acoustic Doppler current profiler currents, CTD salinity data on deck, sea level anomalies of coastal tide gauge stations, and climatological monthly sea level anomalies from Archiving, Validation and Interpretation of Satellite Oceanographic data. Our results show three patterns of outflow and inflow through the Bohai Strait. The first is such that outflow and inflow occur respectively in the southern and northern parts of the strait, as in the traditional understanding. Our results suggest that this pattern occurs only in autumn and winter. Beginning in late September, Ekman currents driven by the northwesterly monsoon carry Bohai Sea water that piles up in the southern part of that sea and then exits eastward to the Yellow Sea. In this process, the pressure and current fields are continuously adjusted, until a quasi balance state between wind stress, Coriolis force and pressure gradient force is reached in winter. Inflow with a compensating property through the northern channel is close to the outflow through the southern channel in winter. The second pattern is a single inflow in spring, and the current and pressure fields are in adjustment. In early spring, the northwesterly monsoon ceases, Yellow Sea water enters the Bohai Sea under the pressure gradient force. With southeasterly monsoon establishment and strengthening, northern Yellow Sea water continually flows into the Bohai Sea and causes sea level rise northward. In the third pattern, outflow is much greater than inflow in summer. The currents run eastward in the central Bohai Sea and then enter the northern Yellow Sea through the northern channel and upper layer of the southern channel, while a westward current with a compensating property enters via the lower layer of the southern channel. Larger

Does an Intrinsic Magnetic Field Inhibit or Enhance Planetary Ionosphere Outflow and Loss?

Science.gov (United States)

Strangeway, R. J.; Russell, C. T.; Luhmann, J. G.; Moore, T. E.; Foster, J. C.; Barabash, S. V.; Nilsson, H.

2017-12-01

A characteristic feature of the planets Earth, Venus and Mars is the observation of the outflow of ionospheric ions, most notably oxygen. The oxygen ion outflow is frequently assumed to be a proxy for the loss of water from the planetary atmosphere. In terms of global outflow rates for the Earth the rate varies from 1025 to 1026 s-1, depending on geomagnetic activity. For both Venus and Mars global rates of the order 5x1024 s-1 have been reported. Venus and Mars do not have a large-scale intrinsic magnetic field, and there are several pathways for atmospheric and ionospheric loss. At Mars, because of its low gravity, neutral oxygen can escape through dissociative recombination. At Venus only processes related to the solar wind interaction with the planet such as sputtering and direct scavenging of the ionosphere by the solar wind can result in oxygen escape. At the Earth the intrinsic magnetic field forms a barrier to the solar wind, but reconnection of the Earth's magnetic field with the Interplanetary Magnetic Field allows solar wind energy and momentum to be transferred into the magnetosphere, resulting in ionospheric outflows. Observations of oxygen ions at the dayside magnetopause suggest that at least some of these ions escape. In terms of the evolution of planetary atmospheres how the solar-wind driven escape rates vary for magnetized versus umagnetized planets is also not clear. An enhanced solar wind dynamic pressure will increase escape from the unmagnetized planets, but it may also result in enhanced reconnection at the Earth, increasing outflow and loss rates for the Earth as well. Continued improvement in our understanding of the different pathways for ionospheric and atmospheric loss will allow us to determine how effective an intrinsic planetary field is in preserving a planetary atmosphere, or if we have to look for other explanations as to why the atmospheres of Venus and Mars have evolved to their desiccated state.

Esophagogastric junction outflow obstruction is often associated with coexistent abnormal esophageal body motility and abnormal bolus transit.

Science.gov (United States)

Zheng, E; Gideon, R M; Sloan, J; Katz, P O

2017-10-01

Currently, the diagnosis of esophageal motility disorders is in part based upon a hierarchical algorithm in which abnormalities of the esophagogastric junction (EGJ) is prioritized. An important metric in evaluating the EGJ is the integrated relaxation pressure (IRP). Patients who do not have achalasia but are found to have an elevated IRP are diagnosed with EGJ outflow obstruction. It has been our observation that a subset of these patients also has a second named motility disorder and may also have abnormal bolus transit. The aim of this study is to determine the frequency of abnormal body motility and or abnormal bolus movement in patients with EGJ outflow obstruction. Further, in an effort to evaluate the potential clinical value in measuring bolus transit as a complement to esophageal manometry, specifically in patients with EGJ outflow obstruction, we analyzed the presenting symptoms of these patients. A total of 807 patients with a mean age of 53 years completed esophageal function testing with impedance monitoring and high-resolution manometry between January 2012 and October 2016. There were 74 patients with achalasia who were excluded from the study. Of the remaining 733 patients, 138 (19%) had an elevated IRP and were given a diagnosis of EGJ outflow obstruction. Among these patients, 56 (40%) were diagnosed with an abnormal motility pattern to liquids (ineffective esophageal motility = 28, distal esophageal spasm = 19, Jackhammer = 6), of which 44 (76%) had abnormal bolus transit to liquids, viscous, or both. In contrast, there were 82 patients with EGJ outflow obstruction and normal esophageal motility, of which 33 (40%) had abnormal bolus transit. Patients with preserved esophageal motility and EGJ outflow obstruction were then evaluated. Of the 733 patients, 299 (40%) had intact esophageal motility. Of the 299 patients with normal esophageal motility, 56 patients had an elevated IRP, of which 16 (28%) had abnormal bolus transit. There were 243 (33

Ultrafast Outflows: Galaxy-scale Active Galactic Nucleus Feedback

Science.gov (United States)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

2013-01-01

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

Energy Technology Data Exchange (ETDEWEB)

Wagner, A. Y.; Umemura, M. [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan); Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

2013-01-20

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

International Nuclear Information System (INIS)

Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

2013-01-01

We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

MOLECULAR OUTFLOWS IN THE SUBSTELLAR DOMAIN: MILLIMETER OBSERVATIONS OF YOUNG VERY LOW MASS OBJECTS IN TAURUS AND ρ OPHIUCHI

International Nuclear Information System (INIS)

Ngoc Phan-Bao; Lee, Chin-Fei; Ho, Paul T. P.; Tang, Ya-Wen

2011-01-01

We report here our search for molecular outflows from young very low mass stars and brown dwarfs in Taurus and ρ Ophiuchi. Using the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy, we have observed four targets at 1.3 mm wavelength (230 GHz) to search for CO J = 2 → 1 outflows. A young very low mass star MHO 5 (in Taurus) with an estimated mass of 90 M J , which is just above the hydrogen-burning limit, shows two gas lobes that are likely outflows. While the CO map of MHO 5 does not show a clear structure of outflow, possibly due to environment gas, its position-velocity diagram indicates two distinct blue- and redshifted components. We therefore conclude that they are components of a bipolar molecular outflow from MHO 5. We estimate an outflow mass of 7.0 x 10 -5 M sun and a mass-loss rate of 9.0 x 10 -10 M sun . These values are over two orders of magnitude smaller than the typical ones for T Tauri stars and somewhat weaker than those we have observed in the young brown dwarf ISO-Oph 102 of 60 M J in ρ Ophiuchi. This makes MHO 5 the first young very low mass star showing a bipolar molecular outflow in Taurus. The detection boosts the scenario that very low mass objects form like low-mass stars but in a version scaled down by a factor of over 100.

Optimization of sound absorbing performance for gradient multi-layer-assembled sintered fibrous absorbers

Science.gov (United States)

Zhang, Bo; Zhang, Weiyong; Zhu, Jian

2012-04-01

The transfer matrix method, based on plane wave theory, of multi-layer equivalent fluid is employed to evaluate the sound absorbing properties of two-layer-assembled and three-layer-assembled sintered fibrous sheets (generally regarded as a kind of compound absorber or structures). Two objective functions which are more suitable for the optimization of sound absorption properties of multi-layer absorbers within the wider frequency ranges are developed and the optimized results of using two objective functions are also compared with each other. It is found that using the two objective functions, especially the second one, may be more helpful to exert the sound absorbing properties of absorbers at lower frequencies to the best of their abilities. Then the calculation and optimization of sound absorption properties of multi-layer-assembled structures are performed by developing a simulated annealing genetic arithmetic program and using above-mentioned objective functions. Finally, based on the optimization in this work the thoughts of the gradient design over the acoustic parameters- the porosity, the tortuosity, the viscous and thermal characteristic lengths and the thickness of each samples- of porous metals are put forth and thereby some useful design criteria upon the acoustic parameters of each layer of porous fibrous metals are given while applying the multi-layer-assembled compound absorbers in noise control engineering.

Cardiac outflow tract malformations in chick embryos exposed to homocysteine

NARCIS (Netherlands)

M.J. Boot (Marit); R.P.M. Steegers-Theunissen (Régine); R.E. Poelmann (Robert); L. van Iperen (Liesbeth); A.C. Gittenberger-De Groot (Adriana)

2004-01-01

textabstractIncreased homocysteine concentrations have been associated with cardiac outflow tract defects. It has been hypothesized that cardiac neural crest cells were the target cells in these malformations. Cardiac neural crest cells migrate from the neural tube and contribute to the condensed

Neutron Absorbing Ability Variation in Neutron Absorbing Material Caused by the Neutron Irradiation in Spent Fuel Storage Facility

Energy Technology Data Exchange (ETDEWEB)

Sohn, Hee Dong; Han, Seul Gi; Lee, Sang Dong; Kim, Ki Hong; Ryu, Eag Hyang; Park, Hwa Gyu [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

2014-10-15

In spent fuel storage facility like high density spent fuel storage racks and dry storage casks, spent fuels are stored with neutron absorbing materials installed as a part of those facilities, and they are used for absorbing neutrons emitted from spent fuels. Usually structural material with neutron absorbing material of racks and casks are located around spent fuels, so it is irradiated by neutrons for long time. Neutron absorbing ability could be changed by the variation of nuclide composition in neutron absorbing material caused by the irradiation of neutrons. So, neutron absorbing materials are continuously faced with spent fuels with boric acid solution or inert gas environment. Major nuclides in neutron absorbing material are Al{sup 27}, C{sup 12}, B{sup 11}, B{sup 10} and they are changed to numerous other ones as radioactive decay or neutron absorption reaction. The B{sup 10} content in neutron absorbing material dominates the neutron absorbing ability, so, the variation of nuclide composition including the decrease of B{sup 10} content is the critical factor on neutron absorbing ability. In this study, neutron flux in spent fuel, the activation of neutron absorbing material and the variation of nuclide composition are calculated. And, the minimum neutron flux causing the decrease of B{sup 10} content is calculated in spent fuel storage facility. Finally, the variation of neutron multiplication factor is identified according to the one of B{sup 10} content in neutron absorbing material. The minimum neutron flux to impact the neutron absorbing ability is 10{sup 10} order, however, usual neutron flux from spent fuel is 10{sup 8} order. Therefore, even though neutron absorbing material is irradiated for over 40 years, B{sup 10} content is little decreased, so, initial neutron absorbing ability could be kept continuously.

Configuring calendar variation based on time series regression method for forecasting of monthly currency inflow and outflow in Central Java

Science.gov (United States)

Setiawan, Suhartono, Ahmad, Imam Safawi; Rahmawati, Noorgam Ika

2015-12-01

Bank Indonesia (BI) as the central bank of Republic Indonesiahas a single overarching objective to establish and maintain rupiah stability. This objective could be achieved by monitoring traffic of inflow and outflow money currency. Inflow and outflow are related to stock and distribution of money currency around Indonesia territory. It will effect of economic activities. Economic activities of Indonesia,as one of Moslem country, absolutely related to Islamic Calendar (lunar calendar), that different with Gregorian calendar. This research aims to forecast the inflow and outflow money currency of Representative Office (RO) of BI Semarang Central Java region. The results of the analysis shows that the characteristics of inflow and outflow money currency influenced by the effects of the calendar variations, that is the day of Eid al-Fitr (moslem holyday) as well as seasonal patterns. In addition, the period of a certain week during Eid al-Fitr also affect the increase of inflow and outflow money currency. The best model based on the value of the smallestRoot Mean Square Error (RMSE) for inflow data is ARIMA model. While the best model for predicting the outflow data in RO of BI Semarang is ARIMAX model or Time Series Regression, because both of them have the same model. The results forecast in a period of 2015 shows an increase of inflow money currency happened in August, while the increase in outflow money currency happened in July.

DETECTION OF A BIPOLAR MOLECULAR OUTFLOW DRIVEN BY A CANDIDATE FIRST HYDROSTATIC CORE

International Nuclear Information System (INIS)

Dunham, Michael M.; Chen Xuepeng; Arce, Héctor G.; Bourke, Tyler L.; Schnee, Scott; Enoch, Melissa L.

2011-01-01

We present new 230 GHz Submillimeter Array observations of the candidate first hydrostatic core Per-Bolo 58. We report the detection of a 1.3 mm continuum source and a bipolar molecular outflow, both centered on the position of the candidate first hydrostatic core. The continuum detection has a total flux density of 26.6 ± 4.0 mJy, from which we calculate a total (gas and dust) mass of 0.11 ± 0.05 M ☉ and a mean number density of 2.0 ± 1.6 × 10 7 cm –3 . There is some evidence for the existence of an unresolved component in the continuum detection, but longer-baseline observations are required in order to confirm the presence of this component and determine whether its origin lies in a circumstellar disk or in the dense inner envelope. The bipolar molecular outflow is observed along a nearly due east-west axis. The outflow is slow (characteristic velocity of 2.9 km s –1 ), shows a jet-like morphology (opening semi-angles ∼8° for both lobes), and extends to the edges of the primary beam. We calculate the kinematic and dynamic properties of the outflow in the standard manner and compare them to several other protostars and candidate first hydrostatic cores with similarly low luminosities. We discuss the evidence both in support of and against the possibility that Per-Bolo 58 is a first hydrostatic core, and we outline future work needed to further evaluate the evolutionary status of this object.

Galactic Outflows, Star Formation Histories, and Timescales in Starburst Dwarf Galaxies from STARBIRDS

Science.gov (United States)

McQuinn, Kristen B. W.; Skillman, Evan D.; Heilman, Taryn N.; Mitchell, Noah P.; Kelley, Tyler

2018-03-01

Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their timescales. Here, we compare galactic outflows traced by diffuse, soft X-ray emission from Chandra Space Telescope archival observations to the star formation histories derived from Hubble Space Telescope imaging of the resolved stellar populations in six starburst dwarfs. We constrain the longevity of a wind to have an upper limit of 25 Myr based on galaxies whose starburst activity has already declined, although a larger sample is needed to confirm this result. We find an average 16% efficiency for converting the mechanical energy of stellar feedback to thermal, soft X-ray emission on the 25 Myr timescale, somewhat higher than simulations predict. The outflows have likely been sustained for timescales comparable to the duration of the starbursts (i.e., 100's Myr), after taking into account the time for the development and cessation of the wind. The wind timescales imply that material is driven to larger distances in the circumgalactic medium than estimated by assuming short, 5-10 Myr starburst durations, and that less material is recycled back to the host galaxy on short timescales. In the detected outflows, the expelled hot gas shows various morphologies which are not consistent with a simple biconical outflow structure. The sample and analysis are part of a larger program, the STARBurst IRregular Dwarf Survey (STARBIRDS), aimed at understanding the lifecycle and impact of starburst activity in low-mass systems.

Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers

Science.gov (United States)

Wu, Meng-Ru; Fernández, Rodrigo; Martínez-Pinedo, Gabriel; Metzger, Brian D.

2016-12-01

We consider r-process nucleosynthesis in outflows from black hole accretion discs formed in double neutron star and neutron star-black hole mergers. These outflows, powered by angular momentum transport processes and nuclear recombination, represent an important - and in some cases dominant - contribution to the total mass ejected by the merger. Here we calculate the nucleosynthesis yields from disc outflows using thermodynamic trajectories from hydrodynamic simulations, coupled to a nuclear reaction network. We find that outflows produce a robust abundance pattern around the second r-process peak (mass number A ˜ 130), independent of model parameters, with significant production of A spike at A = 132 that is absent in the Solar system r-process distribution. The spike arises from convection in the disc and depends on the treatment of nuclear heating in the simulations. We conclude that disc outflows provide an important - and perhaps dominant - contribution to the r-process yields of compact binary mergers, and hence must be included when assessing the contribution of these systems to the inventory of r-process elements in the Galaxy.

Sound Absorbers

Science.gov (United States)

Fuchs, H. V.; Möser, M.

Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

The Circumstellar Disk and Asymmetric Outflow of the EX Lup Outburst System

Science.gov (United States)

Hales, A. S.; Pérez, S.; Saito, M.; Pinte, C.; Knee, L. B. G.; de Gregorio-Monsalvo, I.; Dent, B.; López, C.; Plunkett, A.; Cortés, P.; Corder, S.; Cieza, L.

2018-06-01

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations at 0.″3 resolution of EX Lup, the prototype of the EXor class of outbursting pre-main-sequence stars. The circumstellar disk of EX Lup is resolved for the first time in 1.3 mm continuum emission and in the J = 2–1 spectral line of three isotopologues of CO. At the spatial resolution and sensitivity achieved, the compact dust continuum disk shows no indications of clumps, fragments, or asymmetries above the 5σ level. Radiative transfer modeling constrains the characteristic radius of the dust disk to 23 au and the total dust mass to 1.0 × 10‑4 M ⊙ (33 M ⊕), similar to other EXor sources. The 13CO and C18O line emissions trace the disk rotation and are used to constrain the disk geometry, kinematics, and a total gas disk mass of 5.1 × 10‑4 M ⊙. The 12CO emission extends out to a radius of 200 au and is asymmetric, with one side deviating from Keplerian rotation. We detect blueshifted, 12CO arc-like emission located 0.″8 to the northwest and spatially disconnected from the disk emission. We interpret this extended structure as the brightened walls of a cavity excavated by an outflow, which are more commonly seen in FUor sources. Such outflows have also been seen in the borderline FU/EXor object V1647 Ori, but not toward EXor objects. Our detection provides evidence that the outflow phenomenon persists into the EXor phase, suggesting that FUor and EXor objects are a continuous population in which outflow activity declines with age, with transitional objects such as EX Lup and V1647 Ori.

PROPERTIES OF QSO METAL-LINE ABSORPTION SYSTEMS AT HIGH REDSHIFTS: NATURE AND EVOLUTION OF THE ABSORBERS AND NEW EVIDENCE ON ESCAPE OF IONIZING RADIATION FROM GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Boksenberg, Alec [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Sargent, Wallace L. W., E-mail: boksy@ast.cam.ac.uk [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2015-05-15

Using Voigt-profile-fitting procedures on Keck High Resolution Spectrograph spectra of nine QSOs, we identify 1099 C IV absorber components clumped in 201 systems outside the Lyman forest over 1.6 ≲ z ≲ 4.4. With associated Si IV, C II, Si II  and N V where available, we investigate the bulk statistical and ionization properties of the components and systems and find no significant change in redshift for C IV and Si IV while C II, Si II  and N V change substantially. The C IV components exhibit strong clustering, but no clustering is detected for systems on scales from 150 km s{sup –1} out to 50,000 km s{sup –1}. We conclude that the clustering is due entirely to the peculiar velocities of gas present in the circumgalactic media of galaxies. Using specific combinations of ionic ratios, we compare our observations with model ionization predictions for absorbers exposed to the metagalactic ionizing radiation background augmented by proximity radiation from their associated galaxies and find that the generally accepted means of radiative escape by transparent channels from the internal star-forming sites is spectrally not viable for our stronger absorbers. We develop an active scenario based on runaway stars with resulting changes in the efflux of radiation that naturally enable the needed spectral convergence, and in turn provide empirical indicators of morphological evolution in the associated galaxies. Together with a coexisting population of relatively compact galaxies indicated by the weaker absorbers in our sample, the collective escape of radiation is sufficient to maintain the intergalactic medium ionized over the full range 1.9 < z ≲ 4.4.

EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary

Directory of Open Access Journals (Sweden)

A. T. Aikio

2008-02-01

Full Text Available The dynamics of the polar cap boundary and auroral oval in the nightside ionosphere are studied during late expansion and recovery of a substorm from the region between Tromsø (66.6° cgmLat and Longyearbyen (75.2° cgmLat on 27 February 2004 by using the coordinated EISCAT incoherent scatter radar, MIRACLE magnetometer and Cluster satellite measurements. During the late substorm expansion/early recovery phase, the polar cap boundary (PCB made zig-zag-type motion with amplitude of 2.5° cgmLat and period of about 30 min near magnetic midnight. We suggest that the poleward motions of the PCB were produced by bursts of enhanced reconnection at the near-Earth neutral line (NENL. The subsequent equatorward motions of the PCB would then represent the recovery of the merging line towards the equilibrium state (Cowley and Lockwood, 1992. The observed bursts of enhanced westward electrojet just equatorward of the polar cap boundary during poleward expansions were produced plausibly by particles accelerated in the vicinity of the neutral line and thus lend evidence to the Cowley-Lockwood paradigm.

During the substorm recovery phase, the footpoints of the Cluster satellites at a geocentric distance of 4.4 R_E mapped in the vicinity of EISCAT measurements. Cluster data indicate that outflow of H⁺ and O⁺ ions took place within the plasma sheet boundary layer (PSBL as noted in some earlier studies as well. We show that in this case the PSBL corresponded to a region of enhanced electron temperature in the ionospheric F region. It is suggested that the ion outflow originates from the F region as a result of increased ambipolar diffusion. At higher altitudes, the ions could be further energized by waves, which at Cluster altitudes were observed as BBELF (broad band extra low frequency fluctuations.

The four-satellite configuration of Cluster revealed a sudden poleward expansion of the PSBL by 2° during

Neutron absorbing article

International Nuclear Information System (INIS)

Naum, R.G.; Owens, D.P.; Dooher, G.I.

1979-01-01

A neutron absorbing article, in flat plate form and suitable for use in a storage rack for spent fuel, includes boron carbide particles, diluent particles and a solid, irreversibly cured phenolic polymer cured to a continuous matrix binding the boron carbide and diluent particles. The total conent of boron carbide and diluent particles is a major proportion of the article and the content of cured phenolic polymer present is a minor proportion. By regulation of the ratio of boron carbide particles to diluent particles, normally within the range of 1:9 and 9:1 and preferably within the range of 1:5 to 5:1, the neutron absorbing activity of the product may be controlled, which facilitates the manufacture of articles of particular absorbing activities best suitable for specific applications

A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

Science.gov (United States)

Paquette, John A.; Ferguson, Frank T.; Nuth, Joseph A., III

2011-01-01

Based on its abundance, high bond energy, and recent measurements of its vapor pressure SiO is a natural candidate for dust nucleation in circumstellar outflows around asymptotic giant branch stars. In this paper, we describe a model of the nucleation and growth of silicate dust in such outflows. The sensitivity of the model to varying choices of poorly constrained chemical parameters is explored, and the merits of using scaled rather than classical nucleation theory are briefly considered, An elaboration of the model that includes magnesium and iron as growth species is then presented and discussed. The composition of the bulk of the grains derived from the model is consistent with olivines and pyroxenes, but somewhat metal-rich grains and very small, nearly pure SiO grains are also produced,

Source attribution of insoluble light-absorbing particles in seasonal snow across northern China

Science.gov (United States)

Zhang, R.; Hegg, D. A.; Huang, J.; Fu, Q.

2013-06-01

Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of insoluble light-absorbing particles (ILAP), including all particles that absorb light in the 650-700 nm wavelength interval. The ILAP, together with 14 other analytes, are used as input to a positive matrix factorization (PMF) receptor model to explore the sources of ILAP in the snow. The PMF analysis for ILAP sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured light absorption of snow: a soil dust source, an industrial pollution source, and a biomass and / or biofuel burning source. Soil dust was the main source of the ILAP, accounting for ~53% of ILAP on average.

Source attribution of insoluble light-absorbing particles in seasonal snow across northern China

Directory of Open Access Journals (Sweden)

R. Zhang

2013-06-01

Full Text Available Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of insoluble light-absorbing particles (ILAP, including all particles that absorb light in the 650–700 nm wavelength interval. The ILAP, together with 14 other analytes, are used as input to a positive matrix factorization (PMF receptor model to explore the sources of ILAP in the snow. The PMF analysis for ILAP sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured light absorption of snow: a soil dust source, an industrial pollution source, and a biomass and / or biofuel burning source. Soil dust was the main source of the ILAP, accounting for ~53% of ILAP on average.

Prediction of rumen microbial outflow based on urinary excretion of purine derivatives

International Nuclear Information System (INIS)

Nolan, J.V.

1999-01-01

The method for predicting microbial protein outflow from the rumen based on the excretion of purine derivatives (PD) in the urine is being increasingly used by nutritionists. In contrast to methods that depend on estimates of digesta flow, the PD method does not require animals to be fitted surgically with cannulae into the gut, and studies can be performed with minimal disturbance to the experimental animals. Methods of analysis of PD have been improved and standardized. Certain assumptions, however, are required that could lead to errors when this method is used to predict microbial protein outflow from the rumen. The need for further investigation of these assumptions by means of isotopic tracers and other techniques is examined. (author)

Watching AGN feedback at its birth: HST observations of nascent outflow host IC860

Science.gov (United States)

Alatalo, Katherine

2016-10-01

IC860 is a nearby IR-luminous early-type spiral with a unique set of properties: it is a shocked, poststarburst galaxy that hosts an AGN-driven neutral wind and a compact core of molecular gas. IC860 can serve as a rosetta stone for the early stages of triggering AGN feedback. We propose to use WFC3 on HST to obtain NUV, optical and near-IR imaging of IC860. We will create a spatially-resolved history of star formation quenching through SED-fitting of 7 requested broadband filters, and compare the spatially resolved star formation histories to in different positions within the underlying stellar features (such as spiral structure) that might define a narrative of how star formation is quenching in IC860. These observations will also resolve the super-star cluster sites to trace the most recent star formation. Finally, these observations will trace the mass of the outflow by building an absorption map of the dust. IC860 presents a unique opportunity to study a galaxy at an early stage of transitioning from blue spiral to red early-type galaxy, that also hosts an AGN-driven neutral wind and a compact, turbulent molecular gas core.

Cluster geometry and survival probability in systems driven by reaction-diffusion dynamics

International Nuclear Information System (INIS)

Windus, Alastair; Jensen, Henrik J

2008-01-01

We consider a reaction-diffusion model incorporating the reactions A→φ, A→2A and 2A→3A. Depending on the relative rates for sexual and asexual reproduction of the quantity A, the model exhibits either a continuous or first-order absorbing phase transition to an extinct state. A tricritical point separates the two phase lines. While we comment on this critical behaviour, the main focus of the paper is on the geometry of the population clusters that form. We observe the different cluster structures that arise at criticality for the three different types of critical behaviour and show that there exists a linear relationship for the survival probability against initial cluster size at the tricritical point only.

Iodine-131 monitoring in sewage plant outflow

International Nuclear Information System (INIS)

McGowan, D R; Crawley, M T; Pratt, B E; Hinton, P J; Peet, D J

2014-01-01

Three different hospital sites (Oxford, Sutton and Guildford) have performed sampling of their local sewage plant outflow to determine levels of radioactivity resulting from iodine-131 patients undergoing radionuclide therapies. It was found that a maximum of 20% of activity discharged from the hospitals was present in the sewage plant final effluent channel. This is significantly below the level predicted by mathematical models in current use. The results further show that abatement systems to reduce public exposure are unlikely to be warranted at hospital sites. (paper)

Interferometric Mapping of Perseus Outflows with MASSES

Science.gov (United States)

Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

2017-01-01

The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

ALMA reveals sunburn: CO dissociation around AGB stars in the globular cluster 47 Tucanae

Science.gov (United States)

McDonald, I.; Zijlstra, A. A.; Lagadec, E.; Sloan, G. C.; Boyer, M. L.; Matsuura, M.; Smith, R. J.; Smith, C. L.; Yates, J. A.; van Loon, J. Th.; Jones, O. C.; Ramstedt, S.; Avison, A.; Justtanont, K.; Olofsson, H.; Blommaert, J. A. D. L.; Goldman, S. R.; Groenewegen, M. A. T.

2015-11-01

Atacama Large Millimetre Array observations show a non-detection of carbon monoxide around the four most luminous asymptotic giant branch (AGB) stars in the globular cluster 47 Tucanae. Stellar evolution models and star counts show that the mass-loss rates from these stars should be ˜1.2-3.5 × 10-7 M⊙ yr-1. We would naïvely expect such stars to be detectable at this distance (4.5 kpc). By modelling the ultraviolet radiation field from post-AGB stars and white dwarfs in 47 Tuc, we conclude that CO should be dissociated abnormally close to the stars. We estimate that the CO envelopes will be truncated at a few hundred stellar radii from their host stars and that the line intensities are about two orders of magnitude below our current detection limits. The truncation of CO envelopes should be important for AGB stars in dense clusters. Observing the CO (3-2) and higher transitions and targeting stars far from the centres of clusters should result in the detections needed to measure the outflow velocities from these stars.

On the hydrogen neutral outflowing disks of B[e] supergiants

Czech Academy of Sciences Publication Activity Database

Kraus, Michaela; Borges Fernandes, M.; de Araújo, F. X.

2007-01-01

Roč. 463, č. 2 (2007), s. 627-634 ISSN 0004-6361 R&D Projects: GA ČR GA205/04/1267 Institutional research plan: CEZ:AV0Z10030501 Keywords : supergiants * winds * outflows Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007

The sacral autonomic outflow is parasympathetic: Langley got it right.

Science.gov (United States)

Horn, John P

2018-04-01

A recent developmental study of gene expression by Espinosa-Medina, Brunet and colleagues sparked controversy by asserting a revised nomenclature for divisions of the autonomic motor system. Should we re-classify the sacral autonomic outflow as sympathetic, as now suggested, or does it rightly belong to the parasympathetic system, as defined by Langley nearly 100 years ago? Arguments for rejecting Espinosa-Medina, Brunet et al.'s scheme subsequently appeared in e-letters and brief reviews. A more recent commentary in this journal by Brunet and colleagues responded to these criticisms by labeling Langley's scheme as a historical myth perpetuated by ignorance. In reaction to this heated exchange, I now examine both sides to the controversy, together with purported errors by the pioneers in the field. I then explain, once more, why the sacral outflow should remain known as parasympathetic, and outline suggestions for future experimentation to advance the understanding of cellular identity in the autonomic motor system.

Device for preventing coolant outflow in a reactor

International Nuclear Information System (INIS)

Nemoto, Kiyomitsu; Mochizuki, Keiichi.

1975-01-01

Object: To prevent outflow of coolant from a reactor vessel even in an occurrence of leaking trouble at a low position in a primary cooling system or the like in the reactor vessel. Structure: An inlet at the foremost end of a coolant inlet pipe inserted into a reactor vessel is arranged at a level lower than a core, and a check valve is positioned at a level higher than the core in a rising portion of the inlet. In normal condition, the check valve is pushed up by discharge pressure of a main circulating pump and remains closed, and hence, producing no flow loss of coolant, sodium. However, when a trouble such as rupture occurs at the lower position in the primary cooling system, the attractive force for allowing the coolant to back-flow outside the reactor vessel and the load force of the coolant within the reactor vessel cause the check valve to actuate, as a consequence of which a liquid level of the coolant downwardly moves to the position of the check valve to intake the cover gases into a gas intake, thereby cutting off a flow passage of the coolant to stop outflow thereof. (Kamimura, M.)

MOLECULAR CLUMPS AND INFRARED CLUSTERS IN THE S247, S252, AND BFS52 REGIONS

Energy Technology Data Exchange (ETDEWEB)

Shimoikura, Tomomi; Dobashi, Kazuhito [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Saito, Hiro; Nakamura, Fumitaka [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Matsumoto, Tomoaki [Hosei University, Fujimi, Chiyoda-ku, Tokyo 102-8160 (Japan); Nishimura, Atsushi; Kimura, Kimihiro; Onishi, Toshikazu; Ogawa, Hideo, E-mail: ikura@u-gakugei.ac.jp [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

2013-05-01

We present results of the observations carried out toward the S247, S252, and BFS52 H II regions with various molecular lines using the 1.85 m radio telescope and the 45 m telescope at Nobeyama Radio Observatory. There are at least 11 young infrared clusters (IR clusters) within the observed region. We found that there are two velocity components in {sup 12}CO (J = 2-1), and also that their spatial distributions show an anti-correlation. The IR clusters are located at their interfaces, suggesting that two distinct clouds with different velocities are colliding with each other, which may have induced the cluster formation. Based on {sup 13}CO (J = 1-0) and C{sup 18}O (J = 1-0) observations, we identified 16 clumps in and around the three H II regions. Eleven of the clumps are associated with the IR clusters and the other five clumps are not associated with any known young stellar objects. We investigated variations in the velocity dispersions of the 16 clumps as a function of the distance from the center of the clusters or the clumps. Clumps with clusters tend to have velocity dispersions that increase with distance from the cluster center, while clumps without clusters show a flat velocity dispersion over the clump extents. A {sup 12}CO outflow has been found in some of the clumps with IR clusters but not in the other clumps, supporting a strong relation of these clumps to the broader velocity dispersion region. We also estimated a mean star formation efficiency of {approx}30% for the clumps with IR clusters in the three H II regions.

Effect of amiodarone-induced hyperthyroidism on left ventricular outflow obstruction after septal myectomy for hypertrophic cardiomyopathy.

Science.gov (United States)

Pokorney, Sean D; Stone, Neil J; Passman, Rod; Oyer, David; Rigolin, Vera H; Bonow, Robert O

2010-12-01

Patients with obstructive hypertrophic cardiomyopathy who undergo septal myectomy are at risk for developing postoperative atrial fibrillation. Amiodarone is effective in treating this arrhythmia but is associated with multiple adverse effects, often with delayed onset. A novel case is described of a patient who developed type 2 amiodarone-induced hyperthyroidism that presented as recurrence of outflow obstruction after septal myectomy. The patient's symptoms and echocardiographic findings of outflow obstruction resolved substantially with the treatment of the amiodarone-induced hyperthyroidism. Amiodarone-induced hyperthyroidism of delayed onset can be a subtle diagnosis, requiring a high index of suspicion. In conclusion, recognition of this diagnosis in patients with recurrence of outflow obstruction by symptoms and cardiac imaging after septal myectomy may avoid unnecessary repeat surgical intervention. Copyright © 2010 Elsevier Inc. All rights reserved.

THE SHAPING EFFECT OF COLLIMATED FAST OUTFLOWS IN THE EGG NEBULA

International Nuclear Information System (INIS)

Dinh-V-Trung; Lim, Jeremy

2009-01-01

We present high angular resolution observations of the HC 3 N J = 5-4 line from the Egg nebula, which is the archetype of proto-planetary nebulae (PPNs). We find that the HC 3 N emission in the approaching and receding portion of the envelope traces a clumpy hollow shell, similar to that seen in normal carbon-rich envelopes. Near the systemic velocity, the hollow shell is fragmented into several large blobs or arcs with missing portions correspond spatially to locations of previously reported high-velocity outflows in the Egg nebula. This provides direct evidence for the disruption of the slowly expanding envelope ejected during the AGB phase by the collimated fast outflows initiated during the transition to the PPN phase. From modeling the HC 3 N distribution, we could reproduce qualitatively the spatial kinematics of the HC 3 N J = 5-4 emission using a HC 3 N shell with two pairs of cavities cleared by the collimated high-velocity outflows along the polar direction and in the equatorial plane. We infer a relatively high abundance of HC 3 N/H 2 ∼ 3 x 10 -6 for an estimated mass-loss rate of 3 x 10 -5 M sun yr -1 in the HC 3 N shell. The high abundance of HC 3 N and the presence of some weaker J = 5-4 emission in the vicinity of the central post-AGB star suggest an unusually efficient formation of this molecule in the Egg nebula.

Foreign direct investment outflows in the forest products industry: the case of the United States and Japan

Science.gov (United States)

R.V. Nagubadi; D. Zhang

2008-01-01

This paper investigates the determinants of foreign direct investment (FDI) outflows from two major forest product importing countries: the U.S. and Japan. Exchange rate, per capita income, cost of capital, and cost of labour in host countries have significant impacts on the FDI outflows from these two countries. A complementary relationship is found between forest...

Apical ballooning syndrome complicated by acute severe mitral regurgitation with left ventricular outflow obstruction – Case report

Directory of Open Access Journals (Sweden)

Celermajer David S

2007-02-01

Full Text Available Abstract Background Apical ballooning syndrome (or Takotsubo cardiomyopathy is a syndrome of transient left ventricular apical ballooning. Although first described in Japanese patients, it is now well reported in the Caucasian population. The syndrome mimicks an acute myocardial infarction but is characterised by the absence of obstructive coronary disease. We describe a serious and poorly understood complication of Takotsubo cardiomyopathy. Case Presentation We present the case of a 65 year-old lady referred to us from a rural hospital where she was treated with thrombolytic therapy for a presumed acute anterior myocardial infarction. Four hours after thrombolysis she developed acute pulmonary oedema and a new systolic murmur. It was presumed she had acute mitral regurgitation secondary to a ruptured papillary muscle, ischaemic dysfunction or an acute ventricular septal defect. Echocardiogram revealed severe mitral regurgitation, left ventricular apical ballooning, and systolic anterior motion of the mitral valve with significant left ventricular outflow tract gradient (60–70 mmHg. Coronary angiography revealed no obstructive coronary lesions. She had an intra-aortic balloon pump inserted with no improvement in her parlous haemodynamic state. We elected to replace her mitral valve to correct the outflow tract gradient and mitral regurgitation. Intra-operatively the mitral valve was mildly myxomatous but there were no structural abnormalities. She had a mechanical mitral valve replacement with a 29 mm St Jude valve. Post-operatively, her left ventricular outflow obstruction resolved and ventricular function returned to normal over the subsequent 10 days. She recovered well. Conclusion This case represents a serious and poorly understood association of Takotsubo cardiomyopathy with acute pulmonary oedema, severe mitral regurgitaton and systolic anterior motion of the mitral valve with significant left ventricular outflow tract obstruction. The

The Coldest Place in the Universe: Probing the Ultra-cold Outflow and Dusty Disk in the Boomerang Nebula

Science.gov (United States)

Sahai, R.; Vlemmings, W. H. T.; Nyman, L.-Å.

2017-06-01

Our Cycle 0 ALMA observations confirmed that the Boomerang Nebula is the coldest known object in the universe, with a massive high-speed outflow that has cooled significantly below the cosmic background temperature. Our new CO 1-0 data reveal heretofore unseen distant regions of this ultra-cold outflow, out to ≳120,000 au. We find that in the ultra-cold outflow, the mass-loss rate (\\dot{M}) increases with radius, similar to its expansion velocity (V)—taking V\\propto r, we find \\dot{M}\\propto {r}0.9{--2.2}. The mass in the ultra-cold outflow is ≳ 3.3 M ⊙, and the Boomerang’s main-sequence progenitor mass is ≳ 4 M ⊙. Our high angular resolution (˜ 0\\buildrel{\\prime\\prime}\\over{.} 3) CO J = 3-2 map shows the inner bipolar nebula’s precise, highly collimated shape, and a dense central waist of size (FWHM) ˜1740 au × 275 au. The molecular gas and the dust as seen in scattered light via optical Hubble Space Telescope imaging show a detailed correspondence. The waist shows a compact core in thermal dust emission at 0.87-3.3 mm, which harbors (4{--}7)× {10}-4 M ⊙ of very large (˜millimeter-to-centimeter sized), cold (˜ 20{--}30 K) grains. The central waist (assuming its outer regions to be expanding) and fast bipolar outflow have expansion ages of ≲ 1925 {years} and ≤slant 1050 {years}: the “jet-lag” (I.e., torus age minus the fast-outflow age) in the Boomerang supports models in which the primary star interacts directly with a binary companion. We argue that this interaction resulted in a common-envelope configuration, while the Boomerang’s primary was an RGB or early-AGB star, with the companion finally merging into the primary’s core, and ejecting the primary’s envelope that now forms the ultra-cold outflow.

Launching Cosmic-Ray-Driven Outflows from The Magnetized Interstellar Medium

Czech Academy of Sciences Publication Activity Database

Girichidis, P.; Naab, T.; Walch, S.; Hanasz, M.; Mac Low, M.-M.; Ostriker, J.P.; Gatto, A.; Peters, T.; Wünsch, Richard; Glover, S.C.O.; Klessen, R.S.; Clark, P.C.; Baczynski, C.

2016-01-01

Roč. 816, č. 2 (2016), L19/1-L19/6 ISSN 2041-8205 R&D Projects: GA ČR GAP209/12/1795 Institutional support: RVO:67985815 Keywords : cosmic rays * diffusion * jets and outflows Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.522, year: 2016

Radiation sterilization of absorbent cotton and of absorbent gauze

International Nuclear Information System (INIS)

Hosobuchi, Kazunari; Oka, Mitsuru; Kaneko, Akira; Ishiwata, Hiroshi.

1986-01-01

The bioburden of absorbent cotton and of absorbent gauze and their physical and chemical characteristics after irradiation are investigated. The survey conducted on contaminants of 1890 cotton samples from 53 lots and 805 gauze samples from 56 lots showed maximum numbers of microbes per g of the cotton and gauze were 859 (an average of 21.4) and 777 (an average of 42.2), respectively. Isolation and microbiological and biochemical tests of representative microbes indicated that all of them, except one, were bacilli. The sterilization dose at 10 -6 of sterlity assurance level was found to be 2.0 Mrad when irradiated the spores loaded on paper strips and examined populations having graded D values from 0.10 to 0.28 Mrad. The sterilization dose would be about 1.5 Mrad if subjected the average numbers of contaminants observed in this study to irradiation. No significant differences were found between the irradiated samples and control up to 2 Mrad in tensile strength, change of color, absorbency, sedimentation rate, soluble substances, and pH of solutions used for immersion and other tests conventionally used. These results indicate that these products can be sterilized by irradiation. (author)

CHEMICAL DIAGNOSTICS OF THE MASSIVE STAR CLUSTER-FORMING CLOUD G33.92+0.11. I. {sup 13}CS, CH{sub 3}OH, CH{sub 3}N, OCS, H{sub 2}S, SO{sub 2}, and SiO

Energy Technology Data Exchange (ETDEWEB)

Minh, Young Chol [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong, Daejeon 34055 (Korea, Republic of); Liu, Hauyu Baobab [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Galvań-Madrid, Roberto [Centro de Radioastronoma y Astrofísica, UNAM, A.P. 3-72, Xangari, Morelia 58089 (Mexico)

2016-06-20

Large chemical diversity was found in the gas clumps associated with the massive star cluster-forming G33.92+0.11 region with sub-arcsecond angular resolution (0.″6–0.″8) observations with ALMA. The most prominent gas clumps are associated with the dust emission peaks A1, A2, and A5. The close correlation between CH{sub 3}OH and OCS in the emission distributions strongly suggests that these species share a common origin of hot core grain mantle evaporation. The latest generation of star clusters are forming in the A5 clump, as indicated by multiple SiO outflows and its rich hot core chemistry. We also found a narrow SiO emission associated with the outflows, which may trace a cooled component of the outflows. Part of the chemical complexity may have resulted from the accreting gas from the ambient clouds, especially in the northern part of A1 and the southern part of A2. The chemical diversity found in this region is believed to mainly result from the different chemical evolutionary timescales of massive star formation. In particular, the abundance ratio between CH{sub 3}OH and CH{sub 3}CN may be a good chemical clock for the early phase of star formation.

Cerebrospinal fluid flow waveforms: effect of altered cranial venous outflow. A phase-contrast MR flow imaging study

International Nuclear Information System (INIS)

Bhadelia, R.A.; Wolpert, S.M.

1998-01-01

Our purpose was to assess the effect of alterations in the cranial venous outflow on cerebrospinal fluid (CSF) flow waveforms using phase-contrast MRI. Thirteen healthy subjects were assessed for CSF flow and cerebral vascular flow at the C2-3 level, both before and after jugular venous compression (JVC). The flow waveforms were assessed both as an aggregate, and after dividing subjects in two groups based on percent jugular venous flow (PJVF) i. e. jugular outflow expressed as percent of cerebral arterial inflow. Group 1: 7 subjects with PJVF more than and including median (predominantly jugular outflow); Group 2: 6 subjects with PJVF less than median (predominantly extra-jugular outflow). CSF waveforms: JVC produced rounding of contours and flattening of dicrotic waves, with the effect being greater in group 1 than group 2. In group 1, systolic upslopes of the waveforms increased. No significant aggregate amplitude changes were noted; amplidutes increased in group 1 (P = 0.001), and decreased in group 2 (P = 0.03). Temporal interval to the maximum CSF systolic flow significantly increased in group 1. Vascular flow: Arterial flow significantly decreased in group 1. Jugular flow significantly decreased in both groups. The results suggest that CSF flow waveforms are sensitive to alterations in the cranial venous outflow. Changes in group 1 are most likely because of an elevation in intracranial pressure. Analysis of CSF flow waveforms appears a promising noninvasive tool for assessment of cranial compartment. (orig.)

Dancoff factors of unit cells in cluster geometry with partial absorption of neutrons

International Nuclear Information System (INIS)

Rodrigues, Leticia Jenisch

2011-01-01

In its classical formulation, the Dancoff factor for a perfectly absorbing fuel rod is defined as the relative reduction in the incurrent of resonance neutrons into the rod in the presence of neighboring rods, as compared to the incurrent into a single fuel rod immersed in an infinite moderator. Alternatively, this factor can be viewed as the probability that a neutron emerging from the surface of a fuel rod will enter another fuel rod without any collision in the moderator or cladding. For perfectly absorbing fuel these definitions are equivalent. In the last years, several works appeared in literature reporting improvements in the calculation of Dancoff factors, using both the classical and the collision probability definitions. In this work, we step further reporting Dancoff factors for perfectly absorbing (Black) and partially absorbing (Grey) fuel rods calculated by the collision probability method, in cluster cells with square outer boundaries. In order to validate the results, comparisons are made with the equivalent cylindricalized cell in hypothetical test cases. The calculation is performed considering specularly reflecting boundary conditions, for the square lattice, and diffusive reflecting boundary conditions, for the cylindrical geometry. The results show the expected asymptotic behavior of the solution with increasing cell sizes. In addition, Dancoff factors are computed for the Canadian cells CANDU-37 and CANFLEX by the Monte Carlo and Direct methods. Finally, the effective multiplication factors, k eff , for these cells (cluster cell with square outer boundaries and the equivalent cylindricalized cell) are also computed, and the differences reported for the cases using the perfect and partial absorption assumptions. (author)

CO outflows from high-mass Class 0 protostars in Cygnus-X

Science.gov (United States)

Duarte-Cabral, A.; Bontemps, S.; Motte, F.; Hennemann, M.; Schneider, N.; André, Ph.

2013-10-01

Context. The earliest phases of the formation of high-mass stars are not well known. It is unclear whether high-mass cores in monolithic collapse exist or not, and what the accretion process and origin of the material feeding the precursors of high-mass stars are. As outflows are natural consequences of the accretion process, they represent one of the few (indirect) tracers of accretion. Aims: We aim to search for individual outflows from high-mass cores in Cygnus X and to study the characteristics of the detected ejections. We compare these to what has been found for the low-mass protostars, to understand how ejection and accretion change and behave with final stellar mass. Methods: We used CO (2-1) PdBI observations towards six massive dense clumps, containing a total of 9 high-mass cores. We estimated the bolometric luminosities and masses of the 9 high-mass cores and measured the energetics of outflows. We compared our sample to low-mass objects studied in the literature and developed simple evolutionary models to reproduce the observables. Results: We find that 8 out of 9 high-mass cores are driving clear individual outflows. They are therefore true equivalents of Class 0 protostars in the high-mass regime. The remaining core, CygX-N53 MM2, has only a tentative outflow detection. It could be one of the first examples of a true individual high-mass prestellar core. We also find that the momentum flux of high-mass objects has a linear relation to the reservoir of mass in the envelope, as a scale up of the relations previously found for low-mass protostars. This suggests a fundamental proportionality between accretion rates and envelope masses. The linear dependency implies that the timescale for accretion is similar for high- and low-mass stars. Conclusions: The existence of strong outflows driven by high-mass cores in Cygnus X clearly indicates that high-mass Class 0 protostars exist. The collapsing envelopes of these Class 0 objects have similar sizes and a

Preparation of Active Absorbent for Flue Gas Desulfurization From Coal Bottom Ash: Effect of Absorbent Preparation Variables

Directory of Open Access Journals (Sweden)

Chang Chin Li, Lee Keat Teong, Subhash Bhatia and Abdul Rahman Mohamed

2012-08-01

Full Text Available An active absorbent for flue gas desulfurization was prepared from coal bottom ash, calcium oxide (CaO and calcium sulfate by hydro-thermal process. The absorbent was examined for its micro-structural properties. The experiments conducted were based on Design Of Experiments (DOE according to 23 factorial design. The effect of various absorbent preparation variables such as ratio of CaO to bottom ash (A, hydration temperature (B and hydration period (C towards the BET (Brunauer-Emmett-Teller specific surface area of the absorbent were studied. At a CaO to bottom ash ratio = 2, hydration temperature = 200 ?C and hydration period = 10 hrs, absorbent with a surface area of 90.1 m2/g was obtained. Based on the analysis of the factorial design, it was concluded that factor A and C as well as the interaction of factors ABC and BC are the significant factors that effect the BET surface area of the absorbent. A linear mathematical model that describes the relation between the independent variables and interaction between variables towards the BET specific surface area of the absorbent was also developed. Analysis of variance (ANOVA showed that the model was significant at 1% level.Key Words: Absorbent, Bottom Ash, Design Of Experiments, Desulfurization, Surface Area.

What's in the Wind? Determining the Properties of Outflowing Gas in Powerful Broad Absorption Line Quasars

Science.gov (United States)

Leighly, Karen

2017-08-01

A significant fraction of quasars exhibits blueshifted broadabsorption lines (BALs) in their rest-UV spectra, indicating powerfuloutflows emerging from the central engine. These outflows may removeangular momentum to enable black hole growth, enrich the intergalacticmedium with metals, and trigger quenching of star formation ingalaxies. Despite years of study, the physical conditions of theoutflowing gas are poorly understood. The handful of objects that havebeen subjected to detailed analysis are atypical and characterized byrelatively narrow lines where blending is unimportant. However,investigating more powerful BAL quasars will give us better insightinto the types of outflows much more likely to impact galaxyevolution.SimBAL is a novel spectral synthesis fitting method for BAL quasarsthat uses Bayesian model calibration to compare synthetic to observedspectra. With the model inputs of ionization parameter, columndensity, and covering fraction specified, the gas properties givingrise to the BAL features can be determined. We propose to applySimBAL to archival spectra of a sample of 14 luminous BAL quasars to characterize their bulk outflow properties as a function of velocityfor the first time. Our results will show the range of parameterstypical of powerful outflows, an essential step towards constrainingthe physics behind quasar winds and thus their impact on theirenvironments.

Nutrient Shielding in Clusters of Cells

Science.gov (United States)

Lavrentovich, Maxim O.; Koschwanez, John H.; Nelson, David R.

2014-01-01

Cellular nutrient consumption is influenced by both the nutrient uptake kinetics of an individual cell and the cells’ spatial arrangement. Large cell clusters or colonies have inhibited growth at the cluster's center due to the shielding of nutrients by the cells closer to the surface. We develop an effective medium theory that predicts a thickness ℓ of the outer shell of cells in the cluster that receives enough nutrient to grow. The cells are treated as partially absorbing identical spherical nutrient sinks, and we identify a dimensionless parameter ν that characterizes the absorption strength of each cell. The parameter ν can vary over many orders of magnitude between different cell types, ranging from bacteria and yeast to human tissue. The thickness ℓ decreases with increasing ν, increasing cell volume fraction ϕ, and decreasing ambient nutrient concentration ψ∞. The theoretical results are compared with numerical simulations and experiments. In the latter studies, colonies of budding yeast, Saccharomyces cerevisiae, are grown on glucose media and imaged under a confocal microscope. We measure the growth inside the colonies via a fluorescent protein reporter and compare the experimental and theoretical results for the thickness ℓ. PMID:23848711

FOREIGN DIRECT INVESTMENT OUTFLOWS FROM CHINA AND INDIA

OpenAIRE

K. C. FUNG; ALICIA GARCIA-HERRERO

2012-01-01

In this paper, we examine the determinants of Indian and Chinese FDI outflows. There are three sets of results. First, Chinese investment is attracted to more corrupt countries, while India is attracted to economies with better rule of law. Further analysis suggests that our result of China investing in more corrupt destinations is mostly driven by Chinese investment in the sub-sample of African countries. While we do not conduct economic welfare analysis, several studies in the literature re...

Maja Valles, Mars: A Multi-Source Fluvio-Volcanic Outflow Channel System

Science.gov (United States)

Keske, A.; Christensen, P. R.

2017-12-01

The resemblance of martian outflow channels to the channeled scablands of the Pacific Northwest has led to general consensus that they were eroded by large-scale flooding. However, the observation that many of these channels are coated in lava issuing from the same source as the water source has motivated the alternative hypothesis that the channels were carved by fluid, turbulent lava. Maja Valles is a circum-Chryse outflow channel whose origin was placed in the late Hesperian by Baker and Kochel (1979), with more recent studies of crater density variations suggesting that its formation history involved multiple resurfacing events (Chapman et al., 2003). In this study, we have found that while Maja Valles indeed host a suite of standard fluvial landforms, its northern portion is thinly coated with lava that has buried much of the older channel landforms and overprinted them with effusive flow features, such as polygons and bathtub rings. Adjacent to crater pedestals and streamlined islands are patches of dark, relatively pristine material pooled in local topographic lows that we have interpreted as ponds of lava remaining from one or more fluid lava flows that flooded the channel system and subsequently drained, leaving marks of the local lava high stand. Despite the presence of fluvial landforms throughout the valles, lava flow features exist in the northern reaches of the system alone, 500-1200 km from the channels' source. The flows can instead be traced to a collection of vents in Lunae Plaum, west of the valles. In previously studied fluvio-volcanic outflow systems, such as Athabasca Valles, the sources of the volcanic activity and fluvial activity have been indistinguishable. In contrast, Maja Valles features numerous fluvio-volcanic landforms bearing similarity to those identified in other channel systems, yet the source of its lava flows is distinct from the source of its channels. Furthermore, in the absence of any channels between the source of the lava

Burnable neutron absorbers

International Nuclear Information System (INIS)

Radford, K.C.; Carlson, W.G.

1983-01-01

A neutron-absorber body for use in burnable poison rods in a nuclear reactor. The body is composed of a matrix of Al 2 O 3 containing B 4 C, the neutron absorber. Areas of high density polycrystalline Al 2 O 3 particles are predominantly encircled by pores in some of which there are B 4 C particles. This body is produced by initially spray drying a slurry of A1 2 O 3 powder to which a binder has been added. The powder of agglomerated spheres of the A1 2 O 3 with the binder are dry mixed with B 4 C powder. The mixed powder is formed into a green body by isostatic pressure and the green body is sintered. The sintered body is processed to form the neutron-absorber body. In this case the B 4 C particles are separate from the spheres resulting from the spray drying instead of being embedded in the sphere

Quenching of Star Formation in Molecular Outflow Host NGC 1266

NARCIS (Netherlands)

Alatalo, K.; Nyland, K. E.; Graves, G.; Deustua, S.; Young, L. M.; Davis, T. A.; Crocker, A. F.; Bureau, M.; Bayet, E.; Blitz, L.; Bois, M.; Bournaud, F.; Cappellari, M.; Davies, R. L.; de Zeeuw, P. T.; Emsellem, E.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; McDermid, R. M.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.; Wong, Tony; Ott, Jürgen

We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a

Neutron absorbers and methods of forming at least a portion of a neutron absorber

Energy Technology Data Exchange (ETDEWEB)

Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

2014-12-02

Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

Cluster geometry and survival probability in systems driven by reaction-diffusion dynamics

Energy Technology Data Exchange (ETDEWEB)

Windus, Alastair; Jensen, Henrik J [The Institute for Mathematical Sciences, 53 Prince' s Gate, South Kensington, London SW7 2PG (United Kingdom)], E-mail: h.jensen@imperial.ac.uk

2008-11-15

We consider a reaction-diffusion model incorporating the reactions A{yields}{phi}, A{yields}2A and 2A{yields}3A. Depending on the relative rates for sexual and asexual reproduction of the quantity A, the model exhibits either a continuous or first-order absorbing phase transition to an extinct state. A tricritical point separates the two phase lines. While we comment on this critical behaviour, the main focus of the paper is on the geometry of the population clusters that form. We observe the different cluster structures that arise at criticality for the three different types of critical behaviour and show that there exists a linear relationship for the survival probability against initial cluster size at the tricritical point only.

Revealing the ultrafast outflow in IRAS 13224-3809 through spectral variability

Science.gov (United States)

Parker, M. L.; Alston, W. N.; Buisson, D. J. K.; Fabian, A. C.; Jiang, J.; Kara, E.; Lohfink, A.; Pinto, C.; Reynolds, C. S.

2017-08-01

We present an analysis of the long-term X-ray variability of the extreme narrow-line Seyfert 1 galaxy IRAS 13224-3809 using principal component analysis (PCA) and fractional excess variability (Fvar) spectra to identify model-independent spectral components. We identify a series of variability peaks in both the first PCA component and Fvar spectrum which correspond to the strongest predicted absorption lines from the ultrafast outflow (UFO) discovered by Parker et al. (2017). We also find higher order PCA components, which correspond to variability of the soft excess and reflection features. The subtle differences between RMS and PCA results argue that the observed flux-dependence of the absorption is due to increased ionization of the gas, rather than changes in column density or covering fraction. This result demonstrates that we can detect outflows from variability alone and that variability studies of UFOs are an extremely promising avenue for future research.

Radioactive iodine absorbing properties of tetrathiafulvalene

Energy Technology Data Exchange (ETDEWEB)

Ito, Tomiyasu; Nakamura, Asao (Ajinomoto Co. Inc., Kawasaki, Kanagawa (Japan). Central Research Labs.); Nogawa, Norio; Oohashi, Kunio; Morikawa, Naotake

1989-05-01

For the purpose of searching some effective absorbents of gaseous radioactive iodine, 16 substances considered as having an affinity for iodine were investigated with regular iodine and /sup 125/I. In a preliminary survey, only tetrathiafulvalene (TTF) was found to have satisfactory absorbing properties comparable to activated charcoal. A further detailed comparison of the properties between TTF and activated charcoal led us to the conclusion that the former has more preferable properties as absorbent of radioactive iodine than the latter in all points studied. The results are summarized as follows: (1) The absorption of iodine on TTF in atmosphere was about twice as much as that on activated charcoal. Desorption of iodine from saturatedly absorbed iodine on TTF was practically negligible except trace amount of initial desorption, while that on activated charcoal was considerable (3%/50h) even in the air at room temperature. (2) Absorbed amount of iodine on activated charcoal decreased with increasing gaseous iodine concentration, air flow rate, on humidity of flowing-air. On the other hand, those factors scarcely affected that on TTF. Under an air flow rate of 1m/s, activated charcoal absorbs only 80% of iodine, while TTF absorbs more than 99%. (3) In flowing-air saturated with water vapor, iodine absorbed on activated charcoal was gradually liberated although by small amount (0.08%/100h), while that on TTF was much more stable for a long period (0.004%/100h). As a conclusion, TTF is considered to be useful as a quite effective radioactive iodine absorbent, especially in the case where protection from radioactive iodine should be serious, though it is expensive now. (author).

Radioactive iodine absorbing properties of tetrathiafulvalene

International Nuclear Information System (INIS)

Ito, Tomiyasu; Nakamura, Asao; Nogawa, Norio; Oohashi, Kunio; Morikawa, Naotake.

1989-01-01

For the purpose of searching some effective absorbents of gaseous radioactive iodine, 16 substances considered as having an affinity for iodine were investigated with regular iodine and 125 I. In a preliminary survey, only tetrathiafulvalene (TTF) was found to have satisfactory absorbing properties comparable to activated charcoal. A further detailed comparison of the properties between TTF and activated charcoal led us to the conclusion that the former has more preferable properties as absorbent of radioactive iodine than the latter in all points studied. The results are summarized as follows: (1) The absorption of iodine on TTF in atmosphere was about twice as much as that on activated charcoal. Desorption of iodine from saturatedly absorbed iodine on TTF was practically negligible except trace amount of initial desorption, while that on activated charcoal was considerable (3%/50h) even in the air at room temperature. (2) Absorbed amount of iodine on activated charcoal decreased with increasing gaseous iodine concentration, air flow rate, on humidity of flowing-air. On the other hand, those factors scarcely affected that on TTF. Under an air flow rate of 1m/s, activated charcoal absorbs only 80% of iodine, while TTF absorbs more than 99%. (3) In flowing-air saturated with water vapor, iodine absorbed on activated charcoal was gradually liberated although by small amount (0.08%/100h), while that on TTF was much more stable for a long period (0.004%/100h). As a conclusion, TTF is considered to be useful as a quite effective radioactive iodine absorbent, especially in the case where protection from radioactive iodine should be serious, though it is expensive now. (author)

Neutron absorbing article

International Nuclear Information System (INIS)

Naum, R.G.; Owens, D.P.; Dooker, G.I.

1981-01-01

A neutron-absorbing article suitable for use in spent fuel racks is described. It comprises boron carbide particles, diluent particles, and a phenolic polymer cured to a continuous matrix. The diluent may be silicon carbide, graphite, amorphous carbon, alumina, or silica. The combined boron carbide-diluent phase contains no more than 2 percent B 2 O 3 , and the neutron-absorbing article contains from 20 to 40 percent phenol resin. The ratio of boron carbide to diluent particles is in the range 1:9 to 9:1

Mechanical shock absorber

International Nuclear Information System (INIS)

Vrillon, Bernard.

1973-01-01

The mechanical shock absorber described is made of a constant thickness plate pierced with circular holes regularly distributed in such a manner that for all the directions along which the strain is applied during the shock, the same section of the substance forming the plate is achieved. The shock absorber is made in a metal standing up to extensive deformation before breaking, selected from a group comprising mild steels and austenitic stainless steels. This apparatus is used for handling pots of fast neutron reactor fuel elements [fr

Particulate waste outflow from fish-farming cages. How much is uneaten feed?

Science.gov (United States)

Ballester-Moltó, M; Sanchez-Jerez, P; Cerezo-Valverde, J; Aguado-Giménez, F

2017-06-15

Particulate wastes drive benthic organic enrichment from cage fish farming. Differentiation between faeces and uneaten feed estimates at cage level are of great value to both economize the feeding process and reduce waste. This study estimates the particulate waste outflowing cages at different depths and orientations, and the wasted feed component by combining in situ measurements and modelling. Particulate matter flux (PMF) was greater vertically through the cage bottoms (60.89%), but lateral outflow was also substantial (39.11%). PMF occurs all around the cages, and the influence of the mainstream current was low. Wasted feed was greatly variable, reaching high values (about 50% of supplied feed. The self-application of feed wastage monitoring and estimates by fish farmers is recommended to improve sustainability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quasar Feedback in the Ultraluminous Infrared Galaxy F11119+3257: Connecting the Accretion Disk Wind with the Large-scale Molecular Outflow

Science.gov (United States)

Veilleux, S.; Bolatto, A.; Tombesi, F.; Meléndez, M.; Sturm, E.; González-Alfonso, E.; Fischer, J.; Rupke, D. S. N.

2017-07-01

In Tombesi et al., we reported the first direct evidence for a quasar accretion disk wind driving a massive (>100 M ⊙ yr-1) molecular outflow. The target was F11119+3257, an ultraluminous infrared galaxy (ULIRG) with unambiguous type 1 quasar optical broad emission lines. The energetics of the accretion disk wind and molecular outflow were found to be consistent with the predictions of quasar feedback models where the molecular outflow is driven by a hot energy-conserving bubble inflated by the inner quasar accretion disk wind. However, this conclusion was uncertain because the mass outflow rate, momentum flux, and mechanical power of the outflowing molecular gas were estimated from the optically thick OH 119 μm transition profile observed with Herschel. Here, we independently confirm the presence of the molecular outflow in F11119+3257, based on the detection of ˜±1000 km s-1 blue- and redshifted wings in the CO(1-0) emission line profile derived from deep ALMA observations obtained in the compact array configuration (˜2.″8 resolution). The broad CO(1-0) line emission appears to be spatially extended on a scale of at least ˜7 kpc from the center. Mass outflow rate, momentum flux, and mechanical power of (80-200) {R}7-1 M ⊙ yr-1, (1.5-3.0) {R}7-1 L AGN/c, and (0.15-0.40)% {R}7-1 {L}{AGN}, respectively, are inferred from these data, assuming a CO-to-H2 conversion factor appropriate for a ULIRG (R 7 is the radius of the outflow normalized to 7 kpc, and L AGN is the AGN luminosity). These rates are time-averaged over a flow timescale of 7 × 106 yr. They are similar to the OH-based rates time-averaged over a flow timescale of 4 × 105 yr, but about a factor of 4 smaller than the local (“instantaneous” ≲105 yr) OH-based estimates cited in Tombesi et al. The implications of these new results are discussed in the context of time-variable quasar-mode feedback and galaxy evolution. The need for an energy-conserving bubble to explain the molecular outflow

Dynamic Changes of QRS Morphology of Premature Ventricular Contractions During Ablation in the Right Ventricular Outflow Tract: A Case Report.

Science.gov (United States)

Yue-Chun, Li; Jia-Feng, Lin; Jia-Xuan, Lin

2015-10-01

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare.This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin.Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm.The ndings could be strong evidence for a preferential conduction via the myocardial bers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

Burst Activity and Heart Rhythm Modulation in the Sympathetic Outflow to the Heart

National Research Council Canada - National Science Library

Baselli, G

2001-01-01

In 13 decerebrate, artificially ventilated cats preganglionic sympathetic outflow to the heart was recorded with ECG and ventilation signal, A novel algorithm was implemented that extracts weighted...

DENSE CLUMPS AND CANDIDATES FOR MOLECULAR OUTFLOWS IN W40

Energy Technology Data Exchange (ETDEWEB)

Shimoikura, Tomomi; Dobashi, Kazuhito [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Nakamura, Fumitaka; Hara, Chihomi; Kawabe, Ryohei [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tanaka, Tomohiro [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Shimajiri, Yoshito [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Sugitani, Kouji, E-mail: ikura@u-gakugei.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan)

2015-06-20

We report the results of the {sup 12}CO (J = 3−2) and HCO{sup +} (J = 4−3) observations of the W40 H ii region with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope (HPBW ≃ 22″) to search for molecular outflows and dense clumps. We found that the velocity field in the region is highly complex, consisting of at least four distinct velocity components at V{sub LSR} ≃ 3, 5, 7, and 10 km s{sup −1}. The ∼7 km s{sup −1} component represents the systemic velocity of cold gas surrounding the entire region, and causes heavy absorption in the {sup 12}CO spectra over the velocity range 6 ≲ V{sub LSR} ≲ 9 km s{sup −1}. The ∼5 and ∼10 km s{sup −1} components exhibit high {sup 12}CO temperature (≳40 K) and are found mostly around the H ii region, suggesting that these components are likely to be tracing dense gas interacting with the expanding shell around the H ii region. Based on the {sup 12}CO data, we identified 13 regions of high velocity gas, which we interpret as candidate outflow lobes. Using the HCO{sup +} data, we also identified six clumps and estimated their physical parameters. On the basis of the ASTE data and near-infrared images from 2MASS, we present an updated three-dimensional model of this region. In order to investigate molecular outflows in W40, the SiO (J = 1−0, v = 0) emission line and some other emission lines at 40 GHz were also observed with the 45 m telescope at the Nobeyama Radio Observatory, but they were not detected at the present sensitivity.

Enhanced ion acoustic fluctuations and ion outflows

Directory of Open Access Journals (Sweden)

F. R. E. Forme

1999-02-01

Full Text Available A number of observations showing enhanced ion acoustic echoes observed by means of incoherent scatter radars have been reported in the literature. The received power is extremely enhanced by up to 1 or 2 orders of magnitude above usual values, and it is mostly contained in one of the two ion acoustic lines. This spectral asymmetry and the intensity of the received signal cannot be resolved by the standard analysis procedure and often causes its failure. As a result, and in spite of a very clear spectral signature, the analysis is unable to fit the plasma parameters inside the regions of ion acoustic turbulence. We present European Incoherent Scatter radar (EISCAT observations of large ion outflows associated with the simultaneous occurrence of enhanced ion acoustic echoes. The ion fluxes can reach 1014 m-2 s-1 at 800 km altitude. From the very clear spectral signatures of these echoes, a method is presented to extract estimates of the electron temperature and the ion drift within the turbulent regions. It is shown that the electron gas is strongly heated up to 11 000 K. Also electron temperature gradients of about 0.02 K/m exist. Finally, the estimates of the electron temperature and of the ion drift are used to study the possible implications for the plasma transport inside turbulent regions. It is shown that strong electron temperature gradients cause enhancement of the ambipolar electric field and can account for the observed ion outflows.Key words. Ionosphere (auroral ionosphere; ionosphere · magnetosphere interactions; plasma waves and instabilities.

Calcium absorbability from milk products, an imitation milk, and calcium carbonate

International Nuclear Information System (INIS)

Recker, R.R.; Bammi, A.; Barger-Lux, M.J.; Heaney, R.P.

1988-01-01

Whole milk, chocolate milk, yogurt, imitation milk (prepared from dairy and nondairy products), cheese, and calcium carbonate were labeled with 45 Ca and administered as a series of test meals to 10 healthy postmenopausal women. Carrier Ca content of the test meals was held constant at 250 mg and subjects fasted before each meal. The absorbability of Ca from the six sources was compared by measuring fractional absorption by the double isotope method. The mean absorption values for all six sources were tightly clustered between 21 and 26% and none was significantly different from the others using one-way analysis of variance. We conclude that none of the sources was significantly superior or inferior to the others

Discovering a misaligned CO outflow related to the red MSX source G034.5964-01.0292

Science.gov (United States)

Paron, S.; Ortega, M. E.; Petriella, A.; Rubio, M.

2014-07-01

Aims: The red MSX source G034.5964-01.0292 (MSXG34), catalogued as a massive young stellar object, was observed in molecular lines with the aim of discovering and studying molecular outflows. Methods: We mapped a region of 3'× 3' centred at MSXG34 using the Atacama Submillimeter Telescope Experiment in the 12CO J = 3-2 and HCO+J = 4-3 lines with an angular and spectral resolution of 22'' and 0.11 km s-1. Additionally, public 13CO J = 1-0 and near-IR UKIDSS data obtained from the Galactic Ring Survey and the WFCAM Sciencie Archive were analysed. Results: We found that the 12CO spectra towards the YSO present a self-absorption dip, as is common in star-forming regions, and spectral wings that indicate outflow activity. The HCO+ was detected only towards the MSXG34 position at vLSR ~ 14.2 km s-1, in coincidence with the 12CO absorption dip and approximately with the velocity of previous ammonia observations. HCO+ and NH3 are known to be enhanced in molecular outflows. When we analysed the spectral wings of the 12CO line, we discovered misaligned red- and blue-shifted molecular outflows associated with MSXG34. The near-IR emission shows a cone-like nebulosity composed of two arc-like features related to the YSO, which might be due to a cavity cleared in the circumstellar material by a precessing jet. This can explain the misalignment in the molecular outflows. From the analysis of the 13CO J = 1-0 data we suggest that the YSO is very likely related to a molecular clump ranging between 10 and 14 km s-1. This suggests that MSXG34, with an associated central velocity of about 14 km s-1, may be located in the background of this clump. Thus, the blue-shifted outflow is probably deflected by the interaction with dense gas along the line of sight. From a spectral energy distribution analysis of MSXG34 we found that its central object probably is an intermediate-mass protostar.

Low Absorbance Measurements

Science.gov (United States)

Harris, T. D.; Williams, A. M.

1983-10-01

The application of low absorption measurements to dilute solute determination requires specific instrumental characteristics. The use of laser intracavity absorption and thermal lens calorimetry to measure concentration is shown. The specific operating parameters that determine sensitivity are delineated along with the limits different measurement strategies impose. Finally areas of improvement in components that would result in improve sensitivity, accuracy, and reliability are discussed. During the past decade, a large number of methods have been developed for measuring the light absorbed by transparent materials. These include measurements on gases, liquids, and solids. The activity has been prompted by a variety of applications and a similar variety of disciplines. In Table 1 some representative examples of these methods is shown along with their published detection limits.1 It is clear that extraordinarily small absorbances can be measured. Most of the methods can be conveniently divided into two groups. These groups are those that measure the transmission of the sample and those that measure the light absorbed by the sample. The light absorbed methods are calorimetric in character. The advantages and disadvantages of each method varies depending on the principal application for which they were developed. The most prevalent motivation has been to characterize the bulk optical properties of transparent materials. Two examples are the development of extremely transparent glasses for use as fiber optic materials and the development of substrates for high power laser operation.

Screen Channel Liquid Acquisition Device Outflow Tests in Liquid Hydrogen

Science.gov (United States)

Hartwig, Jason W.; Chato, David J.; McQuillen, J. B.; Vera, J.; Kudlac, M. T.; Quinn, F. D.

2013-01-01

This paper presents experimental design and test results of the recently concluded 1-g inverted vertical outflow testing of two 325x2300 full scale liquid acquisition device (LAD) channels in liquid hydrogen (LH2). One of the channels had a perforated plate and internal cooling from a thermodynamic vent system (TVS) to enhance performance. The LADs were mounted in a tank to simulate 1-g outflow over a wide range of LH2 temperatures (20.3 - 24.2 K), pressures (100 - 350 kPa), and flow rates (0.010 - 0.055 kg/s). Results indicate that the breakdown point is dominated by liquid temperature, with a second order dependence on mass flow rate through the LAD. The best performance is always achieved in the coldest liquid states for both channels, consistent with bubble point theory. Higher flow rates cause the standard channel to break down relatively earlier than the TVS cooled channel. Both the internal TVS heat exchanger and subcooling the liquid in the propellant tank are shown to significantly improve LAD performance.

New noninvasive treatment for prostate outflow obstruction

International Nuclear Information System (INIS)

Richards, D.; Milroy, E.; Chapple, C.; Eldin, A.; Wallstein, H.

1989-01-01

Sixteen patients with prostatic outflow obstruction underwent implantation of the Wallstent endoprothesis, a woven mesh of fine stainless steel, mounted on a 9-F delivery system with an unconstrained diameter of 14 mm. The stent was inserted under local anesthesia, and placement was guided by linear transrectal US and flexible urethroscopy. In no patient was the distal sphincter mechanism compromised. In four, stent balloon dilation was needed. Urodynamic parameters (especially flow rate, voiding detrusor pressure, and postvoid residual) improved in all patients. Our experience showed the Wallstent endoprosthesis to be a safe, clinically acceptable, and minimally invasive alternative to prostatectomy

Shock absorber in Ignalina NPP

International Nuclear Information System (INIS)

Bulavas, A.; Muralis, J.

1996-09-01

Theoretical calculation and experimental analysis of models of shock absorber in Ignalina NPP is presented. The results obtained from the investigation with model of shock absorber coincide with the theoretical calculation. (author). 2 figs., 3 refs

Liquid metal reactor absorber technology

International Nuclear Information System (INIS)

Pitner, A.L.

1990-10-01

The selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts. 3 refs., 3 figs

On the definition of absorbed dose

International Nuclear Information System (INIS)

Grusell, Erik

2015-01-01

Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before. - Highlights: • A stringent definition of absorbed dose is given. • This requires the definition of an irradiation and a suitable probability space. • A stringent definition is important for an understanding of the concept absorbed dose

Indirect photometric detection of boron cluster anions electrophoretically separated in methanol.

Science.gov (United States)

Vítová, Lada; Fojt, Lukáš; Vespalec, Radim

2014-04-18

3,5-Dinitrobenzoate and picrate are light absorbing anions pertinent to indirect photometric detection of boron cluster anions in buffered methanolic background electrolytes (BGEs). Tris(hydroxymethyl)aminomethane and morpholine have been used as buffering bases, which eliminated baseline steps, and minimized the baseline noise. In methanolic BGEs, mobilities of boron cluster anions depend on both ionic constituents of the BGE buffer. This dependence can be explained by ion pair interaction of detected anions with BGE cations, which are not bonded into ion pairs with the BGE anions. The former ion pair interaction decreases sensitivity of the indirect photometric detection. Copyright © 2014 Elsevier B.V. All rights reserved.

Outflows of groundwater in lakes: case study of Lake Raduńske Górne

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Cieśliński Roman

2014-12-01

Full Text Available The aim of the study was to locate and describe groundwater outflows in a selected lake basin. The study hypothesis was based on the fact that, according to the specialist literature, one of the forms of lake water supply is through groundwater outflows. It was also assumed that the lakes of the Kashubian Lake District are characterised by such a form of lake water supply. The time scope of the work included the period from January 2011 to September 2012. The spatial scope of the work included the area of Lake Raduńskie Górne, located in the Kashubian Lake District in north Poland. The research plot was in the north-eastern part of the lake. Office works were aimed at gathering and studying source materials and maps. Cartographic materials were analysed with the use of the MapInfo Professional 9.5. The purpose of the field work was to find the groundwater outflows in the basin of Lake Raduńskie Górne. During the field research diving was carried out in the lake. During the dive audiovisual documentation was conducted using a Nikon D90 camera with Ikelite underwater housing for Nikon D90 and an Ikelite DS 161 movie substrobe, as well as a GoPro HD HERO 2 Outdoor camera. During the project, four groundwater outflows were found. In order to examine these springs audiovisual and photographic documentation was made. To systematise the typology of the discovered springs, new nomenclature was suggested, namely under-lake springs with subtypes: an under-lake slope spring and under-lake offshore spring

Improvement in Outflow Facility by Two Novel Microinvasive Glaucoma Surgery Implants

Science.gov (United States)

Hays, Cassandra L.; Gulati, Vikas; Fan, Shan; Samuelson, Thomas W.; Ahmed, Iqbal Ike K.; Toris, Carol B.

2014-01-01

Purpose. To determine improvement in outflow facility (C) in human anterior segments implanted with a novel Schlemm's canal scaffold or two trabecular micro-bypasses. Methods. Human anterior segments were isolated from 12 pairs of eyes from donors with no history of ocular disease and then perfused at 50, 40, 30, 20, and 10 mm Hg pressures for 10 minutes each. Baseline C was calculated from perfusion pressures and flow rates. The scaffold was implanted into Schlemm's canal of one anterior segment, and two micro-bypasses were implanted three clock-hours apart in the contralateral anterior segment. Outflow facility and resistance were compared at various standardized perfusion pressures and between each device. Results. Compared to baseline, C increased by 0.16 ± 0.12 μL/min/mm Hg (74%) with the scaffold, and 0.08 ± 0.12 μL/min/mm Hg (34%) with two micro-bypasses. The scaffold increased C at perfusion pressures of 50, 40, 30, and 20 mm Hg (P glaucoma. PMID:24550367

Burnable neutron absorbers

International Nuclear Information System (INIS)

Radford, K.C.; Carlson, W.G.

1985-01-01

This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al 2 O 3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B 4 C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

Science.gov (United States)

Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

1989-01-01

The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

HIGH-VELOCITY MOLECULAR OUTFLOW IN CO J = 7-6 EMISSION FROM THE ORION HOT CORE

International Nuclear Information System (INIS)

Furuya, Ray S.; Shinnaga, Hiroko

2009-01-01

Using the Caltech Submillimeter Observatory 10.4 m telescope, we performed sensitive mapping observations of 12 CO J = 7-6 emission at 807 GHz toward Orion IRc2. The image has an angular resolution of 10'', which is the highest angular resolution data toward the Orion Hot Core published for this transition. In addition, thanks to the on-the-fly mapping technique, the fidelity of the new image is rather high, particularly in comparison with previous images. We have succeeded in mapping the northwest-southeast high-velocity molecular outflow, whose terminal velocity is shifted by ∼70-85 km s -1 with respect to the systemic velocity of the cloud. This yields an extremely short dynamical time scale of ∼900 years. The estimated outflow mass loss rate shows an extraordinarily high value, on the order of 10 -3 M sun yr -1 . Assuming that the outflow is driven by Orion IRc2, our result agrees with the picture so far obtained for a 20 M sun (proto)star in the process of formation.

A Global Model for Circumgalactic and Cluster-core Precipitation

Science.gov (United States)

Voit, G. Mark; Meece, Greg; Li, Yuan; O'Shea, Brian W.; Bryan, Greg L.; Donahue, Megan

2017-08-01

We provide an analytic framework for interpreting observations of multiphase circumgalactic gas that is heavily informed by recent numerical simulations of thermal instability and precipitation in cool-core galaxy clusters. We start by considering the local conditions required for the formation of multiphase gas via two different modes: (1) uplift of ambient gas by galactic outflows, and (2) condensation in a stratified stationary medium in which thermal balance is explicitly maintained. Analytic exploration of these two modes provides insights into the relationships between the local ratio of the cooling and freefall timescales (I.e., {t}{cool}/{t}{ff}), the large-scale gradient of specific entropy, and the development of precipitation and multiphase media in circumgalactic gas. We then use these analytic findings to interpret recent simulations of circumgalactic gas in which global thermal balance is maintained. We show that long-lasting configurations of gas with 5≲ \\min ({t}{cool}/{t}{ff})≲ 20 and radial entropy profiles similar to observations of cool cores in galaxy clusters are a natural outcome of precipitation-regulated feedback. We conclude with some observational predictions that follow from these models. This work focuses primarily on precipitation and AGN feedback in galaxy-cluster cores, because that is where the observations of multiphase gas around galaxies are most complete. However, many of the physical principles that govern condensation in those environments apply to circumgalactic gas around galaxies of all masses.

The Red Sea outflow regulated by the Indian monsoon

Science.gov (United States)

Aiki, Hidenori; Takahashi, Keiko; Yamagata, Toshio

2006-08-01

To investigate why the Red Sea water overflows less in summer and more in winter, we have developed a locally high-resolution global OGCM with transposed poles in the Arabian peninsula and India. Based on a series of sensitivity experiments with different sets of idealized atmospheric forcing, the present study shows that the summer cessation of the strait outflow is remotely induced by the monsoonal wind over the Indian Ocean, in particular that over the western Arabian Sea. During the southwest monsoon (May-September), thermocline in the Gulf of Aden shoals as a result of coastal Ekman upwelling induced by the predominantly northeastward wind in the Gulf of Aden and the Arabian Sea. Because this shoaling is maximum during the southwest summer monsoon, the Red Sea water is blocked at the Bab el Mandeb Strait by upwelling of the intermediate water of the Gulf of Aden in late summer. The simulation also shows the three-dimensional evolution of the Red Sea water tongue at the mid-depths in the Gulf of Aden. While the tongue meanders, the discharged Red Sea outflow water (RSOW) (incoming Indian Ocean intermediate water (IOIW)) is always characterized by anticyclonic (cyclonic) vorticity, as suggested from the potential vorticity difference.

Angular distributions of photoelectrons from free Na clusters

International Nuclear Information System (INIS)

Wopperer, P.; Dinh, P. M.; Faber, B.; Reinhard, P.-G.; Suraud, E.

2010-01-01

We explore, from a theoretical perspective, photoelectron angular distributions (PADs) of the Na clusters Na 8 , Na 10 , Na 12 , Na 18 , Na 3 + , Na 11 + , Na 13 + , and Na 19 + . The basis of the description is the time-dependent local-density approximation (TDLDA), augmented by a self-interaction correction (SIC) to describe ionization properties correctly. The scheme is solved on a numerical grid in coordinate space with absorbing bounds. We assume for each cluster system an isotropic ensemble of free clusters and develop for the case of one-photon emission analytical formulas for computing the orientation-averaged PAD on the basis of a few TDLDA-SIC calculations for properly chosen reference orientations. It turns out that all the information in the averaged PAD is contained in one anisotropy parameter. We find that this parameter varies very little with system size, but as a whole is crucially influenced by the detailed ionic structure. We also make comparisons with direct orientation averaging and consider one example reaching outside the perturbative regime.

The Origin of Fast Molecular Outflows in Quasars: Molecule Formation in AGN-Driven Galactic Winds

Science.gov (United States)

Richings, Alexander James; Faucher-Giguere, Claude-Andre

2017-07-01

Observations of AGN host galaxies have detected fast molecular outflows, with velocities up to 1000 km s-1. However, the origin of these molecular outflows is currently unclear. One possibility is that they are formed from molecular gas that is swept up from the host galaxy by the AGN wind. However, previous studies have suggested that molecular clouds that are swept up by an AGN wind are unlikely to survive being accelerated to such high velocities. An alternative scenario is that molecules may form within the AGN wind material itself. We present a suite of 3D hydrodynamic simulations of an idealised AGN wind that we have run to explore this scenario. These simulations are coupled to a time-dependent chemical model to follow the creation and destruction of molecules, including H2, CO, OH and HCO+. We find that molecules do form within the wind, with molecular outflow rates up to 140 M⊙ yr-1 after 1 Myr. This is sensitive to the ambient ISM density, metallicity, and AGN luminosity. We also compute observable CO emission lines from these simulations using a radiative transfer code in post-processing. The CO-derived outflow rates are comparable to those seen in observations, although the maximum line of sight velocities are a factor ≍2 lower than observed. We find a CO (1-0) to H2 conversion factor of αCO = 0.15 M⊙ (K km s-1 pc2)-1 at solar metallicity, 5 times lower than is typically assumed in observations of such systems.

Dynamic testing of airplane shock-absorbing struts

Science.gov (United States)

Langer, P; Thome, W

1932-01-01

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Liquid absorber experiments in ZED-2

International Nuclear Information System (INIS)

McDonnell, F.N.

1975-07-01

A set of liquid absorber experiments was performed in ZED-2 to provide data with which to test the adequacy of calculational methods for zone controller and refuelling studies associated with advanced reactor concepts. The absorber consisted of a full length aluminum tube, containing either i)H 2 O, ii)H 2 O + boron (2.5 mg/ml) or iii)H 2 O + boron (8.0 mg/ml). The tube was suspended vertically at interstitial or in-channel locations. A U-tube absorber was also simulated using two absorber tubes with appropriate spacers. Experiments were carried out at two different square lattice pitches, 22.86 and 27.94 cm. Measurements were made of the reactivity effects of the absorbers and, in some cases, of the detailed flux distribution near the perturbation. The results from one calculational method, the source-sink approach, were compared with the data from selected experiments. (author)

Clustering of near clusters versus cluster compactness

International Nuclear Information System (INIS)

Yu Gao; Yipeng Jing

1989-01-01

The clustering properties of near Zwicky clusters are studied by using the two-point angular correlation function. The angular correlation functions for compact and medium compact clusters, for open clusters, and for all near Zwicky clusters are estimated. The results show much stronger clustering for compact and medium compact clusters than for open clusters, and that open clusters have nearly the same clustering strength as galaxies. A detailed study of the compactness-dependence of correlation function strength is worth investigating. (author)

A chiral microwave absorbing absorbent of Fe–CoNiP coated on spirulina

Energy Technology Data Exchange (ETDEWEB)

Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yuan, Liming [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Zhang, Deyuan [School of Mechanical Engineering and Automation, Beihang University, Beijing, 100191 (China)

2015-11-15

A chiral bio-absorbent of Fe–CoNiP coated on the spirulina was fabricated by the electroless and chemical vapor decomposition. The scanning electron microscopy (SEM) was used to evaluate the spirulina cells particle morphology. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The permittivity and permeability was measured by a vector network analyzer in frequency 8–18 GHz, and the reflection loss (RL) was calculated. The results showed the carbonyl iron particles (CIPs) and CoNiP were bonded to the spirulina surface, the permittivity and permeability could be enlarged as Fe films coated on the particles compared with the CoNiP spirulina, it was attributed to the excellent electromagnetic property of CIPs. The chiral Fe–CoNiP composites had a better absorbing property at 8–18 GHz than the CoNiP spirulina composite, the RL was −16.26 dB at 10.48 GHz, the absorbing band was 9.5–11.5 GHz of RL less than −10 dB, which indicated the Fe–CoNiP spirulina could be an effective absorbent used in 8–18 GHz. - Highlights: • Absorbers filled with Fe–CoNiP coating on the spirulina were fabricated. • The permittivity and permeability increased as CIPs coated. • The Fe material enhanced the electromagnetic property. • The spirulina coated Fe–CoNiP was effective in 8–18 GHz.

Effect of right ventricular electrode location (outflow tract vs. apex) on mechanical Ventricular synchrony in patients that underwent pacemaker implant therapy

International Nuclear Information System (INIS)

Rincon, Oscar S; Saenz, Luis C; Salazar, Gabriel; Hernandez, Edgar

2008-01-01

Objective: to assess in depth the effect of ventricular stimulation from the right ventricular outflow tract and the apex on mechanical ventricular synchrony. Materials And Methods: cohort analytical study. 20 patients with indication of definitive pacemaker indication underwent trans thoracic echocardiogram before and after pacemaker implant with electrode implantation in the right ventricular outflow tract and in the apex (10 patients in each group). There was no structural cardiopathy, ejection fraction was ? 50%, QRS and AV conduction were normal. Mechanical ventricular asynchrony (M mode and tissue doppler) and implant and device parameters were evaluated. Statistical Analysis: results are given as mean values, standard deviation or percentages.Continuous variables were compared using Chi-square test and ANOVA. A p <0.05 value was considered statistically significant. Results: in five patients (25%) a pre-implant ventricular asynchrony was found; in seven (70%) ventricular asynchrony post-implant in the right ventricle outflow tract and in 5 (50%) in the apex. Mean interventricular pot-implant delay was 21,6 ms in the right ventricular outflow tract and 11,5 ms in the apex (p = 0,8); mean septal to lateral wall delay was 73 ms in the right ventricular outflow tract and 26 ms in the apex (p = 0,8). QRS post-implant delay was 134 ms in the right ventricular outflow tract and 140 ms in the apex (p = 0,1). No differences between implant parameters and device programming were found. Conclusions: presence of ventricular asynchrony was evidenced in patients with normal QRS and structurally healthy heart. Ventricular stimulation with pacemaker from the apex or the right ventricular outflow tract suggests acute ventricular asynchrony at least in 60% of the cases, without statistically significant difference between both groups.

Absorber rod drive for nuclear reactors

International Nuclear Information System (INIS)

Acher, H.

1985-01-01

The invention concerns a further addition to the invention of DE 33 42 830 A1. The free contact of the hollow piston with the nut due to hydraulic pressure is replaced by a hydraulic or spring attachment. The pressure system required to produce the hydraulic pressure is therefore omitted, and the electrical power required for driving the pump or the mass flow is also omitted. The absorber rod slotted along its longitudinal axis is replaced by an absorber rod, in the longitudinal axis of which a hollow piston is connected together with the absorber rod. This makes the absorber rod more stable, and assembly is simplified. (orig./HP) [de

Intra- and Inter-rater Agreement of Superior Vena Cava Flow and Right Ventricular Outflow Measurements in Late Preterm and Term Neonates.

Science.gov (United States)

Mahoney, Liam; Fernandez-Alvarez, Jose R; Rojas-Anaya, Hector; Aiton, Neil; Wertheim, David; Seddon, Paul; Rabe, Heike

2018-02-24

To explore the intra- and inter-rater agreement of superior vena cava (SVC) flow and right ventricular (RV) outflow in healthy and unwell late preterm neonates (33-37 weeks' gestational age), term neonates (≥37 weeks' gestational age), and neonates receiving total-body cooling. The intra- and inter-rater agreement (n = 25 and 41 neonates, respectively) rates for SVC flow and RV outflow were determined by echocardiography in healthy and unwell late preterm and term neonates with the use of Bland-Altman plots, the repeatability coefficient, the repeatability index, and intraclass correlation coefficients. The intra-rater repeatability index values were 41% for SVC flow and 31% for RV outflow, with intraclass correlation coefficients indicating good agreement for both measures. The inter-rater repeatability index values for SVC flow and RV outflow were 63% and 51%, respectively, with intraclass correlation coefficients indicating moderate agreement for both measures. If SVC flow or RV outflow is used in the hemodynamic treatment of neonates, sequential measurements should ideally be performed by the same clinician to reduce potential variability. © 2018 by the American Institute of Ultrasound in Medicine.

Trend-outflow method for understanding interactions of surface water with groundwater and atmospheric water for eight reaches of the Upper Rio Grande

Science.gov (United States)

Liu, Yi; Sheng, Zhuping

2011-11-01

SummaryAtmospheric water, surface water, and groundwater interact very actively through hydrologic processes such as precipitation, infiltration, seepage, irrigation, drainage, evaporation, and evapotranspiration in the Upper Rio Grande Basin. A trend-outflow method has been developed in this paper to gain a better understanding of the interactions based on cumulated inflow and outflow data for any river reaches of interest. A general trend-outflow equation was derived by associating the net interaction of surface water with atmospheric water as a polynomial of inflow and the net interaction of surface water with groundwater as a constant based on surface water budget. Linear and quadratic relations are probably two common trend-outflow types in the real world. It was found that trend-outflows of the Upper Rio Grande reaches, Española, Albuquerque, Socorro-Engle, Palomas, and Rincon are linear with inflow, while those of reaches, Belen, Mesilla and Hueco are quadratic. Reaches Belen, Mesilla and Hueco are found as water deficit reaches mainly for irrigated agriculture in extreme drought years.

Cluster-cluster clustering

International Nuclear Information System (INIS)

Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.; Yale Univ., New Haven, CT; California Univ., Santa Barbara; Cambridge Univ., England; Sussex Univ., Brighton, England)

1985-01-01

The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references

A simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations

Directory of Open Access Journals (Sweden)

Yibao Li

2017-01-01

Full Text Available Many researchers have proposed special treatments for outlet boundary conditions owing to lack of information at the outlet. Among them, the simplest method requires a large enough computational domain to prevent or reduce numerical errors at the boundaries. However, an efficient method generally requires special treatment to overcome the problems raised by the outlet boundary condition used. For example, mass flux is not conserved and the fluid field is not divergence-free at the outlet boundary. Overcoming these problems requires additional computational cost. In this paper, we present a simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations, aiming to reduce the computational domain for simulating flow inside a long channel in the streamwise direction. The proposed outflow boundary condition is based on the transparent equation, where a weak formulation is used. The pressure boundary condition is derived by using the Navier–Stokes equations and the outlet flow boundary condition. In the numerical algorithm, a staggered marker-and-cell grid is used and temporal discretization is based on a projection method. The intermediate velocity boundary condition is consistently adopted to handle the velocity–pressure coupling. Characteristic numerical experiments are presented to demonstrate the robustness and accuracy of the proposed numerical scheme. Furthermore, the agreement of computational results from small and large domains suggests that our proposed outflow boundary condition can significantly reduce computational domain sizes.

The role of nuclear power generation in aspects of the foreign currency outflow

International Nuclear Information System (INIS)

Kim, Seung Su; Lee, Man Ki

2005-01-01

Korea has little domestic energy resources and so imported almost all of the primary energy consumed from the foreign countries, with the foreign energy dependency being about more than 97% in recent years. In the meantime, the import amount of energy together with the rapid economic growth has increased continuously during the past 30 years to be 49.6 billion dollar in 2004 while the Current Account Balance was 27.6 billion dollar in the same year. Especially, the growth rate of electric consumption greatly surpassed ones in GDP and primary energy over the past 20 years. Nuclear power generation has played an important role in Korean society by supporting the industrial development as well as stabilizing downward the electricity price. The steady progress in the localization of nuclear construction has decreased the amount of foreign currency outflow by the nuclear power plant construction. In addition, nuclear fuel cost is the most competitive among those of the other fossil fuel power sources, so that this situation resulted in the large decrease of foreign currency outflow in power sector. In this thesis, we focused on the savings effect in foreign currency outflow by nuclear power generation using the scenario method. We tried to evaluate what amount of foreign currency has been saved by the introduction of nuclear power plant instead of the other fossil fuel power plants

ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

Energy Technology Data Exchange (ETDEWEB)

McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Lockman, F. J. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Dickey, J. M. [School of Physics and Mathematics, University of Tasmania, TAS 7001 (Australia); Gaensler, B. M.; Green, A. J., E-mail: naomi.mcclure-griffiths@csiro.au [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

2013-06-10

We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

International Nuclear Information System (INIS)

McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S.; Lockman, F. J.; Dickey, J. M.; Gaensler, B. M.; Green, A. J.

2013-01-01

We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of ∼14 km s –1 , and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at ∼200 km s –1 in a Galactic wind.

Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart.

Science.gov (United States)

Poelmann, Robert E; Gittenberger-de Groot, Adriana C; Biermans, Marcel W M; Dolfing, Anne I; Jagessar, Armand; van Hattum, Sam; Hoogenboom, Amanda; Wisse, Lambertus J; Vicente-Steijn, Rebecca; de Bakker, Merijn A G; Vonk, Freek J; Hirasawa, Tatsuya; Kuratani, Shigeru; Richardson, Michael K

2017-01-01

Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. We studied embryonic stages of reptile hearts (lizard, turtle and crocodile) and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population) forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard) or it is vestigial (turtle). Crocodiles are unique in bearing a central shunt, the

Multiband Negative Permittivity Metamaterials and Absorbers

Directory of Open Access Journals (Sweden)

Yiran Tian

2013-01-01

Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

Liquid Acquisition Device Hydrogen Outflow Testing on the Cryogenic Propellant Storage and Transfer Engineering Design Unit

Science.gov (United States)

Zimmerli, Greg; Statham, Geoff; Garces, Rachel; Cartagena, Will

2015-01-01

As part of the NASA Cryogenic Propellant Storage and Transfer (CPST) Engineering Design Unit (EDU) testing with liquid hydrogen, screen-channel liquid acquisition devices (LADs) were tested during liquid hydrogen outflow from the EDU tank. A stainless steel screen mesh (325x2300 Dutch T will weave) was welded to a rectangular cross-section channel to form the basic LAD channel. Three LAD channels were tested, each having unique variations in the basic design. The LADs fed a common outflow sump at the aft end of the 151 cu. ft. volume aluminum tank, and included a curved section along the aft end and a straight section along the barrel section of the tank. Wet-dry sensors were mounted inside the LAD channels to detect when vapor was ingested into the LADs during outflow. The use of warm helium pressurant during liquid hydrogen outflow, supplied through a diffuser at the top of the tank, always led to early breakdown of the liquid column. When the tank was pressurized through an aft diffuser, resulting in cold helium in the ullage, LAD column hold-times as long as 60 minutes were achieved, which was the longest duration tested. The highest liquid column height at breakdown was 58 cm, which is 23 less than the isothermal bubble-point model value of 75 cm. This paper discusses details of the design, construction, operation and analysis of LAD test data from the CPST EDU liquid hydrogen test.

Absorber materials in CANDU PHWR's

International Nuclear Information System (INIS)

Price, E.G.; Boss, C.R.; Novak, W.Z.; Fong, R.W.L.

1995-03-01

In a CANDU reactor the fuel channels are arranged on a square lattice in a calandria filled with heavy water moderator. This arrangement allows five types of tubular neutron absorber devices to be located in a relatively benign environment of low pressure, low temperature heavy water between neighbouring rows of columns of fuel channels. This paper will describe the roles of the devices and outline the design requirements of the absorber component from a reactor physics viewpoint. Nuclear heating and activation problems associated with the different absorbers will be briefly discussed. The design and manufacture of the devices will be also discussed. The control rod absorbers and shut off materials are cadmium and stainless steel. In the tubular arrangement, the cadmium is sandwiched between stainless steel tubes. This type of device has functioned well, but there is now concern over the availability and expense of cadmium which is used in two types of CANDU control devices. There are also concerns about the toxicity of cadmium during the fabrication of the absorbers. These concerns are prompting AECL to study alternatives. To minimize design changes, pure boron-10 alloyed in stainless steel is a favoured option. Work is underway to confirm the suitability of the boron-loaded steel and identify other encapsulated absorber materials for practical application. Because the reactivity devices or their guide tubes span the calandria vessel, the long slender components must be sufficiently rigid to resist operational vibration and also be seismically stable. Some of these components are made of Zircaloy to minimize neutron absorption. Slow irradiation growth and creep can reduce the spring tension, and periodic adjustments to the springs are required. Experience with the control absorber devices has generally been good. In one instance liquid zone controllers had a problem of vibration induced fretting but a designed back-fit resolved the problem. (author). 3 refs., 1

TPX/TFTR Neutral Beam energy absorbers

International Nuclear Information System (INIS)

Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

1993-01-01

The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET

Two-dimensional QR-coded metamaterial absorber

Science.gov (United States)

Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Zhang, Jieqiu; Qu, Shaobo

2016-01-01

In this paper, the design of metamaterial absorbers is proposed based on QR coding and topology optimization. Such absorbers look like QR codes and can be recognized by decoding softwares as well as mobile phones. To verify the design, two lightweight wideband absorbers are designed, which can achieve wideband absorption above 90 % in 6.68-19.30 and 7.00-19.70 GHz, respectively. More importantly, polarization-independent absorption over 90 % can be maintained under incident angle within 55°. The QR code absorber not only can achieve wideband absorption, but also can carry information such as texts and Web sites. They are of important values in applications such identification and electromagnetic protection.

The structure of high altitude O+ energization and outflow: a case study

Directory of Open Access Journals (Sweden)

H. Nilsson

2004-07-01

Full Text Available Multi-spacecraft observations from the CIS ion spectrometers on board the Cluster spacecraft have been used to study the structure of high-altitude oxygen ion energization and outflow. A case study taken from 12 April 2004 is discussed in more detail. In this case the spacecraft crossed the polar cap, mantle and high-altitude cusp region at altitudes between 4RE and 8RE and 2 of the spacecraft provided data. The oxygen ions were seen as a beam with narrow energy distribution, and increasing field-aligned velocity and temperature at higher altitude further in the upstream flow direction. The peak O+ energy was typically just above the highest energy of observed protons. The observed energies reached the upper limit of the CIS ion spectrometer, i.e. 38keV. Moment data from the spacecraft have been cross-correlated to determine cross-correlation coefficients, as well as the phase delay between the spacecraft. Structures in ion density, temperature and field-aligned flow appear to drift with the observed field-perpendicular drift. This, together with a velocity dispersion analysis, indicates that much of the structure can be explained by transverse heating well below the spacecraft. However, temperature isotropy and the particle flux as a function of field-aligned velocity are inconsistent with a single altitude Maxwellian source. Heating over extended altitude intervals, possibly all the way up to the observation point, seem consistent with the observations.

Forecasting Inflow and Outflow of Money Currency in East Java Using a Hybrid Exponential Smoothing and Calendar Variation Model

Science.gov (United States)

Susanti, Ana; Suhartono; Jati Setyadi, Hario; Taruk, Medi; Haviluddin; Pamilih Widagdo, Putut

2018-03-01

Money currency availability in Bank Indonesia can be examined by inflow and outflow of money currency. The objective of this research is to forecast the inflow and outflow of money currency in each Representative Office (RO) of BI in East Java by using a hybrid exponential smoothing based on state space approach and calendar variation model. Hybrid model is expected to generate more accurate forecast. There are two studies that will be discussed in this research. The first studies about hybrid model using simulation data that contain pattern of trends, seasonal and calendar variation. The second studies about the application of a hybrid model for forecasting the inflow and outflow of money currency in each RO of BI in East Java. The first of results indicate that exponential smoothing model can not capture the pattern calendar variation. It results RMSE values 10 times standard deviation of error. The second of results indicate that hybrid model can capture the pattern of trends, seasonal and calendar variation. It results RMSE values approaching the standard deviation of error. In the applied study, the hybrid model give more accurate forecast for five variables : the inflow of money currency in Surabaya, Malang, Jember and outflow of money currency in Surabaya and Kediri. Otherwise, the time series regression model yields better for three variables : outflow of money currency in Malang, Jember and inflow of money currency in Kediri.

SUZAKU MONITORING OF THE SEYFERT 1 GALAXY NGC 5548: WARM ABSORBER LOCATION AND ITS IMPLICATION FOR COSMIC FEEDBACK

International Nuclear Information System (INIS)

Krongold, Y.; Andrade-Velazquez, M.; Binette, L.; Jimenez-Bailon, E.; Elvis, M.; Nicastro, F.; Brickhouse, N. S.; Liu, Y.; Wilkes, B.; Mathur, S.; Reeves, J. N.; Grupe, D.; McHardy, I. M.; Minezaki, T.; Yoshii, Y.

2010-01-01

We present a 2 month Suzaku X-ray monitoring of the Seyfert 1 galaxy NGC 5548. The campaign consists of seven observations (with exposure time of ∼30 ks each), separated by ∼1 week. This paper focus on the X-ray Imaging Spectrometer data of NGC 5548. We analyze the response in the opacity of the gas that forms the well-known ionized absorber in this source for ionizing flux variations. Despite variations by a factor of ∼4 in the impinging continuum, the soft X-ray spectra of the source show little spectral variations, suggesting no response from the ionized absorber. A detailed time modeling of the spectra confirms the lack of opacity variations for an absorbing component with high ionization (U X ∼ -0.85), and high outflow velocity (v out ∼ 1040 km s -1 ), as the ionization parameter was found to be consistent with a constant value during the whole campaign. Instead, the models suggest that the ionization parameter of a low ionization (U X ∼ -2.8), low velocity (v out ∼ 590 km s -1 ) absorbing component might be changing linearly with the ionizing flux, as expected for gas in photoionization equilibrium. However, given the lack of spectral variations among observations, we consider the variations in this component as tentative. Using the lack of variations, we set an upper limit of n e 7 cm -3 for the electron density of the gas forming the high ionization, high velocity component. This implies a large distance from the continuum source (R>0.033 pc; R>5000R S ). If the variations in the low ionization, low velocity component are real, they imply n e >9.8 x 10 4 cm -3 and R 1.2 x 10 56 erg) can be enough to disrupt the interstellar medium, possibly quenching or regulating large-scale star formation. However, the total mass and energy ejected by the wind may still be lower than the one required for cosmic feedback, even when extrapolated to quasar luminosities. Such feedback would require that we are observing the wind before it is fully accelerated.

Estimation of Absorbed Dose in Occlusal Radiography

International Nuclear Information System (INIS)

Yoo, Young Ah; Choi, Karp Shick; Lee, Sang Han

1990-01-01

The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone ) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

Double-peaked Emission Lines Due to a Radio Outflow in KISSR 1219

Energy Technology Data Exchange (ETDEWEB)

Kharb, P.; Vaddi, S. [National Centre for Radio Astrophysics—Tata Institute of Fundamental Research, Postbag 3, Ganeshkhind, Pune 411007 (India); Subramanian, S. [Kavli Institute for Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871 (China); Das, M. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Paragi, Z., E-mail: kharb@ncra.tifr.res.in [Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo (Netherlands)

2017-09-01

We present the results from 1.5 and 5 GHz phase-referenced VLBA and 1.5 GHz Karl G. Jansky Very Large Array (VLA) observations of the Seyfert 2 galaxy KISSR 1219, which exhibits double-peaked emission lines in its optical spectrum. The VLA and VLBA data reveal a one-sided core-jet structure at roughly the same position angles, providing evidence of an active galactic nucleus outflow. The absence of dual parsec-scale radio cores puts the binary black-hole picture in doubt for the case of KISSR 1219. The high brightness temperatures of the parsec-scale core and jet components (>10{sup 6} K) are consistent with this interpretation. Doppler boosting with jet speeds of ≳0.55 c to ≳0.25 c , going from parsec to kiloparsec scales, at a jet inclination ≳50° can explain the jet one-sidedness in this Seyfert 2 galaxy. A blueshifted broad emission line component in [O iii] is also indicative of an outflow in the emission line gas at a velocity of ∼350 km s{sup −1}, while the [O i] doublet lines suggest the presence of shock-heated gas. A detailed line ratio study using the MAPPINGS III code further suggests that a shock+precursor model can explain the line ionization data well. Overall, our data suggest that the radio outflow in KISSR 1219 is pushing the emission line clouds, both ahead of the jet and in a lateral direction, giving rise to the double peak emission line spectra.

Rayleigh Scattering Density Measurements, Cluster Theory, and Nucleation Calculations at Mach 10

Science.gov (United States)

Balla, R. Jeffrey; Everhart, Joel L.

2012-01-01

In an exploratory investigation, quantitative unclustered laser Rayleigh scattering measurements of density were performed in the air in the NASA Langley Research Center's 31 in. Mach 10 wind tunnel. A review of 20 previous years of data in supersonic and Mach 6 hypersonic flows is presented where clustered signals typically overwhelmed molecular signals. A review of nucleation theory and accompanying nucleation calculations are also provided to interpret the current observed lack of clustering. Data were acquired at a fixed stagnation temperature near 990Kat five stagnation pressures spanning 2.41 to 10.0 MPa (350 to 1454 psi) using a pulsed argon fluoride excimer laser and double-intensified charge-coupled device camera. Data averaged over 371 images and 210 pixels along a 36.7mmline measured freestream densities that agree with computed isentropic-expansion densities to less than 2% and less than 6% at the highest and lowest densities, respectively. Cluster-free Mach 10 results are compared with previous clustered Mach 6 and condensation-free Mach 14 results. Evidence is presented indicating vibrationally excited oxygen and nitrogen molecules are absorbed as the clusters form, release their excess energy, and inhibit or possibly reverse the clustering process. Implications for delaying clustering and condensation onset in hypersonic and hypervelocity facilities are discussed.

Photoelectron antibunching and absorber theory

International Nuclear Information System (INIS)

Pegg, D.T.

1980-01-01

The recently detected photoelectron antibunching effect is considered to be evidence for the quantised electromagnetic field, i.e. for the existence of photons. Direct-action quantum absorber theory, on the other hand, has been developed on the basis that the quantised field is illusory, with quantisation being required only for atoms. In this paper it is shown that photoelectron antibunching is readily explicable in terms of absorber theory and in fact is directly attributable to the quantum nature of the emitting and detecting atoms alone. The physical nature of the reduction of the wavepacket associated with the detection process is briefly discussed in terms of absorber theory. (author)

GALACTIC-SCALE ABSORPTION OUTFLOW IN THE LOW-LUMINOSITY QUASAR IRAS F04250-5718: HUBBLE SPACE TELESCOPE/COSMIC ORIGINS SPECTROGRAPH OBSERVATIONS

International Nuclear Information System (INIS)

Edmonds, Doug; Borguet, Benoit; Arav, Nahum; Dunn, Jay P.; Penton, Steve; Kriss, Gerard A.; Korista, Kirk; Bautista, Manuel; Costantini, Elisa; Kaastra, Jelle; Steenbrugge, Katrien; Ignacio Gonzalez-Serrano, J.; Benn, Chris; Aoki, Kentaro; Behar, Ehud; Micheal Crenshaw, D.; Everett, John; Gabel, Jack; Moe, Maxwell; Scott, Jennifer

2011-01-01

We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C IV, N V, and O VI) as well as low ionization ions (e.g., C II and Si III). We identify three kinematic components with central velocities ranging from ∼-50 to ∼-230 km s -1 . Velocity-dependent, non-black saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C II, we are able to determine that the electron number density in the main component of the outflow is ∼ -3 . Photoionization analysis yields an ionization parameter log U H ∼ -1.6 ± 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is ∼>3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.

An omnidirectional electromagnetic absorber made of metamaterials

International Nuclear Information System (INIS)

Cheng Qiang; Cui Tiejun; Jiang Weixiang; Cai Bengeng

2010-01-01

In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.

Additive manufacturing of RF absorbers

Science.gov (United States)

Mills, Matthew S.

The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

The launch region of the SVS 13 outflow and jet

Energy Technology Data Exchange (ETDEWEB)

Hodapp, Klaus W. [Institute for Astronomy, University of Hawaii, 640 North Aohoku Place, Hilo, HI 96720 (United States); Chini, Rolf, E-mail: hodapp@ifa.hawaii.edu, E-mail: rolf.chini@astro.ruhr-uni-bochum.de [Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, D-44801 Bochum (Germany)

2014-10-20

We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H{sub 2} 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

The Launch Region of the SVS 13 Outflow and Jet

Science.gov (United States)

Hodapp, Klaus W.; Chini, Rolf

2014-10-01

We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H2 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

The launch region of the SVS 13 outflow and jet

International Nuclear Information System (INIS)

Hodapp, Klaus W.; Chini, Rolf

2014-01-01

We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H 2 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

Three-dimensional Shock Structure of the Orion KL Outflow with IGRINS

Science.gov (United States)

Oh, Heeyoung; Pyo, Tae-Soo; Kaplan, Kyle; Yuk, In-Soo; Park, Byeong-Gon; Mace, Gregory; Park, Chan; Chun, Moo-Young; Pak, Soojong; Kim, Kang-Min; Sok Oh, Jae; Jeong, Ueejeong; Yu, Young Sam; Lee, Jae-Joon; Kim, Hwihyun; Hwang, Narae; Lee, Hye-In; Nguyen Le, Huynh Anh; Lee, Sungho; Jaffe, Daniel T.

2016-12-01

We report a study of the three-dimensional (3D) outflow structure of a 15″ × 13″ area around the H2 peak 1 in Orion KL with slit-scan observations (13 slits) using the Immersion Grating Infrared Spectrograph. The datacubes have a high-velocity resolution (˜7.5 km s-1), provide high-contrast imaging within ultra-narrow bands, and enable the detection of the main stream of the previously reported H2 outflow fingers. We identified 31 distinct fingers in the H2 1-0 S(1) λ2.122 μm emission. The line profile at each finger shows multiple-velocity peaks with a strong low-velocity component around the systemic velocity at {V}{LSR} = +8 km s-1 and high-velocity emission (| {V}{LSR}| = 45-135 km s-1), indicating a typical bow-shock. The observed radial velocity gradients of ˜4 km s-1 arcsec-1 agree well with the velocities inferred from large-scale proper motions, where the projected motion is proportional to the distance from a common origin. We construct a conceptual 3D map of the fingers with estimated inclination angles of 57°-74°. The extinction difference (ΔA v > 10 mag) between blueshifted and redshifted fingers indicates high internal extinction. The extinction, the overall angular spread, and the scale of the flow argue for an ambient medium with a very high density (105-106 cm-3), consistent with molecular line observations of the Orion Molecular Cloud core. The radial velocity gradients and the 3D distributions of the fingers together support the hypothesis of a simultaneous radial explosion of the Orion KL outflow. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

Energy Technology Data Exchange (ETDEWEB)

Andrews, Brett H. [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Weinberg, David H.; Schönrich, Ralph; Johnson, Jennifer A., E-mail: andrewsb@pitt.edu [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2017-02-01

Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]–[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracks in [O/Fe]–[Fe/H] unlike the observed bimodality (separate high- α and low- α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]–[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α -elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.

Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

International Nuclear Information System (INIS)

Andrews, Brett H.; Weinberg, David H.; Schönrich, Ralph; Johnson, Jennifer A.

2017-01-01

Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]–[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracks in [O/Fe]–[Fe/H] unlike the observed bimodality (separate high- α and low- α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]–[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α -elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.

Preparation of super absorbent by irradiation polymerization

International Nuclear Information System (INIS)

Hua Fengjun; Tan Chunhong; Qian Mengping

1995-01-01

A kind of absorbent is prepared by gamma-rays irradiated by reversed-phase suspension polymerization. Drying particles have 1400 (g/g) absorbency in de-ionic water. Effects of reactive conditions, e.g.: dose-rate, dose, monomer concentration, degree of monomer neutralization and crosslinking agents on absorbency in de-ionic water are discussed. The cause of absorbing de-ionic water by polymer is related to its network structure and ionic equilibrium in particle. Accordingly, a suit reactive condition is chosen for preparation of hydro gel spheres

Frequency Tuning of Vibration Absorber Using Topology Optimization

Science.gov (United States)

Harel, Swapnil Subhash

A tuned mass absorber is a system for reducing the amplitude in one oscillator by coupling it to a second oscillator. If tuned correctly, the maximum amplitude of the first oscillator in response to a periodic driver will be lowered, and much of the vibration will be 'transferred' to the second oscillator. The tuned vibration absorber (TVA) has been utilized for vibration control purposes in many sectors of Civil/Automotive/Aerospace Engineering for many decades since its inception. Time and again we come across a situation in which a vibratory system is required to run near resonance. In the past, approaches have been made to design such auxiliary spring mass tuned absorbers for the safety of the structures. This research focuses on the development and optimization of continuously tuned mass absorbers as a substitute to the discretely tuned mass absorbers (spring- mass system). After conducting the study of structural behavior, the boundary condition and frequency to which the absorber is to be tuned are determined. The Modal analysis approach is used to determine mode shapes and frequencies. The absorber is designed and optimized using the topology optimization tool, which simultaneously designs, optimizes and tunes the absorber to the desired frequency. The tuned, optimized absorber, after post processing, is attached to the target structure. The number of the absorbers are increased to amplify bandwidth and thereby upgrade the safety of structure for a wide range of frequency. The frequency response analysis is carried out using various combinations of structure and number of absorber cell.

COMPARISON OF ABSORBABLE EXTRA LONG TERM POLY HYDROXY BUTYRATE SUTURE VS NON ABSORBABLE (POLYPROPYLENE SUTURE FOR ABDOMINAL WALL CLOSURE

Directory of Open Access Journals (Sweden)

Mallikarjun

2015-07-01

Full Text Available PURPOSE: The aim of study is to compare Continuous technique with non - absorbable sutures, Interrupted technique with non - absorbable sutures and Continuous technique with slowly absorbable sutures Focusing mainly on incidence of incisional hernias, burst abdomen, wound infections, chronic wound pain, suture sinus, stitch granuloma, time for rectus closure. METHODOLOGY : Study was conducted for a period of one year on 271 randomized patients with primary elective midline laparotomy in our hospital . patients are divided into group I includes 102 patients with continuous technique using non absorbable polypropylene, group II includes 91 patients with interrupted technique using non absorbable polypropylene and group III includes 78 patients with continuous slowly absorbable polyhydroxybutyrate. RESULTS: No significant difference observed in incidence of wound infections and burst abdomen in all the 3 groups but relatively higher incidence of wound infections in noted our hospital. Incidence of stich granuloma suture sinus and chronic wound pain is more with interrupted technique than continuous technique and are more with non - absor bable suture material. CONCLUSION: Incidence of incisional hernias, suture complications like suture sinus, stitch granuloma can be more effectively reduced with slowly absorbable continuous sutures.

Shock absorber

International Nuclear Information System (INIS)

Nemeth, J.D.

1981-01-01

A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

21 CFR 880.5300 - Medical absorbent fiber.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device...

Temporal features of the outflow of heavy ionospheric ions in response to a high altitude plasma cavity

International Nuclear Information System (INIS)

Singh, Nagendra; Hwang, K.S.; Torr, D.G.; Richards, P.

1989-01-01

Using a hydrodynamic model for the plasma, it is demonstrated that the auroral plasma cavity is capable of drawing an appreciably large flux of oxygen ions, which are normally gravitationally bound. This escape mechanism of O + does not involve any additional heating or acceleration of the plasma in the ionosphere. The temporal evolution of the outflow shows that it starts near the cavity and penetrates into the ionosphere with a flux front moving down with the ion-acoustic speed. A steady outflow is reached in a few hours for a cavity at a height of one R e if the cavity is maintained. This time reduces to + (Γ o + ) increases; for the lower edge of the cavity in the altitude range 3-10 x 10 3 km, the steady flux is found to be in the range 10 9 > Γ o + (cm -3 s -1 ) > 10 7 . An analysis for the steady state shows that outflow is controlled by the density scale height in the cavity

Cooking a `Sausage': the impact of merger shocks in cluster gas and galaxy evolution

Science.gov (United States)

Stroe, Andra; Sobral, David; Harwood, Jeremy; Van Weeren, Reinout J.; Rumsey, Clare; Intema, Huib; Röttgering, Huub; Brüggen, Marcus; Saunders, Richard; Hardcastle, Martin; Hoeft, Matthias

2015-01-01

Galaxy clusters mainly grow through mergers with other clusters and groups. Major mergers give rise to important astrophysical phenomena such as the segregation of dark and luminous matter and the formation of cluster-wide traveling shocks and also drive galaxy evolution. The observable effects of shock waves can be seen at radio wavelengths as relics: elongated, diffuse synchrotron emitting areas located at the periphery of merging clusters. Despite the great interest in relics, candidates with simple geometry, undisturbed morphology and high surface brightness are scarce. The `Sausage' cluster hosts an extraordinary Mpc-wide relic, which enables us to study to study particle acceleration and the effects of shocks on cluster galaxies. We use a unique combination of facilities (INT, WHT, Keck, Subaru, CFHT, GMRT, WSRT, AMI) to obtain the first cluster-wide, multi-wavelength, multi-method analysis aimed at giving a complete picture of a merging cluster with relics. Using the radio data, we derive shock properties and the magnetic field structure for the relic. Using spectral modeling, we test acceleration and electron energy-loss mechanisms and resolve the discrepancy between the Mach number calculated from the radio and X-rays. Our results indicate that particles are shock-accelerated, but turbulent re-acceleration or unusually efficient transport of particles in the downstream area and line-of-sight mixing are important effects. We demonstrate the feasibility of high-frequency observations of radio relics, by presenting a 16 GHz detection of the `Sausage' relic. The radio analysis is complemented by Hα mapping of the cluster volume, aimed at providing the first direct test as to whether the shock drives or prohibits star formation. We find numerous Hα emitting galaxies in close proximity to the radio relic which are extremely massive, metal-rich, mostly star-forming with evidence for gas mass loss though outflows. We speculate that the complex interaction

Inactivation of Bmp4 from the Tbx1 Expression Domain Causes Abnormal Pharyngeal Arch Artery and Cardiac Outflow Tract Remodeling

Science.gov (United States)

Nie, Xuguang; Brown, Christopher B.; Wang, Qin; Jiao, Kai

2011-01-01

Maldevelopment of outflow tract and aortic arch arteries is among the most common forms of human congenital heart diseases. Both Bmp4 and Tbx1 are known to play critical roles during cardiovascular development. Expression of these two genes partially overlaps in pharyngeal arch areas in mouse embryos. In this study, we applied a conditional gene inactivation approach to test the hypothesis that Bmp4 expressed from the Tbx1 expression domain plays a critical role for normal development of outflow tract and pharyngeal arch arteries. We showed that inactivation of Bmp4 from Tbx1-expressing cells leads to the spectrum of deformities resembling the cardiovascular defects observed in human DiGeorge syndrome patients. Inactivation of Bmp4 from the Tbx1 expression domain did not cause patterning defects, but affected remodeling of outflow tract and pharyngeal arch arteries. Our further examination revealed that Bmp4 is required for normal recruitment/differentiation of smooth muscle cells surrounding the PAA4 and survival of outflow tract cushion mesenchymal cells. PMID:21123999

The right ventricular outflow tract in tetralogy of Fallot by preoperative cardiac angiography

Energy Technology Data Exchange (ETDEWEB)

Lee, Yong Chul; Lee, Jung Sook; Yoo, Soo Woong; Yu, Hoe Sung; Kim, Han Suk [National Medical Center, Seoul (Korea, Republic of)

1979-06-15

The underdevelopment of the right ventricular outflow tract is the essence among the main components of the tetralogy of Fallot. The detail and exact information about the states of the outflow tract in each patients with tetralogy of Fallot are very important to cardiac surgery. Fourteen patients of tetralogy of Fallet (12 undergone open heart surgery and 2, palliative) are available for their clinical chart and for cardiac angiography reviews. Analysis of them focusing the right ventricular outflow tract discloses the following results: 1. Average ratios of the systole to diastole of the pulmonary infundibulum are 0.63 {+-} 0.03 with the range of 0.44 to 1.0 cm P-A, and 0.64 {+-} 0.12 with the range of 0.5 to 0.83 on lateral projections. These results indicate relatively fixed infundibular stenosis of TOF. 2. Average infundibular systole to pulmonary bulb ratios are 0.24 {+-} 0.05 on P-A, and 0.36 {+-} 0.17 on lateral projections, which mean the underdeveloped and narrowed infundibulum more than the pulmonary truck in TOF. 3. Average pulmonary to aortic bulb ratios are 0.59 {+-} 0.01 on P-A, 0.54 {+-} 0.01 on lateral projections. These suggest hypoplasia of the pulmonary truck and anteriorly displaced conus septum and truncus septum from a developmental point of view. 4. The overriding degree of the aorta in our series are from 25% to 50% by Kjellberg et al classification.

The right ventricular outflow tract in tetralogy of Fallot by preoperative cardiac angiography

International Nuclear Information System (INIS)

Lee, Yong Chul; Lee, Jung Sook; Yoo, Soo Woong; Yu, Hoe Sung; Kim, Han Suk

1979-01-01

The underdevelopment of the right ventricular outflow tract is the essence among the main components of the tetralogy of Fallot. The detail and exact information about the states of the outflow tract in each patients with tetralogy of Fallot are very important to cardiac surgery. Fourteen patients of tetralogy of Fallet (12 undergone open heart surgery and 2, palliative) are available for their clinical chart and for cardiac angiography reviews. Analysis of them focusing the right ventricular outflow tract discloses the following results: 1. Average ratios of the systole to diastole of the pulmonary infundibulum are 0.63 ± 0.03 with the range of 0.44 to 1.0 cm P-A, and 0.64 ± 0.12 with the range of 0.5 to 0.83 on lateral projections. These results indicate relatively fixed infundibular stenosis of TOF. 2. Average infundibular systole to pulmonary bulb ratios are 0.24 ± 0.05 on P-A, and 0.36 ± 0.17 on lateral projections, which mean the underdeveloped and narrowed infundibulum more than the pulmonary truck in TOF. 3. Average pulmonary to aortic bulb ratios are 0.59 ± 0.01 on P-A, 0.54 ± 0.01 on lateral projections. These suggest hypoplasia of the pulmonary truck and anteriorly displaced conus septum and truncus septum from a developmental point of view. 4. The overriding degree of the aorta in our series are from 25% to 50% by Kjellberg et al classification.

Model for collimated outflows in molecular clouds and the case of HH 7-11

Energy Technology Data Exchange (ETDEWEB)

Silvestro, G; Ferrari, A; Rosner, R; Trussoni, E; Tsinganos, K

1987-01-15

Modelling is carried out for collimated outflows of high-velocity gas in molecular clouds, which is often observed to be associated with linear chains of optical emission knots. A wind-flow model is proposed to account for the phenomenon, based on the structural similarities between the outflows and jets from active galactic nuclei and quasars. The chain of Herbig-Haro objects HH7-11 is used to illustrate the proposal. The model is based on flows in a channel of variable cross-sectional area due to Kelvin-Helmholtz instabilities between the flow and the ambient medium. Solutions of the Mach number equation for such a channel are presented, which possess multiple critical points and shocks identified with observed optical knots. (U.K.).

An ultra-broadband multilayered graphene absorber

KAUST Repository

Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

2013-01-01

An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon

High-efficiency ventilated metamaterial absorber at low frequency

Science.gov (United States)

Wu, Xiaoxiao; Au-Yeung, Ka Yan; Li, Xin; Roberts, Robert Christopher; Tian, Jingxuan; Hu, Chuandeng; Huang, Yingzhou; Wang, Shuxia; Yang, Zhiyu; Wen, Weijia

2018-03-01

We demonstrate a ventilated metamaterial absorber operating at low frequency (90%) has been achieved in both simulations and experiments. This high-efficiency absorption under the ventilation condition originates from the weak coupling of two identical split tube resonators constituting the absorber, which leads to the hybridization of the degenerate eigenmodes and breaks the absorption upper limit of 50% for conventional transmissive symmetric acoustic absorbers. The absorber can also be extended to an array and work in free space. The absorber should have potential applications in acoustic engineering where both noise reduction and ventilation are required.

Thermal Shielding Effects of a Damaged Shock Absorber and an Intact Shock Absorber

Energy Technology Data Exchange (ETDEWEB)

Bang, K. S.; Lee, J. C.; Kim, K. Y.; Seo, C. S.; Seo, K. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

In order to safely transport the radioactive waste arising from the hot test of an ACP(Advanced Spent Fuel Conditioning Process) a shipping package is required. Therefore, KAERI is developing a shipping package to transport the radioactive waste arising from the ACPF during a hot test. The regulatory requirements for a Type B package are specified in the Korea Most Act 2009-37, IAEA Safety Standard Series No. TS-R-1, and US 10 CFR Part. These regulatory guidelines classify the hot cell cask as a Type B package, and state that the Type B package for transporting radioactive materials should be able to withstand a test sequence consisting of a 9 m drop onto an unyielding surface, a 1 m drop onto a puncture bar, and a 30 minute fully engulfing fire. Greiner et al. investigated the thermal protection provided by shock absorbers by using the CAFE computer code. To evaluate the thermal shielding effect of the shock absorber, the thermal test was performed by using a 1/2 scale model with a shock absorber which was damaged by both a 9 m drop test and a 1 m puncture test. For the purpose of comparison, the thermal test was also carried out by using a 1/2 scale model with the intact shock absorber

On (m, n)-absorbing ideals of commutative rings

Indian Academy of Sciences (India)

with respect to various ring theoretic constructions and study (m, n)-absorbing ideals in several commutative rings. For example, in a Bézout ring or a Boolean ring, an ideal is an (m, n)-absorbing ideal if and only if it is an n-absorbing ideal, and in an almost. Dedekind domain every (m, n)-absorbing ideal is a product of at ...

Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart

Directory of Open Access Journals (Sweden)

Robert E. Poelmann

2017-05-01

Full Text Available Abstract Background Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. Results We studied embryonic stages of reptile hearts (lizard, turtle and crocodile and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard or it is vestigial (turtle. Crocodiles

Design of a nonlinear torsional vibration absorber

Science.gov (United States)

Tahir, Ammaar Bin

Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

Human cerebral venous outflow pathway depends on posture and central venous pressure

Science.gov (United States)

Gisolf, J; van Lieshout, J J; van Heusden, K; Pott, F; Stok, W J; Karemaker, J M

2004-01-01

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R2 = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins. PMID:15284348

Performance evaluation of CFRP-rubber shock absorbers

Science.gov (United States)

Lamanna, Giuseppe; Sepe, Raffaele

2014-05-01

In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers' safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

Performance evaluation of CFRP-rubber shock absorbers

Energy Technology Data Exchange (ETDEWEB)

Lamanna, Giuseppe, E-mail: giuseppe.lamanna@unina2.it; Sepe, Raffaele, E-mail: giuseppe.lamanna@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, via Roma, 29 - 81031 Aversa (Italy)

2014-05-15

In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

A PROPER MOTION STUDY OF THE HARO 6-10 OUTFLOW: EVIDENCE FOR A SUBARCSECOND BINARY

International Nuclear Information System (INIS)

Wilking, Bruce A.; Gerling, Bradley M.; Gibb, Erika; Marvel, Kevin B.; Claussen, Mark J.; Wootten, Alwyn

2012-01-01

We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.''3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of ∼45°. They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions (∼220°) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH 410, HH 411, HH 412, and HH 184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of ∼190°) must also originate in the vicinity of Haro 6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro 6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H 2 emission in the spectrum of the northern component of the binary, Haro 6-10N, none of outflows/jets can be tied directly to this young stellar object.

A PROPER MOTION STUDY OF THE HARO 6-10 OUTFLOW: EVIDENCE FOR A SUBARCSECOND BINARY

Energy Technology Data Exchange (ETDEWEB)

Wilking, Bruce A.; Gerling, Bradley M.; Gibb, Erika [Department of Physics and Astronomy, University of Missouri-St. Louis, 1 University Boulevard, St. Louis, MO 63121 (United States); Marvel, Kevin B. [American Astronomical Society, 2000 Florida Avenue, NW, Suite 400, Washington, DC 20009 (United States); Claussen, Mark J. [National Radio Astronomy Observatory (NRAO), Array Operations Center, P.O. Box 0, 1003 Lopezville Road, Socorro, NM 87801 (United States); Wootten, Alwyn, E-mail: bwilking@umsl.edu, E-mail: bmg5333@truman.edu, E-mail: gibbe@umsl.edu, E-mail: marvel@aas.org, E-mail: mclausse@nrao.edu, E-mail: awootten@nrao.edu [NRAO, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)

2012-07-10

We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.''3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of {approx}45 Degree-Sign . They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions ({approx}220 Degree-Sign ) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH 410, HH 411, HH 412, and HH 184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of {approx}190 Degree-Sign ) must also originate in the vicinity of Haro 6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro 6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H{sub 2} emission in the spectrum of the northern component of the binary, Haro 6-10N, none of outflows/jets can be tied directly to this young stellar object.

Burnable absorber coated nuclear fuel

International Nuclear Information System (INIS)

Chubb, W.; Radford, K.C.; Parks, B.H.

1984-01-01

A nuclear fuel body which is at least partially covered by a burnable neutron absorber layer is provided with a hydrophobic overcoat generally covering the burnable absorber layer and bonded directly to it. In a method for providing a UO 2 fuel pellet with a zirconium diboride burnable poison layer, the fuel body is provided with an intermediate niobium layer. (author)

Precision test method by x-ray absorbent clay

International Nuclear Information System (INIS)

Nakadai, Toru; Matsukawa, Hideyuki; Sekita, Jun-ichiro; Murakoshi, Atsushi.

1982-01-01

In X-ray penetration photography of such as welds with reinforcing metal and castings of complex shape, the X-ray absorbent clay developed to eliminate various disadvantages of the conventional absorbents was further studied for better application. The results of the usage are as follows. Because the X-ray absorbent is clay, it is flexible in form, and gives good adhesion to test objects. In the welds and castings mentioned, it is effective for reducing the scattered ray, accordingly, it results in superior images. The following matters are described: contrast in radiographs, the required conditions for X-ray absorbents in general, the properties of the absorbent (absorption coefficient, consistency, density), improvement in radiographs by means of the X-ray absorbent clay (wall thickness compensation, masking, the application together with narrow-field irradiation photography). (Mori, K.)

An ultra-broadband multilayered graphene absorber

KAUST Repository

Amin, Muhammad

2013-01-01

An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

Energy Absorbing Effectiveness – Different Approaches

Directory of Open Access Journals (Sweden)

Kotełko Maria

2018-03-01

Full Text Available In the paper the study of different crashworthiness indicators used to evaluate energy absorbing effectiveness of thin-walled energy absorbers is presented. Several different indicators are used to assess an effectiveness of two types of absorbing structures, namely thin-walled prismatic column with flaws and thin-walled prismatic frustum (hollow or foam filled in both cases subjected to axial compressive impact load. The indicators are calculated for different materials and different geometrical parameters. The problem of selection of the most appropriate and general indicators is discussed.

Microwave absorbing property of a hybrid absorbent with carbonyl irons coating on the graphite

Energy Technology Data Exchange (ETDEWEB)

Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yan, Zhenqiang; Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

2015-11-30

Graphical abstract: The absorbing property could be enhanced as the CIPs coated on the graphite. - Highlights: • Absorbers filled with CIPs coating on the graphite was fabricated. • The permittivity and permeability increased as CIPs coated. • The CIP materials enhanced the electromagnetic property. • The graphite coated CIPs were effective in 2–18 GHz. - Abstract: The hybrid absorbent filled with carbonyl iron particles (CIPs) coating on the graphite was prepared using a chemical vapor decomposition (CVD) process. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. The results showed that α-Fe appeared in the super-lattice diffraction peaks in XRD graph. The composites added CIPs coating on the graphite had a higher permittivity and imaginary permeability due to the superior microwave dielectric loss and magnetic loss of the CIPs. The reflection loss (RL) result showed that composites filled with 5 vol% Fe-graphite had an excellent absorbing property in the 2–18 GHz, the minimum RL was −25.14 dB at 6 mm and −26.52 dB at 8 mm, respectively.

Adjustable Shock Absorbers

OpenAIRE

Adamiec, Radek

2012-01-01

Bakalářská práce obsahuje přehled používaných tlumičů osobních automobilů, závodních automobilů a motocyklů. Jsou zde popsány systémy t lumením, konstrukce tlumičů a vidlic používaných u motocyklů. Dále je zde přehled prvků používaných u podvozků automobilů. This bachelor´s thesis contains the survey of the shock absorbers of passenger cars, racing cars and motorcycles. Are described damping systems, the design used shock absorbers and forks for motorcycles. Then there is the list of the e...

Slow and Fast Light in an Electro-Absorber

DEFF Research Database (Denmark)

Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador

2006-01-01

We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated.......We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

Percutaneous Creation of Bare Intervascular Tunnels for Salvage of Thrombosed Hemodialysis Fistulas Without Recanalizable Outflow

International Nuclear Information System (INIS)

Chen, Matt Chiung-Yu; Wang, Yen-Chi; Weng, Mei-Jui

2015-01-01

PurposeThis study aimed to retrospectively assess the efficacy of a bare intervascular tunnel for salvage of a thrombosed hemodialysis fistula. We examined the clinical outcomes and provided follow-up images of the bare intervascular tunnel.Materials and MethodsEight thrombosed fistulas lacked available recanalizable outflow veins were included in this study. These fistulas were salvaged by re-directing access site flow to a new outflow vein through a percutaneously created intervascular tunnel without stent graft placement. The post-intervention primary and secondary access patency rates were calculated using the Kaplan–Meier method.ResultsThe procedural and clinical success rates were 100 %. Post-intervention primary and secondary access patency at 300 days were 18.7 ± 15.8 and 87.5 ± 11.7 %, respectively. The mean follow-up period was 218.7 days (range 10–368 days). One patient died of acute myocardial infarction 10 days after the procedure. No other major complications were observed. Minor complications, such as swelling, ecchymosis, and pain around the tunnel, occurred in all of the patients.ConclusionsPercutaneous creation of a bare intervascular tunnel is a treatment option for thrombosed hemodialysis fistulas without recanalizable outflow in selected patients

Performance of an absorbing concentrating solar collectors

International Nuclear Information System (INIS)

Imadojemu, H.

1990-01-01

This paper reports on a comparison of the efficiency of an absorbing fluid parabolic trough concentrating solar collector and a traditional concentrating collector that was made. In the absorbing fluid collector, black liquid flows through a glass tube absorber while the same black liquid flows through a selective black coated copper tube absorber while the same black fluid flows through a selective black coated copper tube absorber in the traditional collector. After a careful study of the properties of available black liquids, a mixture of water and black ink was chosen as the black absorbing medium or transfer fluid. In the black liquid glass collector there is a slightly improved efficiency based on beam radiation as a result of the direct absorption process and an increase in the effective transmittance absorptance. At worst the efficiency of this collector equals that of the traditional concentrating collector when the efficiency is based on total radiation. The collector's reflecting surfaces were made of aluminum sheet, parabolic line focus and with cylindrical receivers. The ease of manufacture and reduced cost per unit energy collected, in addition to the clean and pollution free mode of energy conversion, makes it very attractive