K- and M-type dwarf stars within 25 parsecs of the sun. I. The age-chromospheric activity relations from H-alpha equivalent widths

Energy Technology Data Exchange (ETDEWEB)

Eggen, O.J. (Observatorio Interamericano de Cerro Totolo, La Serena (Chile))

1990-02-01

The available equivalent-width measurements of H-alpha in dwarf K and M stars within 25 pc of the sun indicate that, as a chromospheric diagnostic, the H-alpha decay rate is about t exp 0.5. The decay rate of line emission in Mg II h and k (Ca II H and K) is about t exp 0.3. The decay rates are derived from observations of members of a few stellar superclusters and groups, for which the consistency of results argues strongly for the importance of more data. The only major inconsistency encountered is for the unique HR 1614 group which, in the age/chromospheric-activity progression, gives different results from Mg II h and k and from WH-alpha. 63 refs.

Dust Attenuation and H(alpha) Star Formation Rates of Z Approx. 0.5 Galaxies

Science.gov (United States)

Ly, Chun; Malkan, Matthew A.; Kashikawa, Nobunari; Ota, Kazuaki; Shimasaku, Kazuhiro; Iye, Masanori; Currie, Thayne

2012-01-01

Using deep narrow-band and broad-band imaging, we identify 401 z approximately 0.40 and 249 z approximately 0.49 H-alpha line-emitting galaxies in the Subaru Deep Field. Compared to other H-alpha surveys at similar redshifts, our samples are unique since they probe lower H-alpha luminosities, are augmented with multi-wavelength (rest-frame 1000AA--1.5 microns) coverage, and a large fraction (20%) of our samples has already been spectroscopically confirmed. Our spectra allow us to measure the Balmer decrement for nearly 60 galaxies with H-beta detected above 5-sigma. The Balmer decrements indicate an average extinction of A(H-alpha)=0.7(uparrow){+1.4}_{-0.7} mag. We find that the Balmer decrement systematically increases with higher H-alpha luminosities and with larger stellar masses, in agreement with previous studies with sparser samples. We find that the SFRs estimated from modeling the spectral energy distribution (SED) is reliable---we derived an "intrinsic" H-alpha luminosity which is then reddened assuming the color excess from SED modeling. The SED-predicted H-alpha luminosity agrees with H-alpha narrow-band measurements over 3 dex (rms of 0.25 dex). We then use the SED SFRs to test different statistically-based dust corrections for H-alpha and find that adopting one magnitude of extinction is inappropriate: galaxies with lower luminosities are less reddened. We find that the luminosity-dependent dust correction of Hopkins et al. yields consistent results over 3 dex (rms of 0.3 dex). Our comparisons are only possible by assuming that stellar reddening is roughly half of nebular reddening. The strong correspondence argue that with SED modeling, we can derive reliable intrinsic SFRs even in the absence of H-alpha measurements at z approximately 0.5.

COMPARING H{alpha} AND H I SURVEYS AS MEANS TO A COMPLETE LOCAL GALAXY CATALOG IN THE ADVANCED LIGO/VIRGO ERA

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Metzger, Brian D. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08542 (United States); Kaplan, David L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Berger, Edo, E-mail: bmetzger@astro.princeton.edu, E-mail: kaplan@uwm.edu, E-mail: eberger@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-02-20

Identifying the electromagnetic counterparts of gravitational wave (GW) sources detected by upcoming networks of advanced ground-based interferometers will be challenging, due in part to the large number of unrelated astrophysical transients within the {approx}10-100 deg{sup 2} sky localizations. A potential way to greatly reduce the number of such false positives is to limit detailed follow-up to only those candidates near galaxies within the GW sensitivity range of {approx}200 Mpc for binary neutron star mergers. Such a strategy is currently hindered by the fact that galaxy catalogs are grossly incomplete within this volume. Here, we compare two methods for completing the local galaxy catalog: (1) a narrowband H{alpha} imaging survey and (2) an H I emission line radio survey. Using H{alpha} fluxes, stellar masses (M {sub *}), and star formation rates (SFRs) from galaxies in the Sloan Digital Sky Survey (SDSS), combined with H I data from the GALEX Arecibo SDSS Survey and the Herschel Reference Survey, we estimate that an H{alpha} survey with a luminosity sensitivity of L {sub H{alpha}} = 10{sup 40} erg s{sup -1} at 200 Mpc could achieve a completeness of f {sup H{alpha}} {sub SFR} Almost-Equal-To 75% with respect to total SFR, but only f{sub M* Star-Operator }{sup H{alpha}} approx. 33% with respect to M {sub *} (due to lack of sensitivity to early-type galaxies). These numbers are significantly lower than those achieved by an idealized spectroscopic survey due to the loss of H{alpha} flux resulting from resolving out nearby galaxies and the inability to correct for the underlying stellar continuum. An H I survey with sensitivity similar to the proposed WALLABY survey on ASKAP could achieve f{sub SFR}{sup H{sub I}} Almost-Equal-To 80% and f{sub M Star-Operator }{sup H{sub I}} Almost-Equal-To 50%, somewhat higher than that of the H{alpha} survey. Finally, both H{alpha} and H I surveys should achieve {approx}> 50% completeness with respect to the host galaxies of

DISSECTION OF H{alpha} EMITTERS : LOW-z ANALOGS OF z > 4 STAR-FORMING GALAXIES

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Shim, Hyunjin [Department of Earth Science Education, Kyungpook National University (Korea, Republic of); Chary, Ranga-Ram, E-mail: hjshim@knu.ac.kr [U.S. Planck Data Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States)

2013-03-01

Strong H{alpha} emitters (HAEs) dominate the z {approx} 4 Lyman-break galaxy (LBG) population. We have identified local analogs of these HAEs using the Sloan Digital Sky Survey. At z < 0.4, only 0.04% of the galaxies are classified as HAEs with H{alpha} equivalent widths ({approx}> 500 A) comparable to that of z {approx} 4 HAEs. Local HAEs have lower stellar mass and lower ultraviolet (UV) luminosity than z {approx} 4 HAEs, yet the H{alpha}-to-UV luminosity ratio, as well as their specific star formation rate, is consistent with that of z {approx} 4 HAEs, indicating that they are scaled-down versions of high-z star-forming galaxies. Compared to the previously studied local analogs of LBGs selected using rest-frame UV properties, local HAEs show similar UV luminosity surface density, weaker D{sub n} (4000) break, lower metallicity, and lower stellar mass. This implies that the local HAEs are less evolved galaxies than the traditional Lyman break analogs. In the stacked spectrum, local HAEs show a significant He II {lambda}4686 emission line suggesting a population of hot, massive stars similar to that seen in some Wolf-Rayet galaxies. Low [N II]/[O III] line flux ratios imply that local HAEs are inconsistent with being systems that host bright active galactic nuclei. Instead, it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons as in the case of Wolf-Rayet galaxies.

The microwave and H-alpha sources of the 1992 January 13 flare

Science.gov (United States)

Wang, H.; Gary, D. E.; Zirin, H.; Kosugi, T.; Schwartz, R. A.; Linford, G.

1995-01-01

We compare X-ray, microwave and H-alpha observations for the 1992 January 13 limb flare. The soft and hard X-ray images of the flare have been studied thoroughly by Masuda et al. (1994) with Yohkoh SXT and HXT images. We find that during the hard X-ray emission peak there is no H-alpha brightening on the disk nor at the limb, so the main ribbons of this flare must be beyond the limb. The microwave source maintains a fixed distance about 10 arcsecs from the optical limb in the frequency range 2.8-14.0 GHz. We interpret this limit in source position as due to the presence of a microwave limb that extends higher than the white-light limb -- to a height of 7300 +/- 1500 km. We believe that the high-frequency microwave emissions are occulted by this extended limb, while the soft and hard X-ray emissions are able to pass through largely unaffected. We also believe, however, that the hard X-ray footpoints are also partially occulted by the photospheric limb, despite the appearance of 'footpoint sources' in HXT data shown by Masuda et al. The smooth X-ray and microwave time profiles, microwave-rich emission relative to hard X-rays, and progressive hard X-ray spectral hardening through the flare peak are all characteristics that we interpret as being a direct result of the occultation of footpoint emission.

A survey of northern Bok globules for H-alpha emission stars

International Nuclear Information System (INIS)

Ogura, Katsuo; Hasegawa, Tatsuhiko.

1983-01-01

Northern globules in the catalog of Bok and Cordwell (1973) have been surveyed for Hα-emission stars of T Tau type by using the Kiso Schmidt telescope with an objective prism. The results for 15 globules are presented here. A total of 60 emission-line stars, of which 80 % are new, and 17 suspected ones have been discovered. Some of them are known T Tau stars; one star shows Ca 2 H and K lines in emission on objective-prism plates in the blue-violet and presumably is a new T Tau star. The celestial coordinates and rough estimates of magnitude and color are given for all of the objects. (author)

A study of solar flare energy transport based on coordinated H-alpha and X-ray observations

International Nuclear Information System (INIS)

Canfield, R.C.; Wulser, J.; Zarro, D.M.; Dennis, B.R.

1991-01-01

The temporal evolution of the ratio between H-alpha to nonthermal hard X-ray emission was investigated using coordinated H-alpha and hard- and soft-X-ray observations of five solar flares (on May 7, June 23, June 24, and June 25, 1980 and on April 30, 1985). These observations were used to estimate the emitted flare energy flux F(H-alpha) in H-alpha, the flux of F(2O) energy deposited by nonthermal electrons with energies above 20 keV, and the pressure p(c) of soft X-ray-emitting plasma as functions of time during the impulsive phase of each flare. It was found that the F(H-alpha)/F(2O) ratio shows a power-law dependence on F(2O), with a slope that differs slightly from that predicted by the static thick-target model of solar transport. Results also indicate that the power-law dependence is modified by hydrostatic pressure effects. 25 refs

Supernova rates, galaxy emission, and Hubble type

International Nuclear Information System (INIS)

Van Den Bergh, S.

1991-01-01

Supernova discovery frequency is found to correlate with emission-line (H-alpha + forbidden N II line) equivalent width, except for the most active galaxies in which some supernovae might be hidden by dust. SNII occur preferentially in active galaxies with emission-line EW not less than 20 A, whereas SNIa favor less active galaxies with EW less than 20 A. The intrinsic frequency of supernovae is found to be an order of magnitude higher in Sc galaxies than it is in early type spirals. The relatively high frequency of SNIa in late-type galaxies suggests that not all such objects have old progenitors. 13 refs

Solar Imagery - Chromosphere - H-Alpha

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of H-alpha photographic datasets contributed by a number of national and private solar observatories located worldwide. Solar...

Galaxy-Wide Shocks in the H$\\alpha$ Emission of Nearby Galaxy Mergers

Science.gov (United States)

Mortazavi, S. Alireza; Lotz, Jennifer M.

2018-01-01

We examine the properties of shocked gas produced as a result of binary galaxy interactions, using H$\\alpha$ emission in a sample 22 mergers observed with SparsePak Integral Field Unit (IFU) at Kitt Peak National Observatory (KPNO). Our sample consists of major and minor tidally interacting galaxies (mass ratio $1text{f}_\\text{shocked}$, and examine the spatial distribution of shocks. We find that close galaxy pairs have, on average, a higher shock fraction than wide pairs, and our coalesced mergers have the highest average $\\text{f}_\\text{shocked}$. Additionally, we find for the first time, correlations between mass ratio, mass of the companion, and $\\text{f}_\\text{shocked}$ in tidally interacting galaxy pairs. Among the non-coalesced systems in our sample, the galaxy pairs with more equal light ratio (stellar mass ratio) tend to have a higher average $\\text{f}_\\text{shocked}$. Also, the primary (more massive) companions are on average slightly more shocked than the secondary (less massive) ones. Utilizing dynamical models in the literature and this work, we inspect trends between $\\text{f}_\\text{shocked}$ and the reconstructed encounter parameters. In this very limited sample, we find that the orbital pericentric separation is correlated with shock fraction, consistent with shocks being produced by the chain of events caused by the tidal impulse during the first passage. These results lay a basis for furture analysis using the higher statistics provided by the on-going and future IFU galaxy surveys.

Recurrent mass ejections observed in H-alpha and CIV

International Nuclear Information System (INIS)

Schmieder, B.; Simon, G.

1984-01-01

Time sequences of recurrent mass ejections have been observed during a coordinated SMY program (Sept. 1, 1980 - Sept. 23, 1980 - Oct. 2, 1980). Comparison of the temporal evolution of H-alpha and CIV brightnesses shows a weak phase lag between H-alpha and CIV maxima, in the case of homologous flares, with CIV brightness maxima preceding H-alpha maxima. The analysis of the variation of the ejection velocities is expected to lead to the determination of an energy balance. Such recurrent ejections could be due to periodic energy storage and periodic reorganization of magnetic field as envisaged to occur for flares, but at lower energy levels

Emission-Line Galaxies from the PEARS Hubble Ultra Deep Field: A 2-D Detection Method and First Results

Science.gov (United States)

Gardner, J. P.; Straughn, Amber N.; Meurer, Gerhardt R.; Pirzkal, Norbert; Cohen, Seth H.; Malhotra, Sangeeta; Rhoads, james; Windhorst, Rogier A.; Gardner, Jonathan P.; Hathi, Nimish P.;

Spectral Ly{alpha}, Ly{beta}, and H{alpha} line shapes for the H atom in the presence of a magnetic field in a plasma; Profils des raies spectrales Ly{alpha}, Ly{beta}, et H{alpha} de l'atome H en presence d'un champ magnetique dans un plasma

Energy Technology Data Exchange (ETDEWEB)

Nguyen, H; Herman, L [Laboratoire de Recherches Physiques, Faculte des sciences, 9 Quai Saint Bernard, 75 - Paris (France); Drawin, H W [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-02-15

This report contains numerical data of the line shapes of Ly{alpha}, Ly{beta}, and H{alpha} for the following parameters: 1. 10{sup 2} {<=} H [gauss] {<=} 1.2. 10{sup 5} 1. 10{sup 15}{<=} N [cm{sup -3}] {<=} 1. 10{sup 18} cm{sup -3} 1. 10{sup 4} {<=} T [deg. K] {<=} 4. 10{sup 4} where H = magnetic field strength, K = density of plasma ions, T = electron temperature. (authors) [French] Dans ce rapport, on donne les valeurs numeriques des contours des raies spectrales Ly{alpha}, Ly{beta}, et H{alpha} pour les valeurs suivantes des parametres H, N et T 1. 10{sup 2} {<=} H [gauss] {<=} 1.2. 10{sup 5} 1. 10{sup 15}{<=} N [cm{sup -3}] {<=} 1. 10{sup 18} cm{sup -3} 1. 10{sup 4} {<=} T [deg. K] {<=} 4. 10{sup 4} ou H intensite du champ magnetique, N = densite des ions, T = temperature electronique. (auteurs)

Spectral properties of X-ray selected narrow emission line galaxies

Science.gov (United States)

Romero-Colmenero, E.

1998-03-01

This thesis reports a study of the X-ray and optical properties of two samples of X-ray selected Narrow Emission Line Galaxies (NELGs), and their comparison with the properties of broad line Active Galactic Nuclei (AGN). One sample (18 NELGs) is drawn from the ROSAT International X-ray Optical Survey (RIXOS), the other (19 NELGs and 33 AGN) from the ROSAT UK Deep Survey. ROSAT multi-channel X-ray spectra have been extracted and fitted with power-law, bremsstrahlung and black body models for the brighter RIXOS sources. In most cases, power-law and bremsstrahlung models provide the best results. The average spectral energy index, alpha, of the RIXOS NELGs is 0.96 +/- 0.07, similar to that of AGN (alpha~1). For the fainter RIXOS NELGs, as well as for all the UK Deep Survey sources, counts in three spectral bands have been extracted and fitted with a power-law model, assuming the Galactic value for N_H. The brighter RIXOS sources demonstrated that the results obtained by these two different extraction and fitting procedures provide consistent results. Two average X-ray spectra, one for the NELGs and another for the AGN, were created from the UK Deep Survey sources. The power-law slope of the average NELG is alpha = 0.45 +/- 0.09, whilst that of the AGN is alpha = 0.96 +/- 0.03. ROSAT X-ray surveys have shown that the fractional surface density of NELGs increases with respect to AGN at faint fluxes (case for NELGs to be major contributors to the XRB at the fainter fluxes. The analysis of optical spectroscopy, obtained on La Palma and Hawaii, shows that NELGs form a very heterogeneous group, made up of a mixture of Seyfert 2, LINER and HII-region like galaxies. Seyfert 2 galaxies are found to possess in general the steepest X-ray slopes. Ways to explain this in the context of the unified model of AGN are discussed. The FWHM of some emission lines (Halpha, Hbeta, [NII]) in the NELGs appears to increase with steepening X-ray spectral slope. In the case of the Balmer lines

New T Tauri stars in Chamaeleon I and Chamaeleon II

Science.gov (United States)

Hartigan, Patrick

1993-01-01

A new objective prism survey of the entire Chamaeleon I dark cloud and 2/3 of the Chamaeleon II cloud has uncovered 26 new H-alpha emission line objects that were missed by previous H-alpha plate surveys. The new H-alpha emission line objects have similar IR colors and spatial distributions to the known T Tauri stars in these dark clouds, and could represent the very low mass end of the stellar population in these clouds or an older, less active component to the usual classical T Tauri star population. The new H-alpha survey identified 70 percent of the total known Young Stellar Objects (YSOs) in Cha I, compared with 35 percent for IRAS, and 25 percent from the Einstein X-ray survey. Ten of the new objects are weak-lined stars, with H-alpha equivalent widths less than 10 A. Weak-lined T Tauri stars make up about half of the total population of young stars in the Chamaeleon I cloud, a proportion similar to the Taurus-Auriga cloud. Presented are coordinates, finding charts, and optical and IR photometry of the new emission-line objects.

Spectroscopy of chromospheric lines of giants in the globular cluster

Science.gov (United States)

Dupree, A. K.; Hartmann, Lee; Smith, Graeme H.; Rodgers, A. W.; Roberts, W. H.; Zucker, D. B.

1994-01-01

Spectroscopic observations of chromospheric transitions (Mg II, H-alpha, and Ca II K) from two red giants (A31 and A59) in the globular cluster NGC 6572 were made with the Goddard High Resolution Spectrograph on the Hubble Space Telescope and the coude spectrograph of the 1.9 m telescope at the Mount Stromlo Observatory. These measurements give evidence for chromospheric activity and outward motions within the atmospheres. The surface flux of the Mg II emission is comparable to that in disk population giants of similar (B-V) color. The Mg II profiles are asymmetric, which is most likely caused by absorption in an expanding stellar atmosphere and/or by possible interstellar features. Notches are found in the core of the H-alpha line of A59, which are similar to those found in Cepheids. This suggests that shocks are present in the atmosphere of A59 and indicates that hydrodynamic phenomena are influencing the levvel of chromospheric emission and producing upper atmospheric motions which may lead to mass loss.

Discovering Interacting Binaries with Halpha Surveys

NARCIS (Netherlands)

Witham, A.; Knigge, C.; Drew, J.; Groot, P.J.; Greimel, R.; Parker, Q.

2005-01-01

A deep (R ~ 19.5) photographic Halpha Survey of the southern Galactic Plane was recently completed using the UK Schmidt Telescope at the AAO. In addition, we have recently started a similar, CCD-based survey of the northern Galactic Plane using the Wide Field Camera on the INT. Both surveys aim to

Database of emission lines

Science.gov (United States)

Binette, L.; Ortiz, P.; Joguet, B.; Rola, C.

1998-11-01

A widely accessible data bank (available through Netscape) and consiting of all (or most) of the emission lines reported in the litterature is being built. It will comprise objects as diverse as HII regions, PN, AGN, HHO. One of its use will be to define/refine existing diagnostic emission line diagrams.

CANDIDATES OF H{alpha} EMITTING REGIONS IN THE MAGELLANIC STREAM IV CLOUD

Energy Technology Data Exchange (ETDEWEB)

Yagi, Masafumi; Komiyama, Yutaka [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yoshida, Michitoshi, E-mail: YAGI.Masafumi@nao.ac.jp [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)

2012-04-10

From H{alpha} narrowband observations, we identified three H{alpha} emitting regions in the direction of Magellanic Stream IV (MS IV). They consist of three parallel filaments of 2 arcmin width and 6-30 arcmin length at 12 arcmin intervals. Their mean surface brightness (SB) is {approx}2 Multiplication-Sign 10{sup -18} erg s{sup -1} cm{sup -2} arcsec{sup -2}. Because of their low SB, the regions were not detected in previous H{alpha} surveys. In the H I map, the position of the filaments overlap MS, suggesting that they are parts of the MS, but there also exists a local H I structure. If the filaments are associated with the MS, the sizes are 30 pc Multiplication-Sign 100-500 pc. The filaments lie at the leading edge of a downstream cloud, which supports shock heating and its propagation (shock cascade) model for the ionizing source. If they are local objects, on the other hand, Fossil Stroemgren Trails of more than two stars is a possible interpretation, and the sizes would be 0.1 pc Multiplication-Sign 0.3-1.5 pc at 180 pc distance. The positional information of the H{alpha} filaments presented in this Letter enables future spectroscopic observations to clarify their nature.

Full-disk Solar H-alpha Images From GONG

Science.gov (United States)

Harvey, J. W.; Bolding, J.; Clark, R.; Hauth, D.; Hill, F.; Kroll, R.; Luis, G.; Mills, N.; Purdy, T.; Henney, C.; Holland, D.; Winter, J.

2011-05-01

Since mid-2010 the Global Oscillation Network Group (GONG) has collected H-alpha images at six sites around the world. These images provide a near real-time solar activity patrol for use in space weather applications and also an archive for research purposes. Images are collected once per minute, dark, smear, and flat corrected, compressed and then sent via the Internet to a 'cloud' server where reduction is completed. Various reduced images are usually available within a minute after exposure. The H-alpha system is an add-on to the normal GONG helioseismology instrument and does not interfere with regular observations. A polarizing beamsplitter sends otherwise unused 656 nm light through two lenses to a Daystar 0.04 nm mica etalon filter. The filter is matched to an image of the GONG light feed entrance pupil and sees an image of the Sun at infinity. Two lenses behind the filter form the solar image on a DVC-4000 2k x 2k interline transfer CCD camera. Exposure times are automatically adjusted to maintain the quiet disk center at 20% of full dynamic range to avoid saturation by bright flares. Image resolution is limited by diffraction, seeing and some high-order wavefront errors in the filters. A unique dual-heater system was developed by Daystar to homogenize the passband characteristics of the mica etalons. The data are in regular use for space weather forecasting by the U.S. Air Force Weather Agency, which funded construction and installation of the instruments. Operational and reduction improvements are underway and archived data are already being used for research projects. The Web site URL is http://halpha.nso.edu.

Rotation and chromospheric emission among F, G, and K dwarfs of the Pleiades

Science.gov (United States)

Soderblom, David R.; Stauffer, John R.; Hudon, J. D.; Jones, Burton F.

1993-01-01

High-resolution echelle spectra of more than 100 F, G, and K dwarfs in the Pleiades are reported. Chromospheric activity in these stars is measured via comparisons of the profiles of H-alpha and the Ca II IR triplet to chromospherically inactive field stars. Consistent dereddened colors are determined from the available photometry and temperatures are derived. Most G and K dwarfs in the Pleiades rotate slowly, but about 20 percent of the stars are ultrafast rotators (UFRs). That fraction of UFRs is independent of color, and the highest rotation rates are found among the K dwarfs. The Pleiades exhibit a broad range in the strength of chromospheric emission at any one color. Most G and K dwarfs in the Pleiades show H-alpha and the IR triple in absorption, with filling in of the line cores.

THE NATURE OF A GALAXY ALONG THE SIGHT LINE TO PKS 0454+039

Energy Technology Data Exchange (ETDEWEB)

Takamiya, Marianne [Physics and Astronomy Department, University of Hawaii Hilo, Hilo, HI 96720 (United States); Chun, Mark [Institute for Astronomy, University of Hawaii Manoa, HI 96822 (United States); Kulkarni, Varsha P.; Gharanfoli, Soheila, E-mail: takamiya@hawaii.edu [Department of Physics and Astronomy, University of South Carolina, SC 29208 (United States)

2012-10-01

We report on the properties of a faint blue galaxy (G1) along the line of sight to the QSO PKS 0454+039 from spectroscopic and imaging data. We measured emission lines of H{alpha}, [S II] {lambda}{lambda}6716, 6732, and [N II] {lambda}6584 in the spectrum of G1 obtained with the Gemini/GMOS instrument. The spectroscopic redshift of G1 is z = 0.0715 {+-} 0.0002. From the extinction-corrected H{alpha} flux, we determine a modest star formation rate of SFR = 0.07 M{sub Sun} yr{sup -1} and a specific SFR of log (sSFR) -8.4. Using three different abundance indicators, we determine a nebular abundance 12 + log (O/H) ranging from 7.6 to 8.2. Based on the velocity dispersion inferred from the emission line widths and the observed surface brightness profile, we estimate the virial mass of G1 to be M{sub vir} {approx} 6.7 Multiplication-Sign 10{sup 9} M{sub Sun} with an effective radius of 2.0 kpc. We estimate the stellar mass of G1 using spectral energy distribution fitting to be M{sub *} Almost-Equal-To 1.2 Multiplication-Sign 10{sup 7} M{sub Sun} and an r'-luminosity of L{sub r'} = 1.5x10{sup 8} L{sub Sun }. Overall, G1 is a faint, low-mass, low-metallicity Im/H II galaxy. We also report on the line flux limits of another source (G3) which is the most likely candidate for the absorber system at z = 0.8596. From the spectrum of the QSO itself, we report a previously undetected Mg II {lambda}{lambda}2796, 2803 absorption line system at z = 1.245.

Correction of UBV Photometry for Emission Lines

Directory of Open Access Journals (Sweden)

Skopal A.

2003-12-01

Full Text Available We investigate the effect on U,B,V magnitudes of the removal of emission lines from the spectra of some symbiotic stars and novae during their nebular phases. We approach this problem by the precise reconstruction of the composite UV/optical continuum and the line spectrum. The corrections ΔU, ΔB and ΔV are determined from the ratio of fluxes with and without emission lines. We demonstrate the effect for symbiotic nova V1016 Cyg during its nebular phase. We find that about 68%, 78% and 66% of the observed flux in the U, B and V filters is radiated in the emission lines. The effect should be taken into account before using the observed color indices of emission-line objects for diagnosis of their radiation in the continuum.

MICROLENSING OF QUASAR BROAD EMISSION LINES: CONSTRAINTS ON BROAD LINE REGION SIZE

Energy Technology Data Exchange (ETDEWEB)

Guerras, E.; Mediavilla, E. [Instituto de Astrofisica de Canarias, Via Lactea S/N, La Laguna E-38200, Tenerife (Spain); Jimenez-Vicente, J. [Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Campus de Fuentenueva, E-18071 Granada (Spain); Kochanek, C. S. [Department of Astronomy and the Center for Cosmology and Astroparticle Physics, The Ohio State University, 4055 McPherson Lab, 140 West 18th Avenue, Columbus, OH 43221 (United States); Munoz, J. A. [Departamento de Astronomia y Astrofisica, Universidad de Valencia, E-46100 Burjassot, Valencia (Spain); Falco, E. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Motta, V. [Departamento de Fisica y Astronomia, Universidad de Valparaiso, Avda. Gran Bretana 1111, Valparaiso (Chile)

2013-02-20

We measure the differential microlensing of the broad emission lines between 18 quasar image pairs in 16 gravitational lenses. We find that the broad emission lines are in general weakly microlensed. The results show, at a modest level of confidence (1.8{sigma}), that high ionization lines such as C IV are more strongly microlensed than low ionization lines such as H{beta}, indicating that the high ionization line emission regions are more compact. If we statistically model the distribution of microlensing magnifications, we obtain estimates for the broad line region size of r{sub s} = 24{sup +22} {sub -15} and r{sub s} = 55{sup +150} {sub -35} lt-day (90% confidence) for the high and low ionization lines, respectively. When the samples are divided into higher and lower luminosity quasars, we find that the line emission regions of more luminous quasars are larger, with a slope consistent with the expected scaling from photoionization models. Our estimates also agree well with the results from local reveberation mapping studies.

UV line emission of symbiotic stars

International Nuclear Information System (INIS)

Nussbaumer, H.

1982-01-01

General characteristics of emission line spectra from symbiotic stars are outlined. Data from some special line ratios in the 1000 A - 3000 A range, and others connecting the visual and the far UV lines are presented, and their application to symbiotic stars is discussed. Integrated fractional abundances for ions easily observed in the far UV are given to facilitate abundance determinations for nebular conditions. It is found that the physical conditions of the regions emitting the emission line spectra differ considerably among different symbiotic stars. (Auth.)

The Of emission lines near 4650 A

International Nuclear Information System (INIS)

Underhill, A.B.; Gilroy, K.K.; Hill, G.M.

1989-01-01

Rectified, normalized, high S/N intensity tracings of nine Of stars were obtained from Reticon spectra in the 4550-4800-A region. The well-known relatively sharp Of emission lines are seen to stand on pedestals of broad weak emission somewhat like the broad emission lines from WR stars. It is suggested that cascades following dielectronic recombination may be an important process driving some lines of N III, C III, and C IV into the emission of Of stars, and that the sharp Of lines come from plasma that is stationary with respect to the star. The broad emission features show an extensive low-density wind from each star. The results imply that the detection of two, more or less equal, broad jumps in the rest spectra of galaxies at about 4640 and 4686 A is more indicative of Of stars than of WR stars. 32 refs

FIRST SIMULTANEOUS OBSERVATION OF AN H{alpha} MORETON WAVE, EUV WAVE, AND FILAMENT/PROMINENCE OSCILLATIONS

Energy Technology Data Exchange (ETDEWEB)

Asai, Ayumi; Isobe, Hiroaki [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Ishii, Takako T.; Kitai, Reizaburo; Ichimoto, Kiyoshi; UeNo, Satoru; Nagata, Shin' ichi; Morita, Satoshi; Nishida, Keisuke; Shibata, Kazunari [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Shiota, Daikou [Advanced Science Institute, RIKEN, Wako, Saitama 351-0198 (Japan); Oi, Akihito [College of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan); Akioka, Maki, E-mail: asai@kwasan.kyoto-u.ac.jp [Hiraiso Solar Observatory, National Institute of Information and Communications Technology, Hitachinaka, Ibaraki 311-1202 (Japan)

2012-02-15

We report on the first simultaneous observation of an H{alpha} Moreton wave, the corresponding EUV fast coronal waves, and a slow and bright EUV wave (typical EIT wave). We observed a Moreton wave, associated with an X6.9 flare that occurred on 2011 August 9 at the active region NOAA 11263, in the H{alpha} images taken by the Solar Magnetic Activity Research Telescope at Hida Observatory of Kyoto University. In the EUV images obtained by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory we found not only the corresponding EUV fast 'bright' coronal wave, but also the EUV fast 'faint' wave that is not associated with the H{alpha} Moreton wave. We also found a slow EUV wave, which corresponds to a typical EIT wave. Furthermore, we observed, for the first time, the oscillations of a prominence and a filament, simultaneously, both in the H{alpha} and EUV images. To trigger the oscillations by the flare-associated coronal disturbance, we expect a coronal wave as fast as the fast-mode MHD wave with the velocity of about 570-800 km s{sup -1}. These velocities are consistent with those of the observed Moreton wave and the EUV fast coronal wave.

Development of the prototype data management system of the solar H-alpha full disk observation

Science.gov (United States)

Wei, Ka-Ning; Zhao, Shi-Qing; Li, Qiong-Ying; Chen, Dong

2004-06-01

The Solar Chromospheric Telescope in Yunnan Observatory generates about 2G bytes fits format data per day. Huge amounts of data will bring inconvenience for people to use. Hence, data searching and sharing are important at present. Data searching, on-line browsing, remote accesses and download are developed with a prototype data management system of the solar H-alpha full disk observation, and improved by the working flow technology. Based on Windows XP operating system and MySQL data management system, a prototype system of browse/server model is developed by JAVA and JSP. Data compression, searching, browsing, deletion need authority and download in real-time have been achieved.

QSOs with narrow emission lines

International Nuclear Information System (INIS)

Baldwin, J.A.; Mcmahon, R.; Hazard, C.; Williams, R.E.

1988-01-01

Observations of two new high-redshift, narrow-lined QSOs (NLQSOs) are presented and discussed together with observations of similar objects reported in the literature. Gravitational lensing is ruled out as a possible means of amplifying the luminosity for one of these objects. It is found that the NLQSOs have broad bases on their emission lines as well as the prominent narrow cores which define this class. Thus, these are not pole-on QSOs. The FWHM of the emission lines fits onto the smoothly falling tail of the lower end of the line-width distribution for complete QSO samples. The equivalent widths of the combined broad and narrow components of the lines are normal for QSOs of the luminosity range under study. However, the NLQSOs do show ionization differences from broader-lined QSOs; most significant, the semiforbidden C III/C IV intensity ratio is unusually low. The N/C abundance ratio in these objects is found to be normal; the Al/C abundance ratio may be quite high. 38 references

OPTICAL MONITORING OF THE BROAD-LINE RADIO GALAXY 3C 390.3

Energy Technology Data Exchange (ETDEWEB)

Dietrich, Matthias; Peterson, Bradley M.; Grier, Catherine J.; Bentz, Misty C.; Eastman, Jason; Frank, Stephan; Gonzalez, Raymond; Marshall, Jennifer L.; DePoy, Darren L.; Prieto, Jose L., E-mail: dietrich@astronomy.ohio-state.edu [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2012-09-20

We have undertaken a new ground-based monitoring campaign on the broad-line radio galaxy 3C 390.3 to improve the measurement of the size of the broad emission-line region and to estimate the black hole mass. Optical spectra and g-band images were observed in late 2005 for three months using the 2.4 m telescope at MDM Observatory. Integrated emission-line flux variations were measured for the hydrogen Balmer lines H{alpha}, H{beta}, H{gamma}, and for the helium line He II{lambda}4686, as well as g-band fluxes and the optical active galactic nucleus (AGN) continuum at {lambda} = 5100 A. The g-band fluxes and the optical AGN continuum vary simultaneously within the uncertainties, {tau}{sub cent} (0.2 {+-} 1.1) days. We find that the emission-line variations are delayed with respect to the variable g-band continuum by {tau}(H{alpha}) 56.3{sup +2.4}{sub -6.6} days, {tau}(H{beta}) = 44.3{sup +3.0}{sub -3.3} days, {tau}(H{gamma}) = 58.1{sup +4.3}{sub -6.1} days, and {tau}(He II 4686) = 22.3{sup +6.5}{sub -3.8} days. The blue and red peaks in the double-peaked line profiles, as well as the blue and red outer profile wings, vary simultaneously within {+-}3 days. This provides strong support for gravitationally bound orbital motion of the dominant part of the line-emitting gas. Combining the time delay of the strong Balmer emission lines of H{alpha} and H{beta} and the separation of the blue and red peaks in the broad double-peaked profiles in their rms spectra, we determine M {sup vir}{sub bh} = 1.77{sup +0.29}{sub -0.31} Multiplication-Sign 10{sup 8} M{sub Sun} and using {sigma}{sub line} of the rms spectra M {sup vir}{sub bh} 2.60{sup +0.23}{sub -0.31} Multiplication-Sign 10{sup 8} M{sub Sun} for the central black hole of 3C 390.3, respectively. Using the inclination angle of the line-emitting region which is measured from superluminal motion detected in the radio range, accretion disk models to fit the optical double-peaked emission-line profiles, and X-ray observations

SUB-THz AND H{alpha} ACTIVITY DURING THE PREFLARE AND MAIN PHASES OF A GOES CLASS M2 EVENT

Energy Technology Data Exchange (ETDEWEB)

Kaufmann, Pierre; Gimenez de Castro, C. Guillermo; Raulin, Jean-Pierre; Correia, Emilia; Fernandes, Luis Olavo; De Souza, Rodney V. [CRAAM, Escola de Engenharia, Universidade Presbiteriana Mackenzie, Sao Paulo (Brazil); Marcon, Rogerio [IFGW, Universidade Estadual de Campinas (Brazil); White, Stephen M. [AFRL, Space Vehicles Directorate, Albuquerque, NM (United States); Godoy, Rodolfo; Marun, Adolfo; Pereyra, Pablo [Complejo Astronomico El Leoncito, CONICET, San Juan (Argentina)

2011-12-01

Radio and optical observations of the evolution of flare-associated phenomena have shown an initial and rapid burst at 0.4 THz only followed subsequently by a localized chromospheric heating producing an H{alpha} brightening with later heating of the whole active region. A major instability occurred several minutes later producing one impulsive burst at microwaves only, associated with an M2.0 GOES X-ray flare that exhibited the main H{alpha} brightening at the same site as the first flash.The possible association between long-enduring time profiles at soft X-rays, microwaves, H{alpha}, and sub-THz wavelengths is discussed. In the decay phase, the H{alpha} movie shows a disrupting magnetic arch structure ejecting dark, presumably chromospheric, material upward. The time sequence of events suggests genuine interdependent and possibly non-thermal instabilities triggering phenomena, with concurrent active region plasma heating and material ejection.

HIGH-REDSHIFT SDSS QUASARS WITH WEAK EMISSION LINES

International Nuclear Information System (INIS)

Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Jiang Linhua; Kim, J. Serena; Schmidt, Gary D.; Smith, Paul S.; Vestergaard, Marianne; Young, Jason E.; Brandt, W. N.; Shemmer, Ohad; Gibson, Robert R.; Schneider, Donald P.; Strauss, Michael A.; Shen Yue; Anderson, Scott F.; Carilli, Christopher L.; Richards, Gordon T.

2009-01-01

We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent tail of the Lyα + N v equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission lines, namely BL Lac objects. We find that WLQs exhibit hot (T ∼ 1000 K) thermal dust emission and have rest-frame 0.1-5 μm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most probable scenario for WLQs involves broad-line region properties that are physically distinct from those of normal quasars.

BLACK HOLE MASS ESTIMATES BASED ON C IV ARE CONSISTENT WITH THOSE BASED ON THE BALMER LINES

Energy Technology Data Exchange (ETDEWEB)

Assef, R. J.; Denney, K. D.; Kochanek, C. S.; Peterson, B. M.; Kozlowski, S.; Dietrich, M.; Grier, C. J.; Khan, R. [Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States); Ageorges, N.; Buschkamp, P.; Gemperlein, H.; Hofmann, R. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstr., D-85748 Garching (Germany); Barrows, R. S. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Falco, E.; Kilic, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Feiz, C.; Germeroth, A. [Landessternwarte, ZAH, Koenigstuhl 12, D-69117 Heidelberg (Germany); Juette, M.; Knierim, V. [Astron. Institut der Ruhr Univ. Bochum, Universitaetsstr. 150, D-44780 Bochum (Germany); Laun, W., E-mail: rjassef@astronomy.ohio-state.edu [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); and others

2011-12-01

Using a sample of high-redshift lensed quasars from the CASTLES project with observed-frame ultraviolet or optical and near-infrared spectra, we have searched for possible biases between supermassive black hole (BH) mass estimates based on the C IV, H{alpha}, and H{beta} broad emission lines. Our sample is based upon that of Greene, Peng, and Ludwig, expanded with new near-IR spectroscopic observations, consistently analyzed high signal-to-noise ratio (S/N) optical spectra, and consistent continuum luminosity estimates at 5100 A. We find that BH mass estimates based on the full width at half-maximum (FWHM) of C IV show a systematic offset with respect to those obtained from the line dispersion, {sigma}{sub l}, of the same emission line, but not with those obtained from the FWHM of H{alpha} and H{beta}. The magnitude of the offset depends on the treatment of the He II and Fe II emission blended with C IV, but there is little scatter for any fixed measurement prescription. While we otherwise find no systematic offsets between C IV and Balmer line mass estimates, we do find that the residuals between them are strongly correlated with the ratio of the UV and optical continuum luminosities. This means that much of the dispersion in previous comparisons of C IV and H{beta} BH mass estimates are due to the continuum luminosities rather than to any properties of the lines. Removing this dependency reduces the scatter between the UV- and optical-based BH mass estimates by a factor of approximately two, from roughly 0.35 to 0.18 dex. The dispersion is smallest when comparing the C IV {sigma}{sub l} mass estimate, after removing the offset from the FWHM estimates, and either Balmer line mass estimate. The correlation with the continuum slope is likely due to a combination of reddening, host contamination, and object-dependent SED shapes. When we add additional heterogeneous measurements from the literature, the results are unchanged. Moreover, in a trial observation of a

PG 0308 + 096 and PG 1026 + 002 - Two new short period binary stars resulting from common-envelope evolution

Science.gov (United States)

Saffer, Rex A.; Wade, Richard A.; Liebert, James; Green, Richard F.; Sion, Edward M.; Bechtold, J.; Foss, Diana; Kidder, K.

1993-01-01

Ultraviolet spectroscopy, optical spectroscopy, and spectrophotometry have been used to study the excess UV stars PG 0308 + 096 and PG 1026 + 002. Both objects are short-period binary systems, each containing a DA white dwarf star and a dM star. Orbital periods of approximately 0.284 day for PG 0308 + 096, and aproximately 0.597 day for PG 1026, have been found by spectroscopic analysis of the H-alpha emission line. Ly-alpha and Balmer line profile fitting were used to estimate the mass of white dwarf stars; mass estimates for the dM stars are based on their spectral types. The orbital inclinations are derived from these masses, the periods, and amplitudes of the H-alpha radial velocity curves. The equivalent width of the H-alpha emission line, in each binary system, varies with the orbital phase in such a manner as to imply that it arises, in large part at least, from the hemisphere of the M star that faces the white dwarf star.

Optical emission line spectra of Seyfert galaxies and radio galaxies

International Nuclear Information System (INIS)

Osterbrock, D.E.

1978-01-01

Many radio galaxies have strong emission lines in their optical spectra, similar to the emission lines in the spectra of Seyfert galaxies. The range of ionization extends from [O I] and [N I] through [Ne V] and [Fe VII] to [Fe X]. The emission-line spectra of radio galaxies divide into two types, narrow-line radio galaxies whose spectra are indistinguishable from Seyfert 2 galaxies, and broad-line radio galaxies whose spectra are similar to Seyfert 1 galaxies. However on the average the broad-line radio galaxies have steeper Balmer decrements, stronger [O III] and weaker Fe II emission than the Seyfert 1 galaxies, though at least one Seyfert 1 galaxy not known to be a radio source has a spectrum very similar to typical broad-line radio galaxies. Intermediate-type Seyfert galaxies exist that show various mixtures of the Seyfert 1 and Seyfert 2 properties, and the narrow-line or Seyfert 2 property seems to be strongly correlated with radio emission. (Auth.)

GAME: GAlaxy Machine learning for Emission lines

Science.gov (United States)

Ucci, G.; Ferrara, A.; Pallottini, A.; Gallerani, S.

2018-06-01

We present an updated, optimized version of GAME (GAlaxy Machine learning for Emission lines), a code designed to infer key interstellar medium physical properties from emission line intensities of ultraviolet /optical/far-infrared galaxy spectra. The improvements concern (a) an enlarged spectral library including Pop III stars, (b) the inclusion of spectral noise in the training procedure, and (c) an accurate evaluation of uncertainties. We extensively validate the optimized code and compare its performance against empirical methods and other available emission line codes (PYQZ and HII-CHI-MISTRY) on a sample of 62 SDSS stacked galaxy spectra and 75 observed HII regions. Very good agreement is found for metallicity. However, ionization parameters derived by GAME tend to be higher. We show that this is due to the use of too limited libraries in the other codes. The main advantages of GAME are the simultaneous use of all the measured spectral lines and the extremely short computational times. We finally discuss the code potential and limitations.

GAME: GAlaxy Machine learning for Emission lines

Science.gov (United States)

Ucci, G.; Ferrara, A.; Pallottini, A.; Gallerani, S.

2018-03-01

We present an updated, optimized version of GAME (GAlaxy Machine learning for Emission lines), a code designed to infer key interstellar medium physical properties from emission line intensities of UV/optical/far infrared galaxy spectra. The improvements concern: (a) an enlarged spectral library including Pop III stars; (b) the inclusion of spectral noise in the training procedure, and (c) an accurate evaluation of uncertainties. We extensively validate the optimized code and compare its performance against empirical methods and other available emission line codes (pyqz and HII-CHI-mistry) on a sample of 62 SDSS stacked galaxy spectra and 75 observed HII regions. Very good agreement is found for metallicity. However, ionization parameters derived by GAME tend to be higher. We show that this is due to the use of too limited libraries in the other codes. The main advantages of GAME are the simultaneous use of all the measured spectral lines, and the extremely short computational times. We finally discuss the code potential and limitations.

Activity in X-ray-selected late-type stars

International Nuclear Information System (INIS)

Takalo, L.O.; Nousek, J.A.

1988-01-01

A spectroscopic study has been conducted of nine X-ray bright late-type stars selected from two Einstein X-ray surveys: the Columbia Astrophysical Laboratory Survey (five stars) and the CFA Medium Sensitivity Survey (MSS; four stars). Spectral classes were determined and radial and V sin(i) velocities were measured for the stars. Four of the Columbia Survey stars were found to be new RS CVn-type binaries. The fifth Columbia survey star was found to be an active G dwarf star without evidence for binarity. None of the four MSS stars were found to be either binaries or optically active stars. Activity in these stars was assessed by measuring the excess emission in H-alpha and the Ca II IRT (8498, 8542) lines in comparison with inactive stars of similar spectral types. A correlation was found between X-ray luminosity and V sin(i) and H-alpha line excess. The measured excess line emission in H-alpha was also correlated with V sin(i) but not with the IRT line excess. 36 references

Intrinsic polarization changes and the H-alpha and CA II emission features in T-Tauri stars

Science.gov (United States)

Svatos, J.; Solc, M.

1981-12-01

On the basis of the correlation between polarization and emission features observed in certain T-Tauri stars, it is concluded that flaring effects associated with UV and/or X-ray irradiation and with increased magnetic field are responsible for the intrinsic polarization changes in T-Tauri stars. The correlation between emission Ca II lines and polarization degree both in Miras and T-Tau stars is thought to support the contention that the intrinsic polarization changes are due to the irradiation of silicate-like grains. In some T-Tau stars the increase in the magnetic field can be the principal agent causing the polarization increase due to the enhanced orientation of elongated grains.

DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS

International Nuclear Information System (INIS)

Plotkin, Richard M.; Gallo, Elena; Shemmer, Ohad; Trakhtenbrot, Benny; Anderson, Scott F.; Brandt, W. N.; Luo, Bin; Schneider, Donald P.; Fan, Xiaohui; Lira, Paulina; Richards, Gordon T.; Strauss, Michael A.; Wu, Jianfeng

2015-01-01

Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hβ, Hα) in individual objects. We detect broad Hβ and Hα emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hβ has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hβ FWHM ≲ 4000 km s −1 , and significant C iv blueshifts (≈1000–5500 km s −1 ) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum

A spectroscopic search for colliding stellar winds in O-type close binary systems. IV - Iota Orionis

Science.gov (United States)

Gies, Douglas R.; Wiggs, Michael S.; Bagnuolo, William G., Jr.

1993-01-01

We present H-alpha and He I 6678 A line profiles for the eccentric orbit binary Iota Ori. We have applied a tomography algorithm which uses the established orbital velocity curves and intensity ratio to reconstruct the spectral line profiles for each star. The He I profiles appear as pure photospheric lines, and H-alpha shows variable emission in the line core throughout the orbit (which is typical of O giants) and in the blue wing near periastron passage. We show that the blue wing emission is consistent with an origin between the stars which probably results from a dramatic focusing of the primary's stellar wind at periastron. We also present IUE archival spectra of the UV wind lines N V 1240 A and C IV 1550 A.

High-redshift SDSS Quasars with Weak Emission Lines

DEFF Research Database (Denmark)

Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

2009-01-01

We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a promine...

Emission line galaxies and active galactic nuclei in WINGS clusters

Science.gov (United States)

Marziani, P.; D'Onofrio, M.; Bettoni, D.; Poggianti, B. M.; Moretti, A.; Fasano, G.; Fritz, J.; Cava, A.; Varela, J.; Omizzolo, A.

2017-03-01

We present the analysis of the emission line galaxies members of 46 low-redshift (0.04 employing diagnostic diagrams. We examined the emission line properties and frequencies of star-forming galaxies, transition objects, and active galactic nuclei (AGNs: LINERs and Seyferts), unclassified galaxies with emission lines, and quiescent galaxies with no detectable line emission. A deficit of emission line galaxies in the cluster environment is indicated by both a lower frequency, and a systematically lower Balmer emission line equivalent width and luminosity with respect to control samples; this implies a lower amount of ionized gas per unit mass and a lower star formation rate if the source is classified as Hii region. A sizable population of transition objects and of low-luminosity LINERs (≈ 10-20% of all emission line galaxies) are detected among WINGS cluster galaxies. These sources are a factor of ≈1.5 more frequent, or at least as frequent, as in control samples with respect to Hii sources. Transition objects and LINERs in clusters are most affected in terms ofline equivalent width by the environment and appear predominantly consistent with so-called retired galaxies. Shock heating can be a possible gas excitation mechanism that is able to account for observed line ratios. Specific to the cluster environment, we suggest interaction between atomic and molecular gas and the intracluster medium as a possible physical cause of line-emitting shocks. The data whose description is provided in Table B.1, and emission line catalog of the WINGS database are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A83

Emission-line galaxies toward the booetes void

International Nuclear Information System (INIS)

Moody, J.W.

1986-01-01

Galaxies with strong emission are potentially useful as probes of the large-scale galaxian distribution. However, to serve as probes, their relative frequency and clustering properties must be known. This dissertation presents a study of these properties for field galaxies having [OIII] λ5007 emission equivalent widths greater than 10 A and reports on a search for galaxies with [OIII] λ5007 emission in the direction of the Booetes void, a volume located at α = 4/sup h/48/sup m/, δ = 47 0 , and cz = 15,000 km/sec that has been demonstrated to be under-abundant in galaxies by a factor of at least four. The study of field emission-line galaxies was done in two magnitude limited surveys consisting of 341 galaxies from both the north and south galactic caps having previously published redshifts and photometry. The galaxy spectra used for redshifts were examined and supplemented by new observations for 56 objects, primarily those with confirmed or suspected emission. Emission-line galaxies were found to comprise 8.8% of galaxies in a Illa-J selected sample or 6.6% of galaxies in a Illa-F selected sample. A search for emission-line galaxies towards the Booetes void was undertaken using the Burrell Schmidt telescope and an objective prism giving a reciprocal dispersion of 900 A/mm at Hβ. Three galaxies were found to lie within it, a result consistent with distributions through the void ranging from uniform to under-abundant by a factor of three

High-dispersion observations of H-alpha in the suspected brown dwarf, white dwarf binary system G29-38

International Nuclear Information System (INIS)

Liebert, J.; Saffer, R.A.; Pilachowski, C.A.

1989-01-01

High-dispersion spectroscopy of the H-alpha absorption line of the cool DA white dwarf G29-38 is reported. This is the star for which a recently detected IR excess has been suggested to be due to a possible brown dwarf companion. Three echelle spectra show no evidence for radial-velocity variations larger than about 1.1 + or - 8.7 km/s and are used to derive a weighted heliocentric radial velocity of 33.7 + or - 4.3 kms/s for the white dwarf. The observations of a sharp absorption-line core restricts the possible rotation of the white dwarf to 40 km/s or less and ensures that any surface magnetic field has a strength of 100,000 G or less. These results make it unlikely that the DA white dwarf has previously been in a cataclysmic variable accretion phase. 18 references

Nebular Continuum and Line Emission in Stellar Population Synthesis Models

Energy Technology Data Exchange (ETDEWEB)

Byler, Nell; Dalcanton, Julianne J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Conroy, Charlie; Johnson, Benjamin D., E-mail: ebyler@astro.washington.edu [Department of Astronomy, Harvard University, Cambridge, MA 02138 (United States)

2017-05-01

Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emissions can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on H α , and physical properties derived from broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies, when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions. The models are integrated into current versions of FSPS and include self-consistent nebular emission predictions for MIST and Padova+Geneva evolutionary tracks.

Line emissions from sonoluminescence in aqueous solutions of halide salts without noble gases

Energy Technology Data Exchange (ETDEWEB)

Liang, Jinfu, E-mail: liang.shi2007@163.com [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China); School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001 (China); Chen, Weizhong, E-mail: wzchen@nju.edu.cn [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China); Zhou, Chao; Cui, Weicheng; Chen, Zhan [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China)

2015-02-20

Line emissions of trivalent terbium (Tb{sup 3+}) ion were observed from single-bubble sonoluminescence (SL) in an aqueous solution of terbium chloride (TbCl{sub 3}) that contained no noble gas. In addition, sodium (Na) lines were observed in multi-bubble SL in aqueous solutions of various halide salts that contained no noble gas. These observations show that the halide ions, such as Cl{sup −}, Br{sup −}, and I{sup −}, help for line emissions as the noble gases. The intensity of a line emission depends on both the chemical species produced by cavitation bubbles and the temperature of SL bubble that responds to the driving ultrasound pressure. With the increase of driving pressure, some line emissions attached to the continuous spectrum may become increasingly clear, while other line emissions gradually become indistinct. - Highlights: • Line emissions of Tb(III) ions were observed without the presence of noble gases. • The halide ions help to generate a line emission during sonoluminescence. • The intensity of a line emission mainly depends on the bubble's temperature. • The definition of a line emission is related to the temperature of caviation bubble and the kind of host liquid.

Emission Line Correlations as Diagnostics of Quasar Winds

Science.gov (United States)

Sheldon, Keziah; Richards, Gordon

2018-01-01

We investigate correlations between UV and optical emission line properties for a sample of z~0.5 SDSS (Sloan Digital Sky Survey) quasars that have recently been observed by HST. The sample is designed to be comparable in luminosity to the existing reverberation mapping (RM) sample, but less biased in terms of their "eigenvector 1" properties. We seek to understand the conditions under which high-ionization emission lines become dominated by a wind. Our analysis takes advantage of spectral decomposition through Independent Component Analysis (ICA) and archival UV HST spectroscopy of SDSS quasars. With these data we will clarify the needs for RM analysis of quasars with wind-dominated emission features.

Shift and broadening of emission lines in Nd 3: YAG laser crystal ...

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Shift and broadening of emission lines in Nd3+:YAG laser crystal influenced by input energy. POURMAND SEYED EBRAHIM REZAEI ... Keywords. Nd3+:YAG crystal; heat generation; three-level emission lines; four-level emission lines; input energy.

Comportamiento de la cromósfera solar en la línea H-alpha durante el ciclo 23

Science.gov (United States)

Davoli, D.; Aquilano, R.; Missio, H.

Using the instrumental of the Observatorio Astronómico Municipal de Rosario (OAMR), we analyze the solar chromospheric activity during an approximate period of 11 years. The instrument is a Carl Zeiss refractor telescope of 150 mm aperture and 2250 mm of focal distance with monochromatic filter in the H-alpha line. We take as proxy for the solar activity the area covered by chromospheric plages. Simultaneously, we determine the relative wolf number from observations of the solar photosphere. We describe our technique and the results obtained. We observe 2 maxima of solar activity in the years 2000 and 2001 respectively, and a later decrease of this activity with low average values starting around 2006 that corresponds to the end of cycle 23. FULL TEXT IN SPANISH

Classification spectra of Sanduleak and Stephenson emission-line stars

International Nuclear Information System (INIS)

Allen, D.A.

1978-01-01

Low dispersion slit spectra of 89 emission-line stars are described; these stars were originally located and classified by Sanduleak and Stephenson in an objective-prism survey. The new data broadly confirm the classification scheme adopted by Sanduleak and Stephenson. In particular most of the large number of symbiotic stars they classified have been confirmed and others found. Many of these contain strong, broad emission bands in their red spectra. Two new Wolf-Rayet stars, one new planetary nebula and two new bipolar reflection nebulae involving hidden emission-line stars have been found. (author)

Classification spectra of Sanduleak and Stephenson emission-line stars

Energy Technology Data Exchange (ETDEWEB)

Allen, D A [Anglo-Australian Observatory, Epping (Australia)

1978-09-01

Low dispersion slit spectra of 89 emission-line stars are described; these stars were originally located and classified by Sanduleak and Stephenson in an objective-prism survey. The new data broadly confirm the classification scheme adopted by Sanduleak and Stephenson. In particular most of the large number of symbiotic stars they classified have been confirmed and others found. Many of these contain strong, broad emission bands in their red spectra. Two new Wolf-Rayet stars, one new planetary nebula and two new bipolar reflection nebulae involving hidden emission-line stars have been found.

Emission lines of Mg2 and Ca2 in planetary nebulae

International Nuclear Information System (INIS)

Gurzadyan, G.A.

1979-01-01

Conditions of exciting resonance lines in the emission of ionized magnesium (lambda lambda 2796+2803 Mg2) and calcium (lambda lambda 3934+3968 Ca2) in planetary nebulae have been analyzed. It is shown that the allowed lines are excited with the same mechanism, as the forbidden lines, i.e. inelastic electron collisions, but not with common fluorescence. The emission line lambda 2800 Mg2 of enough force can be observed only in the spectra of planetary nebulae with mean excitation (IC 2149) as well as in the spectra of diffuse nebulae. The line must not be observed in high-excited planetary nebulae (NGC 7026, 7662). The absence of emission lines H and K Ca2 in planetary nebulae spectra results from the fact, that their expected intensity is by 3-4 orders less than the intensity of the line lambda 2800 Mg2 or Hsub(β) hydrogen

X-ray Emission Line Spectroscopy of Nearby Galaxies

Science.gov (United States)

Wang, Daniel

What are the origins of the diffuse soft X-ray emission from non-AGN galaxies? Preliminary analysis of XMM-Newton RGS spectra shows that a substantial fraction of the emission cannot arise from optically-thin thermal plasma, as commonly assumed, and may originate in charge exchange at the interface with neutral gas. We request the support for a comprehensive observing, data analysis, and modeling program to spectroscopically determine the origins of the emission. First, we will use our scheduled XMM-Newton AO-10 368 ks observations of the nearest compact elliptical galaxy M32 to obtain the first spectroscopic calibration of the cumulative soft X-ray emission from the old stellar population and will develop a spectral model for the charge exchange, as well as analysis tools to measure the spatial and kinematic properties of the X-ray line- emitting plasma. Second, we will characterize the truly diffuse emission from the hot plasma and/or its interplay with the neutral gas in a sample of galactic spheroids and active star forming/starburst regions in nearby galaxies observed by XMM-Newton. In particular, we will map out the spatial distributions of key emission lines and measure (or tightly constrain) the kinematics of hot plasma outflows for a few X-ray-emitting regions with high-quality RGS data. For galaxies with insufficient counting statistics in individual emission lines, we will conduct a spectral stacking analysis to constrain the average properties of the X-ray-emitting plasma. We will use the results of these X-ray spectroscopic analyses, together with complementary X-ray CCD imaging/spectral data and observations in other wavelength bands, to test the models of the emission. In addition to the charge exchange, alternative scenarios such as resonance scattering and relic AGN photo-ionization will also be examined for suitable regions. These studies are important to the understanding of the relationship between the diffuse soft X-ray emission and various

The size of the narrow-line-emitting region in the Seyfert 1 galaxy NGC 5548 from emission-line variability

International Nuclear Information System (INIS)

Peterson, B. M.; Denney, K. D.; De Rosa, G.; Grier, C. J.; Pogge, R. W.; Kochanek, C. S.; Bentz, M. C.; Vestergaard, M.; Kilerci-Eser, E.; G. Galilei, Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy))" data-affiliation=" (Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy))" >Dalla Bontà, E.; G. Galilei, Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy))" data-affiliation=" (Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Vicolo dell'Osservatorio 3 I-35122, Padova (Italy))" >Ciroi, S.

2013-01-01

The narrow [O III] λλ4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow-line-emitting region has a radius of only 1-3 pc and is denser (n e ∼ 10 5 cm –3 ) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass. Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad Hβ emission-line light curves for the period 1988-2008.

The size of the narrow-line-emitting region in the Seyfert 1 galaxy NGC 5548 from emission-line variability

Energy Technology Data Exchange (ETDEWEB)

Peterson, B. M.; Denney, K. D.; De Rosa, G.; Grier, C. J.; Pogge, R. W.; Kochanek, C. S. [Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, 25 Park Place, Suite 610, Atlanta, GA 30303 (United States); Vestergaard, M.; Kilerci-Eser, E. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Dalla Bontà, E.; Ciroi, S. [Dipartimento di Fisica e Astronomia " G. Galilei," Università di Padova, Vicolo dell' Osservatorio 3 I-35122, Padova (Italy)

2013-12-20

The narrow [O III] λλ4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow-line-emitting region has a radius of only 1-3 pc and is denser (n {sub e} ∼ 10{sup 5} cm{sup –3}) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass. Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad Hβ emission-line light curves for the period 1988-2008.

Extended emission-line regions in active galaxies

International Nuclear Information System (INIS)

Hutchings, J.B.; Hickson, P.

1988-01-01

Long-slit spectra of four active galaxies in the redshift range 0.06-0.10 are presented. Two have interacting companions. Spectra of the galaxies show extended narrow emission lines in all cases. Continuum color changes, emision-line ratio changes, and velocity changes with 1 arcsec resolution can be detected. Relative velocities between AGN and companion galaxies are also given. These objects appear to lie in galaxies in which there is considerable star-formation activity, and very extended line emision. 20 references

Emission line spectra of Herbig-Haro objects

International Nuclear Information System (INIS)

Brugel, E.W.; Boehm, K.H.; Mannery, E.

1981-01-01

Spectrophotometric data have been obtained for 12 Herbig-Haro nebulae with the multichannel spectrometer on the Mt. Palomar 5.08 m telescope and with the image intensified dissector scanner on the Kitt Peak 2.13 m telescope. Optical emission line fluxes are presented for the following Herbig-Haro objects: H-H 1 (NW), H-H 1 (SE), H-H 2A, H-H 2G, H-H 2H, H-H 3, H-H 7, H-H 11, H-H 24A, H-H 30, H-H 32, and H-H 40. Values for the electron temperature and electron density have been determined for 10 of these condensations. Significant inhomogeneities in the line-forming regions of these H-H objects are indicated by the derived N/sub e/-T/sub e/ diagrams. Empirical two-component density models have been constructed to interpret the emission line spectra of the five brightest condensations. Slightly less satisfactory homogeneous models are presented for the remaining five objects

An emission-line model for AM Herculis systems

International Nuclear Information System (INIS)

Ferrario, L.; Tuohy, I.R.; Wickramasinghe, D.T.; Australian National Univ., Canberra)

1989-01-01

The optical spectra of the AM Herculis binaries are characterized by extremely complex emission lines whose profiles can be resolved into at least three components which are formed in different regions of the accretion stream leading from the companion star toward the magnetic white dwarf. A theoretical model is presented for the radial velocity and velocity dispersion of the broad emission line component assuming that it originates mainly in the gas which is diverted out of the orbital plane and funneled onto the white dwarf surface along magnetic field lines. The model is used to locate the line-forming region in three AM Her variables: E1405-451, CW 1103+254, and EXO 033319-2554.2, using as constraints the radial velocity and velocity dispersion data. The analyses of these systems show that the material is threaded by the magnetic field in a very azimuthally extended coupling region located 0.5-0.75 of the way between the white dwarf and the inner Lagrange point. 36 refs

Thermal wind model for the broad emission line region of quasars

International Nuclear Information System (INIS)

Weymann, R.J.; Scott, J.S.; Schiano, A.V.R.; Christiansen, W.A.

1982-01-01

Arguments are summarized for supposing that the clouds giving rise to the broad emission lines of QSOs are confined by the pressure of an expanding thermal gas and that a flux of relativistic particles with luminosity comparable to the photon luminosity streams through this gas. The resulting heating and momentum deposition produces a transonic thermal wind whose dynamical properties are calculated in detail. This wind accelerates and confines the emission line clouds, thereby producing the broad emission line (BEL) profiles. In a companion paper, the properties of the wind at much larger distances (approx.kpc) than the BEL region are used to explain the production of the broad absorption lines (BAL) observed in some QSOs. The same set of wind parameters can account for the properties of both the BEL and BAL regions, and this unification in the physical description of the BEL and BAL regions is one of the most important advantages of this model. A characteristic size of approx.1 pc for the QSO emission line region is one consequence of the model. This characteristic size is shown to depend upon luminosity in such a way that the ionization parameter is roughly constant over a wide range of luminosities. An X-ray luminosity due to thermal bremsstrahlung of approx.1%--10% of the optical luminosity is another consequence of the model. The trajectories of clouds under the combined influence of ram pressure acceleration and radiative acceleration are calculated. From these trajectories emission line profiles are also calculated, as well as the wind and cloud parameters yielding profiles in fair agreement with observed profiles explored. Opacity in the wind due to electron scattering displaces the line cores of optically thin lines to the blue. This is roughly compensated for by the redward skewing of optically thick lines due to preferential emission of photons from the back side of the clouds.void rapid depletion due to Compton losses are discussed

Structure, shape, and evolution of radiatively accelerated QSO emission-line clouds

International Nuclear Information System (INIS)

Blumenthal, G.R.; Mathews, W.G.

1979-01-01

The possibility that the broad emission-line regions of QSOs and active galactic nuclei are formed by a multitude of small clouds which are radiatively accelerated is discussed. Although this model is by no means certain at present, it has four virtues: (1) Observed emission-line widths can be produced with observationally allowed electron densities, UV luminosities, and ionization levels. (2) The acceleration force is coherent in each cloud are found. (3) Reasonable line profiles can result for all emission lines. (4) Photoionization of hydrogen accounts for both heating and acceleration of the emission-line gas. A self-consistent model is developed for the structure, shape, and evolution of radiatively accelerated clouds. The shape varies with cloud mass, and two distinct types of clouds. Fully ionized clouds of very low mass approach a nearly spherical shape. However, all clouds having masses greater than some critical mass adopt a ''pancake'' shape. The condition for constant cloud mass in the cloud frame is shown to be equivalent to the equation of motion of a cloud in the rest frame of the QSO. The emission-line profiles can be sensitive to radial variations in the properties of the intercloud medium, and those properties that correspond to observed profiles are discussed. Finally, the covering factor of a system of pancake clouds is estimated along with the total number of clouds required--approximately 10 14 clouds in each QSO

Unification in the low radio luminosity regime: evidence from optical line emission

Science.gov (United States)

Marchã, M. J. M.; Browne, I. W. A.; Jethava, N.; Antón, S.

2005-08-01

We address the question of whether or not the properties of all low-luminosity flat spectrum radio sources, not just the obvious BL Lac objects, are consistent with them being the relativistically beamed counterparts of the low radio luminosity radio galaxies (the Fanaroff-Riley type 1, FR I). We have accumulated data on a well-defined sample of low redshift, core-dominated, radio sources all of which have one-sided core-jet structures seen with very long baseline interferometry, just like most BL Lac objects. We first compare the emission-line luminosities of the sample of core-dominated radio sources with a matched sample of FR I radio galaxies. The emission lines in the core-dominated objects are on average significantly more luminous than those in the comparison sample, inconsistent with the simplest unified models in which there is no orientation dependence of the line emission. We then compare the properties of our core-dominated sample with those of a sample of radio-emitting UGC galaxies selected without bias to core strength. The core-dominated objects fit well on the UGC correlation between line emission and radio core strength found by Verdoes Kleijn et al. The results are not consistent with all the objects participating in a simple unified model in which the observed line emission is orientation independent, though they could fit a single, unified model provided that some FR I radio galaxies have emission line regions that become more visible when viewed along the jet axis. However, they are equally consistent with a scenario in which, for the majority of objects, beaming has minimal effect on the observed core luminosities of a large fraction of the FR I population and that intrinsically stronger cores simply give rise to stronger emission lines. We conclude that FR I unification is much more complex than usually portrayed, and models combining beaming with an intrinsic relationship between core and emission line strengths need to be explored.

Emission-line maps with OSIRIS-TF: The case of M101

Science.gov (United States)

Méndez-Abreu, J.

2013-05-01

We investigate the suitability of GTC/OSIRIS Tunable Filters (TFs) for obtaining emission-line maps of extended objects. We developed a technique to reconstruct an emission-line image from a set of images taken at consecutive central wavelengths. We demonstrate the feasibility of the reconstruction method by generating a flux calibrated Hα image of the well-known spiral galaxy M101. We tested our emission-line fluxes and ratios by using data present in the literature. We found that the differences in both Hα fluxes and N II/Hα line ratios are ~15% and ~50%, respectively. These results are fully in agreement with the expected values for our observational setup. The proposed methodology will allow us to use OSIRIS/GTC to perform accurate spectrophotometric studies of extended galaxies in the local Universe.

New Constraints on Quasar Broad Absorption and Emission Line Regions from Gravitational Microlensing

Energy Technology Data Exchange (ETDEWEB)

Hutsemékers, Damien; Braibant, Lorraine; Sluse, Dominique [Institut d' Astrophysique et de Géophysique, Université de Liège, Liège (Belgium); Anguita, Timo [Departamento de Ciencias Fisicas, Universidad Andres Bello, Santiago (Chile); Goosmann, René, E-mail: hutsemekers@astro.ulg.ac.be [Observatoire Astronomique de Strasbourg, Université de Strasbourg, Strasbourg (France)

2017-09-29

Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the intrinsic absorption hidden in the P Cygni-type line profiles observed in the broad absorption line quasar H1413+117, as well as the existence of an extended continuum source. In addition, polarization microlensing provides constraints on the scattering region. In the quasar Q2237+030, microlensing differently distorts the Hα and CIV broad emission line profiles, indicating that the low- and high-ionization broad emission lines must originate from regions with distinct kinematical properties. We also present simulations of the effect of microlensing on line profiles considering simple but representative models of the broad emission line region. Comparison of observations to simulations allows us to conclude that the Hα emitting region in Q2237+030 is best represented by a Keplerian disk.

New Constraints on Quasar Broad Absorption and Emission Line Regions from Gravitational Microlensing

Directory of Open Access Journals (Sweden)

Damien Hutsemékers

2017-09-01

Full Text Available Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the intrinsic absorption hidden in the P Cygni-type line profiles observed in the broad absorption line quasar H1413+117, as well as the existence of an extended continuum source. In addition, polarization microlensing provides constraints on the scattering region. In the quasar Q2237+030, microlensing differently distorts the Hα and CIV broad emission line profiles, indicating that the low- and high-ionization broad emission lines must originate from regions with distinct kinematical properties. We also present simulations of the effect of microlensing on line profiles considering simple but representative models of the broad emission line region. Comparison of observations to simulations allows us to conclude that the Hα emitting region in Q2237+030 is best represented by a Keplerian disk.

Wolf-Rayet stars featured in emission-line galaxies

International Nuclear Information System (INIS)

Kunth, D.

1982-01-01

In the galaxy Tololo 3 (NGC 3125) recent observations by the author and Sargent (1981) have revealed the presence of an unusual strong and broad He II 4686 emission. The origin of this line together with some nitrogen lines (e.g. N V 4620 and N III 4638) is attributed to Wolf-Rayet stars, mostly of WN types. (Auth.)

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.

THE NATURE OF ACTIVE GALACTIC NUCLEI WITH VELOCITY OFFSET EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

Müller-Sánchez, F.; Comerford, J. [Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Harrison, F. A. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2016-10-10

We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field spectroscopy to probe the morphology and kinematics of the ionized gas in four velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey. These objects possess optical emission lines that are offset in velocity from systemic as measured from stellar absorption features. At a resolution of ∼0.″18, OSIRIS allows us to distinguish which velocity offset emission lines are produced by the motion of an AGN in a dual supermassive black hole system, and which are produced by outflows or other kinematic structures. In three galaxies, J1018+2941, J1055+1520, and J1346+5228, the spectral offset of the emission lines is caused by AGN-driven outflows. In the remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that contains the peak of Pa α emission 0.″2 from the center of the galaxy. The most plausible explanation for the origin of this spatially and kinematically offset peak is that it is a region of enhanced Pa α emission located at the intersection zone between the nuclear disk and the bar of the galaxy. In all four objects, the peak of ionized gas emission is not spatially coincident with the center of the galaxy as traced by the peak of the near-IR continuum emission. The peaks of ionized gas emission are spatially offset from the galaxy centers by 0.″1–0.″4 (0.1–0.7 kpc). We find that the velocity offset originates at the location of this peak of emission, and the value of the offset can be directly measured in the velocity maps. The emission-line ratios of these four velocity-offset AGNs can be reproduced only with a mixture of shocks and AGN photoionization. Shocks provide a natural explanation for the origin of the spatially and spectrally offset peaks of ionized gas emission in these galaxies.

Line Emission and X-ray Line Polarization of Multiply Ionized Mo Ions

Science.gov (United States)

Petkov, E. E.; Safronova, A. S.; Kantsyrev, V. L.; Shlyaptseva, V. V.; Stafford, A.; Safronova, U. I.; Shrestha, I. K.; Schultz, K. A.; Childers, R.; Cooper, M. C.; Beiersdorfer, P.; Hell, N.; Brown, G. V.

2016-10-01

We present a comprehensive experimental and theoretical study of the line emission from multiply ionized Mo ions produced by two different sets of experiments: at LLNL EBIT and the pulsed power generator Zebra at UNR. Mo line emission and polarization measurements were accomplished at EBIT for the first time. In particular, benchmarking experiments at the LLNL EBIT with Mo ions produced at electron beam energies from 2.75 keV up to 15 keV allowed us to break down these very complicated spectra into spectra with only few ionization stages and to select processes that influence them as well as to measure line polarization. The EBIT data were recorded using the EBIT Calorimeter Spectrometer and a crystal spectrometer with a Ge crystal. X-ray Mo spectra and pinhole images were collected from Z-pinch plasmas produced from various wire loads. Non-LTE modeling, high-precision relativistic atomic and polarization data were used to analyze L-shell Mo spectra. The influence of different plasma processes including electron beams on Mo line radiation is summarized. This work was supported by NNSA under DOE Grant DE-NA0002954. Experiments at the NTF/UNR were funded in part by DE-NA0002075. Work at LLNL was performed under the auspices of the U.S. DOE under contract DE-AC52-07NA27344.

Analyais of solar X-ray emission line profiles

International Nuclear Information System (INIS)

Burek, A.J.; Marrus, D.M.; Blake, R.L.; Fenimore, E.E.

1981-01-01

We report results of the analysis of the X-ray emission line profiles for the Ne X La and Fe XVII 4d 1 P 1 lines produced in an active region that was undergoing a radio and X-ray gradual rise and fall (GRF) in intensity. The spectra were obtained with collimated Bragg spectrometers launched on a rocket from White Sands Missile Range on 1976 March 26. Using a crystal of ammonium acid phthalate, we have fully resolved the Ne X La and Fe XVII 4d 1 P 1 lines, permitting an accurate determinination of the Ne X La intensity and allowing Doppler broadened profiles for lines formed from ions having greatly different atomic mass and charge to be measured. An isothermal model derived from the Ne IX/Ne X resonance line intensity ratio gives an electron temperature of 3.4 x 10 6 K. An isothermal model, however, fails to account for the intensities of all lines and continuum observed. All multitemperature models that do reproduce the observed relative line intensities require the presence of a hot plasma component with an electron temperature in excess of 5 x 10 6 K. The presence of a high temperature component is also suggested by the measured line to continuum ratio of 3.6 in the 12--15 A wavelength interval. Interpretation of the line profiles in terms of a multitemperature model requires an rms turbulence velocity of 48 +- 15 km s -1 for Fe XVII 1 P 1 and 74 +- 54 km s - 2exclamation for Ne X La at the 95% confidence level. Collimated scans across the active region show the presence of a compact source of intense X-ray emission close to the magnetic neutral line, which is very probably the GRF plasma

A Link Between X-ray Emission Lines and Radio Jets in 4U 1630-47?

Science.gov (United States)

Neilsen, Joseph; Coriat, Mickaël; Fender, Rob; Lee, Julia C.; Ponti, Gabriele; Tzioumis, A.; Edwards, Phillip; Broderick, Jess

2014-06-01

Recently, Díaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. We present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find a strong disk wind but no evidence for any relativistic X-ray emission lines. Indeed, despite ˜5× brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is ˜20× weaker than the line observed by Díaz Trigo et al. Thus we can conclusively say that radio emission is not universally associated with relativistically Doppler-shifted emission lines in 4U 1630-47. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby ISM, in which case the X-ray emission lines might be unrelated to the radio emission.

Millimeter emission lines in Orion A

International Nuclear Information System (INIS)

Lovas, F.J.; Johnson, D.R.; Buhl, D.; Snyder, L.E.

1976-01-01

During the course of a search of Orion A for signals from three large, organic molecules, several millimeter wave lines from known interstellar molecules were observed. Results of observations on methanol (CH 3 OH), methyl cyanide (CH 3 CN), methyl acetylene (CH 3 CCH), acetaldehyde (CH 3 CHO) and 29 SiO are reported here. Emission signals from two hydrogen recombination lines (H41α and H42α) detected from the H II region of Orion A are also reported. Negative results were obtained for several millimeter wave transitions of ethylene oxide (CH 2 OCH 2 ), acetone [(CH 3 ) 2 CO], and cyclopropenone (HCCOCH)

X-ray emission lines from photoionized plasmas

International Nuclear Information System (INIS)

Liedahl, D.A.

1992-11-01

Plasma emission codes have become a standard tool for the analysis of spectroscopic data from cosmic X-ray sources. However, the assumption of collisional equilibrium, typically invoked in these codes, renders them inapplicable to many important astrophysical situations, particularly those involving X-ray photoionized nebulae, which are likely to exist in the circumsource environments of compact X-ray sources. X-ray line production in a photoionized plasma is primarily the result of radiative cascades following recombination. Through the development of atomic models of several highly-charged ions, this work extends the range of applicability of discrete spectral models to plasmas dominated by recombination. Assuming that ambient plasma conditions lie in the temperature range 10 5 --10 6 K and the density range 10 11 --10 16 cm -3 , X-ray line spectra are calculated over the wavelength range 5--45 angstrom using the HULLAC atomic physics package. Most of the work focuses on the Fe L-shell ions. Line ratios of the form (3s-2p)/(3d-2p) are shown to characterize the principal mode of line excitation, thereby providing a simple signature of photoionization. At electron densities exceeding 10 12 cm -3 , metastable state populations in the ground configurations approach their LTE value, resulting in the enrichment of the Fe L-shell recombination spectrum and a set of density-sensitive X-ray line ratios. Radiative recombination continua and emission lines produced selectively by Δn = 0 dielectronic recombination are shown to provide two classes of temperature diagnostics. Because of the extreme overionization, the recombination continua are expected to be narrow (ΔE/E much-lt 1), with ΔE = kT. Dielectronic recombination selectively drives radiative transitions that originate on states with vacancies in the 2s subshell, states that are inaccessible under pure RR population kinetics

Dark matter line emission constraints from NuSTAR observations of the Bullet Cluster

DEFF Research Database (Denmark)

Riemer-Sørensen, S.; Wik, D.; Madejski, G.

2015-01-01

Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. We present the first search for dark matter line emission in the range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line...... emission and instead we derive upper limits (95% CL) on the flux, and interpret these constraints in the context of sterile neutrinos and more generic dark matter candidates. NuSTAR does not have the sensitivity to constrain the recently claimed line detection at , but improves on the constraints...... for energies of 10–25 keV....

Measurement of the deuterium Balmer series line emission on EAST

Energy Technology Data Exchange (ETDEWEB)

Wu, C. R.; Xu, Z.; Jin, Z.; Zhang, P. F. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031 (China); Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, Anhui 230031 (China); Huang, J., E-mail: juan.huang@ipp.ac.cn; Gao, W.; Gao, W.; Chang, J. F.; Xu, J. C.; Duan, Y. M.; Chen, Y. J.; Zhang, L.; Wu, Z. W.; Li, J. G. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031 (China); Hou, Y. M. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2016-11-15

Volume recombination plays an important role towards plasma detachment for magnetically confined fusion devices. High quantum number states of the Balmer series of deuterium are used to study recombination. On EAST (Experimental Advanced Superconducting Tokamak), two visible spectroscopic measurements are applied for the upper/lower divertor with 13 channels, respectively. Both systems are coupled with Princeton Instruments ProEM EMCCD 1024B camera: one is equipped on an Acton SP2750 spectrometer, which has a high spectral resolution ∼0.0049 nm with 2400 gr/mm grating to measure the D{sub α}(H{sub α}) spectral line and with 1200 gr/mm grating to measure deuterium molecular Fulcher band emissions and another is equipped on IsoPlane SCT320 using 600 gr/mm to measure high-n Balmer series emission lines, allowing us to study volume recombination on EAST and to obtain the related line averaged plasma parameters (T{sub e}, n{sub e}) during EAST detached phases. This paper will present the details of the measurements and the characteristics of deuterium Balmer series line emissions during density ramp-up L-mode USN plasma on EAST.

Spectrophotometry of emission-line stars in the magellanic clouds

Science.gov (United States)

Bohannan, Bruce

1990-01-01

The strong emission lines in the most luminous stars in the Magellanic Clouds indicate that these stars have such strong stellar winds that their photospheres are so masked that optical absorption lines do not provide an accurate measure of photospheric conditions. In the research funded by this grant, temperatures and gravities of emission-line stars both in the Large (LMC) and Small Magellanic Clouds (SMC) have been measured by fitting of continuum ultraviolet-optical fluxes observed with IUE with theoretical model atmospheres. Preliminary results from this work formed a major part of an invited review 'The Distribution of Types of Luminous Blue Variables'. Interpretation of the IUE observations obtained in this grant and archive data were also included in a talk at the First Boulder-Munich Hot Stars Workshop. Final results of these studies are now being completed for publication in refereed journals.

Inferring physical properties of galaxies from their emission-line spectra

Science.gov (United States)

Ucci, G.; Ferrara, A.; Gallerani, S.; Pallottini, A.

2017-02-01

We present a new approach based on Supervised Machine Learning algorithms to infer key physical properties of galaxies (density, metallicity, column density and ionization parameter) from their emission-line spectra. We introduce a numerical code (called GAME, GAlaxy Machine learning for Emission lines) implementing this method and test it extensively. GAME delivers excellent predictive performances, especially for estimates of metallicity and column densities. We compare GAME with the most widely used diagnostics (e.g. R23, [N II] λ6584/Hα indicators) showing that it provides much better accuracy and wider applicability range. GAME is particularly suitable for use in combination with Integral Field Unit spectroscopy, both for rest-frame optical/UV nebular lines and far-infrared/sub-millimeter lines arising from photodissociation regions. Finally, GAME can also be applied to the analysis of synthetic galaxy maps built from numerical simulations.

Shock-related radio emission during coronal mass ejection lift-off?

OpenAIRE

Pohjolainen, S.

2008-01-01

Aims: We identify the source of fast-drifting decimetric-metric radio emission that is sometimes observed prior to the so-called flare continuum emission. Fast-drift structures and continuum bursts are also observed in association with coronal mass ejections (CMEs), not only flares. Methods: We analyse radio spectral features and images acquired at radio, H-alpha, EUV, and soft X-ray wavelengths, during an event close to the solar limb on 2 June 2003. Results: The fast-drifting decimetric-met...

EMISSION LINES BETWEEN 1 AND 2 keV IN COMETARY X-RAY SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Ewing, Ian; Christian, Damian J. [Department of Physics and Astronomy, California State University, 18111 Nordhoff Street, Northridge, CA 91330 (United States); Bodewits, Dennis [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Dennerl, Konrad [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85741 Garching Germany (Germany); Lisse, Carey M. [Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723 (United States); Wolk, Scott J., E-mail: ian.ewing.794@my.csun.edu, E-mail: daman.christian@csun.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-01-20

We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

The photoionization mechanism of LINERs - Stellar and nonstellar

Science.gov (United States)

Ho, Luis C.; Filippenko, Alexei V.

1993-01-01

We present high quality spectroscopic observations of a sample of 14 LINERs. Starlight removal is achieved by the subtraction of a suitable absorption-line 'template' galaxy, allowing accurate measurements of emission lines. We use these line fluxes to examine the possible excitation mechanisms of LINERs. We suggest that LINERs with weak forbidden O I 6300-A emission may be H II regions photoionized by unusually hot O-type stars. LINERs with forbidden O I/H-alpha approximately greater than 1/6 may be powered by photoionization from a nonstellar continuum. This is supported by the detection of broad H-alpha emission, a correlation between line width and critical density, and pointlike X-ray emission in several of these objects.

A LINK BETWEEN X-RAY EMISSION LINES AND RADIO JETS IN 4U 1630-47?

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Joseph [Department of Astronomy, Boston University, Boston, MA 02215 (United States); Coriat, Mickaël [Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa); Fender, Rob; Broderick, Jess W. [Department of Physics, Oxford University, Oxford OX1 3RH (United Kingdom); Lee, Julia C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Ponti, Gabriele [Max Planck Institute fur Extraterrestriche Physik, D-85748 Garching (Germany); Tzioumis, Anastasios K.; Edwards, Philip G., E-mail: neilsenj@bu.edu [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)

2014-03-20

Recently, Díaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite ∼5 × brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is ≳ 20 × weaker than the line observed by Díaz Trigo et al. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby interstellar medium, in which case the X-ray emission lines might be unrelated to the radio emission.

A LINK BETWEEN X-RAY EMISSION LINES AND RADIO JETS IN 4U 1630-47?

International Nuclear Information System (INIS)

Neilsen, Joseph; Coriat, Mickaël; Fender, Rob; Broderick, Jess W.; Lee, Julia C.; Ponti, Gabriele; Tzioumis, Anastasios K.; Edwards, Philip G.

2014-01-01

Recently, Díaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite ∼5 × brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is ≳ 20 × weaker than the line observed by Díaz Trigo et al. We explore several scenarios that could explain our differing results, including variations in the geometry of the jet or a mass-loading process or jet baryon content that evolves with the accretion state of the black hole. We also consider the possibility that the radio emission arises in an interaction between a jet and the nearby interstellar medium, in which case the X-ray emission lines might be unrelated to the radio emission

NEBULAR EMISSION-LINES IN IRAS 10215-5916

NARCIS (Netherlands)

GARCIALARIO, P; MANCHADO, A; PARTHASARATHY, M; POTTASCH, [No Value

From low and high resolution spectroscopic observations of IRAS 10215 - 5916 we have discovered the presence of nebular emission lines in this G-type supergiant star in the post-AGB stage. From its high resolution spectrum we derived an expansion velocity of 17 km s-1 for the shell, similar to the

Extreme Ultraviolet Emission Lines of Iron Fe XI-XIII

Science.gov (United States)

Lepson, Jaan; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Brickhouse, N. S.; Dupree, A. K.

2013-04-01

The extreme ultraviolet (EUV) spectral region (ca. 20--300 Å) is rich in emission lines from low- to mid-Z ions, particularly from the middle charge states of iron. Many of these emission lines are important diagnostics for astrophysical plasmas, providing information on properties such as elemental abundance, temperature, density, and even magnetic field strength. In recent years, strides have been made to understand the complexity of the atomic levels of the ions that emit the lines that contribute to the richness of the EUV region. Laboratory measurements have been made to verify and benchmark the lines. Here, we present laboratory measurements of Fe XI, Fe XII, and Fe XIII between 40-140 Å. The measurements were made at the Lawrence Livermore electron beam ion trap (EBIT) facility, which has been optimized for laboratory astrophysics, and which allows us to select specific charge states of iron to help line identification. We also present new calculations by the Hebrew University - Lawrence Livermore Atomic Code (HULLAC), which we also utilized for line identification. We found that HULLAC does a creditable job of reproducing the forest of lines we observed in the EBIT spectra, although line positions are in need of adjustment, and line intensities often differed from those observed. We identify or confirm a number of new lines for these charge states. This work was supported by the NASA Solar and Heliospheric Program under Contract NNH10AN31I and the DOE General Plasma Science program. Work was performed in part under the auspices of the Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC52-07NA27344.

Constraints on the outer radius of the broad emission line region of active galactic nuclei

Science.gov (United States)

Landt, Hermine; Ward, Martin J.; Elvis, Martin; Karovska, Margarita

2014-03-01

Here we present observational evidence that the broad emission line region (BELR) of active galactic nuclei (AGN) generally has an outer boundary. This was already clear for sources with an obvious transition between the broad and narrow components of their emission lines. We show that the narrow component of the higher-order Paschen lines is absent in all sources, revealing a broad emission line profile with a broad, flat top. This indicates that the BELR is kinematically separate from the narrow emission line region. We use the virial theorem to estimate the BELR outer radius from the flat top width of the unblended profiles of the strongest Paschen lines, Paα and Paβ, and find that it scales with the ionizing continuum luminosity roughly as expected from photoionization theory. The value of the incident continuum photon flux resulting from this relationship corresponds to that required for dust sublimation. A flat-topped broad emission line profile is produced by both a spherical gas distribution in orbital motion and an accretion disc wind if the ratio between the BELR outer and inner radius is assumed to be less than ˜100-200. On the other hand, a pure Keplerian disc can be largely excluded, since for most orientations and radial extents of the disc the emission line profile is double-horned.

Frequency lock of a dye laser emission on iron atomic line top

International Nuclear Information System (INIS)

Durand, P.

1995-03-01

The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

Shift and broadening of emission lines in Nd :YAG laser crystal ...

Indian Academy of Sciences (India)

1Department of Optics and Laser Engineering, Estahban Branch, Islamic Azad ... Nd3+:YAG crystal; heat generation; three-level emission lines; four-level emission ... Modelling of high-power solid-state lasers requires precise knowledge of ...

H{alpha} ACTIVITY OF OLD M DWARFS: STELLAR CYCLES AND MEAN ACTIVITY LEVELS FOR 93 LOW-MASS STARS IN THE SOLAR NEIGHBORHOOD

Energy Technology Data Exchange (ETDEWEB)

Robertson, Paul; Endl, Michael; Cochran, William D.; Dodson-Robinson, Sarah E., E-mail: paul@astro.as.utexas.edu [Department of Astronomy and McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States)

2013-02-10

Through the McDonald Observatory M Dwarf Planet Search, we have acquired nearly 3000 high-resolution spectra of 93 late-type (K5-M5) stars over more than a decade using the High Resolution Spectrograph on the Hobby-Eberly Telescope. This sample provides a unique opportunity to investigate the occurrence of long-term stellar activity cycles for low-mass stars. In this paper, we examine the stellar activity of our targets as reflected in the H{alpha} feature. We have identified periodic signals for six stars, with periods ranging from days to more than 10 years, and find long-term trends for seven others. Stellar cycles with P {>=} 1 year are present for at least 5% of our targets. Additionally, we present an analysis of the time-averaged activity levels of our sample, and search for correlations with other stellar properties. In particular, we find that more massive, earlier type (M0-M2) stars tend to be more active than later type dwarfs. Furthermore, high-metallicity stars tend to be more active at a given stellar mass. We also evaluate H{alpha} variability as a tracer of activity-induced radial velocity (RV) variation. For the M dwarf GJ 1170, H{alpha} variation reveals stellar activity patterns matching those seen in the RVs, mimicking the signal of a giant planet, and we find evidence that the previously identified stellar activity cycle of GJ 581 may be responsible for the recently retracted planet f in that system. In general, though, we find that H{alpha} is not frequently correlated with RV at the precision (typically 6-7 m s{sup -1}) of our measurements.

EMISSION SIGNATURES FROM SUB-PARSEC BINARY SUPERMASSIVE BLACK HOLES. I. DIAGNOSTIC POWER OF BROAD EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Khai; Bogdanović, Tamara [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta GA 30332 (United States)

2016-09-10

Motivated by advances in observational searches for sub-parsec supermassive black hole binaries (SBHBs) made in the past few years, we develop a semi-analytic model to describe spectral emission-line signatures of these systems. The goal of this study is to aid the interpretation of spectroscopic searches for binaries and to help test one of the leading models of binary accretion flows in the literature: SBHB in a circumbinary disk. In this work, we present the methodology and a comparison of the preliminary model with the data. We model SBHB accretion flows as a set of three accretion disks: two mini-disks that are gravitationally bound to the individual black holes and a circumbinary disk. Given a physically motivated parameter space occupied by sub-parsec SBHBs, we calculate a synthetic database of nearly 15 million broad optical emission-line profiles and explore the dependence of the profile shapes on characteristic properties of SBHBs. We find that the modeled profiles show distinct statistical properties as a function of the semimajor axis, mass ratio, eccentricity of the binary, and the degree of alignment of the triple disk system. This suggests that the broad emission-line profiles from SBHB systems can in principle be used to infer the distribution of these parameters and as such merit further investigation. Calculated profiles are more morphologically heterogeneous than the broad emission lines in observed SBHB candidates and we discuss improved treatment of radiative transfer effects, which will allow a direct statistical comparison of the two groups.

EMISSION SIGNATURES FROM SUB-PARSEC BINARY SUPERMASSIVE BLACK HOLES. I. DIAGNOSTIC POWER OF BROAD EMISSION LINES

International Nuclear Information System (INIS)

Nguyen, Khai; Bogdanović, Tamara

2016-01-01

Motivated by advances in observational searches for sub-parsec supermassive black hole binaries (SBHBs) made in the past few years, we develop a semi-analytic model to describe spectral emission-line signatures of these systems. The goal of this study is to aid the interpretation of spectroscopic searches for binaries and to help test one of the leading models of binary accretion flows in the literature: SBHB in a circumbinary disk. In this work, we present the methodology and a comparison of the preliminary model with the data. We model SBHB accretion flows as a set of three accretion disks: two mini-disks that are gravitationally bound to the individual black holes and a circumbinary disk. Given a physically motivated parameter space occupied by sub-parsec SBHBs, we calculate a synthetic database of nearly 15 million broad optical emission-line profiles and explore the dependence of the profile shapes on characteristic properties of SBHBs. We find that the modeled profiles show distinct statistical properties as a function of the semimajor axis, mass ratio, eccentricity of the binary, and the degree of alignment of the triple disk system. This suggests that the broad emission-line profiles from SBHB systems can in principle be used to infer the distribution of these parameters and as such merit further investigation. Calculated profiles are more morphologically heterogeneous than the broad emission lines in observed SBHB candidates and we discuss improved treatment of radiative transfer effects, which will allow a direct statistical comparison of the two groups.

The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

Science.gov (United States)

Spinoglio, Luigi; Smith, Howard A.; Gonzalez-Alfonso, Eduardo; Fisher, Jacqueline

2005-01-01

We report on the analysis of the first complete far-infrared spectrum (43-197 microns) of the Seyfert 2 galaxy NGC 1068 as observed with the Long Wavelength Spectrometer (LWS) onboard the Infrared Space Observatory (ISO). In addition to the 7 expected ionic fine structure emission lines, the OH rotational lines at 79, 119 and 163 microns were all detected in emission, which is unique among galaxies with full LWS spectra, where the 119 micron line, where detected, is always in absorption. The observed line intensities were modelled together with IS0 Short Wavelength Spectrometer (SWS) and optical and ultraviolet line intensities from the literature, considering two independent emission components: the AGN component and the starburst component in the circumnuclear ring of approximately 3kpc in size. Using the UV to mid-IR emission line spectrum to constrain the nuclear ionizing continuum, we have confirmed previous results: a canonical power-law ionizing spectrum is a poorer fit than one with a deep absorption trough, while the presence of a big blue bump is ruled out. Based on the instantaneous starburst age of 5 Myr constrained by the Br gamma equivalent width in the starburst ring, and starburst synthesis models of the mid- and far-infrared fine-structure line emission, a low ionization parameter (U=10(exp -3.5)) and low densities (n=100 cm (exp -3)) are derived. Combining the AGN and starburst components, we succeed in modeling the overall UV to far-IR atomic spectrum of SGC 1068, reproducing the line fluxes to within a factor 2.0 on average with a standard deviation of 1.4. The OH 119 micron emission indicates that the line is collisionally excited, and arises in a warm and dense region. The OH emission has been modeled using spherically symmetric, non-local, non-LTE radiative transfer models. The models indicate that the bulk of the emission arises from the nuclear region, although some extended contribution from the starburst is not ruled out. The OH abundance

PROBING THE FLARE ATMOSPHERES OF M DWARFS USING INFRARED EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Sarah J.; Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Wisniewski, John P.; Tofflemire, Benjamin M., E-mail: sjschmidt@astro.washington.edu [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada (Canada)

2012-01-20

We present the results of a campaign to monitor active M dwarfs using infrared spectroscopy, supplemented with optical photometry and spectroscopy. We detected 16 flares during nearly 50 hr of observations on EV Lac, AD Leo, YZ CMi, and VB 8. The three most energetic flares also showed infrared emission, including the first reported detections of P{beta}, P{gamma}, He I {lambda}10830, and Br{gamma} during an M dwarf flare. The strongest flare ({Delta}u = 4.02 on EV Lac) showed emission from H{gamma}, H{delta}, He I {lambda}4471, and Ca II K in the UV/blue and P{beta}, P{gamma}, P{delta}, Br{gamma}, and He I {lambda}10830 in the infrared. The weaker flares ({Delta}u = 1.68 on EV Lac and {Delta}U = 1.38 on YZ CMi) were only observed with photometry and infrared spectroscopy; both showed emission from P{beta}, P{gamma}, and He I {lambda}10830. The strongest infrared emission line, P{beta}, occurred in the active mid-M dwarfs with a duty cycle of {approx}3%-4%. To examine the most energetic flare, we used the static NLTE radiative transfer code RH to produce model spectra based on a suite of one-dimensional model atmospheres. Using a hotter chromosphere than previous one-dimensional atmospheric models, we obtain line ratios that match most of the observed emission lines.

Measurement of X-ray emission efficiency for K-lines.

Science.gov (United States)

Procop, M

2004-08-01

Results for the X-ray emission efficiency (counts per C per sr) of K-lines for selected elements (C, Al, Si, Ti, Cu, Ge) and for the first time also for compounds and alloys (SiC, GaP, AlCu, TiAlC) are presented. An energy dispersive X-ray spectrometer (EDS) of known detection efficiency (counts per photon) has been used to record the spectra at a takeoff angle of 25 degrees determined by the geometry of the secondary electron microscope's specimen chamber. Overall uncertainty in measurement could be reduced to 5 to 10% in dependence on the line intensity and energy. Measured emission efficiencies have been compared with calculated efficiencies based on models applied in standardless analysis. The widespread XPP and PROZA models give somewhat too low emission efficiencies. The best agreement between measured and calculated efficiencies could be achieved by replacing in the modular PROZA96 model the original expression for the ionization cross section by the formula given by Casnati et al. (1982) A discrepancy remains for carbon, probably due to the high overvoltage ratio.

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

International Nuclear Information System (INIS)

Lane, Ryan A.; Shemmer, Ohad; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

2011-01-01

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 ≤ z ≤ 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame ∼0.1-5 μm spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

THE ULTRAVIOLET-TO-MID-INFRARED SPECTRAL ENERGY DISTRIBUTION OF WEAK EMISSION LINE QUASARS

Energy Technology Data Exchange (ETDEWEB)

Lane, Ryan A.; Shemmer, Ohad [Department of Physics, University of North Texas, Denton, TX 76203 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Plotkin, Richard M. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam (Netherlands); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A., E-mail: RyanLane@my.unt.edu, E-mail: ohad@unt.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

2011-12-20

We present Spitzer Space Telescope photometry of 18 Sloan Digital Sky Survey (SDSS) quasars at 2.7 {<=} z {<=} 5.9 which have weak or undetectable high-ionization emission lines in their rest-frame ultraviolet (UV) spectra (hereafter weak-lined quasars, or WLQs). The Spitzer data are combined with SDSS spectra and ground-based, near-infrared (IR) photometry of these sources to produce a large inventory of spectral energy distributions (SEDs) of WLQs across the rest-frame {approx}0.1-5 {mu}m spectral band. The SEDs of our sources are inconsistent with those of BL Lacertae objects which are dominated by synchrotron emission due to a jet aligned close to our line of sight, but are consistent with the SED of ordinary quasars with similar luminosities and redshifts that exhibit a near-to-mid-IR 'bump', characteristic of hot dust emission. This indicates that broad emission lines in WLQs are intrinsically weak, rather than suffering continuum dilution from a jet, and that such sources cannot be selected efficiently from traditional photometric surveys.

Anisotropic ionizing radiation in Seyfert galaxies. I - The extended narrow-line region in Markarian 573

Science.gov (United States)

Tsvetanov, Zlatan; Walsh, J. R.

1992-01-01

The morphology, kinematics, and ionization state of the nuclear extended narrow-line region (ENLR) of the Seyfert 2 galaxy Mrk 573 are studied using narrow-band images of a grid of long-slit spectra. The entire ENLR is mapped spectroscopically, and velocity structure is studied. The velocity field map shows a typical galactic rotation picture with some important deviations. A simple geometric model, in accordance with the 'unified schemes', is employed to study the effects of various parameters of the observed picture. The best match is achieved when a biconical radiation field illuminates the ISM of the host galaxy that takes part in a normal galaxy rotation but also has radial motions close to the nucleus. The emission-line images reveal an ENLR elongated along the radio axis in the northwest-southeast direction, but a map of the flux ratio forbidden O III 5007/(H-alpha + forbidden N II) shows a different structure, with the highest excitation peak offset by about 4 arcsec along the radio axis to the southeast.

SPIRAL STRUCTURE OF M51 - DISTRIBUTION AND KINEMATICS OF THE ATOMIC AND IONIZED HYDROGEN

NARCIS (Netherlands)

TILANUS, RPJ; ALLEN, RJ

The atomic hydrogen (H I) and the H-alpha emission lines in the grand-design spiral galaxy M51 have been observed with the Westerbork Synthesis Radio Telescope and the TAURUS Fabry-Perot imaging spectrometer, respectively. Across the inner spiral arms significant tangential and radial velocity

KINEMATICS AND EXCITATION OF THE RAM PRESSURE STRIPPED IONIZED GAS FILAMENTS IN THE COMA CLUSTER OF GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Yagi, Masafumi; Komiyama, Yutaka; Kashikawa, Nobunari [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Furusawa, Hisanori [Astronomical Data Center, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Hattori, Takashi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' Ohoku Place, Hilo, HI 96720 (United States); Okamura, Sadanori, E-mail: yoshidam@hiroshima-u.ac.jp [Department of Astronomy, University of Tokyo, Tokyo 113-0033 (Japan)

2012-04-10

We present the results of deep imaging and spectroscopic observations of very extended ionized gas (EIG) around four member galaxies of the Coma Cluster of galaxies: RB 199, IC 4040, GMP 2923, and GMP 3071. The EIGs were serendipitously found in an H{alpha} narrowband imaging survey of the central region of the Coma Cluster. The relative radial velocities of the EIGs with respect to the systemic velocities of the parent galaxies from which they emanate increase almost monotonically with the distance from the nucleus of the respective galaxies, reaching {approx} - 400 to - 800 km s{sup -1} at around 40-80 kpc from the galaxies. The one-sided morphologies and the velocity fields of the EIGs are consistent with the predictions of numerical simulations of ram pressure stripping. We found a very low velocity filament (v{sub rel} {approx} -1300 km s{sup -1}) at the southeastern edge of the disk of IC 4040. Some bright compact knots in the EIGs of RB 199 and IC 4040 exhibit blue continuum and strong H{alpha} emission. The equivalent widths of the H{alpha} emission exceed 200 A and are greater than 1000 Angstrom-Sign for some knots. The emission-line intensity ratios of the knots are basically consistent with those of sub-solar abundance H II regions. These facts indicate that intensive star formation occurs in the knots. Some filaments, including the low-velocity filament of the IC 4040 EIG, exhibit shock-like emission-line spectra, suggesting that shock heating plays an important role in ionization and excitation of the EIGs.

Design of a portable optical emission tomography system for microwave induced compact plasma for visible to near-infrared emission lines

Energy Technology Data Exchange (ETDEWEB)

Rathore, Kavita, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in; Munshi, Prabhat, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in [Nuclear Engineering and Technology Programme, Indian Institute of Technology Kanpur, Kanpur (India); Bhattacharjee, Sudeep, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

2016-03-15

A new non-invasive diagnostic system is developed for Microwave Induced Plasma (MIP) to reconstruct tomographic images of a 2D emission profile. A compact MIP system has wide application in industry as well as research application such as thrusters for space propulsion, high current ion beams, and creation of negative ions for heating of fusion plasma. Emission profile depends on two crucial parameters, namely, the electron temperature and density (over the entire spatial extent) of the plasma system. Emission tomography provides basic understanding of plasmas and it is very useful to monitor internal structure of plasma phenomena without disturbing its actual processes. This paper presents development of a compact, modular, and versatile Optical Emission Tomography (OET) tool for a cylindrical, magnetically confined MIP system. It has eight slit-hole cameras and each consisting of a complementary metal–oxide–semiconductor linear image sensor for light detection. The optical noise is reduced by using aspheric lens and interference band-pass filters in each camera. The entire cylindrical plasma can be scanned with automated sliding ring mechanism arranged in fan-beam data collection geometry. The design of the camera includes a unique possibility to incorporate different filters to get the particular wavelength light from the plasma. This OET system includes selected band-pass filters for particular argon emission 750 nm, 772 nm, and 811 nm lines and hydrogen emission H{sub α} (656 nm) and H{sub β} (486 nm) lines. Convolution back projection algorithm is used to obtain the tomographic images of plasma emission line. The paper mainly focuses on (a) design of OET system in detail and (b) study of emission profile for 750 nm argon emission lines to validate the system design.

COMPLEX GAS KINEMATICS IN COMPACT, RAPIDLY ASSEMBLING STAR-FORMING GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Amorin, R.; Vilchez, J. M.; Perez-Montero, E. [Instituto de Astrofisica de Andalucia-CSIC, Glorieta de la Astronomia S/N, E-18008 Granada (Spain); Haegele, G. F.; Firpo, V. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad de la Plata, Paseo del Bosque S/N, 1900 La Plata (Argentina); Papaderos, P., E-mail: amorin@iaa.es [Centro de Astrofisica and Faculdade de Ciencias, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)

2012-08-01

Deep, high-resolution spectroscopic observations have been obtained for six compact, strongly star-forming galaxies at redshift z {approx} 0.1-0.3, most of them also known as green peas. Remarkably, these galaxies show complex emission-line profiles in the spectral region including H{alpha}, [N II] {lambda}{lambda}6548, 6584, and [S II] {lambda}{lambda}6717, 6731, consisting of the superposition of different kinematical components on a spatial extent of few kiloparsecs: a very broad line emission underlying more than one narrower component. For at least two of the observed galaxies some of these multiple components are resolved spatially in their two-dimensional spectra, whereas for another one a faint detached H{alpha} blob lacking stellar continuum is detected at the same recessional velocity {approx}7 kpc away from the galaxy. The individual narrower H{alpha} components show high intrinsic velocity dispersion ({sigma} {approx} 30-80 km s{sup -1}), suggesting together with unsharped masking Hubble Space Telescope images that star formation proceeds in an ensemble of several compact and turbulent clumps, with relative velocities of up to {approx}500 km s{sup -1}. The broad underlying H{alpha} components indicate in all cases large expansion velocities (full width zero intensity {>=}1000 km s{sup -1}) and very high luminosities (up to {approx}10{sup 42} erg s{sup -1}), probably showing the imprint of energetic outflows from supernovae. These intriguing results underline the importance of green peas for studying the assembly of low-mass galaxies near and far.

A photoionization model for the optical line emission from cooling flows

Science.gov (United States)

Donahue, Megan; Voit, G. M.

1991-01-01

The detailed predictions of a photoionization model previously outlined in Voit and Donahue (1990) to explain the optical line emission associated with cooling flows in X-ray emitting clusters of galaxies are presented. In this model, EUV/soft X-ray radiation from condensing gas photoionizes clouds that have already cooled. The energetics and specific consequences of such a model, as compared to other models put forth in the literature is discussed. Also discussed are the consequences of magnetic fields and cloud-cloud shielding. The results illustrate how varying the individual column densities of the ionized clouds can reproduce the range of line ratios observed and strongly suggest that the emission-line nebulae are self-irradiated condensing regions at the centers of cooling flows.

Identification of the lines in the L emission spectrum of cerium and samarium

International Nuclear Information System (INIS)

Shrivastava, B.D.; Singh, D.

1992-01-01

The occurrence of a line at 2.1556 A in the L emission spectrum of cerium and two lines at 1.6679 and 1.8379 A in the L emission spectrum of samarium, reported many years ago, has remained a puzzle. These have now been identified as EXAFS minima occurring at the L absorption edges of the respective elements. (author)

Evidence for explosive chromospheric evaporation in a solar flare observed with SMM

Science.gov (United States)

Zarro, D. M.; Saba, J. L. R.; Strong, K. T.; Canfield, R. C.; Metcalf, T.

1986-01-01

SMM soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined in a study of the impulsive phase of a solar flare. A blue asymmetry, indicative of upflow motions, was observed in the coronal Ca XIX line during the soft X-ray rise phase. H-alpha redshifts, indicative of downward motions, were observed simultaneously in bright flare kernels during the period of hard X-ray emission. It is shown that, to within observational errors, the impulsive phase momentum transported by the upflowing soft X-ray plasma is equivalent to that of the downward moving chromospheric material.

DUST EXTINCTION FROM BALMER DECREMENTS OF STAR-FORMING GALAXIES AT 0.75 {<=} z {<=} 1.5 WITH HUBBLE SPACE TELESCOPE/WIDE-FIELD-CAMERA 3 SPECTROSCOPY FROM THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY

Energy Technology Data Exchange (ETDEWEB)

Dominguez, A.; Siana, B.; Masters, D. [Department of Physics and Astronomy, University of California Riverside, Riverside, CA 92521 (United States); Henry, A. L.; Martin, C. L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Scarlata, C.; Bedregal, A. G. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Malkan, M.; Ross, N. R. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States); Atek, H.; Colbert, J. W. [Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States); Teplitz, H. I.; Rafelski, M. [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); McCarthy, P.; Hathi, N. P.; Dressler, A. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Bunker, A., E-mail: albertod@ucr.edu [Department of Physics, Oxford University, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom)

2013-02-15

Spectroscopic observations of H{alpha} and H{beta} emission lines of 128 star-forming galaxies in the redshift range 0.75 {<=} z {<=} 1.5 are presented. These data were taken with slitless spectroscopy using the G102 and G141 grisms of the Wide-Field-Camera 3 (WFC3) on board the Hubble Space Telescope as part of the WFC3 Infrared Spectroscopic Parallel survey. Interstellar dust extinction is measured from stacked spectra that cover the Balmer decrement (H{alpha}/H{beta}). We present dust extinction as a function of H{alpha} luminosity (down to 3 Multiplication-Sign 10{sup 41} erg s{sup -1}), galaxy stellar mass (reaching 4 Multiplication-Sign 10{sup 8} M {sub Sun }), and rest-frame H{alpha} equivalent width. The faintest galaxies are two times fainter in H{alpha} luminosity than galaxies previously studied at z {approx} 1.5. An evolution is observed where galaxies of the same H{alpha} luminosity have lower extinction at higher redshifts, whereas no evolution is found within our error bars with stellar mass. The lower H{alpha} luminosity galaxies in our sample are found to be consistent with no dust extinction. We find an anti-correlation of the [O III] {lambda}5007/H{alpha} flux ratio as a function of luminosity where galaxies with L {sub H{alpha}} < 5 Multiplication-Sign 10{sup 41} erg s{sup -1} are brighter in [O III] {lambda}5007 than H{alpha}. This trend is evident even after extinction correction, suggesting that the increased [O III] {lambda}5007/H{alpha} ratio in low-luminosity galaxies is likely due to lower metallicity and/or higher ionization parameters.

A new method of organizing spectral line intensity ratio fluctuations of nightglow emissions

International Nuclear Information System (INIS)

Thelin, B.

1986-02-01

In this paper a new kind of linearization effect between the atmospheric night airglow emissions is presented. The same kind of linearization effect has previously been studied with spectrochemical light sources together with a spectrometer. A linear graph was obtained for atomic spectral lines and vibrational bandspectra when the spectral line intensity ratio fluctuations were plotted versus the photon energies of these emissions. To study this effect data from a number of different photometer investigations of night airglow emissions at different times and places have been used. (author)

Coronal emission-line polarization from the statistical equilibrium of magnetic sublevels. I. Fe XII

International Nuclear Information System (INIS)

House, L.L.

1977-01-01

A general formulation for the polarization of coronal emission lines is presented, and the physics is illustrated through application of the formulation to the lines of Fe XIII at 10747 and 10798 A. The goal is to present a foundation for the determination of the orientation of coronal magnetic fields from emission-line polarization measurements. The physics of emission-line polarization is discussed using the statistical equilibrium equations for the magnetic sublevels of a coronal ion. The formulation of these equations, which describe the polarization of the radiation field in terms of Stokes parameters, is presented; and the various rate parameters: both radiative and collisional: are considered. The emission Stokes vector is constructed from the solution of the equilibrium equations for a point in the corona where the magnetic field has an arbitrary orientation. On the basis of a model, a computer code for the calculation of emission-line polarization is briefly described and illustrated with a number of sample calculations for Fe XIII. Calculations are carried out for three-dimensional models that demonstrate the physics of the formation of emission-line polarization and illustrate how the degree of polarization and angle of polarization and their variations over the corona are related to the density and magnetic field structure. The models considered range from simple cases in which the density distribution with height is spherically symmetric and the field is radial or dipole to a complex case in which both the density and magnetic field distributions are derived from realistic three-dimensional distributions for the 1973 eclipse on the basis of K-coronameter measurements for the density and potential-field extrapolation of surface magnetic fields in the corona

Hα Emission Line Morphologies in Markarian Starburst Galaxies A ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging Solutions)

images of a sample of optically selected starburst galaxies from the Markar- ian lists. .... to the size of the galaxy and the histograms were sky dominated. .... simplest qualitative method is to visually examine the distribution of the emission line.

Audio-frequency noise emissions from high-voltage overhead power lines

International Nuclear Information System (INIS)

Semmler, M.; Straumann, U.; Roero, C.; Teich, T. H.

2005-01-01

This article discusses the noise-emissions caused by high-voltage overhead power lines that can occur under certain atmospheric conditions. These emissions, caused by electric discharges around the conductors, can achieve disturbing values, depending on the conditions prevailing at the time in question. The causes of the discharges are examined and the ionisation processes involved are looked at. The parameters influencing the discharges are discussed and measures that can be taken to reduce such audio-frequency emissions are looked at. The authors note that a reduction of peripheral field strengths can reduce emissions and that hydrophilic coatings can lead to faster reduction of such effects after rainfall

40 CFR 63.1569 - What are my requirements for HAP emissions from bypass lines?

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true What are my requirements for HAP emissions from bypass lines? 63.1569 Section 63.1569 Protection of Environment ENVIRONMENTAL PROTECTION... HAP emissions from bypass lines? (a) What work practice standards must I meet? (1) You must meet each...

The extinction to the H2 line emission in the DR 21 outflow source

International Nuclear Information System (INIS)

Nadeau, D.; Riopel, M.; Geballe, T.R.

1991-01-01

The v = 1-0 S(1) and Q(3) lines of H2 have been measured in four regions of the DR 21 H2 line-emission source, in order to determine whether the observed morphology of the emission represents the distribution of the excited H2 or is modified by nonuniform extinction across the source. The measured lines originate from the same upper level, and their ratio is a direct measure of the reddening. The line ratios show that the extinction is quite uniform across the source and that there is no correlation between the intensity and the extinction. This result implies that the gap between the two lobes of emission is not due to increased extinction but rather is a region where there is little excited H2 gas. 13 refs

An Intrinsic Baldwin Effect in the H Beta Broad Emission Line in the Spectrum of NGC 5548

Science.gov (United States)

Gilbert, Karoline M.; Peterson, Bradley M.

2003-01-01

We investigate the possibility of an intrinsic Baldwin effect (i.e., nonlinear emission-line response to continuum variations) in the broad HP emission line of the active galaxy NGC 5548 using crosscorrelation techniques to remove light-travel time effects from the data. We find a nonlinear relationship between the HP emission line and continuum fluxes that is in good agreement with theoretical predictions. We suggest that similar analysis of multiple lines might provide a useful diagnostic of physical conditions in the broad-line region.

TAURUS observations of the emission-line velocity field of Centaurus A (NGC 5128)

International Nuclear Information System (INIS)

Taylor, K.; Atherton, P.D.

1983-01-01

Using TAURUS - an Imaging Fabry Perot system in conjunction with the IPCS on the AAT, the authors have studied the velocity field of the Hα emission line at a spatial resolution of 1.7'' over the dark lane structure of Centaurus A. The derived velocity field is quite symmetrical and strongly suggests that the emission line material is orbiting the elliptical component, as a warped disc. (orig.)

Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

Science.gov (United States)

Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.;

Spectroscopic classification of AT2018aes as a supernova impostor

Science.gov (United States)

Andrews, Jennifer; Smith, Nathan; Van Dyk, Schuyler D.

2018-03-01

A visual-wavelength optical spectrum of AT2018aes obtained on UT 2018 Mar 13 (JD 2458190.84) with the Magellan Clay telescope (+ LDSS3 spectrograph, VPH-all grism) reveals a narrow H-alpha emission line with a velocity of 525 km/s, with wings extending to roughly +/-1000 km/s.

Observations of the 12.3 micron Mg I emission line during a major solar flare

Science.gov (United States)

Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Hewagama, Tilak

1990-01-01

The extremely Zeeman-sensitive 12.32 micron Mg I solar emission line was observed during a 3B/X5.7 solar flare on October 24, 1989. When compared to postflare values, Mg I emission-line intensity in the penumbral flare ribbon was 20 percent greater at the peak of the flare in soft X-rays, and the 12 micron continuum intensity was 7 percent greater. The flare also excited the emission line in the umbra where it is normally absent. The umbral flare emission exhibits a Zeeman splitting 200 G less than the adjacent penumbra, suggesting that it is excited at higher altitude. The absolute penumbral magnetic field strength did not change by more than 100 G between the flare peak and postflare period. However, a change in the inclination of the field lines, probably related to the formation and development of the flare loop system, was seen.

Linearized spectrum correlation analysis for line emission measurements.

Science.gov (United States)

Nishizawa, T; Nornberg, M D; Den Hartog, D J; Sarff, J S

2017-08-01

A new spectral analysis method, Linearized Spectrum Correlation Analysis (LSCA), for charge exchange and passive ion Doppler spectroscopy is introduced to provide a means of measuring fast spectral line shape changes associated with ion-scale micro-instabilities. This analysis method is designed to resolve the fluctuations in the emission line shape from a stationary ion-scale wave. The method linearizes the fluctuations around a time-averaged line shape (e.g., Gaussian) and subdivides the spectral output channels into two sets to reduce contributions from uncorrelated fluctuations without averaging over the fast time dynamics. In principle, small fluctuations in the parameters used for a line shape model can be measured by evaluating the cross spectrum between different channel groupings to isolate a particular fluctuating quantity. High-frequency ion velocity measurements (100-200 kHz) were made by using this method. We also conducted simulations to compare LSCA with a moment analysis technique under a low photon count condition. Both experimental and synthetic measurements demonstrate the effectiveness of LSCA.

Synthetic nebular emission from massive galaxies - I: origin of the cosmic evolution of optical emission-line ratios

Science.gov (United States)

Hirschmann, Michaela; Charlot, Stephane; Feltre, Anna; Naab, Thorsten; Choi, Ena; Ostriker, Jeremiah P.; Somerville, Rachel S.

2017-12-01

Galaxies occupy different regions of the [O III]λ5007/H β-versus-[N II]λ6584/H α emission-line ratio diagram in the distant and local Universe. We investigate the origin of this intriguing result by modelling self-consistently, for the first time, nebular emission from young stars, accreting black holes (BHs) and older, post-asymptotic giant branch (post-AGB) stellar populations in galaxy formation simulations in a full cosmological context. In post-processing, we couple new-generation nebular-emission models with high-resolution, cosmological zoom-in simulations of massive galaxies to explore which galaxy physical properties drive the redshift evolution of the optical-line ratios [O III]λ5007/H β, [N II]λ6584/H α, [S II]λλ6717, 6731/H α and [O I]λ6300/H α. The line ratios of simulated galaxies agree well with observations of both star-forming and active local Sloan Digital Sky Survey galaxies. Towards higher redshifts, at fixed galaxy stellar mass, the average [O III]/H β is predicted to increase and [N II]/H α, [S II]/H α and [O I]/H α to decrease - widely consistent with observations. At fixed stellar mass, we identify star formation history, which controls nebular emission from young stars via the ionization parameter, as the primary driver of the cosmic evolution of [O III]/H β and [N II]/H α. For [S II]/H α and [O I]/H α, this applies only to redshifts greater than z = 1.5, the evolution at lower redshift being driven in roughly equal parts by nebular emission from active galactic nuclei and post-AGB stellar populations. Instead, changes in the hardness of ionizing radiation, ionized-gas density, the prevalence of BH accretion relative to star formation and the dust-to-metal mass ratio (whose impact on the gas-phase N/O ratio we model at fixed O/H) play at most a minor role in the cosmic evolution of simulated galaxy line ratios.

Study of Opacity Effects on Emission Lines at EXTRAP T2R RFP

Science.gov (United States)

Stancalie, Viorica; Rachlew, Elisabeth

We have investigated the influence of opacity on hydrogen (H-α and Ly-β) and Li-like oxygen emission lines from the EXTRAP T2R reversed field pinch. We used the Atomic Data Analysis System (AzDAS) based on the escape factor approximation for radiative transfer to calculate metastable and excited population densities via a collisional-radiative model. Population escape factor, emergent escape factor and modified line profiles are plotted vs. optical depth. The simulated emission line ratios in the density/temperature plane are in good agreement with experimental data for electron density and temperature measurements.

Near UV-visible line emission from tungsten highly-charged ions in Large Helical Device

International Nuclear Information System (INIS)

Kato, D.; Sakaue, H.A.; Murakami, I.; Goto, M.; Oishi, T.; Morita, S.; Fujii, K.; Nakamura, N.; Koike, F.; Sasaki, Akira; Ding, X.-B.; Dong, C.-Z.

2015-01-01

Wavelengths of emission lines from tungsten highly-charged ions have been precisely measured in near UV-visible range (320 - 356 nm and 382 - 402 nm) at Large Helical Device (LHD) by tungsten pellet injection. The tungsten emission lines were assigned based on its line-integrated intensity profiles on a poloidal cross section. The ground-term magnetic-dipole (M1) lines of W 26+,27+ and an M1 line of a metastable excited state of W 28+ , whose wavelengths have been determined by measurements using electron-beam-ion-traps (EBITs), are identified in the LHD spectra. The present results partially compliment wavelength data of tungsten highly-charged ions in the near UV-visible range. (author)

Time variations of oxygen emission lines and solar wind dynamic parameters in low latitude region

Science.gov (United States)

Jamlongkul, P.; Wannawichian, S.; Mkrtichian, D.; Sawangwit, U.; A-thano, N.

2017-09-01

Aurora phenomenon is an effect of collision between precipitating particles with gyromotion along Earth’s magnetic field and Earth’s ionospheric atoms or molecules. The particles’ precipitation occurs normally around polar regions. However, some auroral particles can reach lower latitude regions when they are highly energetic. A clear emission from Earth’s aurora is mostly from atomic oxygen. Moreover, the sun’s activities can influence the occurrence of the aurora as well. This work studies time variations of oxygen emission lines and solar wind parameters, simultaneously. The emission’s spectral lines were observed by Medium Resolution Echelle Spectrograph (MRES) along with 2.4 meters diameter telescope at Thai National Observatory, Intanon Mountain, Chiang Mai, Thailand. Oxygen (OI) emission lines were calibrated by Dech-Fits spectra processing program and Dech95 2D image processing program. The correlations between oxygen emission lines and solar wind dynamics will be analyzed. This result could be an evidence of the aurora in low latitude region.

Redshift of the BL Lacertae object PKS 2005-489

Energy Technology Data Exchange (ETDEWEB)

Falomo, R.; Maraschi, L.; Treves, A.; Tanzi, E.G.

1987-07-01

In a high-resolution spectrum of PKS 2005-489 taken on Aug. 16, 1986 two weak emission lines (EW = about 1 A) were detected at 7031 and 7051 A. Identification with H-alpha and the 6583-A forbidden line of N II is proposed at a redshift z = 0.071. The observations correspond to a relatively faint state of the source with B = about 14.7. 12 references.

Redshift of the BL Lacertae object PKS 2005-489

International Nuclear Information System (INIS)

Falomo, R.; Maraschi, L.; Treves, A.; Tanzi, E.G.; Milano Universita, Milan, Italy; CNR, Istituto di Fisica Cosmica, Milan, Italy)

1987-01-01

In a high-resolution spectrum of PKS 2005-489 taken on Aug. 16, 1986 two weak emission lines (EW = about 1 A) were detected at 7031 and 7051 A. Identification with H-alpha and the 6583-A forbidden line of N II is proposed at a redshift z = 0.071. The observations correspond to a relatively faint state of the source with B = about 14.7. 12 references

Polarisation of auroral emission lines in the Earth's upper atmosphere : first results and perspectives

Science.gov (United States)

Lamy, H.; Barthelemy, M.; Simon Wedlund, C.; Lilensten, J.; Bommier, V.

2011-12-01

Polarisation of light is a key observable to provide information about asymmetry or anisotropy within a radiative source. Following the pioneering and controversial work of Duncan in 1959, the polarisation of auroral emission lines in the Earth's upper atmosphere has been overlooked for a long time, even though the red intense auroral line (6300Å) produced by collisional impacts with electrons precipitating along magnetic field lines is a good candidate to search for polarisation. This problem was investigated again by Lilensten et al (2006) and observations were obtained by Lilensten et al (2008) confirming that the red auroral emission line is polarised. More recent measurements obtained by Barthélemy et al (2011) are presented and discussed. The results are compared to predictions of the theoretical work of Bommier et al (2011) and are in good agreement. Following these encouraging results, a new dedicated spectropolarimeter is currently under construction between BIRA-IASB and IPAG to provide simultaneously the polarisation of the red line and of other interesting auroral emission lines such as N2+ 1NG (4278Å), other N2 bands, etc... Perspectives regarding the theoretical polarisation of some of these lines will be presented. The importance of these polarisation measurements in the framework of atmospheric modeling and geomagnetic activity will be discussed.

Electron density in the emission-line region of Wolf-Rayet stars

International Nuclear Information System (INIS)

Varshni, Y.P.

1978-01-01

The Inglis-Teller relation, generalized for a hydrogen-like or alkali-like ion with an arbitrary core charge, is used to estimate the electron density in the emission-like region of Wolf-Rayet stars. It is found that the electron density in the region which gives rise to He II emission lines is approximately = 4 x 10 14 cm -3 . (Auth.)

A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey

DEFF Research Database (Denmark)

Jiang, Linhua; Fan, Xiaohui; Vestergaard, Marianne

2008-01-01

We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \\AA) at 1.7......We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \\AA) at 1.7...

NON-DETECTION OF L-BAND LINE EMISSION FROM THE EXOPLANET HD189733b

International Nuclear Information System (INIS)

Mandell, Avi M.; Deming, L. Drake; Mumma, Michael J.; Villanueva, Geronimo L.; Blake, Geoffrey A.; Knutson, Heather A.; Salyk, Colette

2011-01-01

We attempt to confirm bright non-local thermodynamic equilibrium (non-LTE) emission from the exoplanet HD 189733b at 3.25 μm, as recently reported by Swain et al. based on observations at low spectral resolving power (λ/δλ ∼ 30). Non-LTE emission lines from gas in an exoplanet atmosphere will not be significantly broadened by collisions, so the measured emission intensity per resolution element must be substantially brighter when observed at high spectral resolving power. We observed the planet before, during, and after a secondary eclipse event at a resolving power λ/δλ = 27, 000 using the NIRSPEC spectrometer on the Keck II telescope. Our spectra cover a spectral window near the peak found by Swain et al., and we compare emission cases that could account for the magnitude and wavelength dependence of the Swain et al. result with our final spectral residuals. To model the expected line emission, we use a general non-equilibrium formulation to synthesize emission features from all plausible molecules that emit in this spectral region. In every case, we detect no line emission to a high degree of confidence. After considering possible explanations for the Swain et al. results and the disparity with our own data, we conclude that an astrophysical source for the putative non-LTE emission is unlikely. We note that the wavelength dependence of the signal seen by Swain et al. closely matches the 2ν 2 band of water vapor at 300 K, and we suggest that an imperfect correction for telluric water is the source of the feature claimed by Swain et al.

Non-LTE line-blanketed model atmospheres of hot stars. 2: Hot, metal-rich white dwarfs

Science.gov (United States)

Lanz, T.; Hubeny, I.

1995-01-01

We present several model atmospheres for a typical hot metal-rich DA white dwarf, T(sub eff) = 60,000 K, log g = 7.5. We consider pure hydrogen models, as well as models with various abundances of two typical 'trace' elements-carbon and iron. We calculte a number of Local Thermodynamic Equilibrium (LTE) and non-LTE models, taking into account the effect of numerous lines of these elements on the atmospheric structure. We demostrate that while the non-LTE effects are notvery significant for pure hydrogen models, except for describing correctly the central emission in H-alpha they are essential for predicting correctly the ionization balance of metals, such as carbon and iron. Previously reported discrepancies in LTE abundances determinations using C III and C IV lines are easily explained by non-LTE effects. We show that if the iron abundance is larger than 10(exp -5), the iron line opacity has to be considered not only for the spectrum synthesis, but also in the model construction itself. For such metal abundances, non-LTE metal line-blanketed models are needed for detailed abundance studies of hot, metal-rich white dwarfs. We also discuss the predicted Extreme Ultraviolet (EUV) spectrum and show that it is very sensitive to metal abundances, as well as to non-LTE effects.

On the Origin of the Flare Emission in IRIS ’ SJI 2832 Filter:Balmer Continuum or Spectral Lines?

Energy Technology Data Exchange (ETDEWEB)

Kleint, Lucia; Krucker, Säm [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland); Heinzel, Petr [Astronomical Institute, The Czech Academy of Sciences, Fričova 298, 25165 Ondřejov (Czech Republic)

2017-03-10

Continuum (“white-light,” WL) emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS ’ SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed slitjaw images (SJI) emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.

On the Origin of the Flare Emission in IRIS ’ SJI 2832 Filter:Balmer Continuum or Spectral Lines?

International Nuclear Information System (INIS)

Kleint, Lucia; Krucker, Säm; Heinzel, Petr

2017-01-01

Continuum (“white-light,” WL) emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS ’ SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed slitjaw images (SJI) emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.

Emission lines in the hydrogen-deficient variable MV Sagittarii near maximum light

International Nuclear Information System (INIS)

Herbig, G.H.

1975-01-01

The H-deficient R CrB type variable MV Sgr near maximum light shows a rich emission spectrum in the 5800--8600 A region. Most of these lines are due to Fe ii, but Si ii, N i, O i, and Hα also are present. Such a spectrum has not been observed in any other R CrB star, but there is some resemblance to v Sgr. The emission lines in MV Sgr probably originate in an extended region of low temperature, which may also be responsible for the infrared excess observed by Feast and Glass

Improved documentation of spectral lines for inductively coupled plasma emission spectrometry

Science.gov (United States)

Doidge, Peter S.

2018-05-01

An approach to improving the documentation of weak spectral lines falling near the prominent analytical lines used in inductively coupled plasma optical emission spectrometry (ICP-OES) is described. Measurements of ICP emission spectra in the regions around several hundred prominent lines, using concentrated solutions (up to 1% w/v) of some 70 elements, and comparison of the observed spectra with both recent published work and with the output of a computer program that allows calculation of transitions between the known energy levels, show that major improvements can be made in the coverage of spectral atlases for ICP-OES, with respect to "classical" line tables. It is argued that the atomic spectral data (wavelengths, energy levels) required for the reliable identification and documentation of a large majority of the weak interfering lines of the elements detectable by ICP-OES now exist, except for most of the observed lines of the lanthanide elements. In support of this argument, examples are provided from a detailed analysis of a spectral window centered on the prominent Pb II 220.353 nm line, and from a selected line-rich spectrum (W). Shortcomings in existing analyses are illustrated with reference to selected spectral interferences due to Zr. This approach has been used to expand the spectral-line library used in commercial ICP-ES instruments (Agilent 700-ES/5100-ES). The precision of wavelength measurements is evaluated in terms of the shot-noise limit, while the absolute accuracy of wavelength measurement is characterised through comparison with a small set of precise Ritz wavelengths for Sb I, and illustrated through the identification of Zr III lines; it is further shown that fractional-pixel absolute wavelength accuracies can be achieved. Finally, problems with the wavelengths and classifications of certain Au I lines are discussed.

Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 2

Science.gov (United States)

Kelly, R. L.

1979-01-01

A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 1

Science.gov (United States)

Kelly, R. L.

1979-01-01

A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

Calculation and reduction of the sound emissions of overhead power lines

International Nuclear Information System (INIS)

Straumann, U.

2007-01-01

In this dissertation, Ulrich Straumann of the Swiss Federal Institute of Technology in Zurich, Switzerland, discusses the reduction of sound emissions from overhead power lines. Corona-discharges occur during wet weather or when foggy or icing conditions prevail. Apart from these wide-band crackling noises, low-frequency, tonal emissions also occur. The CONOR (Corona Noise Reduction) project examined these emissions at a frequency of twice the mains frequency and looked for economically feasible solutions to the problems caused by them. The source of these emissions and the mechanisms causing them are discussed. Also, ways of calculating their strength are presented. The effects of varying cable geometry and construction are discussed, as are hydrophilic coatings that could be used to reduce sound emissions.

A New Diagnostic Diagram of Ionization Sources for High-redshift Emission Line Galaxies

Science.gov (United States)

Zhang, Kai; Hao, Lei

2018-04-01

We propose a new diagram, the kinematics–excitation (KEx) diagram, which uses the [O III] λ5007/Hβ line ratio and the [O III] λ5007 emission line width (σ [O III]) to diagnose the ionization source and physical properties of active galactic nuclei (AGNs) and star-forming galaxies (SFGs). The KEx diagram is a suitable tool to classify emission line galaxies at intermediate redshift because it uses only the [O III] λ5007 and Hβ emission lines. We use the main galaxy sample of SDSS DR7 and the Baldwin‑Phillips‑Terlevich (BPT) diagnostic to calibrate the diagram at low redshift. The diagram can be divided into three regions: the KEx-AGN region, which consists mainly of pure AGNs, the KEx-composite region, which is dominated by composite galaxies, and the KEx-SFG region, which contains mostly SFGs. LINERs strongly overlap with the composite and AGN regions. AGNs are separated from SFGs in this diagram mainly because they preferentially reside in luminous and massive galaxies and have higher [O III]/Hβ than SFGs. The separation between AGNs and SFGs is even cleaner thanks to the additional 0.15/0.12 dex offset in σ [O III] at fixed luminosity/stellar mass. We apply the KEx diagram to 7866 galaxies at 0.3 Survey, and compare it to an independent X-ray classification scheme using Chandra observations. X-ray AGNs are mostly located in the KEx-AGN region, while X-ray SFGs are mostly located in the KEx-SFG region. Almost all Type 1 AGNs lie in the KEx-AGN region. These tests support the reliability of this classification diagram for emission line galaxies at intermediate redshift. At z ∼ 2, the demarcation line between SFGs and AGNs is shifted by ∼0.3 dex toward higher values of σ [O III] due to evolution effects.

Why is observable radio recombination line emission from galactic HII regions always close to LTE

International Nuclear Information System (INIS)

Shaver, P.A.

1980-01-01

There is no evidence for significant deviations from LTE in single-dish observations of radio recombination line emission from galactic HII regions. This is in agreement with the known properties of HII regions, particularly their density variations and limited range of excitation parameters; the optimum configuration for strong observable non-LTE effects, low electron density and high emission measure, simply does not exist in galactic HII regions, and the observed lines are emitted under near-LTE conditions. Models of the Orion Nebulae and NGC 6604 are presented which fit all available data and show only weak stimulated emission. It is concluded that reliable electron temperatures can indeed be obtained from straightforward analysis of appropriate radio recombination lines. (orig.)

ALMA WILL DETERMINE THE SPECTROSCOPIC REDSHIFT z > 8 WITH FIR [O III] EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

Inoue, A. K.; Shimizu, I. [College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Tamura, Y. [Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-0015 (Japan); Matsuo, H. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Okamoto, T. [Department of Cosmosciences, Graduate School of Science, Hokkaido University, N10 W8, Kitaku, Sapporo 060-0810 (Japan); Yoshida, N., E-mail: akinoue@las.osaka-sandai.ac.jp [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033 (Japan)

2014-01-10

We investigate the potential use of nebular emission lines in the rest-frame far-infrared (FIR) for determining spectroscopic redshift of z > 8 galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA). After making a line emissivity model as a function of metallicity, especially for the [O III] 88 μm line which is likely to be the strongest FIR line from H II regions, we predict the line fluxes from high-z galaxies based on a cosmological hydrodynamics simulation of galaxy formation. Since the metallicity of galaxies reaches at ∼0.2 Z {sub ☉} even at z > 8 in our simulation, we expect the [O III] 88 μm line as strong as 1.3 mJy for 27 AB objects, which is detectable at a high significance by <1 hr integration with ALMA. Therefore, the [O III] 88 μm line would be the best tool to confirm the spectroscopic redshifts beyond z = 8.

A NEW Hα EMISSION-LINE SURVEY IN THE ORION NEBULA CLUSTER

International Nuclear Information System (INIS)

Szegedi-Elek, E.; Kun, M.; Pál, A.; Balázs, L. G.; Reipurth, B.; Willman, M.

2013-01-01

We present results from an Hα emission line survey in a 1 deg 2 area centered on the Orion Nebula Cluster, obtained with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii. We identified 587 stars with Hα emission, 99 of which, located mainly in the outer regions of the observed area, have not appeared in previous Hα surveys. We determined the equivalent width (EW) of the line and, based on this, classified 372 stars as classical T Tauri stars (CTTSs) and 187 as weak-line T Tauri stars (WTTSs). Simultaneous r', i' photometry indicates a limiting magnitude of r' ∼ 20 mag, but the sample is incomplete at r' > 17 mag. The surface distribution of the Hα emission stars reveals a clustered population and a dispersed population, the former consisting of younger and more massive young stars than the latter. Comparison of the derived EWs with those found in the literature indicates variability of the Hα line. We found that the typical amplitudes of the variability are not greater than a factor of two to three in most cases. We identified a subgroup of low-EW stars with infrared signatures indicative of optically thick accretion disks. We studied the correlations between the EW and other properties of the stars. Based on literature data, we examined several properties of our CTTS and WTTS subsamples and found significant differences in mid-infrared color indices, average rotational periods, and spectral energy distribution characteristics of the subsamples

A NEW Hα EMISSION-LINE SURVEY IN THE ORION NEBULA CLUSTER

Energy Technology Data Exchange (ETDEWEB)

Szegedi-Elek, E.; Kun, M.; Pál, A.; Balázs, L. G. [Konkoly Observatory, H-1121 Budapest, Konkoly Thege út 15-17 (Hungary); Reipurth, B.; Willman, M., E-mail: eelza@konkoly.hu [Institute for Astronomy, University of Hawaii at Manoa, 640 N. Aohoku Place, Hilo, HI 96720 (United States)

2013-10-01

We present results from an Hα emission line survey in a 1 deg{sup 2} area centered on the Orion Nebula Cluster, obtained with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii. We identified 587 stars with Hα emission, 99 of which, located mainly in the outer regions of the observed area, have not appeared in previous Hα surveys. We determined the equivalent width (EW) of the line and, based on this, classified 372 stars as classical T Tauri stars (CTTSs) and 187 as weak-line T Tauri stars (WTTSs). Simultaneous r', i' photometry indicates a limiting magnitude of r' ∼ 20 mag, but the sample is incomplete at r' > 17 mag. The surface distribution of the Hα emission stars reveals a clustered population and a dispersed population, the former consisting of younger and more massive young stars than the latter. Comparison of the derived EWs with those found in the literature indicates variability of the Hα line. We found that the typical amplitudes of the variability are not greater than a factor of two to three in most cases. We identified a subgroup of low-EW stars with infrared signatures indicative of optically thick accretion disks. We studied the correlations between the EW and other properties of the stars. Based on literature data, we examined several properties of our CTTS and WTTS subsamples and found significant differences in mid-infrared color indices, average rotational periods, and spectral energy distribution characteristics of the subsamples.

THE IMPORTANCE OF NEBULAR CONTINUUM AND LINE EMISSION IN OBSERVATIONS OF YOUNG MASSIVE STAR CLUSTERS

International Nuclear Information System (INIS)

Reines, Amy E.; Nidever, David L.; Whelan, David G.; Johnson, Kelsey E.

2010-01-01

In this spectroscopic study of infant massive star clusters, we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths. In addition, we find that nebular line emission is significant in many commonly used broadband Hubble Space Telescope (HST) filters including the F814W I-band, the F555W V-band, and the F435W B-band. Two young massive clusters (YMCs) in the nearby starburst galaxy NGC 4449 were targeted for follow-up spectroscopic observations after Reines et al. discovered an F814W I-band excess in their photometric study of radio-detected clusters in the galaxy. The spectra were obtained with the Dual Imaging Spectrograph (DIS) on the 3.5 m Apache Point Observatory (APO) telescope and have a spectral range of ∼3800-9800 A. We supplement these data with HST and Sloan Digital Sky Survey photometry of the clusters. By comparing our data to the Starburst99 and GALEV evolutionary synthesis models, we find that nebular continuum emission competes with the stellar light in our observations and that the relative contribution from the nebular continuum is largest in the U- and I-bands, where the Balmer (3646 A) and Paschen jumps (8207 A) are located. The spectra also exhibit strong line emission including the [S III] λλ9069, 9532 lines in the HST F814W I-band. We find that the combination of nebular continuum and line emission can account for the F814W I-band excess previously found by Reines et al. In an effort to provide a benchmark for estimating the impact of ionized gas emission on photometric observations of young massive stellar populations, we compute the relative contributions of the stellar continuum, nebular continuum, and emission lines to the total observed flux of a 3 Myr old cluster through various HST filter/instrument combinations, including filters in the Wide Field Camera 3. We urge caution when comparing observations of YMCs to evolutionary synthesis models since nebular continuum and line emission can

FIRST DETECTION OF NEAR-INFRARED LINE EMISSION FROM ORGANICS IN YOUNG CIRCUMSTELLAR DISKS

Energy Technology Data Exchange (ETDEWEB)

Mandell, Avi M.; Mumma, Michael J.; Villanueva, Geronimo [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bast, Jeanette; Van Dishoeck, Ewine F. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Blake, Geoffrey A. [California Institute of Technology, Division of Geological and Planetary Sciences, MS 150-21, Pasadena, CA 91125 (United States); Salyk, Colette, E-mail: Avi.Mandell@nasa.gov [Department of Astronomy, University of Texas, Austin, TX 78712 (United States)

2012-03-10

We present an analysis of high-resolution spectroscopy of several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope, revealing the first detections of emission from HCN and C{sub 2}H{sub 2} in circumstellar disks at near-infrared wavelengths. Using advanced data reduction techniques, we achieve a dynamic range with respect to the disk continuum of {approx}500 at 3 {mu}m, revealing multiple emission features of H{sub 2}O, OH, HCN, and C{sub 2}H{sub 2}. We also present stringent upper limits for two other molecules thought to be abundant in the inner disk, CH{sub 4} and NH{sub 3}. Line profiles for the different detected molecules are broad but centrally peaked in most cases, even for disks with previously determined inclinations of greater than 20 Degree-Sign , suggesting that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We apply two different modeling strategies to constrain the molecular abundances and temperatures: we use a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we compare these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU).

A new method of organizing spectral line intensity ratio fluctuations of auroral emissions

International Nuclear Information System (INIS)

Thelin, B.

1986-02-01

In this paper a new kind of linearization effect between the atmospheric auroral emissions is presented. The same kind of linearization effect has previously been found in nightglow emissions from photometer measurements and in the spectrochemical field from studies of optical light sources. Linear graphs have been obtained for atomic spectral lines and vibrational bandspectra when the spectral line ratio fluctuations were plotted versus the photon energies of these emissions. This new effect has been studied with a spectrophotometer in auroral emissions, where linear graphs have been obtained on different auroral occasions. By doing such studies of auroral light it is possible to see the importance of the inelastic scattering cross section between electrons - atoms and electrons - molecules. In this way it has shown to be possible to determine the mean energy of the interacting thermal electrons that are active in the different auroral phases. (author)

Space density and clustering properties of a new sample of emission-line galaxies

International Nuclear Information System (INIS)

Wasilewski, A.J.

1982-01-01

A moderate-dispersion objective-prism survey for low-redshift emission-line galaxies has been carried out in an 825 sq. deg. region of sky with the Burrell Schmidt telescope of Case Western Reserve University. A 4 0 prism (300 A/mm at H#betta#) was used with the Illa-J emulsion to show that a new sample of emission-line galaxies is available even in areas already searched with the excess uv-continuum technique. The new emission-line galaxies occur quite commonly in systems with peculiar morphology indicating gravitational interaction with a close companion or other disturbance. About 10 to 15% of the sample are Seyfert galaxies. It is suggested that tidal interaction involving matter infall play a significant role in the generation of an emission-line spectrum. The space density of the new galaxies is found to be similar to the space density of the Makarian galaxies. Like the Markarian sample, the galaxies in the present survey represent about 10% of all galaxies in the absolute magnitude range M/sub p/ = -16 to -22. The observations also indicate that current estimates of dwarf galaxy space densities may be too low. The clustering properties of the new galaxies have been investigated using two approaches: cluster contour maps and the spatial correlation function. These tests suggest that there is weak clustering and possibly superclustering within the sample itself and that the galaxies considered here are about as common in clusters of ordinary galaxies as in the field

The BAT AGN Spectroscopic Survey (BASS)

Science.gov (United States)

Koss, Michael

2017-08-01

We present the Swift BAT AGN Spectroscopic Survey (BASS) and discus the first four papers. The catalog represents an unprecedented census of hard-X-ray selected AGN in the local universe, with ~90% of sources at zpast studies. Consistent with previous surveys, we find an increase in the fraction of un-obscured (type 1) AGN, as measured from broad Hbeta and Halpha, with increasing 14-195 keV and 2-10 keV luminosity. We find the FWHM of the emission lines to show broad agreement with the X-ray obscuration measurements. Compared to narrow line AGN in the SDSS, the X-ray selected AGN in our sample with emission lines have a larger fraction of dustier galaxies suggesting these types of galaxies are missed in optical AGN surveys using emission line diagnostics.

H(alpha) Proxies for EIT Crinkles: Further Evidence for Preflare "Breakout"-Type Activity in an Ejective Solar Eruption

Science.gov (United States)

Sterling, Alphonse C.; Qiu, Jiong; Wang, Haimin; Moore, Ronald L.

2001-01-01

We present H(alpha) observations from Big Bear Solar Observatory of an eruptive flare in NOAA Active Region 8210, occurring near 22:30 UT on 1998 May 1. Previously, using the Extreme Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) spacecraft, we found that a pattern of transient, localized brightenings, which we call 'EIT crinkles,' appears in the neighborhood of the eruption near the time of flare onset. These EIT crinkles occur at a location in the active region well separated from the sheared core magnetic fields, which is where the most intense features of the eruption are concentrated. We also previously found that high-cadence images from the Soft X-ray Telescope (SXT) on Yohkoh indicate that soft X-ray intensity enhancements in the core begin after the start of the EIT crinkles. With the H(alpha) data, we find remote flare brightening counterparts to the EIT crinkles. Light curves as functions of time of various areas of the active region show that several of the remote flare brightenings undergo intensity increases prior to the onset of principal brightenings in the core region, consistent with our earlier findings from EIT and SXT data. These timing relationships are consistent with the eruption onset mechanism known as the breakout model, introduced by Antiochos and colleagues, which proposes that eruptions begin with reconnection at a magnetic null high above the core region. Our observations are also consistent with other proposed mechanisms that do not involve early reconnection in the core region. As a corollary, our observations are not consistent with the so-called tether-cutting models, which say that the eruption begins with reconnection in the core. The H(alpha) data further show that a filament in the core region becomes activated near the time of EIT crinkle onset, but little if any of the filament actually erupts, despite the presence of a halo coronal mass ejection (CME) associated with this event.

M2-9 - a planetary nebula with an eruptive nucleus?

International Nuclear Information System (INIS)

Balick, B.

1989-01-01

M2-9 is a striking bipolar, or butterfly, planetary nebula (PN) whose nuclear spectrum is uncharacteristic of PN nuclei. Narrow lines ranging in ionization from O I, Fe II, forbidden Fe II, and Si II through forbidden O III are observed in the stellar spectrum. The H-alpha emission line has wings extending nearly 11,000 km/s at the base, and there is a deep self-absorption feature near the H-alpha line peak at the same velocity as nebular gas observed in one of the two bipolar lobes. The spectrum of M2-9's nucleus is more similar to the slow nova RR Tel, some symbiotic stars, and Seyfert (type 1.9) galactic nuclei than the central stars of most other PNs. Although its morphology, size, and nebular spectrum share many similarities with other PNs, M2-9 may not share a common evolutionary history with that class of objects. 31 references

ORIGIN OF THE GALACTIC DIFFUSE X-RAY EMISSION: IRON K-SHELL LINE DIAGNOSTICS

Energy Technology Data Exchange (ETDEWEB)

Nobukawa, Masayoshi [Department of Teacher Training and School Education, Nara University of Education, Takabatake-cho, Nara, 630-8528 (Japan); Uchiyama, Hideki [Faculty of Education, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529 (Japan); Nobukawa, Kumiko K.; Koyama, Katsuji [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto, 606-8502 (Japan); Yamauchi, Shigeo, E-mail: nobukawa@nara-edu.ac.jp [Department of Physics, Nara Women’s University, Kitauoyanishimachi, Nara, 630-8506 (Japan)

2016-12-20

This paper reports detailed K-shell line profiles of iron (Fe) and nickel (Ni) of the Galactic Center X-ray Emission (GCXE), Galactic Bulge X-ray Emission (GBXE), Galactic Ridge X-ray Emission (GRXE), magnetic Cataclysmic Variables (mCVs), non-magnetic Cataclysmic Variables (non-mCVs), and coronally Active Binaries (ABs). For the study of the origin of the GCXE, GBXE, and GRXE, the spectral analysis is focused on equivalent widths of the Fe i-K α , Fe xxv-He α , and Fe xxvi-Ly α  lines. The global spectrum of the GBXE is reproduced by a combination of the mCVs, non-mCVs, and ABs spectra. On the other hand, the GRXE spectrum shows significant data excesses at the Fe i-K α and Fe xxv-He α  line energies. This means that additional components other than mCVs, non-mCVs, and ABs are required, which have symbiotic phenomena of cold gas and very high-temperature plasma. The GCXE spectrum shows larger excesses than those found in the GRXE spectrum at all the K-shell lines of iron and nickel. Among them the largest ones are the Fe i-K α , Fe xxv-He α , Fe xxvi-Ly α , and Fe xxvi-Ly β  lines. Together with the fact that the scale heights of the Fe i-K α , Fe xxv-He α , and Fe xxvi-Ly α lines are similar to that of the central molecular zone (CMZ), the excess components would be related to high-energy activity in the extreme envelopment of the CMZ.

Extinction of H II regions

International Nuclear Information System (INIS)

Israel, F.P.; Kennicutt, R.C.

1980-01-01

Visual extinction of H II regions in nine nearby galaxies as derived from the ratio of the radio continuum emission to H-alpha emission is systematically larger than visual extinction deduced from the Balmer lines alone, if one assumes a value Av/E(B-V) 3. An optically-limited sample of about 30 extragalactic H II regions has a mean extinction of 1.7 m in the visual while about 1.2 m is not seen in the reddening of the Balmer lines. Both reddening and extinction decreases with increasing galactic radius, at least for M33 and M101

FLARE-LIKE VARIABILITY OF THE Mg II {lambda}2800 EMISSION LINE IN THE {gamma}-RAY BLAZAR 3C 454.3

Energy Technology Data Exchange (ETDEWEB)

Leon-Tavares, J. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland); Chavushyan, V.; Patino-Alvarez, V.; Carraminana, A.; Carrasco, L. [Instituto Nacional de Astrofisica Optica y Electronica (INAOE), Apartado Postal 51 y 216, 72000 Puebla (Mexico); Valtaoja, E. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-20100 Turku (Finland); Arshakian, T. G. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Popovic, L. C. [Astronomical Observatory, Volgina 7, 11160 Belgrade 74 (Serbia); Tornikoski, M.; Laehteenmaeki, A. [Aalto University Metsaehovi Radio Observatory, Metsaehovintie 114, FI-02540 Kylmaelae (Finland); Lobanov, A. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

2013-02-01

We report the detection of a statistically significant flare-like event in the Mg II {lambda}2800 emission line of 3C 454.3 during the outburst of autumn 2010. The highest levels of emission line flux recorded over the monitoring period (2008-2011) coincide with a superluminal jet component traversing through the radio core. This finding crucially links the broad emission line fluctuations to the non-thermal continuum emission produced by relativistically moving material in the jet and hence to the presence of broad-line region clouds surrounding the radio core. If the radio core were located at several parsecs from the central black hole, then our results would suggest the presence of broad-line region material outside the inner parsec where the canonical broad-line region is envisaged to be located. We briefly discuss the implications of broad emission line material ionized by non-thermal continuum in the context of virial black hole mass estimates and gamma-ray production mechanisms.

Spectroscopic survey of emission-line stars - I. B[e] stars

Czech Academy of Sciences Publication Activity Database

Aret, A.; Kraus, Michaela; Šlechta, Miroslav

2016-01-01

Roč. 456, č. 2 (2016), s. 1424-1437 ISSN 0035-8711 R&D Projects: GA ČR(CZ) GA14-21373S Institutional support: RVO:67985815 Keywords : circumstellar matter * stars * emission line Subject RIV: BN - Astronomy , Celestial Mechanics, Astrophysics Impact factor: 4.961, year: 2016

OXYGEN METALLICITY DETERMINATIONS FROM OPTICAL EMISSION LINES IN EARLY-TYPE GALAXIES

International Nuclear Information System (INIS)

Athey, Alex E.; Bregman, Joel N.

2009-01-01

We measured the oxygen abundances of the warm (T ∼ 10 4 K) phase of gas in seven early-type galaxies through long-slit observations. A template spectra was constructed from galaxies void of warm gas and subtracted from the emission-line galaxies, allowing for a clean measurement of the nebular lines. The ratios of the emission lines are consistent with photoionization, which likely originates from the ultraviolet flux of postasymototic giant branch stars. We employ H II region photoionization models to determine a mean oxygen metallicity of 1.01 ± 0.50 solar for the warm interstellar medium (ISM) in this sample. This warm ISM 0.5-1.5 solar metallicity is consistent with modern determinations of the metallicity in the hot (T ∼ 10 6 -10 7 K) ISM and the upper range of this warm ISM metallicity is consistent with stellar population metallicity determinations. A solar metallicity of the warm ISM favors an internal origin for the warm ISM such as asymptotic giant branch mass loss within the galaxy.

THE HETDEX PILOT SURVEY. I. SURVEY DESIGN, PERFORMANCE, AND CATALOG OF EMISSION-LINE GALAXIES

International Nuclear Information System (INIS)

Adams, Joshua J.; Blanc, Guillermo A.; Gebhardt, Karl; Hao, Lei; Byun, Joyce; Fry, Alex; Jeong, Donghui; Komatsu, Eiichiro; Hill, Gary J.; Cornell, Mark E.; MacQueen, Phillip J.; Drory, Niv; Bender, Ralf; Hopp, Ulrich; Kelzenberg, Ralf; Ciardullo, Robin; Gronwall, Caryl; Finkelstein, Steven L.; Gawiser, Eric; Kelz, Andreas

2011-01-01

We present a catalog of emission-line galaxies selected solely by their emission-line fluxes using a wide-field integral field spectrograph. This work is partially motivated as a pilot survey for the upcoming Hobby-Eberly Telescope Dark Energy Experiment. We describe the observations, reductions, detections, redshift classifications, line fluxes, and counterpart information for 397 emission-line galaxies detected over 169 □' with a 3500-5800 A bandpass under 5 A full-width-half-maximum (FWHM) spectral resolution. The survey's best sensitivity for unresolved objects under photometric conditions is between 4 and 20x 10 -17 erg s -1 cm -2 depending on the wavelength, and Lyα luminosities between 3 x 10 42 and 6 x 10 42 erg s -1 are detectable. This survey method complements narrowband and color-selection techniques in the search of high-redshift galaxies with its different selection properties and large volume probed. The four survey fields within the COSMOS, GOODS-N, MUNICS, and XMM-LSS areas are rich with existing, complementary data. We find 105 galaxies via their high-redshift Lyα emission at 1.9 44 □' which appear to be extended Lyα nebulae. We also find three high-z objects with rest-frame Lyα EW above the level believed to be achievable with normal star formation, EW 0 >240 A. Future papers will investigate the physical properties of this sample.

Solar Flare Termination Shock and Synthetic Emission Line Profiles of the Fe xxi 1354.08 Å Line

Energy Technology Data Exchange (ETDEWEB)

Guo, Lijia [Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA (United States); Li, Gang [Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL (United States); Reeves, Kathy; Raymond, John, E-mail: gang.li@uah.edu [Harvard-Smithsonian Center for Astrophysics, Boston, MA (United States)

2017-09-01

Solar flares are among the most energetic phenomena that occur in the solar system. In the standard solar flare model, a fast mode shock, often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the TS has been recently related to spectral hardening of a flare’s hard X-ray spectra at energies >300 keV. Observations of the Fe xxi 1354.08 Å line during solar flares by the Interface Region Imaging Spectrograph ( IRIS ) spacecraft have found significant redshifts with >100 km s{sup −1}, which is consistent with a reconnection downflow. The ability to detect such a redshift with IRIS suggests that one may be able to use IRIS observations to identify flare TSs. Using a magnetohydrodynamic simulation to model magnetic reconnection of a solar flare and assuming the existence of a TS in the downflow of the reconnection plasma, we model the synthetic emission of the Fe xxi 1354.08 line in this work. We show that the existence of the TS in the solar flare may manifest itself in the Fe xxi 1354.08 Å line.

Neutral Hydrogen and Its Emission Lines in the Solar Corona

Science.gov (United States)

Vial, Jean-Claude; Chane-Yook, Martine

2016-12-01

Since the Lyman-α rocket observations of Gabriel ( Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic-equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisional and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations ( e.g. Lα from Ultraviolet Coronal Spectrometer) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 Å wide) bandpass filter.

Effective collision strengths of quasar ultraviolet emission lines

International Nuclear Information System (INIS)

Osterbrock, D.E.; Wallace, R.K.

1977-01-01

The best available published collision strengths for excitation of permitted and semiforbidden emission lines of abundant ions observed or expected in quasars have been collected and averaged over Maxwellian velocity distributions. For a few ions for which calculations are not available, extrapolation along isoelectronic sequences or in principal quantum number n was used to estimate values. These collision strengths were used to correct differentially published photoionization models of quasars, and the corrected models compared with published observational data

Galaxy emission line classification using three-dimensional line ratio diagrams

Energy Technology Data Exchange (ETDEWEB)

Vogt, Frédéric P. A.; Dopita, Michael A.; Kewley, Lisa J.; Sutherland, Ralph S. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Scharwächter, Julia [Observatoire de Paris, LERMA (CNRS: UMR8112), 61 Av. de l' Observatoire, F-75014 Paris (France); Basurah, Hassan M.; Ali, Alaa; Amer, Morsi A., E-mail: frederic.vogt@anu.edu.au [Astronomy Department, King Abdulaziz University, P.O. Box 80203, Jeddah (Saudi Arabia)

2014-10-01

Two-dimensional (2D) line ratio diagnostic diagrams have become a key tool in understanding the excitation mechanisms of galaxies. The curves used to separate the different regions—H II-like or excited by an active galactic nucleus (AGN)—have been refined over time but the core technique has not evolved significantly. However, the classification of galaxies based on their emission line ratios really is a multi-dimensional problem. Here we exploit recent software developments to explore the potential of three-dimensional (3D) line ratio diagnostic diagrams. We introduce the ZQE diagrams, which are a specific set of 3D diagrams that separate the oxygen abundance and the ionization parameter of H II region-like spectra and also enable us to probe the excitation mechanism of the gas. By examining these new 3D spaces interactively, we define the ZE diagnostics, a new set of 2D diagnostics that can provide the metallicity of objects excited by hot young stars and that cleanly separate H II region-like objects from the different classes of AGNs. We show that these ZE diagnostics are consistent with the key log [N II]/Hα versus log [O III]/Hβ diagnostic currently used by the community. They also have the advantage of attaching a probability that a given object belongs to one class or the other. Finally, we discuss briefly why ZQE diagrams can provide a new way to differentiate and study the different classes of AGNs in anticipation of a dedicated follow-up study.

The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy

Science.gov (United States)

Maseda, Michael V.; van der Wel, Arjen; Rix, Hans-Walter; Momcheva, Ivelina; Brammer, Gabriel B.; Franx, Marijn; Lundgren, Britt F.; Skelton, Rosalind E.; Whitaker, Katherine E.

2018-02-01

The multiplexing capability of slitless spectroscopy is a powerful asset in creating large spectroscopic data sets, but issues such as spectral confusion make the interpretation of the data challenging. Here we present a new method to search for emission lines in the slitless spectroscopic data from the 3D-HST survey utilizing the Wide-Field Camera 3 on board the Hubble Space Telescope. Using a novel statistical technique, we can detect compact (extended) emission lines at 90% completeness down to fluxes of 1.5(3.0)× {10}-17 {erg} {{{s}}}-1 {{cm}}-2, close to the noise level of the grism exposures, for objects detected in the deep ancillary photometric data. Unlike previous methods, the Bayesian nature allows for probabilistic line identifications, namely redshift estimates, based on secondary emission line detections and/or photometric redshift priors. As a first application, we measure the comoving number density of Extreme Emission Line Galaxies (restframe [O III] λ5007 equivalent widths in excess of 500 Å). We find that these galaxies are nearly 10× more common above z ∼ 1.5 than at z ≲ 0.5. With upcoming large grism surveys such as Euclid and WFIRST, as well as grisms featured prominently on the NIRISS and NIRCam instruments on the James Webb Space Telescope, methods like the one presented here will be crucial for constructing emission line redshift catalogs in an automated and well-understood manner. This work is based on observations taken by the 3D-HST Treasury Program and the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Image isocon observations of emission lines in the spectrum of lambda Cephei

International Nuclear Information System (INIS)

Hutchings, J.B.; Sanyal, A.

1976-01-01

Line profiles of the lambda lambda 4640, 4686 emission lines were observed in the spectrum of lambda Cep, with high time resolution, and high signal-to-noise ratio. Profile changes above the 1 percent level can occur within hours. Possible periodicities in profile changes suggest a connection with rapid stellar rotation. The lambda 4686 profile is consistent with a rotating nonspherical envelope

Outer atmospheres of cool stars. XII - A survey of IUE ultraviolet emission line spectra of cool dwarf stars

Science.gov (United States)

Linsky, J. L.; Bornmann, P. L.; Carpenter, K. G.; Hege, E. K.; Wing, R. F.; Giampapa, M. S.; Worden, S. P.

1982-01-01

Quantitative information is obtained on the chromospheres and transition regions of M dwarf stars, in order to determine how the outer atmospheres of dMe stars differ from dM stars and how they compare with the outer atmospheres of quiet and active G and K type dwarfs. IUE spectra of six dMe and four dM stars, together with ground-based photometry and spectroscopy of the Balmer and Ca II H and K lines, show no evidence of flares. It is concluded, regarding the quiescent behavior of these stars, that emission-line spectra resemble that of the sun and contain emission lines formed in regions with 4000-20,000 K temperatures that are presumably analogous to the solar chromosphere, as well as regions with temperatures of 20,000-200,000 K that are presumably analogous to the solar transition region. Emission-line surface fluxes are proportional to the emission measure over the range of temperatures at which the lines are formed.

Rings of Molecular Line Emission in the Disk Orbiting the Young, Close Binary V4046 Sgr

Science.gov (United States)

Dickson-Vandervelde, Dorothy; Kastner, Joel H.; Qi, C.; Forveille, Thierry; Hily-Blant, Pierre; Oberg, Karin; Wilner, David; Andrews, Sean; Gorti, Uma; Rapson, Valerie; Sacco, Germano; Principe, David

2018-01-01

We present analysis of a suite of subarcsecond ALMA Band 6 (1.1 - 1.4 mm) molecular line images of the circumbinary, protoplanetary disk orbiting V4046 Sgr. The ~20 Myr-old V4046 Sgr system, which lies a mere ~73 pc from Earth, consists of a close (separation ~10 Rsun) pair of roughly solar-mass stars that are orbited by a gas-rich crcumbinary disk extending to ~350 AU in radius. The ALMA images reveal that the molecules CO and HCN and their isotopologues display centrally peaked surface brightness morphologies, whereas the cyanide group molecules (HC3N, CH3CN), deuterated molecules (DCN, DCO+), hydrocarbons (as traced by C2H), and potential CO ice line tracers (N2H+, and H2CO) appear as a sequence of sharp and diffuse rings of increasing radii. The characteristic sizes of these molecular emission rings, which range from ~25 to >100 AU in radius, are evident in radial emission-line surface brightness profiles extracted from the deprojected disk images. We find that emission from 13CO emission transitions from optically thin to thick within ~50 AU, whereas C18O emission remains optically thin within this radius. We summarize the insight into the physical and chemical processes within this evolved protoplanetary disk that can be obtained from comparisons of the various emission-line morphologies with each other and with that of the continuum (large-grain) emission on size scales of tens of AU.This research is supported by NASA Exoplanets program grant NNX16AB43G to RIT

Laboratory measurements of the x-ray line emission from neon-like Fe XVII

International Nuclear Information System (INIS)

Brown, G V; Beiersdorfer, P; Chen, H; Scofield, J; Boyce, K R; Kelley, R L; Kilbourne, C A; Porter, F S; Gu, M F; Kahn, S M; Szymkowiak, A E

2006-01-01

The authors have conducted a systematic study of the dominant x-ray line emission from Fe XVII. These studies include relative line intensities in the optically thin limit, intensities in the presence of radiation from satellite lines from lower charge states of iron, and the absolute excitation cross sections of some of the strongest lines. These measurements were conducted at the Lawrence Livermore National Laboratory electron beam ion trap facility using crystal spectrometers and a NASA-Goddard Space Flight Center microcalorimeter array

Quantum degeneracy corrections to plasma line emission and to Saha equation

International Nuclear Information System (INIS)

Molinari, V.G.; Mostacci, D.; Rocchi, F.; Sumini, M.

2003-01-01

The effect of quantum degeneracy on the electron collisional excitation is investigated, and its effects on line emission evaluated for applications to spectroscopy of dense, cold plasmas. A correction to Saha equation for weakly-degenerate plasmas is also presented

COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. II. BALMER EMISSION

Energy Technology Data Exchange (ETDEWEB)

Morlino, G.; Bandiera, R.; Blasi, P.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

2012-12-01

Strong shocks propagating into a partially ionized medium are often associated with optical Balmer lines. This emission is due to impact excitation of neutral hydrogen by hot protons and electrons in the shocked gas. The structure of such Balmer-dominated shocks has been computed in a previous paper, where the distribution function of neutral particles was derived from the appropriate Boltzmann equation including coupling with ions and electrons through charge exchange and ionization. This calculation showed how the presence of neutrals can significantly modify the shock structure through the formation of a neutral-induced precursor ahead of the shock. Here we follow up on our previous work and investigate the properties of the resulting Balmer emission, with the aim of using the observed radiation as a diagnostic tool for shock parameters. Our main focus is on supernova remnant shocks, and we find that, for typical parameters, the H{alpha} emission typically has a three-component spectral profile, where (1) a narrow component originates from upstream cold hydrogen atoms, (2) a broad component comes from hydrogen atoms that have undergone charge exchange with shocked protons downstream of the shock, and (3) an intermediate component is due to hydrogen atoms that have undergone charge exchange with warm protons in the neutral-induced precursor. The relative importance of these three components depends on the shock velocity, on the original degree of ionization, and on the electron-ion temperature equilibration level. The intermediate component, which is the main signature of the presence of a neutral-induced precursor, becomes negligible for shock velocities {approx}< 1500 km s{sup -1}. The width of the intermediate line reflects the temperature in the precursor, while the width of the narrow one is left unaltered by the precursor. In addition, we show that the profiles of both the intermediate and broad components generally depart from a thermal distribution, as a

H-alpha Proxies for EIT Crinkles: Further Evidence for Pre-Flare "Breakout"-Type Activity in an Ejective Solar Eruption

Science.gov (United States)

Sterling, Alphonse C.; Moore, R. L.; Qiu, J.; Wang, H.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

We present Halpha observations from Big Bear Solar Observatory of an eruptive flare in NOAA AR 8210, occurring near 22:30 UT on 1998 May 1. Previously, using the EUV Imaging Telescope (EIT) on the SOHO spacecraft, we found that a pattern of transient, localized brightenings, which we call "EIT crinkles," appears in the neighborhood of the eruption near the time of flare onset. These EIT crinkles occur at a location in the active region well separated from the sheared core magnetic fields, which is where the most intense features of the eruption are concentrated. We also previously found that high-cadence images from the Soft X-ray Telescope (SXT) on Yohkoh indicate that soft X-ray intensity enhancements in the core begin after the start of the EIT crinkles. With the Halpha data, we find remote flare brightening counterparts to the EIT crinkles. Lightcurves as functions of time of various areas of the active region show that several of the remote flare brightenings undergo intensity increases prior to onset of principle brightenings in the core region, consistent with our earlier findings from EIT and SXT data. These timing relationships are consistent with the eruption onset mechanism known as the breakout model, introduced by Antiochos and colleagues, which proposes that eruptions begin with reconnection at a magnetic null high above the core region. Our observations are also consistent with other proposed mechanisms which do not involve early reconnection in the core region. As a corollary, our observations are not consistent with the so-called tether cutting models, which say that the eruption begins with reconnection in the core. The Halpha data further show that a filament in the core region becomes activated near the time of EIT crinkle onset, but little if any of the filament actually erupts, despite the presence of a halo Coronal Mass Ejection (CME) associated with this event.

CO LINE EMISSION FROM COMPACT NUCLEAR STARBURST DISKS AROUND ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Armour, J. N.; Ballantyne, D. R., E-mail: jarmour3@gatech.edu [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States)

2012-06-20

There is substantial evidence for a connection between star formation in the nuclear region of a galaxy and growth of the central supermassive black hole. Furthermore, starburst activity in the region around an active galactic nucleus (AGN) may provide the obscuration required by the unified model of AGNs. Molecular line emission is one of the best observational avenues to detect and characterize dense, star-forming gas in galactic nuclei over a range of redshift. This paper presents predictions for the carbon monoxide (CO) line features from models of nuclear starburst disks around AGNs. These small-scale ({approx}< 100 pc), dense and hot starbursts have CO luminosities similar to scaled-down ultra-luminous infrared galaxies and quasar host galaxies. Nuclear starburst disks that exhibit a pc-scale starburst and could potentially act as the obscuring torus show more efficient CO excitation and higher brightness temperature ratios than those without such a compact starburst. In addition, the compact starburst models predict strong absorption when J{sub Upper} {approx}> 10, a unique observational signature of these objects. These findings allow for the possibility that CO spectral line energy distributions (SLEDs) could be used to determine if starburst disks are responsible for the obscuration in z {approx}< 1 AGNs. Directly isolating the nuclear CO line emission of such compact regions around AGNs from galactic-scale emission will require high-resolution imaging or selecting AGN host galaxies with weak galactic-scale star formation. Stacking individual CO SLEDs will also be useful in detecting the predicted high-J features.

Discovery of the double Doppler-shifted emission-line systems in the X-ray spectrum of SS 433

Science.gov (United States)

Kotani, Taro; Kawai, Nobuyuki; Aoki, Takashi; Doty, John; Matsuoka, Masaru; Mitsuda, Kazuhisa; Nagase, Fumiaki; Ricker, George; White, Nick E.

1994-01-01

We have used the CCD X-ray spectrometers on ASCA and resolved the X-ray emission line from the jet of SS 433 both into Doppler-shifted components with two distinct velocities, and into emission from different ionization states of iron, i.e., Fe XXV and Fe XXVI. This is the first direct detection of the two Doppler shifted beams in the X-ray spectra of SS 433 and allows the radial velocity of the jet along the line of sight to be determined with an accuracy comparable to the optical spectroscopy. We also found pairs of emission lines from other atomic species, such as ionized silicon and sulfur, with the Doppler shifts consistent with each other. This confirms the origin of the X-ray emission in the high temperature plasma in the jets.

DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Constantin, Anca; Castillo, Christopher A. [Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22807 (United States); Shields, Joseph C. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Barth, Aaron J. [Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2015-12-01

Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ≈ 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude.

The mass and radius of the M dwarf companion to GD 448

OpenAIRE

Maxted, P. F. L.; Marsh, T. R.; Moran, C.; Dhillon, V. S.; Hilditch, R. W.

1998-01-01

We present spectroscopy and photometry of GD 448, a detached white dwarf - M dwarf binary with a period of 2.47h. We find that the NaI 8200A feature is composed of narrow emission lines due to irradiation of the M dwarf by the white dwarf within broad absorption lines that are essentially unaffected by heating. Combined with an improved spectroscopic orbit and gravitational red shift measurement from spectra of the H-alpha line, we are able to derive masses for the white dwarf and M dwarf dir...

40 CFR Table 36 to Subpart Uuu of... - Work Practice Standards for HAP Emissions From Bypass Lines

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Work Practice Standards for HAP Emissions From Bypass Lines 36 Table 36 to Subpart UUU of Part 63 Protection of Environment ENVIRONMENTAL..., Table 36 Table 36 to Subpart UUU of Part 63—Work Practice Standards for HAP Emissions From Bypass Lines...

STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS

International Nuclear Information System (INIS)

Wang Yan; Li Xiangdong

2012-01-01

If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

40 CFR 1045.320 - What happens if one of my production-line engines fails to meet emission standards?

Science.gov (United States)

2010-07-01

...-line engines fails to meet emission standards? 1045.320 Section 1045.320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND VESSELS Testing Production-line Engines § 1045.320 What happens if one of my...

40 CFR 1048.320 - What happens if one of my production-line engines fails to meet emission standards?

Science.gov (United States)

2010-07-01

...-line engines fails to meet emission standards? 1048.320 Section 1048.320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW, LARGE NONROAD SPARK-IGNITION ENGINES Testing Production-line Engines § 1048.320 What happens if one of my production...

Atomic emission spectroscopy for the on-line monitoring of incineration processes

NARCIS (Netherlands)

Timmermans, E.A.H.; de Groote, F.P.J.; Jonkers, J.; Gamero, A.; Sola, A.; Mullen, van der J.J.A.M.

2003-01-01

A diagnostic measurement system based on atomic emission spectroscopy has been developed for the purpose of on-line monitoring of hazardous elements in industrial combustion gases. The aim was to construct a setup with a high durability for rough and variable experimental conditions, e.g. a strongly

Emission-line widths and stellar-wind flows in T Tauri stars

International Nuclear Information System (INIS)

Sa, C.; Lago, M.T.V.T.

1986-01-01

Spectra are reported of T Tauri stars taken with the IPCS on the Isaac Newton Telescope at the Observatorio del Roque de los Muchachos at a dispersion of l7 A mm -1 . These were taken in order to determine emission-line widths and hence flow velocities in the winds of these stars following the successful modelling of the wind from RU Lupi using such data. Line widths in RW Aur suggest a similar pattern to the wind flow as in RU Lupi with velocities rising in the inner chromosphere of the star and then entering a 'ballistic' zone. The wind from DFTau is also similar but velocities are generally much lower and the lines sharper. (author)

THE JET POWER AND EMISSION-LINE CORRELATIONS OF RADIO-LOUD OPTICALLY SELECTED QUASARS

International Nuclear Information System (INIS)

Punsly, Brian; Zhang Shaohua

2011-01-01

In this Letter, the properties of the extended radio emission form Sloan Digital Sky Survey Data Release 7 quasars with 0.4 20-30 kpc). The frequency of quasars with FR II level extended radio emission is ∼2.3% and >0.4% of quasars have FR I level extended radio emission. The lower limit simply reflects the flux density limit of the survey. The distribution of the long-term time-averaged jet powers of these quasars, Q-bar , has a broad peak ∼3 x 10 44 erg s -1 that turns over below 10 44 erg s -1 and sources above 10 45 erg s -1 are extremely rare. It is found that the correlation between the bolometric (total thermal) luminosity of the accretion flow, L bol , and Q-bar is not strong. The correlation of Q-bar with narrow line luminosity is stronger than the correlation with broad line luminosity and the continuum luminosity. It is therefore concluded that previous interpretations of correlations of Q-bar with narrow line strengths in radio galaxies as a direct correlation of jet power and accretion power have been overstated. It is explained why this interpretation mistakenly overlooks the sizeable fraction of sources with weak accretion luminosity and powerful jets discovered by Ogle et al.

Nonlocal electron kinetics and spectral line emission in the positive column of an argon glow discharge

International Nuclear Information System (INIS)

Golubovskii, Yu; Kalanov, D; Gorchakov, S; Uhrlandt, D

2015-01-01

Modern non-local electron kinetics theory predicts several interesting effects connected with spectral line emission from the positive column in the range of low and medium pressures and currents. Some theoretical works describe non-monotonic behavior of the radial profiles of line emission at intermediate pressures and currents between the validity ranges of the non-local and local approximation of the electron kinetics. Despite a great number of publications, there have been no systematic measurements attempting to confirm these theoretical predictions through experiments. In this work the radial profiles of the line emission from the positive column of an argon glow discharge have been measured with high spatial resolution and new effects caused by the narrowing and broadening of the spatial emission profiles with dependence on discharge conditions have been discovered. The effect of intensity maximum shift predicted by theory using a self-consistent model was not found in the experiment. The properties of the spectral line radiation are influenced by the peculiarities of the formation of the high-energy tail of the electron energy distribution function. An interpretation of the observed effects based on the non-local character of the electron kinetics in radially inhomogeneous fields is given. The obtained experimental data are compared with the results of calculations. (paper)

ALMA IMAGING OF THE CO (6-5) LINE EMISSION IN NGC 7130

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yinghe [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Lu, Nanyao [National Astronomical Observatories of China, Chinese Academy of Sciences, Beijing 100012 (China); Xu, C. Kevin; Appleton, Philip; Murphy, Eric [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Gao, Yu [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Barcos-Munõz, Loreto [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Díaz-Santos, Tanio [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Charmandaris, Vassilis [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Armus, Lee [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Van der Werf, Paul [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Evans, Aaron [National Radio Astronomy Observatory, Charlottesville, VA 22904 (United States); Cao, Chen [School of Space Science and Physics, Shandong University at Weihai, Weihai, Shandong 264209 (China); Inami, Hanae, E-mail: zhaoyinghe@gmail.com [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2016-04-01

In this paper, we report our high-resolution (0.″20 × 0.″14 or ∼70 × 49 pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 μm dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are 1230 ± 74 Jy km s{sup −1} and 814 ± 52 mJy, respectively, which account for 100% and 51% of their total fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of ∼70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an active galactic nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-α maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of <100 pc or a large uncertainty in our extinction correction to the observed Pa-α image. Over a larger scale of ∼2.1 kpc, the double-lobed structure found in the CO(6-5) emission agrees well with the dust lanes in the optical/near-infrared images.

ALMA IMAGING OF THE CO (6-5) LINE EMISSION IN NGC 7130

International Nuclear Information System (INIS)

Zhao, Yinghe; Lu, Nanyao; Xu, C. Kevin; Appleton, Philip; Murphy, Eric; Gao, Yu; Barcos-Munõz, Loreto; Díaz-Santos, Tanio; Charmandaris, Vassilis; Armus, Lee; Van der Werf, Paul; Evans, Aaron; Cao, Chen; Inami, Hanae

2016-01-01

In this paper, we report our high-resolution (0.″20 × 0.″14 or ∼70 × 49 pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 μm dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are 1230 ± 74 Jy km s −1 and 814 ± 52 mJy, respectively, which account for 100% and 51% of their total fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of ∼70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an active galactic nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-α maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of <100 pc or a large uncertainty in our extinction correction to the observed Pa-α image. Over a larger scale of ∼2.1 kpc, the double-lobed structure found in the CO(6-5) emission agrees well with the dust lanes in the optical/near-infrared images

X-ray heating and ionization of broad-emission-line regions in QSO's and active galaxies

International Nuclear Information System (INIS)

Weisheit, J.C.; Shields, G.A.; Tarter, C.B.

1980-07-01

Absorption of x-rays deep within the broad-line emitting clouds in QSO's and the nuclei of active galaxies creates extensive zones of warm (T approx. 10 4 K), partially ionized N/sub e//N approx. 0.1) gas. Because Lyman alpha photons are trapped in these regions, the x-ray energy is efficiently channeled into Balmer lines collisionally excited from the n = 2 level. The HI regions plus the HII regions created by ultraviolet photons illuminating the surfaces of the clouds give rise to integrated Lα/Hα line emission ratios between 1 and 2. Enhanced MgII line emission from the HI regions gives rise to integrated MgII/Hα ratios near 0.5. The OI line lambda 8446 is efficiently pumped by trapped Hα photons and in the x-ray heated zone an intensity ratio I (lambda 8446)/I(Hα) approx. < 0.1 is calculated. All of these computed ratios now are in agreement with observations

Determination numbers of ionized atoms from emission and absorption lines

International Nuclear Information System (INIS)

Alizadeh Azimi, A.; Shokouhi, N.

2002-01-01

Saha, M., (1920) estimated that salter chromosphere is not only due to radiation from neutral atoms, but from ionized atoms. The failure to observe these stellar lines in the laboratory was attributed to internal temperature and pressure about 10* E + 6 K 10* E-7 atm. In this research we found that emission lines of ionized atoms (like Cs) could be measured in laboratory condition, (about 10* E-3 atm and 2000 K) by using Graphite France Atomic Absorption with injection 124 u g C sel. We calculated the numbers of ionized atoms from Bottzman law. We also measured these numbers from area under the energy-time curve

Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae.

Science.gov (United States)

Keenan, F P; Aller, L H; Ramsbottom, C A; Bell, K L; Crawford, F L; Hyung, S

2000-04-25

Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed.

Emission-line diagnostics of nearby H II regions including interacting binary populations

Science.gov (United States)

Xiao, Lin; Stanway, Elizabeth R.; Eldridge, J. J.

2018-06-01

We present numerical models of the nebular emission from H II regions around young stellar populations over a range of compositions and ages. The synthetic stellar populations include both single stars and interacting binary stars. We compare these models to the observed emission lines of 254 H II regions of 13 nearby spiral galaxies and 21 dwarf galaxies drawn from archival data. The models are created using the combination of the BPASS (Binary Population and Spectral Synthesis) code with the photoionization code CLOUDY to study the differences caused by the inclusion of interacting binary stars in the stellar population. We obtain agreement with the observed emission line ratios from the nearby star-forming regions and discuss the effect of binary-star evolution pathways on the nebular ionization of H II regions. We find that at population ages above 10 Myr, single-star models rapidly decrease in flux and ionization strength, while binary-star models still produce strong flux and high [O III]/H β ratios. Our models can reproduce the metallicity of H II regions from spiral galaxies, but we find higher metallicities than previously estimated for the H II regions from dwarf galaxies. Comparing the equivalent width of H β emission between models and observations, we find that accounting for ionizing photon leakage can affect age estimates for H II regions. When it is included, the typical age derived for H II regions is 5 Myr from single-star models, and up to 10 Myr with binary-star models. This is due to the existence of binary-star evolution pathways, which produce more hot Wolf-Rayet and helium stars at older ages. For future reference, we calculate new BPASS binary maximal starburst lines as a function of metallicity, and for the total model population, and present these in Appendix A.

MID-INFRARED ATOMIC FINE-STRUCTURE EMISSION-LINE SPECTRA OF LUMINOUS INFRARED GALAXIES: SPITZER/IRS SPECTRA OF THE GOALS SAMPLE

Energy Technology Data Exchange (ETDEWEB)

Inami, H. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Armus, L.; Stierwalt, S.; Díaz-Santos, T.; Surace, J.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Groves, B. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Kewley, L. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Petric, A. [Department of Astronomy, California Institute of Technology, MS 320-47, Pasadena, CA 91125 (United States); Rich, J. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Haan, S. [CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Mazzarella, J.; Lord, S. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Appleton, P. [NASA Herschel Science Center, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Spoon, H. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Matsuhara, H., E-mail: inami@noao.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan); and others

2013-11-10

We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne V], [Ne III], [S III]{sub 18.7{sub μm}}, [O IV], [Fe II], [S III]{sub 33.5{sub μm}}, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne V]/[Ne II] line flux ratios and equivalent width of the 6.2 μm polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S IV]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z{sub ☉}, and ionization parameters of 2-8 × 10{sup 7} cm s{sup –1}. Based on the [S III]{sub 33.5{sub μm}}/[S III]{sub 18.7{sub μm}} ratios, the electron density in LIRG nuclei is typically one to a few hundred cm{sup –3}, with a median electron density of ∼300 cm{sup –3}, for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM ≥600 km s{sup –1}) and five show clear differences in the velocities of the [Ne III] or [Ne V] emission lines, relative to [Ne II], of more than 200 km s{sup –1}. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential

Optimization of soft x-ray line emission from laser-produced carbon ...

Indian Academy of Sciences (India)

Intense XUV soft x-ray emission from laser-produced plasma sources is currently ... absorption edges of oxygen and carbon respectively) is particularly attractive as it permits ... ability of the target element producing intense discrete lines in the water .... ficient due to Pert [17] and dielectronic recombination coefficient due to ...

Status and Needs Research for On-line Monitoring of VOCs Emissions from Stationary Sources

Science.gov (United States)

Zhou, Gang; Wang, Qiang; Zhong, Qi; Zhao, Jinbao; Yang, Kai

2018-01-01

Based on atmospheric volatile organic compounds (VOCs) pollution control requirements during the twelfth-five year plan and the current status of monitoring and management at home and abroad, instrumental architecture and technical characteristics of continuous emission monitoring systems (CEMS) for VOCs emission from stationary sources are investigated and researched. Technological development needs of VOCs emission on-line monitoring techniques for stationary sources in china are proposed from the system sampling pretreatment technology and analytical measurement techniques.

(Sub)millimeter emission lines of molecules in born-again stars

Science.gov (United States)

Tafoya, D.; Toalá, J. A.; Vlemmings, W. H. T.; Guerrero, M. A.; De Beck, E.; González, M.; Kimeswenger, S.; Zijlstra, A. A.; Sánchez-Monge, Á.; Treviño-Morales, S. P.

2017-04-01

Context. Born-again stars provide a unique possibility to study the evolution of the circumstellar envelope of evolved stars in human timescales. Up until now, most of the observations of the circumstellar material in these stars have been limited to studying the relatively hot gas and dust. In other evolved stars, the emission from rotational transitions of molecules, such as CO, is commonly used to study the cool component of their circumstellar envelopes. Thus, the detection and study of molecular gas in born-again stars is of great importance when attempting to understand their composition and chemical evolution. In addition, the molecular emission is an invaluable tool for exploring the physical conditions, kinematics, and formation of asymmetric structures in the circumstellar envelopes of these evolved stars. However, up until now, all attempts to detect molecular emission from the cool material around born-again stars have failed. Aims: We searched for emission from rotational transitions of molecules in the hydrogen-deficient circumstellar envelopes of born-again stars to explore the chemical composition, kinematics, and physical parameters of the relatively cool gas. Methods: We carried out observations using the APEX and IRAM 30 m telescopes to search for molecular emission toward four well-studied born-again stars, V4334 Sgr, V605 Aql, A30, and A78, that are thought to represent an evolutionary sequence. Results: For the first time, we detected emission from HCN and H13CN molecules toward V4334 Sgr, and CO emission in V605 Aql. No molecular emission was detected above the noise level toward A30 and A78. The detected lines exhibit broad linewidths ≳150 km s-1, which indicates that the emission comes from gas ejected during the born-again event, rather than from the old planetary nebula. A first estimate of the H12CN/H13CN abundance ratio in the circumstellar environment of V4334 Sgr is ≈3, which is similar to the value of the 12C/13C ratio measured

Balloon observation of the binary X-ray source Her X-1 1.24 sec pulsation and cyclotron line emission

International Nuclear Information System (INIS)

Pietsch, W.; Reppin, C.; Truemper, J.; Voges, W.; Kendziorra, E.; Staubert, R.; Tuebingen Univ.

1978-01-01

During a balloon observation from Palestine, Texas, the authors detected for the first time the 1.24 sec pulsation of Hercules X-1 in the hard X-ray range up to 70 keV and discovered strong line emission in its spectrum at 58 keV. They estimated a line flux of 3x10 -3 photons cm -2 sec -1 and a line width of less than 12 keV. The phenomenon is interpreted as electron cyclotron emission at the basic frequency emitted by the hot polar plasma of the rotating neutron star. The line measured leads to a magnetic field strength of 5.3x10 12 gauss. In further observations during a balloon campaign in Sept./Oct. 1977 the authors confirmed the existence of the line emission and for the first time found pulsed X-ray emission above 15 keV during the 'short on' - and 'off'-state of the Her X-1 35 day cycle. The pulse to interpulse ratio seems to vary with the 35 day phase

X-RAY AND MULTIWAVELENGTH INSIGHTS INTO THE NATURE OF WEAK EMISSION-LINE QUASARS AT LOW REDSHIFT

Energy Technology Data Exchange (ETDEWEB)

Wu Jianfeng; Brandt, W. N.; Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92903 (United States); Hall, Patrick B. [Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, ON M3J 1P3 (Canada); Plotkin, Richard M. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Shemmer, Ohad, E-mail: jfwu@astro.psu.edu [Department of Physics, University of North Texas, Denton, TX 76203 (United States)

2012-03-01

We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the Plotkin et al. catalog of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of {approx}> 5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization 'shielding gas' covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. The mid-infrared-to-UV SEDs of most radio-quiet weak-featured AGNs without sensitive X-ray coverage (34 objects) are also consistent with those of typical SDSS quasars. However, one source in our

X-RAY AND MULTIWAVELENGTH INSIGHTS INTO THE NATURE OF WEAK EMISSION-LINE QUASARS AT LOW REDSHIFT

International Nuclear Information System (INIS)

Wu Jianfeng; Brandt, W. N.; Schneider, Donald P.; Anderson, Scott F.; Diamond-Stanic, Aleksandar M.; Hall, Patrick B.; Plotkin, Richard M.; Shemmer, Ohad

2012-01-01

We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the Plotkin et al. catalog of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of ∼> 5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization 'shielding gas' covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. The mid-infrared-to-UV SEDs of most radio-quiet weak-featured AGNs without sensitive X-ray coverage (34 objects) are also consistent with those of typical SDSS quasars. However, one source in our X

Discovery of flare activity on the dwarf M stars, GI 375 and GI 431

Energy Technology Data Exchange (ETDEWEB)

Doyle, J.G.; Mathioudakis, M.; Panagi, P.M.; Butler, C.J. (Armagh Observatory, (IE))

1990-12-01

Optical and infrared photometry plus spectroscopic data is present for two new flare stars, GI 375 and GI 431. Both of these stars have the hydrogen Balmer lines strongly in emission. Several flares were detected on GI 375 implying a high level of flare activity. The H{alpha} surface flux of 1.0 x 10{sup 6} erg cm{sup -2}s{sup -1} for both stars is similar to that of other active flare stars. Fluxes are given for several of the higher Balmer lines.

SHOCKED SUPERWINDS FROM THE z {approx} 2 CLUMPY STAR-FORMING GALAXY, ZC406690

Energy Technology Data Exchange (ETDEWEB)

Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Shapiro Griffin, Kristen [Aerospace Research Laboratories, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Davies, Ric; Foerster-Schreiber, Natascha M.; Tacconi, Linda J.; Kurk, Jaron; Wuyts, Stijn; Genel, Shy; Buschkamp, Peter; Eisenhauer, Frank; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr.1, D-85748 Garching (Germany); Lilly, Simon J.; Carollo, C. Marcella [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich CH-8093 (Switzerland); Renzini, Alvio; Mancini, Chiara [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, Padova I-35122 (Italy); Bouche, Nicolas [Department of Physics and Astronomy, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); 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); Hicks, Erin, E-mail: sfnewman@berkeley.edu [Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580 (United States); and others

2012-06-20

We have obtained high-resolution data of the z {approx} 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], H{alpha}, H{beta}, [N II], and [S II]. We find broad, blueshifted H{alpha} and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps ({sigma} {approx} 85 km s{sup -1}) and even broader wings (up to 70% of the total H{alpha} flux, with {sigma} {approx} 290 km s{sup -1}) in regions spatially offset from the clumps by {approx}2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8 Multiplication-Sign the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/H{alpha} and [S II]/H{alpha}) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6 Multiplication-Sign 10{sup 7} to 10{sup 8} cm s{sup -1}, based on both the SFR and the O{sub 32} ratio), density (local electron densities of 300-1800 cm{sup -3} in and around the clumps, and ionized gas column densities of 1200-8000 M{sub Sun }pc{sup -2}), and SFR (10-40 M{sub Sun} yr{sup -1}), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal

Mapping low- and high-density clouds in astrophysical nebulae by imaging forbidden line emission

Science.gov (United States)

Steiner, J. E.; Menezes, R. B.; Ricci, T. V.; Oliveira, A. S.

2009-06-01

Emission line ratios have been essential for determining physical parameters such as gas temperature and density in astrophysical gaseous nebulae. With the advent of panoramic spectroscopic devices, images of regions with emission lines related to these physical parameters can, in principle, also be produced. We show that, with observations from modern instruments, it is possible to transform images taken from density-sensitive forbidden lines into images of emission from high- and low-density clouds by applying a transformation matrix. In order to achieve this, images of the pairs of density-sensitive lines as well as the adjacent continuum have to be observed and combined. We have computed the critical densities for a series of pairs of lines in the infrared, optical, ultraviolet and X-rays bands, and calculated the pair line intensity ratios in the high- and low-density limit using a four- and five-level atom approximation. In order to illustrate the method, we applied it to Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (GMOS-IFU) data of two galactic nuclei. We conclude that this method provides new information of astrophysical interest, especially for mapping low- and high-density clouds; for this reason, we call it `the ld/hd imaging method'. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States); the Science and Technology Facilities Council (United Kingdom); the National Research Council (Canada), CONICYT (Chile); the Australian Research Council (Australia); Ministério da Ciência e Tecnologia (Brazil) and Secretaria de Ciencia y Tecnologia (Argentina). E-mail: steiner@astro.iag.usp.br

Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

Energy Technology Data Exchange (ETDEWEB)

Fausnaugh, M. M.; Denney, K. D.; Peterson, B. M.; Kochanek, C. S.; Pogge, R. W.; Brown, Jonathan S.; Coker, C. T. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); Grier, C. J.; Beatty, Thomas G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Rosa, G. De [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Adams, S. M. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Barth, A. J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bhattacharjee, A.; Brotherton, M. S. [Department of Physics and Astronomy, University of Wyoming, 1000 E. University Avenue, Laramie, WY (United States); Borman, G. A. [Crimean Astrophysical Observatory, P/O Nauchny, Crimea 298409 (Russian Federation); Boroson, T. A. [Las Cumbres Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bottorff, M. C. [Fountainwood Observatory, Department of Physics FJS 149, Southwestern University, 1011 E. University Avenue, Georgetown, TX 78626 (United States); Brown, Jacob E. [Department of Physics and Astronomy, University of Missouri, Columbia (United States); Crawford, S. M. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); and others

2017-05-10

We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a “changing look” AGN and a broad-line radio galaxy. Based on continuum-H β lags, we measure black hole masses for all five targets. We also obtain H γ and He ii λ 4686 lags for all objects except 3C 382. The He ii λ 4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100–300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

International Nuclear Information System (INIS)

Fausnaugh, M. M.; Denney, K. D.; Peterson, B. M.; Kochanek, C. S.; Pogge, R. W.; Brown, Jonathan S.; Coker, C. T.; Grier, C. J.; Beatty, Thomas G.; Bentz, M. C.; Rosa, G. De; Adams, S. M.; Barth, A. J.; Bhattacharjee, A.; Brotherton, M. S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brown, Jacob E.; Crawford, S. M.

2017-01-01

We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a “changing look” AGN and a broad-line radio galaxy. Based on continuum-H β lags, we measure black hole masses for all five targets. We also obtain H γ and He ii λ 4686 lags for all objects except 3C 382. The He ii λ 4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100–300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

First light - II. Emission line extinction, population III stars, and X-ray binaries

Science.gov (United States)

Barrow, Kirk S. S.; Wise, John H.; Aykutalp, Aycin; O'Shea, Brian W.; Norman, Michael L.; Xu, Hao

2018-02-01

We produce synthetic spectra and observations for metal-free stellar populations and high-mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far-infrared with enough frequency resolution to discern line emission and absorption profiles. The most common lines in our sample in order of their rate of occurrence are Ly α, the C IV λλ1548, 1551 doublet, H α, and the Ca II λλλ8498, 8542, 8662 triplet. The best scenario for a direct observation of a metal-free stellar population is a merger between two Population III Galaxies. In mergers between metal-enriched and metal-free stellar populations, some characteristics may be inferred indirectly. Single Population III galaxies are too dim to be observed photometrically at z = 15. Ly α emission is discernible by JWST as an increase in J200w - J277w colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.

MULTIWAVELENGTH OBSERVATIONS OF RADIO-QUIET QUASARS WITH WEAK EMISSION LINES

International Nuclear Information System (INIS)

Plotkin, Richard M.; Anderson, Scott F.; MacLeod, Chelsea L.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Shemmer, Ohad

2010-01-01

We present radio and X-ray observations, as well as optical light curves, for a subset of 26 BL Lac candidates from the Sloan Digital Sky Survey (SDSS) lacking strong radio emission and with z < 2.2. Half of these 26 objects are shown to be stars, galaxies, or absorbed quasars. We conclude that the other 13 objects are active galactic nuclei (AGNs) with abnormally weak emission features; 10 of those 13 are definitively radio quiet, and, for those with available optical light curves, their level of optical flux variability is consistent with radio-quiet quasars. We cannot exclude the possibility that some of these 13 AGNs lie on the extremely radio-faint tail of the BL Lac distribution, but our study generally supports the notion that all BL Lac objects are radio-loud. These radio-quiet AGNs appear to have intrinsically weak or absent broad emission line regions (BELRs), and, based on their X-ray properties, we argue that some are low-redshift analogs to weak line quasars (WLQs). SDSS BL Lac searches are so far the only systematic surveys of the SDSS database capable of recovering such exotic low-redshift WLQs. There are 71 more z < 2.2 radio-quiet BL Lac candidates already identified in the SDSS, but not considered here, and many of those might be best unified with WLQs as well. Future studies combining low- and high-redshift WLQ samples will yield new insight on our understanding of the structure and formation of AGN BELRs.

Temperature and emission-line structure at the edges of H II regions

International Nuclear Information System (INIS)

Mallik, D.C.V.

1975-01-01

Models of ionization fronts located at the edges of expanding H ii regions are presented. These fronts are of the weak D-type and are preceded by shocks in the H i clouds. Since the energy input time is smaller than the cooling time, the gas is found to heat up to a high temperature immediately following ionization. At the trailing edge of the front, the temperature decreases and the ionized gas merges with the main bulk of the nebula where the physical processes are in equilibrium. The emission in O ii and N ii lines is greatly enhanced because of the high temperature at the front. The emission in these and other important lines is calculated and compared with Hβ. Effects of different velocities of flow, of different exciting stars, and of different gas densities on the structure of the fronts are also investigated

Modeling particle emission and power flow in pulsed-power driven, nonuniform transmission lines

Directory of Open Access Journals (Sweden)

Nichelle Bruner

2008-04-01

Full Text Available Pulsed-power driven x-ray radiographic systems are being developed to operate at higher power in an effort to increase source brightness and penetration power. Essential to the design of these systems is a thorough understanding of electron power flow in the transmission line that couples the pulsed-power driver to the load. In this paper, analytic theory and fully relativistic particle-in-cell simulations are used to model power flow in several experimental transmission-line geometries fielded on Sandia National Laboratories’ upgraded Radiographic Integrated Test Stand [IEEE Trans. Plasma Sci. 28, 1653 (2000ITPSBD0093-381310.1109/27.901250]. Good agreement with measured electrical currents is demonstrated on a shot-by-shot basis for simulations which include detailed models accounting for space-charge-limited electron emission, surface heating, and stimulated particle emission. Resonant cavity modes related to the transmission-line impedance transitions are also shown to be excited by electron power flow. These modes can drive oscillations in the output power of the system, degrading radiographic resolution.

Rotational emission-line spectrum of Orion A between 247 and 263 GHZ

International Nuclear Information System (INIS)

Blake, G.A.; Sutton, E.C.; Masson, C.R.; Phillips, T.G.

1986-01-01

Results are presented from a molecular line survey of the core of the Orion molecular cloud between 247 and 263 GHz. The spectrum contains a total of 243 resolvable lines from 23 different chemical species. When combined with the earlier survey of Orion from 215 to 247 GHz by Sutton et al (1985), the complete data set includes over 780 emission features from 29 distinct molecules. Of the 23 molecules detected in this survey, only NO, CCH, and HCO + were identified not in the lower frequency data

THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A.; Treu, Tommaso [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Pancoast, Anna [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sand, David J. [Texas Tech University, Physics Department, Box 41051, Lubbock, TX 79409-1051 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Assef, Roberto J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Brewer, Brendon J. [Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, MC 661, Greenbelt, MD 20771 (United States); and others

2015-04-15

In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

Plasma core electron density and temperature measurements using CVI line emissions in TCABR Tokamak

Energy Technology Data Exchange (ETDEWEB)

Nascimento, F. do, E-mail: fellypen@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Componentes Semicondutores; Machida, M. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Fisica Gleb Wataghin; Severo, J.H.F.; Sanada, E.; Ronchi, G. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica

2015-08-15

In this work, we present results of electron temperature (T{sub e} ) and density (n {sub e} ) measurements obtained in Tokamak Chauffage Alfven Bresilien (TCABR) tokamak using visible spectroscopy from CVI line emissions which occurs mainly near the center of the plasma column. The presented method is based on a well-known relationship between the particle flux (Γ {sub ion}) and the photon flux (ø {sub ion}) emitted by an ion species combined with ionizations per photon atomic data provided by the atomic data and analysis structure (ADAS) database. In the experiment, we measured the photon fluxes of three different CVI spectral line emissions, 4685.2, 5290.5, and 6200.6 Å (one line per shot). Using this method it was possible to find out the temporal evolution of T{sub e} and n{sub e} in the plasma. The results achieved are in good agreement with T{sub e} and n{sub e} measurements made using other diagnostic tools. (author)

Emission lines of [K V] in the optical spectra of gaseous nebulae.

Science.gov (United States)

Keenan, Francis P; Aller, Lawrence H; Espey, Brian R; Exter, Katrina M; Hyung, Siek; Keenan, Michael T C; Pollacco, Don L; Ryans, Robert S I

2002-04-02

Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 A)/I(4163.3 A) as a function of electron density (N(e)). This ratio is found to be very sensitive to changes in N(e) over the density range 10(3) to 10(6) cm(-3), but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical N(e) diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne iv], formed in the same region of the nebula as [K v]. This observation provides observational support for the accuracy of the theoretical [K v] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope, reveals that the [K v] 4122.6 A line in this object is badly blended with Fe ii 4122.6 A. Hence, the [K v] diagnostic may not be used for astrophysical sources that show a strong Fe ii emission line spectrum.

A new Be star in an open cluster - NGC 6871-8

Science.gov (United States)

Grigsby, James A.; Morrison, Nancy D.

1988-01-01

Spectroscopic observations of H-alpha show that star eight in the open cluster NGC 6871 is a previously-undiscovered Be star. The H-alpha profile was observed to vary from clear emission to pure absorption over a period of ten days; later observations over a five-day interval show weak emission along with asymmetries and filling in of the profile.

Selective excitation of singly-ionized silver emission lines by Grimm glow discharge plasmas using several different plasma gases

International Nuclear Information System (INIS)

Wagatsuma, K.

1996-01-01

The relative intensities of silver emission lines from Grimm glow discharge plasmas were investigated in the wavelength range from 160 to 600 nm when using different plasma gases. It was characteristic of the plasma excitation that the spectral patterns were strongly dependent on the nature of the plasma gas employed. Intense emission lines of silver ion were observed when argon-helium mixed gases were employed as the plasma gas. Selective excitation of the ionic lines could be principally attributed to the charge transfer collisions between silver atoms and helium ions. (orig.)

The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%

Energy Technology Data Exchange (ETDEWEB)

Rutkowski, Michael J.; Hayes, Matthew [Department of Astronomy, AlbaNova University Centre, Stockholm University, SE-10691 Stockholm (Sweden); Scarlata, Claudia; Mehta, Vihang [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Henry, Alaina; Hathi, Nimish; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Cohen, Seth; Windhorst, Rogier [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281 (United States); Teplitz, Harry I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Haardt, Francesco [DiSAT, Università dellInsubria, via Valleggio 11, I-22100 Como (Italy); Siana, Brian [Department of Physics, University of California, Riverside, CA 92521 (United States)

2017-06-01

Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission ( N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1 σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f {sub esc} ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f {sub esc} ≲ 14.0%. Our observations are not deep enough to detect f {sub esc} ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%

International Nuclear Information System (INIS)

Rutkowski, Michael J.; Hayes, Matthew; Scarlata, Claudia; Mehta, Vihang; Henry, Alaina; Hathi, Nimish; Koekemoer, Anton M.; Cohen, Seth; Windhorst, Rogier; Teplitz, Harry I.; Haardt, Francesco; Siana, Brian

2017-01-01

Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission ( N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1 σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f _e_s_c ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f _e_s_c ≲ 14.0%. Our observations are not deep enough to detect f _e_s_c ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

40 CFR 1051.320 - What happens if one of my production-line vehicles or engines fails to meet emission standards?

Science.gov (United States)

2010-07-01

...-line vehicles or engines fails to meet emission standards? 1051.320 Section 1051.320 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM RECREATIONAL ENGINES AND VEHICLES Testing Production-Line Vehicles and Engines § 1051.320 What happens if one...

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.

Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

Science.gov (United States)

Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

1988-01-01

The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

The spectrum and intrinsic color of the extreme P Cygni-type star HDE 316285

International Nuclear Information System (INIS)

Morrison, N.D.; Rao, S.M.

1990-01-01

In a high-resolution, low-noise, yellow-red CCD spectrum of HDE 316285, P Cygni profiles in H-alpha, He I 5876 A and 6678 A, the Na D lines, and lines of N II, Si II, and Fe II are observed. In addition, forbidden N II, Mg I, and Fe III are observed in emission. Also present is a rich array of diffuse interstellar bands, and their strengths are used to estimate the star's B - V color excess, which is found to be probably not larger than 1.5. 10 refs

GAS MOTION STUDY OF Ly{alpha} EMITTERS AT z {approx} 2 USING FUV AND OPTICAL SPECTRAL LINES {sup ,}

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, Takuya; Shimasaku, Kazuhiro; Nakajima, Kimihiko [Department of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Ouchi, Masami; Ono, Yoshiaki [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Rauch, Michael; Janice Lee [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Okamura, Sadanori, E-mail: thashimoto@astron.s.u-tokyo.ac.jp [Department of Advanced Sciences, Faculty of Science and Engineering, Hosei University, 3-7-2 Kajino-cho, Koganei-shi, Tokyo 184-8584 (Japan)

2013-03-01

We present the results of Magellan/MMIRS and Keck/NIRSPEC spectroscopy for five Ly{alpha} emitters (LAEs) at z {approx_equal} 2.2 for which high-resolution FUV spectra from Magellan/MagE are available. We detect nebular emission lines including H{alpha} on the individual basis and low-ionization interstellar (LIS) absorption lines in a stacked FUV spectrum, and measure average offset velocities of the Ly{alpha} line, {Delta}v {sub Ly{alpha}}, and LIS absorption lines, {Delta}v {sub abs}, with respect to the systemic velocity defined by the nebular lines. For a sample of eight z {approx} 2-3 LAEs without active galactic nucleus from our study and the literature, we obtain {Delta}v {sub Ly{alpha}} = 175 {+-} 35 km s{sup -1}, which is significantly smaller than that of Lyman-break Galaxies (LBGs), {Delta}v {sub Ly{alpha}} {approx_equal} 400 km s{sup -1}. The stacked FUV spectrum gives {Delta}v {sub abs} = -179 {+-} 73 km s{sup -1}, comparable to that of LBGs. These positive {Delta}v {sub Ly{alpha}} and negative {Delta}v {sub abs} suggest that LAEs also have outflows. In contrast to LBGs, however, the LAEs' {Delta}v {sub Ly{alpha}} is as small as |{Delta}v {sub abs}|, suggesting low neutral hydrogen column densities. Such a low column density with a small number of resonant scattering may cause the observed strong Ly{alpha} emission of LAEs. We find an anti-correlation between Ly{alpha} equivalent width (EW) and {Delta}v {sub Ly{alpha}} in a compilation of LAE and LBG samples. Although its physical origin is not clear, this anti-correlation result appears to challenge the hypothesis that a strong outflow, by means of a reduced number of resonant scattering, produces a large EW. If LAEs at z > 6 have similarly small {Delta}v {sub Ly{alpha}} values, constraints on the reionization history derived from the Ly{alpha} transmissivity may need to be revised.

On-chip plasmonic cavity-enhanced spontaneous emission rate at the zero-phonon line

DEFF Research Database (Denmark)

Siampour, Hamidreza; Kumar, Shailesh; Bozhevolnyi, Sergey I.

Highly confined surface plasmon polariton (SPP) modes can be utilized to enhance light-matter interaction at the single emitter level of quantum optical systems [1-4]. Dielectric-loaded SPP waveguides (DLSPPWs) confine SPPs laterally with relatively low propagation loss, enabling to benefit both ...... and an up to 42-fold spontaneous emission rate enhancement at the zero-phonon line (a ∼7-fold resonance enhancement in addition to a ∼6-fold broadband enhancement) is achieved, revealing the potential of our approach for on-chip realization of quantum-optical networks....... from a large Purcell factor and from a large radiative efficiency (low quenching rates) [1, 2]. In this work, we present a DLSPPW-based Bragg cavity resonator to direct emission from a single diamond nitrogen vacancy (NV) center into the zero-phonon line (Fig. 1). A quality factor of ∼70 for the cavity...

Radio ejection and broad forbidden emission lines in the Seyfert galaxy NGC 7674

International Nuclear Information System (INIS)

Unger, S.W.; Pedlar, A.; Axon, D.J.

1988-01-01

The Seyfert nucleus in NGC7674 (Mkn533) is remarkable for its broad asymmetric forbidden line profiles, which extend 2000 kms -1 blueward of the systemic velocity. The galaxy also has a compact nuclear radio source. We have obtained new high-resolution radio observations of NGC7674, using the European VLBI network and the VLA, and optical spectroscopic observations using the Isaac Newton Telescope. The radio maps reveal a triple radio source with a total angular extent of about 0.7 arcsec, and provide evidence that the radio emission is powered by collimated ejection. In the plane of the sky, the ejection axis appears roughly perpendicular to the galactic rotation axis. Although the dominant radio components are separated by 0.5 arcsec, the broad [OIII]λ5007 line emission is confined to within about 0.25 arcsec of the continuum nucleus. (author)

MID-INFRARED PROPERTIES OF THE SWIFT BURST ALERT TELESCOPE ACTIVE GALACTIC NUCLEI SAMPLE OF THE LOCAL UNIVERSE. I. EMISSION-LINE DIAGNOSTICS

International Nuclear Information System (INIS)

Weaver, K. A.; Melendez, M.; Mushotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth, E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

2010-01-01

We compare mid-infrared emission-line properties from high-resolution Spitzer spectra of a hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) active galactic nuclei (AGNs) detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission lines, [O IV] 25.89 μm, [Ne II] 12.81 μm, [Ne III] 15.56 μm, and [Ne V] 14.32/24.32 μm, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations; however, six newly discovered BAT AGNs are under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT fluxes and luminosities suggests that the emission lines primarily arise in gas ionized by the AGNs. We also compare the mid-infrared emission lines in the BAT AGNs with those from published studies of ULIRGs, Palomar-Green quasars, star-forming galaxies, and LINERs. We find that the BAT AGN sample falls into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] ratios. These line ratios are lower in sources that have been previously classified in the mid-infrared/optical as AGNs than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGNs represent the main contribution to the observed line emission. These ratios represent a new emission line diagnostic for distinguishing between AGNs and star-forming galaxies.

Photometry of the 4686 A emission line of gamma(2) Velorum from the South Pole

International Nuclear Information System (INIS)

Taylor, M.

1990-01-01

An automated optical telescope located at the Amundsen-Scott South Pole station on Antarctica, has been used to obtain more than 78 h of photometry of the He II emission line (4686 A) of the spectroscopic binary gamma(2) Velorum. These data were obtained on seven different days during the 1987 austral winter; the longest continuous run spans 19 h. Two independent period search techniques have been used to search for periodic behavior in the strength of the He II emission line of this Wolf-Rayet star. They are: (1) power spectrum analysis and (2) a first-order sine function fit to the data using least squares. Various multiplicities of a period on the order of 1.3 h with amplitudes of a few percent are found in most of these data. According to recent theoretical models of Wolf-Rayet stars, fluctuations in the He II emission line may indicate vibrational instability in gamma(2) Vel. These pulsations may, in turn, give rise to shocks which propagate outward and which may provide the necessary conditions for periodic changes in the state of a given region of the atmosphere to occur. 15 refs

The early-type strong emission-line supergiants of the Magellanic Clouds - A spectroscopic zoology

Science.gov (United States)

Shore, S. N.; Sanduleak, N.

1984-01-01

The results of a spectroscopic survey of 21 early-type extreme emission line supergiants of the Large and Small Magellanic Clouds using IUE and optical spectra are presented. The combined observations are discussed and the literature on each star in the sample is summarized. The classification procedures and the methods by which effective temperatures, bolometric magnitudes, and reddenings were assigned are discussed. The derived reddening values are given along with some results concerning anomalous reddening among the sample stars. The derived mass, luminosity, and radius for each star are presented, and the ultraviolet emission lines are described. Mass-loss rates are derived and discussed, and the implications of these observations for the evolution of the most massive stars in the Local Group are addressed.

Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

DEFF Research Database (Denmark)

Dietrich, M.; Appenzeller, I.; Hamann, F.

2003-01-01

the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\\odot = 4.3 \\pm 0...

Extended Emission-Line Regions: Remnants of Quasar Superwinds?

Science.gov (United States)

Fu, Hai; Stockton, Alan

2009-01-01

We give an overview of our recent integral-field-unit spectroscopy of luminous extended emission-line regions (EELRs) around low-redshift quasars, including new observations of five fields. Previous work has shown that the most luminous EELRs are found almost exclusively around steep-spectrum radio-loud quasars, with apparently disordered global velocity fields, and little, if any, morphological correlation with either the host galaxy or the radio structure. Our new observations confirm and expand these results. The EELRs often show some clouds with velocities exceeding 500 km s-1, ranging up to 1100 km s-1, but the velocity dispersions, with few exceptions, are in the 30-100 km s-1 range. Emission-line ratios show that the EELRs are clearly photoionized by the quasars. Masses of the EELRs range up to 1010Msun. Essentially all of the EELRs show relatively low metallicities, and they are associated with quasars that, in contrast to most, show similarly low metallicities in their broad-line regions. The two objects in our sample that do not have classical double-lobed radio morphologies (3C 48, with a compact-steep-spectrum source; Mrk 1014, radio quiet, but with a weak compact-steep-spectrum source) are the only ones that appear to have recent star formation. While some of the less luminous EELRs may have other origins, the most likely explanation for those in our sample is that they are examples of gas swept out of the host galaxy by a large-solid-angle blast wave accompanying the production of the radio jets. The triggering of the quasar activity is almost certainly the result of the merger of a gas-rich galaxy with a massive, gas-poor galaxy hosting the supermassive black hole. Based in part on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the

On the Baldwin effect of He II emission lines in WR (WN) stars

OpenAIRE

van Gent, J. I.; Lamers, H. J. G. L. M.; de Koter, A.; Morris, P. W.

2001-01-01

We investigate the relation between the equivalent width of He ii emission lines and the monochromatic continuum luminosity at the line wavelength in the spectra of Wolf-Rayet stars. Model stellar atmospheres and spectra are used to show that the equivalent width inversely correlates with the monochromatic continuum luminosity. We find the effect in Wolf-Rayet star models over a large range of stellar parameters. The effect is shown to be connected to density differences among Wolf-Rayet star...

(Talk) Investigating The Star Formation Quenching Across Cosmic Time - A Methodology To Select Galaxies Just After The Quenching Of Star Formation

Science.gov (United States)

Citro, Annalisa; Pozzetti, Lucia; Quai, Salvatore; Moresco, Michele; Vallini, Livia; Cimatti, Andrea

2017-06-01

We propose a method aimed at identifing galaxies in the short evolutionary phase in which they quench their star-formation (SF). We rely on high- to low-ionization emission line ratios, which rapidly disappear after the SF halt due to the softening of the UV ionizing radiation. In particular, we focus on [O III] 5007/Halpha and [Ne III] 3869/[O II] 3727, simulating their time evolution by means of the CLOUDY photoionization code. We find that these two emission line ratios are able to trace the quenching on very short time-scales (i.e. 10-80 Myr), depending on if a sharp or a smoother SF quenching is assumed. We adopt the [N II] 6584/[O II] 3727 ratio as metallicity diagnostic to mitigate the metallicity degeneracy which affects our method. Using a Sloan Digital Sky Survey galaxy sample, we identify 11 examples of extreme quenching candidates within the [O III] 5007/Halpha vs. [N II] 6584/[O II] 3727 plane, characterized by faint [Ne III] 3869, blue dust-corrected spectra and blue (u-r) colours, as expected if the quenching occurred in the recent past. Our results also suggest that the observed fractions of quenching candidates can be used to constrain the quenching mechanism at work and its time-scales.

Emission line relative intensity variations in the symbiotic stars: CI Cygni, BF Cygni, AX Persei and V1016 Cygni

International Nuclear Information System (INIS)

Oliversen, N.A.

1982-01-01

Low resolution spectra (lambda 3800 to lambda 5900) are presented of the symbiotic stars CI Cygni, BF Cygni, AX Persei and V1016 Cygni, which were obtained with the Washburn Observatory Boller and Chivens cassegrain spectrograph and intensified Reticon. The spectra were obtained as part of a monitoring program covering 36 months since November 1978. The nebular electron temperature and density are derived from the [O III] lambda 5007 and lambda 4363 emission lines and the uv intercombination lines of lambda 1661 and lambda 1667. Relative emission line intensity variations were observed in all four stars. The relative emission line changes correlated with photometric minima for CI Cyg, AX Per and possibly BF Cyg. These changes are interpreted as due to a red giant eclipsing a nebula surrounding the exciting source. Based on the [O III] line ratio change, the nebular density of V1016 Cyg has continued to decline since 1978. The thesis also contains a discussion of the use of the emision lines of [Ne III] lambda 3869, [O III] lambda 5007, lambda 4363 and He lambda 5876 to derive nebular electron temperature and density. A decline in the intensity ratios of I(lambda 3869)/(lambda 5007) and I(lambda 5876)/I(lambda 5007) were observed during the 1980 minimum of CI Cyg. The observed I(lambda 3869)/I(lambda 5007) decline was too large to be explained by temperature or density changes. The [Ne III] and He II regions in CI Cyg are therefore closer to the hot source than the more extended (o III] emission region. Contained within the appendix is a discussion of a graphical method of solution ot the nebular temperature and density, which is based on the emission lines of [Ne III], [O III] and He I

Variations of the Hβ-emission line during a large flare on UV Ceti

International Nuclear Information System (INIS)

Moffett, T.J.; Evans, D.S.; Ferland, G.

1977-01-01

Simultaneous high-speed photometry and photoelectric scanner observations of the Hβ-line were obtained for five flare events, one a major flare, on UV Ceti on 1975 January 6. The relative increase in the intensity of the Hβ-line during the large flare was much greater than the relative continuum rise as measured both by the scanner and by broad-band photometric observations. In Hβ the flare lasted nearly 30 times as long as in the continuum. Peak intensity in the Hβ-line occurred later than the continuum maximum. The possibility of using emission line observations to detect flare activity on early spectral-type stars (dK - dG) is discussed. Some speculations on the mechanism of flare production are indulged. (author)

Steep Hard-X-ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-Line Quasars

Science.gov (United States)

Marlar, Andrea; Shemmer, Ohad; Anderson, Scott F.; Brandt, W. Niel; Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Luo, Bin; Plotkin, Richard; Richards, Gordon T.; Schneider, Donald P.; Wu, Jianfeng

2018-06-01

We present XMM-Newton imaging spectroscopy of ten weak emission-line quasars (WLQs) at 0.928 ≤ z ≤ 3.767, six of which are radio quiet and four which are radio intermediate. The new X-ray data enabled us to measure the hard-X-ray power-law photon index (Γ) in each source with relatively high accuracy. These measurements allowed us to confirm previous reports that WLQs have steeper X-ray spectra, therefore indicating higher accretion rates with respect to "typical" quasars. A comparison between the Γ values of our radio-quiet WLQs and those of a carefully-selected, uniform sample of 84 quasars shows that the first are significantly higher, at the ≥ 3σ level. Collectively, the four radio-intermediate WLQs have lower Γ values with respect to the six radio-quiet WLQs, as may be expected if the spectra of the first group are contaminated by X-ray emission from a jet. These results suggest that, in the absence of significant jet emission along our line of sight, WLQs constitute the extreme high end of the accretion rate distribution in quasars. We detect soft excess emission in our lowest-redshift radio-quiet WLQ, in agreement with previous findings suggesting that the prominence of this feature is associated with a high accretion rate. We have not detected signatures of Compton reflection, Fe Kα lines, or strong variability between two X-ray epochs in any of our WLQs.

Transition probabilities of some Si II lines obtained by laser produced plasma emission

International Nuclear Information System (INIS)

Blanco, F.; Botho, B.; Campos, J.

1995-01-01

The absolute transition probabilities for 28 Si II spectral lines have been determined by measurement of emission line intensities from laser-produced plasmas of Si in Ar and Kr atmospheres. The studied plasma has a temperature of about 2 . 10 4 K and 10 17 cm -3 electron density. The local thermodynamic equilibrium conditions and plasma homogeneity have been checked. The results are compared with the available experimental and theoretical data and with present Hartree-Fock calculations in LS coupling. (orig.)

Massive star populations in I Zw 18: A probe of stellar evolution in the early universe

OpenAIRE

Schaerer, Daniel; de Mello, Duilia; Leitherer, Claus; Heldmann, Jennifer

1998-01-01

We present a study of the gaseous and stellar emission in I Zw18, the most metal-poor star-forming galaxy known. Archival HST WFPC2 and FOS data have been used to analyze the spatial distribution of [OIII], Halpha, and HeII 4686. The latter is used to identify Wolf-Rayet stars found by ground-based spectroscopy and to locate nebular HeII emission. Most of the HeII emission is associated with the NW stellar cluster, displaced from the surrounding shell-like [OIII] and Halpha emission. We found...

Constraining Line-of-sight Confusion in the Corona Using Linearly Polarized Observations of the Infrared FeXIII 1075nm and SiX 1430nm Emission Lines

Science.gov (United States)

Dima, G. I.; Kuhn, J. R.; Berdyugina, S.

2017-12-01

Measurements of the coronal magnetic field are difficult because of the intrinsically faint emission of coronal plasma and the large spurious background due to the bright solar disk. This work addresses the problem of resolving the confusion of the line-of-sight (LOS) integration through the optically-thin corona being observed. Work on developing new measuring techniques based on single-point inversions using the Hanle effect has already been described (Dima et al. 2016). It is important to develop a technique to assess when the LOS confusion makes comparing models and observations problematic. Using forward integration of synthetic emission through magnetohydrodynamic (MHD) models together with simultaneous linearly polarized observations of the FeXIII 1075nm and SiX 1430nm emission lines allows us to assess LOS confusion. Since the lines are both in the Hanle saturated regime their polarization angles are expected to be aligned as long as the gas is sampling the same magnetic field. If significant contributions to the emission is taking place from different regions along the LOS due to the additive nature of the polarized brightness the measured linear polarization between the two lines will be offset. The size of the resolution element is important for this determination since observing larger coronal regions will confuse the variation along the LOS with that in the plane-of-sky. We also present comparisons between synthetic linearly polarized emission through a global MHD model and observations of the same regions obtained using the 0.5m Scatter-free Observatory for Limb Active Regions and Coronae (SOLARC) telescope located on Haleakala, Maui. This work is being done in preparation for the type of observations that will become possible when the next generation 4m DKIST telescope comes online in 2020.

Stability of emission line clouds in active galactic nuclei

International Nuclear Information System (INIS)

Krinsky, I.S.

1989-01-01

A numerical model was developed for a Quasar Stellar Object (QSO) broad emission line cloud (ELC) imbedded within a confining hot intercloud medium (HIM) for the purpose of studying its stability to perturbations in its temperature and density. A self-consistent model in radiative, pressure and thermal equilibrium is presented. The effect of trapped line radiation pressure is also included with the total pressure (particle plus radiation) held constant. The equilibrium model is found to have regions with radiation pressure exceeding gas pressure. Energy transport includes the effects of an external broken power law continuum and thermal conduction of heat from the HIM. Conduction is found to be unimportant to the total energy budget of the cloud, but is important to the dynamics of the ELC/HIM interface. Independent of the ELC/HIM model, an extension of second order probabilistic radiative transfer that treats the diffuse radiation field as composed of two oppositely directed streams is presented. The high ionization zone of the ELC is found to be unstable to radiatively driven sound waves. Both the external radiation field and the force of trapped line radiation are potential sources for driving the growth of sound waves. The final picture that emerges is that the ELC must be in a constant state of flux

THE LOCAL [C ii] 158 μ m EMISSION LINE LUMINOSITY FUNCTION

Energy Technology Data Exchange (ETDEWEB)

Hemmati, Shoubaneh; Yan, Lin; Capak, Peter; Faisst, Andreas; Masters, Daniel [Infrared Processing and Analysis Center, Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena CA 91125 (United States); Diaz-Santos, Tanio [Nucleo de Astronomia de la Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito Libertador 441, Santiago (Chile); Armus, Lee, E-mail: shemmati@ipac.caltech.edu [Spitzer Science Center, Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)

2017-01-01

We present, for the first time, the local [C ii] 158 μ m emission line luminosity function measured using a sample of more than 500 galaxies from the Revised Bright Galaxy Sample. [C ii] luminosities are measured from the Herschel PACS observations of the Luminous Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey and estimated for the rest of the sample based on the far-infrared (far-IR) luminosity and color. The sample covers 91.3% of the sky and is complete at S{sub 60μm} > 5.24 Jy. We calculate the completeness as a function of [C ii] line luminosity and distance, based on the far-IR color and flux densities. The [C ii] luminosity function is constrained in the range ∼10{sup 7–9} L{sub ⊙} from both the 1/ V{sub max} and a maximum likelihood methods. The shape of our derived [C ii] emission line luminosity function agrees well with the IR luminosity function. For the CO(1-0) and [C ii] luminosity functions to agree, we propose a varying ratio of [C ii]/CO(1-0) as a function of CO luminosity, with larger ratios for fainter CO luminosities. Limited [C ii] high-redshift observations as well as estimates based on the IR and UV luminosity functions are suggestive of an evolution in the [C ii] luminosity function similar to the evolution trend of the cosmic star formation rate density. Deep surveys using the Atacama Large Millimeter Array with full capability will be able to confirm this prediction.

A DEEP CHANDRA ACIS STUDY OF NGC 4151. III. THE LINE EMISSION AND SPECTRAL ANALYSIS OF THE IONIZATION CONE

International Nuclear Information System (INIS)

Wang, Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.; Dumas, Gaelle; Schinnerer, Eva

2011-01-01

This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert 1 galaxy NGC 4151, devoted to study its complex circumnuclear X-ray emission. Emission features in the soft X-ray spectrum of the bright extended emission (L 0.3-2 k eV ∼ 10 40 erg s –1 ) at r > 130 pc (2'') are consistent with blended brighter O VII, O VIII, and Ne IX lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2 keV. We construct emission line images of these features and find good morphological correlations with the narrow-line region clouds mapped in [O III] λ5007. Self-consistent photoionization models provide good descriptions of the spectra of the large-scale emission, as well as resolved structures, supporting the dominant role of nuclear photoionization, although displacement of optical and X-ray features implies a more complex medium. Collisionally ionized emission is estimated to be ∼ ☉ yr –1 at 130 pc and the kinematic power of the ionized outflow is 1.7 × 10 41 erg s –1 , approximately 0.3% of the bolometric luminosity of the active nucleus in NGC 4151.

Evaluation of self-absorption coefficients of aluminum emission lines in laser-induced breakdown spectroscopy measurements

International Nuclear Information System (INIS)

El Sherbini, A.M.; El Sherbini, Th.M.; Hegazy, H.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

2005-01-01

In quantitative Laser Induced Breakdown Spectroscopy (LIBS) measurements it is essential to account for the effect of self-absorption on the emission lines intensity. In order to quantify this effect, in this paper we propose a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of self-absorption on line intensity. The method, based on a homogeneous plasma model, is applicable when the plasma electron density is known and in particular to lines whose Stark broadening parameter is available

The [CII] 158 μm line emission in high-redshift galaxies

Science.gov (United States)

Lagache, G.; Cousin, M.; Chatzikos, M.

2018-02-01

Gas is a crucial component of galaxies, providing the fuel to form stars, and it is impossible to understand the evolution of galaxies without knowing their gas properties. The [CII] fine structure transition at 158 μm is the dominant cooling line of cool interstellar gas, and is the brightest of emission lines from star forming galaxies from FIR through metre wavelengths, almost unaffected by attenuation. With the advent of ALMA and NOEMA, capable of detecting [CII]-line emission in high-redshift galaxies, there has been a growing interest in using the [CII] line as a probe of the physical conditions of the gas in galaxies, and as a star formation rate (SFR) indicator at z ≥ 4. In this paper, we have used a semi-analytical model of galaxy evolution (G.A.S.) combined with the photoionisation code CLOUDY to predict the [CII] luminosity of a large number of galaxies (25 000 at z ≃ 5) at 4 ≤ z ≤ 8. We assumed that the [CII]-line emission originates from photo-dominated regions. At such high redshift, the CMB represents a strong background and we discuss its effects on the luminosity of the [CII] line. We studied the L[CII ]-SFR and L[ CII ]-Zg relations and show that they do not strongly evolve with redshift from z = 4 and to z = 8. Galaxies with higher [CII] luminosities tend to have higher metallicities and higher SFRs but the correlations are very broad, with a scatter of about 0.5 and 0.8 dex for L[ CII ]-SFR and L[ CII ]-Zg, respectively. Our model reproduces the L[ CII ]-SFR relations observed in high-redshift star-forming galaxies, with [CII] luminosities lower than expected from local L[ CII ]-SFR relations. Accordingly, the local observed L[ CII ]-SFR relation does not apply at high-z (z ≳ 5), even when CMB effects are ignored. Our model naturally produces the [CII] deficit (i.e. the decrease of L[ CII ]/LIR with LIR), which appears to be strongly correlated with the intensity of the radiation field in our simulated galaxies. We then predict the

Differential performance and parasitism of caterpillars on maize inbred lines with distinctly different herbivore-induced volatile emissions.

Directory of Open Access Journals (Sweden)

Thomas Degen

Full Text Available Plant volatiles induced by insect feeding are known to attract natural enemies of the herbivores. Six maize inbred lines that showed distinctly different patterns of volatile emission in laboratory assays were planted in randomized plots in the Central Mexican Highlands to test their ability to recruit parasitic wasps under field conditions. The plants were artificially infested with neonate larvae of the fall armyworm Spodoptera frugiperda, and two of its main endoparasitoids, Campoletis sonorensis and Cotesia marginiventris, were released in the plots. Volatiles were collected from equally treated reference plants in the neighbourhood of the experimental field. The cumulative amount of 36 quantified volatile compounds determined for each line was in good accordance with findings from the laboratory; there was an almost 15-fold difference in total emission between the two extreme lines. We found significant differences among the lines with respect to the numbers of armyworms recovered from the plants, their average weight gain and parasitism rates. Average weight of the caterpillars was negatively correlated with the average total amount of volatiles released by the six inbred lines. However, neither total volatile emission nor any specific single compound within the blend could explain the differential parasitism rates among the lines, with the possible exception of (E-2-hexenal for Campoletis sonorensis and methyl salicylate for Cotesia marginiventris. Herbivore-induced plant volatiles and/or correlates thereof contribute to reducing insect damage of maize plants through direct plant defence and enhanced attraction of parasitoids, alleged indirect defence. The potential to exploit these volatiles for pest control deserves to be further evaluated.

Morphology of the bipolar planetary nebula NGC 2346 from emission line profile studies

Energy Technology Data Exchange (ETDEWEB)

Anandarao, B G; Banerjee, D P.K.; Desai, J N; Jain, S K; Mallik, D C.V.

1988-11-01

High resolution observations of H..cap alpha.. 6563 A, (O III) 5007 A and (N II) 6583 A emission lines in the bipolar planetary nebula NGC 2346 are presented. Expansion velocities (V/sub exp/) of 8 +- 1 km s/sup -1/ in the :O III: line and 11 +- 1 km s/sup -1/ in the :N II: line are observed in the central region. An expansion velocity of 7.5 +- 1.0 km s/sup -1/ in the (O III) line is observed in a position 10 arcsec away from the centre, in the NE lobe of the nebula. From the widths of the H..cap alpha.. and (N II) lines, an ion temperature of T=10 650 +- 2950 K and a turbulent velocity V/sub T/ = 16 +- 2 km s/sup -1/ are derived. Using the detailed radial velocity mapping done by a previous author, a morphological model for the nebula is presented.

Nuclei far from the beta stability line. High-energy beta decay and delayed-particle emission

International Nuclear Information System (INIS)

Hansen, R.G.; Hornshj, P.

1976-01-01

Progress in on-line mass separation together with improved proton accelerators now permit the production of secondary ion-beams of the order of 10 11 atoms per second. Applications to the study of delayed-proton and delayed-alpha emission are discussed. These effects have been used for the estimation of alpha-emission strength functions at 4-6 MeV excitation energy, and for the determination of level densities through fluctuation analysis

Linear polarization measurements at H. beta. of early-type emission line stars

Energy Technology Data Exchange (ETDEWEB)

Clarke, D; McLean, I S [Glasgow Univ. (UK)

1976-02-01

Linear polarization measurements across the H..beta.. emission lines of the stars ..gamma.. Cas, zeta Tau and 48 Per are presented. For the first two stars there is a marked reduction of the polarization at the centre of the line and for ..gamma.. Cas, this varies from night to night. During the H..beta.. observations of zeta Tau, a change of polarization over tens of minutes was indicated in a monitor channel tuned to the continuum on the blue side of H..beta... For the fainter star, 48 Per, the uncertainties of the polarimetry were increased in relation to ..gamma.. Cas and zeta Tau by a factor of about two and at this precision, no differential effects across the line were recorded. Observations of ..cap alpha.. Cyg are also given to demonstrate the reliability of the polarimeter.

Stokes polarimetry of main-line OH emission from stellar masers

International Nuclear Information System (INIS)

Claussen, M.J.; Fix, J.D.

1982-01-01

Main-line OH emission has been measured in all four Stokes parameters from seven late-type variable stars and the F8 supergiant IRC+10420. Linearly polarized features were detected in UX Cyg, U Ori, and IRC+10420 at 1665 MHz. The linearly polarized features in UX Cyg and IRC +10420, when combined with adjacent circularly polarized features suggest Zeeman patterns. A polarization pattern in IRC+10420 is probably the best example of a complete Zeeman pattern yet observed in stellar masers, although it appears to lack the shifted linear (sigma) components. This study, combined with other recent work, shows that linearly polarized features in stellar sources are uncommon. Only about 10% of the stellar OH sources show linearly polarized features. As an aid in accounting for the observed polarization properties of stellar OH masers, model mass flows were calculated using magnetic field structures similar to that of the solar wind. Conclusions drawn from this model were: (1) unpolarized or weakly circularly polarized emission from sources can arise from the entire circumstellar shell; (2) circular polarization without linear polarization can be produced either by emission from the entire shell or by enhanced OH densities in small regions of the shell provided there are sufficient free electrons present to depolarize the linear components; and (3) Zeeman patterns which include both circular and linear polarizations can be produced in OH density enhancements if electron densities are low. The electron densities required for effective Faraday depolarization yield emission measures of the order of 10 9 pc cm -6 . Given the large distances of stellar OH masers, the thermal continuum emission from such depolarizing electrons would probably be undetectable

Emission-line galaxies and quasars in the southern hemisphere. I. Description and applications of an objective-prism survey

International Nuclear Information System (INIS)

Smith, M.G.

1975-01-01

A selection of objects from the first plates of a low-dispersion, objective-prism survey for emission-line galaxies and quasars is used to illustrate the application of the survey to the following lines of research in extragalactic astronomy: quasi-stellar objects, Seyfert galaxies, instabilities in galaxies produced by tidal interaction or explosive events, and rates of star formation and the general chemical evolution of galaxies. Included in the discussion is a description of how the survey provides a new, purely optical, color-independent method for the direct isolation of bright, high-redshift QSOs with strong emission lines (Lα is often directly visible on the Schmidt-survey plates). The newly discovered objects used for illustration are a radio-quiet QSO of redshift 2.07, a luminous, class 2 Seyfert galaxy, a compact blue emission-line galaxy with a jet or streamer, yet with no obvious interacting companion, and a blue galaxy with Hβ flux 50 times that of 30 Doradus, and low metal abundances, which is undergoing a very intense burst of star formation. These objects are to be discussed in greater detail in subsequent papers in this series

A Deep Chandra ACIS Study of NGC 4151. II. The Innermost Emission Line Region and Strong Evidence for Radio Jet-NLR Cloud Collision

Science.gov (United States)

Wang, Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Mundell, Carole G.; Karovska, Margarita; Zezas, Andreas

2011-07-01

We have studied the X-ray emission within the inner ~150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction, including morphological correspondences with regions of X-ray enhancement, peaks of near-infrared [Fe II] emission, and optical clouds. In these regions, moreover, we find evidence of elevated Ne IX/O VII ratios; the X-ray emission of these regions also exceeds that expected from nuclear photoionization. Spectral fitting reveals the presence of a collisionally ionized component. The thermal energy of the hot gas suggests that >~ 0.1% of the estimated jet power is deposited into the host interstellar medium through interaction between the radio jet and the dense medium of the circumnuclear region. We find possible pressure equilibrium between the collisionally ionized hot gas and the photoionized line-emitting cool clouds. We also obtain constraints on the extended iron and silicon fluorescent emission. Both lines are spatially unresolved. The upper limit on the contribution of an extended emission region to the Fe Kα emission is <~ 5% of the total, in disagreement with a previous claim that 65% of the Fe Kα emission originates in the extended narrow line region.

Spectroscopic observations of ion line-emission from a magnetically insulated ion diode

International Nuclear Information System (INIS)

Maron, Y.; Peng, H.S.; Rondeau, G.D.; Hammer, D.A.

1984-01-01

Excited ions, produced in the surface-flashover plasma in a magnetically insulated diode, spontaneously emit light from the anode plasma region as well as (if the life time of the excited level is at least a few ns) from the diode acceleration gap. The emission lines of the ions traversing the gap are shifted from their natural wavelength because of the Stark effect due to the diode electric field. If the light is viewed transverse to the acceleration direction, the line width will be mostly determined by Doppler broadening due to ion transverse velocities. The authors use the OMNI II diode (up to 500 kV, 25 kA, 80 ns) with an insulating B field of ≅12 kG and an A-K gap of ≅7mm. The light emission from the entire 6.5 x 12 cm area in front of the anode is viewed parallel to the applied B field. A spectral resolution of 0.5 A is obtained by dispersing the light using a spectrometer followed by 6 optical fibers attached to PM-tubes. Each channel output is calibrated in situ. The spatial resolution across the gap could be made as small as 0.3 mm and the temporal resolution was varied between a few to a few tens of ns. The line spectral profile is obtained at a single discharge for a given distance from the anode surface

Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters

Energy Technology Data Exchange (ETDEWEB)

Bulbul, Esra; Foster, Adam; Smith, Randall K.; Randall, Scott W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Markevitch, Maxim [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Loewenstein, Michael, E-mail: ebulbul@cfa.harvard.edu [CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-07-01

We detect a weak unidentified emission line at E = (3.55-3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN 'all others' spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50-110 eV of several known lines. The detection is at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with m{sub s} = 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar XVII dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10-20. Confirmation with Astro-H will be critical to determine the nature of this new line.

Spectroscopic and polarimetric study of radio-quiet weak emission line quasars

Science.gov (United States)

Kumar, Parveen; Chand, Hum; Gopal-Krishna; Srianand, Raghunathan; Stalin, Chelliah Subramonian; Petitjean, Patrick

2018-04-01

A small subset of optically selected radio-quiet QSOs with weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with an infant/shielded broad line region (BLR). High polarisation (p > 3-4%), a hallmark of BL Lacs, can be used to test whether some optically selected ‘radio-quiet weak emission line QSOs’ (RQWLQs) show a fractional polarisation high enough to qualify as radio-quiet analogues of BL Lac objects. To check this possibility, we have made optical spectral and polarisation measurements of a sample of 19 RQWLQs. Out of these, only 9 sources show a non-significant proper motion (hence very likely extragalactic) and only two of them are found to have p > 1%. For these two RQWLQs, namely J142505.59+035336.2 and J154515.77+003235.2, we found the highest polarization to be 1.59±0.53%, which is again too low to classify them as (radio-quiet) BL Lacs, although one may recall that even genuine BL Lacs sometimes appear weakly polarised. We also present a statistical comparison of the optical spectral index, for a sample of 45 RQWLQs with redshift-luminosity matched control samples of 900 QSOs and an equivalent sample of 120 blazars, assembled from the literature. The spectral index distribution of RQWLQs is found to differ, at a high significance level, from that of blazars. This, too, is consistent with the common view that the mechanism of the central engine in RQWLQs, as a population, is close to that operating in normal QSOs and the primary difference between them is related to the BLR.

Chromospherically active stars. IV - HD 178450 = V478 Lyr: An early-type BY Draconis type binary

Science.gov (United States)

Fekel, Francis C.

1988-01-01

It is shown that the variable star HD 178450 = V478 Lyr is a chromospherically active G8 V single-lined spectroscopic binary with a period of 2.130514 days. This star is characterized by strong UV emission features and a filled-in H-alpha absorption line which is variable in strength. Classified as an early-type BY Draconis system, it is similar to the BY Dra star HD 175742 = V775 Her. The unseen secondary of HD 178450 has a mass of about 0.3 solar masses and is believed to be an M2-M3 dwarf.

DUST ATTENUATION OF THE NEBULAR REGIONS OF z ∼ 2 STAR-FORMING GALAXIES: INSIGHT FROM UV, IR, AND EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

De Barros, S.; Reddy, N.; Shivaei, I., E-mail: stephane.debarros@oabo.inaf.it [Department of Physics and Astronomy, University of California, Riverside, CA 92507 (United States)

2016-04-01

We use a sample of 149 spectroscopically confirmed UV-selected galaxies at z ∼ 2 to investigate the relative dust attenuation of the stellar continuum and the nebular emission lines. For each galaxy in the sample, at least one rest-frame optical emission line (Hα/[N ii] λ6583 or [O iii] λ5007) measurement has been taken from the litterature, and 41 galaxies have additional Spitzer/MIPS 24 μm observations that are used to infer infrared luminosities. We use a spectral energy distribution (SED) fitting code that predicts nebular line strengths when fitting the stellar populations of galaxies in our sample, and we perform comparisons between the predictions of our models and the observed/derived physical quantities. We find that on average our code is able to reproduce all the physical quantities (e.g., UV β slopes, infrared luminosities, emission line fluxes), but we need to apply a higher dust correction to the nebular emission compared to the stellar emission for the largest star formation rate (SFR) (log SFR/M{sub ⊙} yr{sup −1} > 1.82, Salpeter initial mass function). We find a correlation between SFR and the difference in nebular and stellar color excesses, which could resolve the discrepant results regarding nebular dust correction at z ∼ 2 from previous studies.

Galaxy interactions and star formation: Results of a survey of global H-alpha emission in spiral galaxies in 8 clusters

Science.gov (United States)

Moss, C.

1990-01-01

Kennicutt and Kent (1983) have shown that the global H alpha emission from a spiral galaxy is an indicator of the formation rate of massive stars. Moss, Whittle and Irwin (1988) have surveyed two clusters (Abell 347 and 1367) for galaxies with H alpha emission using a high dispersion objective prism technique. The purpose of the survey is to investigate environmental effects on star formation in spiral galaxies, and in particular to ascertain whether star formation is enhanced in cluster spirals. Approximately 20 percent of CGCG galaxies were detected in emission. Two plates of excellent quality were obtained for each of the two clusters, and galaxies were only identified to have emission if this was detected on both plates of a plate pair. In this way, plate flaws and other spurious identifications of emission could be rejected, and weak emission confirmed. The results of this survey have been discussed by Moss (1987). The detected galaxies are of types SO-a and later. The frequency with which galaxies are detected in emission increases towards later morphological type as expected (cf. Kennicutt and Kent 1983). There is no evidence of any dependence of the frequency of detected emission on the absolute magnitude of the galaxy (cf. Moss and Whittle 1990), but there is a strong correlation between a disturbed morphological appearance of the galaxy and the detection of emission. Furthermore it is found that the emission is more centrally concentrated in those galaxies which show a disturbed morphology. It may be noted that the objective prism plate gives a spectrum of a 400 A region around rest wavelength H alpha, but superposed on this is the H alpha emission from the galaxy which, because the light is essentially monochromatic, results in a true two-dimensional image of the H alpha distribution. The visual appearance of the emission on the prism plates was classified according to its diffuseness on a 5 point scale (very diffuse, diffuse, intermediate, compact, and

A probabilistic approach to emission-line galaxy classification

Science.gov (United States)

de Souza, R. S.; Dantas, M. L. L.; Costa-Duarte, M. V.; Feigelson, E. D.; Killedar, M.; Lablanche, P.-Y.; Vilalta, R.; Krone-Martins, A.; Beck, R.; Gieseke, F.

2017-12-01

We invoke a Gaussian mixture model (GMM) to jointly analyse two traditional emission-line classification schemes of galaxy ionization sources: the Baldwin-Phillips-Terlevich (BPT) and WH α versus [N II]/H α (WHAN) diagrams, using spectroscopic data from the Sloan Digital Sky Survey Data Release 7 and SEAGal/STARLIGHT data sets. We apply a GMM to empirically define classes of galaxies in a three-dimensional space spanned by the log [O III]/H β, log [N II]/H α and log EW(H α) optical parameters. The best-fitting GMM based on several statistical criteria suggests a solution around four Gaussian components (GCs), which are capable to explain up to 97 per cent of the data variance. Using elements of information theory, we compare each GC to their respective astronomical counterpart. GC1 and GC4 are associated with star-forming galaxies, suggesting the need to define a new starburst subgroup. GC2 is associated with BPT's active galactic nuclei (AGN) class and WHAN's weak AGN class. GC3 is associated with BPT's composite class and WHAN's strong AGN class. Conversely, there is no statistical evidence - based on four GCs - for the existence of a Seyfert/low-ionization nuclear emission-line region (LINER) dichotomy in our sample. Notwithstanding, the inclusion of an additional GC5 unravels it. The GC5 appears associated with the LINER and passive galaxies on the BPT and WHAN diagrams, respectively. This indicates that if the Seyfert/LINER dichotomy is there, it does not account significantly to the global data variance and may be overlooked by standard metrics of goodness of fit. Subtleties aside, we demonstrate the potential of our methodology to recover/unravel different objects inside the wilderness of astronomical data sets, without lacking the ability to convey physically interpretable results. The probabilistic classifications from the GMM analysis are publicly available within the COINtoolbox at https://cointoolbox.github.io/GMM_Catalogue/.

The strong 3.3 micron emission line in Wolf-Rayet stars

International Nuclear Information System (INIS)

Williams, P.M.

1982-01-01

A number of Wolf-Rayet stars have been found to show in their spectra a strong emission feature at 3.28 μm, the wavelength of the 'unidentified' feature observed in some nebular spectra. From comparison of the strength of this line from stars of different spectral type and excitation, it is identified with the CIV (11-10) transition group and shown not to be connected with the circumstellar dust associated with some Wolf-Rayet stars. (author)

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

Science.gov (United States)

McCarthy, K. J.; Tamura, N.; Combs, S. K.; García, R.; Hernández Sánchez, J.; Navarro, M.; Panadero, N.; Pastor, I.; Soleto, A.; the TJ-II Team

2018-03-01

43 spectral emission lines from F-like to Li-like sulphur ions have been identified in the wavelength range from 17.5 to 50 nm in spectra obtained following tracer injection into plasmas created in a magnetically confined plasma device, the stellarator TJ-II. Plasmas created and maintained in this heliac device with electron cyclotron resonance heating achieve central electron temperatures and densities up to 1.5 keV and 8 × 1018 m-3, respectively. Tracer injections were performed with ≤6 × 1016 atoms of sulphur contained within ˜300 μm diameter polystyrene capsules, termed tracer encapsulated solid pellets, using a gas propulsion system to achieve velocities between 250 and 450 m s-1. Once ablation of the exterior polystyrene shell by plasma particles is completed, the sulphur is deposited in the plasma core where it is ionized up to S+13 and transported about the plasma. In order to aid line identification, which is made using a number of atomic line emission databases, spectra are collected before and after injection using a 1 m focal length normal incidence spectrometer equipped with a CCD camera. This work is motivated by the need to clearly identify sulphur emission lines in the vacuum ultraviolet range of magnetically confined plasmas, as sulphur x-ray emission lines are regularly observed in both tokamak and stellarator plasmas.

On-line depth measurement for laser-drilled holes based on the intensity of plasma emission

Science.gov (United States)

Ho, Chao-Ching; Chiu, Chih-Mu; Chang, Yuan-Jen; Hsu, Jin-Chen; Kuo, Chia-Lung

2014-09-01

The direct time-resolved depth measurement of blind holes is extremely difficult due to the short time interval and the limited space inside the hole. This work presents a method that involves on-line plasma emission acquisition and analysis to obtain correlations between the machining processes and the optical signal output. Given that the depths of laser-machined holes can be estimated on-line using a coaxial photodiode, this was employed in our inspection system. Our experiments were conducted in air under normal atmospheric conditions without gas assist. The intensity of radiation emitted from the vaporized material was found to correlate with the depth of the hole. The results indicate that the estimated depths of the laser-drilled holes were inversely proportional to the maximum plasma light emission measured for a given laser pulse number.

Depression of molecular emission in the line of sight of Sgr A West

International Nuclear Information System (INIS)

Fukui, Y.; Ogawa, H.; Deguchi, S.; Suzuki, H.

1982-01-01

The galatic center region has been mapped in the 4-mm emission lines of HCCCN (J = 8-7) and H 2 CO (JK-K+ = 1 01 -0 00 ) with a 1.5 arc min beam. The molecular lines are found to show depression in intensity in the line of sight of Sgr A West. Comparison with other molecular data indicates that NH 3 also shows a significant depression while HCN and HCO + show little sign of similar depression. Based on some density estimates we suggest that the depression means abnormally reduced abundance in HCCCN, NH 3 , and H 2 CO in the line of sight of Sgr A West. The difference in the degree of depression could be interpreted in terms of a time-dependent ion-molecule reaction scheme because HCO + and HCN are formed much more rapidly than the other molecules in the scheme

On-line Field Measurements of Speciated PM1 Emission Factors from Common South Asian Combustion Sources

Science.gov (United States)

DeCarlo, P. F.; Goetz, J. D.; Giordano, M.; Stockwell, C.; Maharjan, R.; Adhikari, S.; Bhave, P.; Praveen, P. S.; Panday, A. K.; Jayarathne, T. S.; Stone, E. A.; Yokelson, R. J.

2017-12-01

Characterization of aerosol emissions from prevalent but under sampled combustion sources in South Asia was performed as part of the Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) in April 2015. Targeted emission sources included cooking stoves with a variety of solid fuels, brick kilns, garbage burning, crop-residue burning, diesel irrigation pumps, and motorcycles. Real-time measurements of submicron non-refractory particulate mass concentration and composition were obtained using an Aerodyne mini Aerosol Mass Spectrometer (mAMS). Speciated PM1 mass emission factors were calculated for all particulate species (e.g. organics, sulfates, nitrates, chlorides, ammonium) and for each source type using the carbon mass balance approach. Size resolved emission factors were also acquired using a novel high duty cycle particle time-of-flight technique (ePTOF). Black carbon and brown carbon absorption emission factors and absorption Angström exponents were measured using filter loading and scattering corrected attenuation at 370 nm and 880 nm with a dual spot aethalometer (Magee Scientific AE-33). The results indicate that open garbage burning is a strong emitter of organic aerosol, black carbon, and internally mixed particle phase hydrogen chloride (HCl). Emissions of HCl were attributed to the presence chlorinated plastics. The primarily coal fired brick kilns were found to be large emitters of sulfate but large differences in the organic and light absorbing component of emissions were observed between the two kiln types investigated (technologically advanced vs. traditional). These results, among others, bring on-line and field-tested aerosol emission measurements to an area of atmoshperic research dominated by off-line or laboratory based measurements.

Intensity of emission lines of the quiescent solar corona: comparison between calculated and observed values

Science.gov (United States)

Krissinel, Boris

2018-03-01

The paper reports the results of calculations of the center-to-limb intensity of optically thin line emission in EUV and FUV wavelength ranges. The calculations employ a multicomponent model for the quiescent solar corona. The model includes a collection of loops of various sizes, spicules, and free (inter-loop) matter. Theoretical intensity values are found from probabilities of encountering parts of loops in the line of sight with respect to the probability of absence of other coronal components. The model uses 12 loops with sizes from 3200 to 210000 km with different values of rarefaction index and pressure at the loop base and apex. The temperature at loop apices is 1 400 000 K. The calculations utilize the CHIANTI database. The comparison between theoretical and observed emission intensity values for coronal and transition region lines obtained by the SUMER, CDS, and EIS telescopes shows quite satisfactory agreement between them, particularly for the solar disk center. For the data acquired above the limb, the enhanced discrepancies after the analysis refer to errors in EIS measurements.

Clustering Properties of Emission Line Selected Galaxies over the past 12.5 Gyrs

Science.gov (United States)

Khostovan, Ali Ahmad; Sobral, David; Mobasher, Bahram; Best, Philip N.; Smail, Ian; Matthee, Jorryt; Darvish, Behnam; Nayyeri, Hooshang; Hemmati, Shoubaneh; Stott, John P.

2018-01-01

In this talk, I will present my latest results on the clustering and dark matter halo (DMH) mass properties of ~7000 narrowband-selected [OIII] and [OII] emitters. I will briefly describe the past work that has been done with our samples (e.g., luminosity functions, evolution of equivalent widths) as motivation of using [OIII] and [OII] emitters to study clustering/halo properties. My talk will focus on our findings regarding the line luminosity and stellar mass dependencies with DMH mass. We find strongly increasing and redshift-independent trends between line luminosity and DMH mass with evidence for a shallower slope at the bright end consistent with halo masses of ~ 1012.5-13 M⊙. Similar, but weaker, trends between stellar mass and halo mass have also been found. We investigate the inter-dependencies of these trends on halo mass and find that the correlation with line luminosity is stronger than with stellar mass. This suggest that active galaxies may be connected with their host DMHs simply based on their emission line luminosity. If time permits, I will briefly present our most recent results using our sample of ~4000 Lyα emitters, where we find similar trends to that seen with the [OIII] and [OII] samples, as well as previous Hα measurements, which suggests galaxies selected based on emission lines may be tracing the same subpopulation of star forming galaxies. I will conclude my talk with an interpretation of this connection and suggest that the shallower slope seen for the brightest emitters is evidence for a transitional halo mass as suggested in models where quenching mechanisms truncate star formation activity and reduce the fraction of star forming galaxies with increasing halo mass.

The absorption and emission spectrum of radiative cooling galactic fountain gas

Science.gov (United States)

Benjamin, Robert A.; Shapiro, Paul R.

1993-01-01

We have calculated the time-dependent, nonequilibrium thermal and ionization history of gas cooling radiatively from 10(exp 6) K in a one-dimensional, planar, steady-state flow model of the galactic fountain, including the effects of radiative transfer. Our previous optically thin calculations explored the effects of photoionization on such a flow and demonstrated that self-ionization was sufficient to cause the flow to match the observed galactic halo column densities of C 4, Si 4, and N 5 and UV emission from C 4 and O 3 in the constant density (isochoric) limit, which corresponded to cooling regions homogeneous on scales D less than or approximately equal to 1 kpc. Our new calculations which take full account of radiative transfer confirm the importance of self-ionization in enabling such a flow to match the data but allow a much larger range for cooling region sizes, i.e. D(sub 0) greater than or approximately equal to 15 pc. For an initial flow velocity v(sub 0) approximately equal to 100 km/s, comparable to the sound speed of a 10(exp 6) K gas, the initial density is found to be n(sub h,0) is approximately 2 x 10(exp -2) cm(exp -3), in reasonable agreement with other observation estimates, and D(sub 0) is approximately equal to 40 pc. We also compare predicted H(alpha) fluxes, UV line emission, and broadband x-ray fluxes with observed values. One dimensional numerical hydrodynamical calculations including the effects of radiative cooling are also presented.

A DEEP CHANDRA ACIS STUDY OF NGC 4151. II. THE INNERMOST EMISSION LINE REGION AND STRONG EVIDENCE FOR RADIO JET-NLR CLOUD COLLISION

International Nuclear Information System (INIS)

Wang Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.

2011-01-01

We have studied the X-ray emission within the inner ∼150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction, including morphological correspondences with regions of X-ray enhancement, peaks of near-infrared [Fe II] emission, and optical clouds. In these regions, moreover, we find evidence of elevated Ne IX/O VII ratios; the X-ray emission of these regions also exceeds that expected from nuclear photoionization. Spectral fitting reveals the presence of a collisionally ionized component. The thermal energy of the hot gas suggests that ∼> 0.1% of the estimated jet power is deposited into the host interstellar medium through interaction between the radio jet and the dense medium of the circumnuclear region. We find possible pressure equilibrium between the collisionally ionized hot gas and the photoionized line-emitting cool clouds. We also obtain constraints on the extended iron and silicon fluorescent emission. Both lines are spatially unresolved. The upper limit on the contribution of an extended emission region to the Fe Kα emission is ∼< 5% of the total, in disagreement with a previous claim that 65% of the Fe Kα emission originates in the extended narrow line region.

Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center

Energy Technology Data Exchange (ETDEWEB)

Najarro, F. [Departamento de Astrofísica, Centro de Astrobiología (CSIC-INTA), Ctra. Torrejón a Ajalvir km 4, E-28850 Torrejón de Ardoz (Spain); Geballe, T. R. [Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720 (United States); Figer, D. F. [Center for Detectors, Rochester Institute of Technology, 74 Lomb Memorial Drive, Rochester, NY 14623 (United States); Fuente, D. de la [Instituto de Astronomía, Unidad Académica en Ensenada, Universidad Nacional Autónoma de México, Ensenada 22860, México (Mexico)

2017-08-20

We report the detection of a number of emission lines in the 1.0–2.4 μ m spectra of four of the five bright-infrared dust-embedded stars at the center of the Galactic center’s (GC) Quintuplet Cluster. Spectroscopy of the central stars of these objects is hampered not only by the large interstellar extinction that obscures all of the objects in the GC, but also by the large amounts of warm circumstellar dust surrounding each of the five stars. The pinwheel morphologies of the dust observed previously around two of them are indicative of Wolf–Rayet colliding wind binaries; however, infrared spectra of each of the five have until now revealed only dust continua steeply rising to long wavelengths and absorption lines and bands from interstellar gas and dust. The emission lines detected, from ionized carbon and from helium, are broad and confirm that the objects are dusty late-type carbon Wolf–Rayet stars.

VERY STRONG EMISSION-LINE GALAXIES IN THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY AND IMPLICATIONS FOR HIGH-REDSHIFT GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Atek, H.; Colbert, J.; Shim, H. [Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States); Siana, B.; Bridge, C. [Department of Astronomy, Caltech, Pasadena, CA 91125 (United States); Scarlata, C. [Department of Astronomy, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States); Malkan, M.; Ross, N. R. [Department of Physics and Astronomy, University of California, Los Angeles, CA (United States); McCarthy, P.; Dressler, A.; Hathi, N. P. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Teplitz, H. [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Henry, A.; Martin, C. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Bunker, A. J. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Fosbury, R. A. E. [Space Telescope-European Coordinating Facility, Garching bei Muenchen (Germany)

2011-12-20

The WFC3 Infrared Spectroscopic Parallel Survey uses the Hubble Space Telescope (HST) infrared grism capabilities to obtain slitless spectra of thousands of galaxies over a wide redshift range including the peak of star formation history of the universe. We select a population of very strong emission-line galaxies with rest-frame equivalent widths (EWs) higher than 200 A. A total of 176 objects are found over the redshift range 0.35 < z < 2.3 in the 180 arcmin{sup 2} area that we have analyzed so far. This population consists of young and low-mass starbursts with high specific star formation rates (sSFR). After spectroscopic follow-up of one of these galaxies with Keck/Low Resolution Imaging Spectrometer, we report the detection at z = 0.7 of an extremely metal-poor galaxy with 12 + log(O/H) =7.47 {+-} 0.11. After estimating the active galactic nucleus fraction in the sample, we show that the high-EW galaxies have higher sSFR than normal star-forming galaxies at any redshift. We find that the nebular emission lines can substantially affect the total broadband flux density with a median brightening of 0.3 mag, with some examples of line contamination producing brightening of up to 1 mag. We show that the presence of strong emission lines in low-z galaxies can mimic the color-selection criteria used in the z {approx} 8 dropout surveys. In order to effectively remove low-redshift interlopers, deep optical imaging is needed, at least 1 mag deeper than the bands in which the objects are detected. Without deep optical data, most of the interlopers cannot be ruled out in the wide shallow HST imaging surveys. Finally, we empirically demonstrate that strong nebular lines can lead to an overestimation of the mass and the age of galaxies derived from fitting of their spectral energy distribution (SED). Without removing emission lines, the age and the stellar mass estimates are overestimated by a factor of 2 on average and up to a factor of 10 for the high-EW galaxies

Acoustic emission and magnification of atomic lines resolution for laser breakdown of salt water in ultrasound field

International Nuclear Information System (INIS)

Bulanov, Alexey V.; Nagorny, Ivan G.

2015-01-01

Researches of the acoustic effects accompanying optical breakdown in a water, generated by the focused laser radiation with power ultrasound have been carried out. Experiments were performed by using 532 nm pulses from Brilliant B Nd:YAG laser. Acoustic radiation was produced by acoustic focusing systems in the form hemisphere and ring by various resonance frequencies of 10.7 kHz and 60 kHz. The experimental results are obtained, that show the sharply strengthens effects of acoustic emission from a breakdown zone by the joint influence of a laser and ultrasonic irradiation. Essentially various thresholds of breakdown and character of acoustic emission in fresh and sea water are found out. The experimental result is established, testifying that acoustic emission of optical breakdown of sea water at presence and at absence of ultrasound essentially exceeds acoustic emission in fresh water. Atomic lines of some chemical elements like a Sodium, Magnesium and so on were investigated for laser breakdown of water with ultrasound field. The effect of magnification of this lines resolution for salt water in ultrasound field was obtained

PROPER MOTIONS OF THE HH 110/270 SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Kajdic, P. [Instituto de Astronomia, UNAM, Mexico D.F. (Mexico); Reipurth, B.; Walawender, J. [Institute for Astronomy, University of Hawaii at Manoa, 640 N. A' ohoku Place, Hilo, HI 96720 (United States); Raga, A. C. [Instituto de Ciencias Nucleares, UNAM, Mexico D.F. (Mexico); Bally, J., E-mail: primoz@geofisica.unam.mx, E-mail: reipurth@IfA.Hawaii.Edu, E-mail: raga@nucleares.unam.mx, E-mail: John.Bally@casa.colorado.edu, E-mail: joshw@ifa.hawaii.edu [CASA, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)

2012-05-15

We present a study of the HH 110/270 system based on three sets of optical images obtained with the ESO New Technology Telescope, the Subaru Telescope, and the Hubble Space Telescope (HST). The ground-based observations are made in the H{alpha} and [S II] emission lines and the HST observations are made in the H{alpha} line only. Ground-based observations reveal the existence of nine knots, which have not been previously discussed and offer some important insight into the HH 110/270 history. We perform a kinematic study of the HH 110/270 system and an analysis of its emission properties. We measure proper motions of all the knots in the system. Four of the newly identified knots belong to the HH 270 jet. Their positions indicate that the jet's axis changed its direction in the past. We speculate that similar changes may have occurred many times in the past and this could be part of the reason for the unusual structure of the HH 110 jet. The HST observations allow us to resolve individual knots into their substructures and to measure their proper motions. These measurements show that the knots are highly turbulent structures. Finally, we report the discovery of four new Herbig-Haro (HH) objects located near the HH 110/270 system.

Observation of hard X-rays line emission from Her X-1

Energy Technology Data Exchange (ETDEWEB)

Polcaro, V.F.; Bazzano, A.; la Padula, C.; Ubertini, P.; Vialetto, G.; Manchanda, R.K.; Damle, S.V.

1982-04-01

We present the results of a hard X-ray measurement of the binary source Her X-1, carried out with a balloon borne X-ray telescope consisting of two Multiwire Proportional Counters, having 900 cm/sup 2/ sensitive area each and spectral resolution of 15% and 24% FWHM respectively at 60 keV. The source was observed during the 'Mid-on' state. Our data confirm the previously reported high energy emission line overimposed on the low energy thermal spectrum.

Impurity line emission due to thermal charge exchange in JET edge plasmas

Energy Technology Data Exchange (ETDEWEB)

Maggi, C F; Horton, L D; Koenig, R; Stamp, M [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Summers, H P [Strathclyde Univ., Glasgow (United Kingdom)

1994-07-01

High n-shell emission from hydrogen-like carbon (C VI, n=8-7) has been routinely observed from the plasma edge of JET. By comparing the measured spectral line intensities with the signals predicted by advanced atomic physics modelling of carbon and hydrogen radiation, integrated with modelling of the divertor and edge plasma, it is concluded that charge transfer from excited state hydrogen donors into fully stripped carbon ions can account for the observed spectral emission, but that the hydrogen distribution and to a lesser extent the carbon distribution away from the strike zone predicted by the transport model are too low. Data presented are those of three upper X-point discharges, where the target material was carbon. 5 refs., 1 fig., 3 tabs.

A First Comparison of Millimeter Continuum and Mg ii Ultraviolet Line Emission from the Solar Chromosphere

Energy Technology Data Exchange (ETDEWEB)

Bastian, T. S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Chintzoglou, G.; De Pontieu, B.; Schmit, D. [Lockheed Martin Solar and Astrophysics Lab, Org. A021S, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Shimojo, M. [National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan); Leenaarts, J. [Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Loukitcheva, M., E-mail: tbastian@nrao.edu [Center For Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102 (United States)

2017-08-20

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph ( IRIS ). Both millimeter/submillimeter- λ continuum emission and ultraviolet (UV) line emission originate from the solar chromosphere and both have the potential to serve as powerful and complementary diagnostics of physical conditions in this enigmatic region of the solar atmosphere. The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun’s continuum emission was obtained by ALMA at a wavelength of 1.25 mm (239 GHz). A contemporaneous map was obtained by IRIS in the Mg ii h doublet line at 2803.5 Å. While a clear correlation between the 1.25 mm brightness temperature T{sub B} and the Mg ii h line radiation temperature T {sub rad} is observed, the slope is <1, perhaps as a result of the fact that these diagnostics are sensitive to different parts of the chromosphere and that the Mg ii h line source function includes a scattering component. There is a significant difference (35%) between the mean T{sub B} (1.25 mm) and mean T {sub rad} (Mg ii). Partitioning the maps into “sunspot,” “quiet areas,” and “plage regions” we find the relation between the IRIS Mg ii h line T {sub rad} and the ALMA T {sub B} region-dependent. We suggest this may be the result of regional dependences of the formation heights of the IRIS and ALMA diagnostics and/or the increased degree of coupling between the UV source function and the local gas temperature in the hotter, denser gas in plage regions.

A First Comparison of Millimeter Continuum and Mg ii Ultraviolet Line Emission from the Solar Chromosphere

International Nuclear Information System (INIS)

Bastian, T. S.; Chintzoglou, G.; De Pontieu, B.; Schmit, D.; Shimojo, M.; Leenaarts, J.; Loukitcheva, M.

2017-01-01

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph ( IRIS ). Both millimeter/submillimeter- λ continuum emission and ultraviolet (UV) line emission originate from the solar chromosphere and both have the potential to serve as powerful and complementary diagnostics of physical conditions in this enigmatic region of the solar atmosphere. The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun’s continuum emission was obtained by ALMA at a wavelength of 1.25 mm (239 GHz). A contemporaneous map was obtained by IRIS in the Mg ii h doublet line at 2803.5 Å. While a clear correlation between the 1.25 mm brightness temperature T_B and the Mg ii h line radiation temperature T _r_a_d is observed, the slope is <1, perhaps as a result of the fact that these diagnostics are sensitive to different parts of the chromosphere and that the Mg ii h line source function includes a scattering component. There is a significant difference (35%) between the mean T_B (1.25 mm) and mean T _r_a_d (Mg ii). Partitioning the maps into “sunspot,” “quiet areas,” and “plage regions” we find the relation between the IRIS Mg ii h line T _r_a_d and the ALMA T _B region-dependent. We suggest this may be the result of regional dependences of the formation heights of the IRIS and ALMA diagnostics and/or the increased degree of coupling between the UV source function and the local gas temperature in the hotter, denser gas in plage regions.

Disc structure and variability in dwarf novae

Science.gov (United States)

Harlaftis, Emilios Theofanus

An introduction is given to dwarf novae reviewing the current research status in the field. We present IUE observations of Z Cha which support the mass transfer instability as the cause of the superoutbursts observed in SU UMa type dwarf novae. Comparison between the superoutburst and a normal outburst of Z Cha shows that the disc is flatter and has significantly less azimuthal structure than during superoutburst. Z Cha exhibits a soft x-ray deficit during superoutburst compared to OY Car. We find that the secondary star of Z Cha contributes approximately 30 percent of the infrared flux at peak of outburst. The second part of the thesis presents results from the 1988 International Time Project at the Observatorio del Roque de los Muchachos. Investigation of the behavior of SU UMa and YZ Cnc is carried out through the outburst cycle. The secular changes of the equivalent widths of both systems shows an increasing trend even during quiescence and are caused by the continuum decrease. Both systems show a low-velocity emission component which contaminates the wings of the H(alpha) profile. In addition to doppler broadening, the Stark effect is found to cause significant broadening to the line profile. The radial dependence of the emission lines is discussed in relation to other cataclysmic variables. H(alpha) emission from the secondary star of YZ Cnc is found during superoutburst, during outburst and during quiescence after outburst. Photometry during late decline of outburst shows a sinusoidal, weak variation peaking at 0.5 orbital phase and which is related to heating of the red star or to a transient disc event. During quiescence, the flickering is found to be caused by the bright spot. This modulation increases with time and is maximum before the outburst. Doppler tomography of IP Peg during quiescence reveals an emission line distribution not consistent to the standard model. We find Balmer emission from the secondary star, at a level of only 2.5 percent of the

Ti-44 Gamma-Ray Emission Lines from SN1987A Reveal an Asymmetric Explosion

Science.gov (United States)

Boggs, S. E.; Harrison, F. A.; Miyasaka, H.; Grefenstette, B. W.; Zoglauer, A.; Fryer, C. L.; Reynolds, S. P.; Alexander, D. M.; An, H.; Barret, D.;

44Ti gamma-ray emission lines from SN1987A reveal an asymmetric explosion

DEFF Research Database (Denmark)

Boggs, S. E.; Harrison, F. A.; Miyasaka, H.

2015-01-01

In core-collapse supernovae, titanium-44 (44Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.......32–kilo–electron volt emission lines from decay of 44Ti produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, direct evidence of large-scale asymmetry in the explosion....

Reprocessing of Soft X-ray Emission Lines in Black Hole Accretion Disks

International Nuclear Information System (INIS)

Mauche, C W; Liedahl, D A; Mathiesen, B F; Jimenez-Garate, M A; Raymond, J C

2003-01-01

By means of a Monte Carlo code that accounts for Compton scattering and photoabsorption followed by recombination, we have investigated the radiation transfer of Lyα, Heα, and recombination continua photons of H- and He-like C, N, O, and Ne produced in the photoionized atmosphere of a relativistic black hole accretion disk. We find that photoelectric opacity causes significant attenuation of photons with energies above the O VIII K-edge; that the conversion efficiencies of these photons into lower-energy lines and recombination continua are high; and that accounting for this reprocessing significantly (by factors of 21% to 105%) increases the flux of the Lyα and Heα emission lines of H- and He-like C and O escaping the disk atmosphere

TIME VARIABILITY OF EMISSION LINES FOR FOUR ACTIVE T TAURI STARS. I. OCTOBER-DECEMBER IN 2010

Energy Technology Data Exchange (ETDEWEB)

Chou, Mei-Yin; Takami, Michihiro; Karr, Jennifer L.; Shang Hsien; Liu, Hauyu Baobab [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Manset, Nadine [Canada-France-Hawaii Telescope, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Beck, Tracy [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Pyo, Tae-Soo [Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States); Chen, Wen-Ping; Panwar, Neelam [Institute of Astronomy, National Central University, Taoyuan County 32001, Taiwan (China)

2013-04-15

We present optical spectrophotometric monitoring of four active T Tauri stars (DG Tau, RY Tau, XZ Tau, RW Aur A) at high spectral resolution (R {approx}> 1 Multiplication-Sign 10{sup 4}), to investigate the correlation between time variable mass ejection seen in the jet/wind structure of the driving source and time variable mass accretion probed by optical emission lines. This may allow us to constrain the understanding of the jet/wind launching mechanism, the location of the launching region, and the physical link with magnetospheric mass accretion. In 2010, observations were made at six different epochs to investigate how daily and monthly variability might affect such a study. We perform comparisons between the line profiles we observed and those in the literature over a period of decades and confirm the presence of time variability separate from the daily and monthly variability during our observations. This is so far consistent with the idea that these line profiles have a long-term variability (3-20 yr) related to episodic mass ejection suggested by the structures in the extended flow components. We also investigate the correlations between equivalent widths and between luminosities for different lines. We find that these correlations are consistent with the present paradigm of steady magnetospheric mass accretion and emission line regions that are close to the star.

TIME VARIABILITY OF EMISSION LINES FOR FOUR ACTIVE T TAURI STARS. I. OCTOBER–DECEMBER IN 2010

International Nuclear Information System (INIS)

Chou, Mei-Yin; Takami, Michihiro; Karr, Jennifer L.; Shang Hsien; Liu, Hauyu Baobab; Manset, Nadine; Beck, Tracy; Pyo, Tae-Soo; Chen, Wen-Ping; Panwar, Neelam

2013-01-01

We present optical spectrophotometric monitoring of four active T Tauri stars (DG Tau, RY Tau, XZ Tau, RW Aur A) at high spectral resolution (R ∼> 1 × 10 4 ), to investigate the correlation between time variable mass ejection seen in the jet/wind structure of the driving source and time variable mass accretion probed by optical emission lines. This may allow us to constrain the understanding of the jet/wind launching mechanism, the location of the launching region, and the physical link with magnetospheric mass accretion. In 2010, observations were made at six different epochs to investigate how daily and monthly variability might affect such a study. We perform comparisons between the line profiles we observed and those in the literature over a period of decades and confirm the presence of time variability separate from the daily and monthly variability during our observations. This is so far consistent with the idea that these line profiles have a long-term variability (3-20 yr) related to episodic mass ejection suggested by the structures in the extended flow components. We also investigate the correlations between equivalent widths and between luminosities for different lines. We find that these correlations are consistent with the present paradigm of steady magnetospheric mass accretion and emission line regions that are close to the star.

ALMA DETECTION OF THE VIBRATIONALLY EXCITED HCN J = 4-3 EMISSION LINE IN THE AGN-HOSTING LUMINOUS INFRARED GALAXY IRAS 20551–4250

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A' ohoku Place, Hilo, Hawaii, 96720 (United States); Nakanishi, Kouichiro, E-mail: masa.imanishi@nao.ac.jp [Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago de Chile (Chile)

2013-10-01

We present results from our ALMA Cycle 0 observations, at the frequencies around the HCN, HCO{sup +}, and HNC J = 4-3 transition lines, of the luminous infrared galaxy IRAS 20551–4250 at z = 0.043, which is known to host an energetically important obscured active galactic nucleus (AGN). In addition to the targeted HCN, HCO{sup +}, and HNC J = 4-3 emission lines, two additional strong emission lines are seen, which we attribute to H{sub 2}S and CH{sub 3}CN(+CCH). The HCN-to-HCO{sup +} J = 4-3 flux ratio (∼0.7) is higher than in the other starburst-dominated galaxy (∼0.2) observed in our ALMA Cycle 0 program. We tentatively (∼5σ) detected the vibrationally excited (v {sub 2} = 1) HCN J = 4-3 (l = 1f) emission line, which is important for testing an infrared radiative pumping scenario for HCN. This is the second detection of this molecular transition in external galaxies. The most likely reason for this detection is not only the high flux of this emission line, but also the small molecular line widths observed in this galaxy, suggesting that vibrational excitation of HCN may be relatively common in AGN-hosting galaxies.

Kossel interferences of proton-induced X-ray emission lines in periodic multilayers

Energy Technology Data Exchange (ETDEWEB)

Wu, Meiyi; Le Guen, Karine; André, Jean-Michel [Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Ilakovac, Vita [Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Université de Cergy-Pontoise, F-95031 Cergy-Pontoise (France); Vickridge, Ian [Sorbonne Universités, UPMC Univ Paris 06, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); CNRS UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); Schmaus, Didier [Sorbonne Universités, UPMC Univ Paris 06, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); CNRS UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, boîte courrier 840, F-75252 Paris cedex 05 (France); Université Paris Diderot-P7, F-75205 Paris cedex 13 (France); and others

2016-11-01

The Kossel interferences generated by characteristic X-ray lines produced inside a periodic multilayer have been observed upon proton irradiation, by submitting a Cr/B{sub 4}C/Sc multilayer stack to 2 MeV protons and observing the intensity of the Sc and Cr Kα characteristic emissions as a function of the detection angle. When this angle is close to the Bragg angle corresponding to the emission wavelength and period of the multilayer, an oscillation of the measured intensity is detected. The results are in good agreement with a model based on the reciprocity theorem. The combination of the Kossel measurements and their simulation, will be a useful tool to obtain a good description of the multilayer stack and thus to study nanometer-thick layers and their interfaces.

Lithium abundances, K line emission and ages of nearby solar type stars

International Nuclear Information System (INIS)

Duncan, D.K.

1981-01-01

Li abundances and chromospheric emission fluxes measured in the core of the Ca II K line have been determined in over 100 field F5--G5 dwarfs and subgiants. Although both quantities are known statistically to decrease in older stars, the correlation between them is not good. In particular, there are a number of anomalous solar type stars which show high Li abundances and very little chromospheric flux; the converse is rare. This might be understood if the intensity of chromospheric emission undergoes a sudden decrease when stars reach an age of 1 to 2 x 10 9 years, before much Li depletion occurs. Some of the anomalous stars appear to be older than this, however. Such stars must have preserved their Li from main sequence destruction

Flash photoionization of gamma-ray burst environments

Science.gov (United States)

Band, David L.; Hartmann, Dieter H.

1992-01-01

The H-alpha line emission that a flash-photoionized region emits is calculated. Archival transients, as well as various theoretical predictions, suggest that there may be significant ionizing flux. The limits on the line flux which might be observable indicate that the density must be fairly high for the recombination radiation to be observable. The intense burst radiation is insufficient to melt the dust which will be present in such a dense medium. This dust may attenuate the observable line emission, but does not attenuate the ionizing radiation before it ionizes the neutral medium surrounding the burst source. The dust can also produce a light echo. If there are indeed gamma-ray bursts in dense clouds, then it is possible that the burst was triggered by Bondi-Hoyle accretion from the dense medium, although it is unlikely on statistical grounds that all bursts occur in clouds.

Long-slit optical spectroscopy of powerful far-infrared galaxies - The nature of the nuclear energy source

Science.gov (United States)

Armus, Lee; Heckman, Timothy M.; Miley, George K.

1989-01-01

Optical spectroscopic data are presented for a sample of 47 powerful far-IR galaxies chosen for IR spectral shape, and for six other IR-bright galaxies. The stellar absorption lines expected from a population of old stars are generally very weak in the nuclei of the galaxies. Very weak Mg I absorption is found in regions well off the nucleus, implying that the visible spectrum is dominated by young stars and not by an AGN. At least one, and probably five, of the galaxies have detectable WR emission features, providing additional evidence for a young stellar population. About 20 percent of the galaxies have strong Balmer absorption lines, indicating the presence of a substantial intermediate-age stellar population. The equivalent width of the H-alpha emission line can be modeled as arising from a mixture of a large young population and an intermediate-age population of stars.

Time dependent emission line profiles in the radially streaming particle model of Seyfert galaxy nuclei and quasi-stellar objects

Science.gov (United States)

Hubbard, R.

1974-01-01

The radially-streaming particle model for broad quasar and Seyfert galaxy emission features is modified to include sources of time dependence. The results are suggestive of reported observations of multiple components, variability, and transient features in the wings of Seyfert and quasi-stellar emission lines.

A Deep Chandra ACIS Study of NGC 4151. III. The Line Emission and Spectral Analysis of the Ionization Cone

Science.gov (United States)

Wang, Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.; Dumas, Gaelle; Schinnerer, Eva

2011-11-01

This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert 1 galaxy NGC 4151, devoted to study its complex circumnuclear X-ray emission. Emission features in the soft X-ray spectrum of the bright extended emission (L 0.3-2 keV ~ 1040 erg s-1) at r > 130 pc (2'') are consistent with blended brighter O VII, O VIII, and Ne IX lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2 keV. We construct emission line images of these features and find good morphological correlations with the narrow-line region clouds mapped in [O III] λ5007. Self-consistent photoionization models provide good descriptions of the spectra of the large-scale emission, as well as resolved structures, supporting the dominant role of nuclear photoionization, although displacement of optical and X-ray features implies a more complex medium. Collisionally ionized emission is estimated to be lsim12% of the extended emission. Presence of both low- and high-ionization spectral components and extended emission in the X-ray image perpendicular to the bicone indicates leakage of nuclear ionization, likely filtered through warm absorbers, instead of being blocked by a continuous obscuring torus. The ratios of [O III]/soft X-ray flux are approximately constant (~15) for the 1.5 kpc radius spanned by these measurements, indicating similar relative contributions from the low- and high-ionization gas phases at different radial distances from the nucleus. If the [O III] and X-ray emission arise from a single photoionized medium, this further implies an outflow with a wind-like density profile. Using spatially resolved X-ray features, we estimate that the mass outflow rate in NGC 4151 is ~2 M ⊙ yr-1 at 130 pc and the kinematic power of the ionized outflow is 1.7 × 1041 erg s-1, approximately 0.3% of the bolometric luminosity of the active nucleus in NGC 4151.

Ground-based observation of emission lines from the corona of a red-dwarf star.

Science.gov (United States)

Schmitt, J H; Wichmann, R

2001-08-02

All 'solar-like' stars are surrounded by coronae, which contain magnetically confined plasma at temperatures above 106 K. (Until now, only the Sun's corona could be observed in the optical-as a shimmering envelope during a total solar eclipse.) As the underlying stellar 'surfaces'-the photospheres-are much cooler, some non-radiative process must be responsible for heating the coronae. The heating mechanism is generally thought to be magnetic in origin, but is not yet understood even for the case of the Sun. Ultraviolet emission lines first led to the discovery of the enormous temperature of the Sun's corona, but thermal emission from the coronae of other stars has hitherto been detectable only from space, at X-ray wavelengths. Here we report the detection of emission from highly ionized iron (Fe XIII at 3,388.1 A) in the corona of the red-dwarf star CN Leonis, using a ground-based telescope. The X-ray flux inferred from our data is consistent with previously measured X-ray fluxes, and the non-thermal line width of 18.4 km s-1 indicates great similarities between solar and stellar coronal heating mechanisms. The accessibility and spectral resolution (45,000) of the ground-based instrument are much better than those of X-ray satellites, so a new window to the study of stellar coronae has been opened.

The End of the Lines for OX 169: No Binary Broad-Line Region

Science.gov (United States)

Halpern, J. P.; Eracleous, M.

2000-03-01

We show that unusual Balmer emission-line profiles of the quasar OX 169, frequently described as either self-absorbed or double peaked, are actually neither. The effect is an illusion resulting from two coincidences. First, the forbidden lines are quite strong and broad. Consequently, the [N II] λ6583 line and the associated narrow-line component of Hα present the appearance of twin Hα peaks. Second, the redshift of 0.2110 brings Hβ into coincidence with Na I D at zero redshift, and ISM absorption in Na I D divides the Hβ emission line. In spectra obtained over the past decade, we see no substantial change in the character of the line profiles and no indication of intrinsic double-peaked structure. The Hγ, Mg II, and Lyα emission lines are single peaked, and all of the emission-line redshifts are consistent once they are correctly attributed to their permitted and forbidden-line identifications. A systematic shift of up to 700 km s-1 between broad and narrow lines is seen, but such differences are common and could be due to gravitational and transverse redshift in a low-inclination disk. Stockton & Farnham had called attention to an apparent tidal tail in the host galaxy of OX 169 and speculated that a recent merger had supplied the nucleus with a coalescing pair of black holes that was now revealing its existence in the form of two physically distinct broad-line regions. Although there is no longer any evidence for two broad emission-line regions in OX 169, binary black holes should form frequently in galaxy mergers, and it is still worthwhile to monitor the radial velocities of emission lines that could supply evidence of their existence in certain objects.

Spatially Resolved HST Grism Spectroscopy of a Lensed Emission Line Galaxy at z ~ 1

Science.gov (United States)

Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

2012-07-01

We take advantage of gravitational lensing amplification by A1689 (z = 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i 775 = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of ≈4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M * ≈ 2 × 109 M ⊙) with a high specific star formation rate (≈20 Gyr-1). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 ± 0.2). We break the continuous line-emitting region of this giant arc into seven ~1 kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by ~1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (Hβ) and f ([Ne III])/f (Hβ) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction. Based, in part, on data obtained with the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

The BAT AGN Spectroscopic Survey (BASS) DR1-Spectral Measurements, Derived Quantities, and AGN Demographics

Science.gov (United States)

Koss, Michael; BASS Team

2018-01-01

We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey (BASS). We analyze optical spectra of the majority of AGN (77%, 641/836) detected based on their 14-195 keV emission in the 70-month Swift BAT all-sky catalog. This includes redshift determination, absorption and emission line measurements, and black hole mass and accretion rate estimates for the majority of obscured and un-obscured AGN (74%, 473/641) with 340 measured for the first time. With ~90% of sources at z10^21.9 cm^-2. Seyfert 1.9 show a range of column densities. Compared to narrow line AGN in the SDSS, the X-ray selected AGN have a larger fraction of dusty host galaxies suggesting these types of AGN are missed in optical surveys. Using the most sensitive [OIII]/Hbeta and [NII]/Halpha emission line diagnostic, about half of the sources are classified as Seyferts, ~15% reside in dusty galaxies that lack an Hbeta detection, but for which the line upper limits imply either a Seyfert or LINER, ~15% are in galaxies with weak or no emission lines despite high quality spectra, and a few percent each are LINERS, composite galaxies, HII regions, or in known beamed AGN.

NEBULAR ATTENUATION IN H{alpha}-SELECTED STAR-FORMING GALAXIES AT z = 0.8 FROM THE NewH{alpha} SURVEY

Energy Technology Data Exchange (ETDEWEB)

Momcheva, Ivelina G. [Astronomy Department, Yale University, New Haven, CT 06511 (United States); Lee, Janice C.; Ouchi, Masami [Carnegie Observatories, Pasadena, CA 91101 (United States); Ly, Chun [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Salim, Samir [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Finn, Rose [Physics Department, Siena College, Loudonville, NY 12211 (United States); Ono, Yoshiaki, E-mail: ivelina.momcheva@yale.edu [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2013-02-01

We present measurements of the dust attenuation of H{alpha}-selected emission-line galaxies at z = 0.8 from the NewH{alpha} narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame optical emission lines from [O II] {lambda}3727 to [O III] {lambda}5007. The spectroscopic sample used in this analysis consists of 341 confirmed H{alpha} emitters. We place constraints on the active galactic nucleus (AGN) fraction using diagnostics that can be applied at intermediate redshift. We find that at least 5% of the objects in our spectroscopic sample can be classified as AGNs and 2% are composite, i.e., powered by a combination of star formation and AGN activity. We measure the dust attenuation for individual objects from the ratios of the higher order Balmer lines. The H{beta} and H{gamma} pair of lines is detected with S/N > 5 in 55 individual objects and the H{beta} and H{delta} pair is detected in 50 individual objects. We also create stacked spectra to probe the attenuation in objects without individual detections. The median attenuation at H{alpha} based on the objects with individually detected lines is A(H{alpha}) = 0.9 {+-} 1.0 mag, in good agreement with the attenuation found in local samples of star-forming galaxies. We find that the z = 0.8 galaxies occupy a similar locus of attenuation as a function of magnitude, mass, and star formation rate (SFR) as a comparison sample drawn from the SDSS DR4. Both the results from the individual z = 0.8 galaxies and from the stacked spectra show consistency with the mass-attenuation and SFR-attenuation relations found in the local universe, indicating that these relations are also applicable at intermediate redshift.

A magnetic study of spotted UV Ceti flare stars and related late-type dwarfs

Science.gov (United States)

Vogt, S. S.

1980-09-01

A multichannel photoelectric Zeeman analyzer has been used to investigate the magnetic nature of the spotted UV Ceti flare stars. Magnetic observations were obtained on a sample of 19 program objects, of which 5 were currently spotted dKe-dMe stars, 7 were normal dK-dM stars, 7 were UV Ceti flare stars, and 1 was a possible post-T Tauri star. Contrary to most previously published observations and theoretical expectations, no magnetic fields were detected on any of these objects from either the absorption lines or the H-alpha emission line down to an observational uncertainty level of 100-160 gauss (standard deviation).

An X-ray survey of the central molecular zone: Variability of the Fe Kα emission line

Science.gov (United States)

Terrier, R.; Clavel, M.; Soldi, S.; Goldwurm, A.; Ponti, G.; Morris, M. R.; Chuard, D.

2018-05-01

There is now abundant evidence that the luminosity of the Galactic super-massive black hole (SMBH) has not always been as low as it is nowadays. The observation of varying non-thermal diffuse X-ray emission in molecular complexes in the central 300 pc has been interpreted as delayed reflection of a past illumination by bright outbursts of the SMBH. The observation of different variability timescales of the reflected emission in the Sgr A molecular complex can be well explained if the X-ray emission of at least two distinct and relatively short events (i.e. about 10 yr or less) is currently propagating through the region. The number of such events or the presence of a long-duration illumination are open questions. Variability of the reflected emission all over of the central 300 pc, in particular in the 6.4 keV Fe Kα line, can bring strong constraints. To do so we performed a deep scan of the inner 300 pc with XMM-Newton in 2012. Together with all the archive data taken over the course of the mission, and in particular a similar albeit more shallow scan performed in 2000-2001, this allows for a detailed study of variability of the 6.4 keV line emission in the region, which we present here. We show that the overall 6.4 keV emission does not strongly vary on average, but variations are very pronounced on smaller scales. In particular, most regions showing bright reflection emission in 2000-2001 significantly decrease by 2012. We discuss those regions and present newly illuminated features. The absence of bright steady emission argues against the presence of an echo from an event of multi-centennial duration and most, if not all, of the emission can likely be explained by a limited number of relatively short (i.e. up to 10 yr) events. Images of the Fe Kα emission as FITS files are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A102

Modification of K-line emission profiles in laser-created solid-density plasmas

International Nuclear Information System (INIS)

Sengebusch, A.; Reinholz, H.; Roepke, G.

2010-01-01

Complete text of publication follows. X-ray emissions in the keV energy range have shown to be suitable radiation to investigate the properties of laser-created solid-density plasmas. We use the modifications of inner shell transitions due to the environment to characterize these plasmas. A theoretical treatment of spectral line profiles based on a self-consistent ion sphere model is applied on moderately ionized mid-Z materials, such as titanium, silicon and chlorine. We observe large contributions of satellite transitions due to M-shell ionization and excitation. To determine the composition a mixture of various excited and ionized ionic states embedded in a plasma has to be considered. Plasma polarization effects that cause shifts of the emission and ionization energies are taken into account. K-line profiles are calculated for bulk temperatures up to 100 eV and free electron densities up to 10 24 cm -3 in order to analyze recent measurements with respect to the plasma parameters of electron heated target regions. Moreover, in high-intensity laser-matter interactions, inevitable prepulses are likely to create preplasma and shocks within the target before the main pulse arrives. We investigate the influence of density gradients due to prepulses on the spectral profiles. Further, radial bulk temperature distributions as well the composition of the created warm dense matter are inferred.

A 16 deg2 survey of emission-line galaxies at z SSP Public Data Release 1

Science.gov (United States)

Hayashi, Masao; Tanaka, Masayuki; Shimakawa, Rhythm; Furusawa, Hisanori; Momose, Rieko; Koyama, Yusei; Silverman, John D.; Kodama, Tadayuki; Komiyama, Yutaka; Leauthaud, Alexie; Lin, Yen-Ting; Miyazaki, Satoshi; Nagao, Tohru; Nishizawa, Atsushi J.; Ouchi, Masami; Shibuya, Takatoshi; Tadaki, Ken-ichi; Yabe, Kiyoto

2018-01-01

We present initial results from the Subaru Strategic Program (SSP) with Hyper Suprime-Cam (HSC) on a comprehensive survey of emission-line galaxies at z SSP fields suggests that a survey volume of >5 × 105 Mpc3 is essential to overcome cosmic variance. Since the current data have not reached the full depth expected for the HSC-SSP, the color cut in i - NB816 or z - NB921 induces a bias towards star-forming galaxies with large equivalent widths, primarily seen in the stellar mass functions for the H α emitters at z ≈ 0.25-0.40. Even so, the emission-line galaxies clearly cover a wide range of luminosity, stellar mass, and environment, thus demonstrating the usefulness of the narrowband data from the HSC-SSP for investigating star-forming galaxies at z < 1.5.

Multiwavelength analysis of a well observed flare from SMM. [Solar Maximum Mission

Science.gov (United States)

Macneice, P.; Pallavicini, R.; Mason, H. E.; Simnett, G. M.; Antonucci, E.; Shine, R. A.; Dennis, B. R.

1985-01-01

Observations of an M 1.4 flare which began at 17:00 UT on November 12, 1980, are presented and analyzed. Ground based H-alpha and magnetogram data have been combined with EUV, soft and hard X-ray observations made with instruments on-board the Solar Maximum Mission satellite. The preflare phase was marked by a gradual brightening of the flare site in O v and the disappearance of an H-alpha filament. Filament ejecta were seen in O v moving southward at a speed of about 60 km/s, before the impulsive phase. The flare loop footpoints brightened in H-alpha and the Ca XIX resonance line broadened dramatically 2 min before the impulsive phase. Nonthermal hard X-ray emission was detected from the loop footpoints during the impulsive phase, while during the same period blue-shifts corresponding to upflows of 200-250 km/s were seen in Ca XIX. Evidence was found for energy deposition in both the chromosphere and corona at a number of stages during the flare. Two widely studied mechanisms for the production of the high temperature soft X-ray flare plasma in the corona are considered, i.e. chromospheric evaporation, and a model in which the heating and transfer of material occurs between flux tubes during reconnection.

Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

Directory of Open Access Journals (Sweden)

Hery Suyanto

2016-08-01

Full Text Available A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns and picosecond (ps lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS using He ambient gas.

Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

Energy Technology Data Exchange (ETDEWEB)

Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Lie, Tjung Jie; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha,Bandung 40132 (Indonesia); Kagawa, Kiichiro [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Fukui Science Education Academy, Takagi Chuo 2 chome, Fukui 910-0804 (Japan)

2016-08-15

A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by the fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.

The nature of extreme emission line galaxies at z = 1-2: kinematics and metallicities from near-infrared spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Maseda, Michael V.; Van der Wel, Arjen; Rix, Hans-Walter; Da Cunha, Elisabete; Meidt, Sharon E. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Pacifici, Camilla [Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of); Momcheva, Ivelina; Van Dokkum, Pieter; Nelson, Erica J. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Brammer, Gabriel B.; Ferguson, Henry C.; Koekemoer, Anton M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Franx, Marijn; Fumagalli, Mattia [Leiden Observatory, Leiden University, Leiden (Netherlands); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Förster-Schreiber, Natascha M. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Koo, David C. [UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Lundgren, Britt F. [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Marchesini, Danilo [Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States); Patel, Shannon G., E-mail: maseda@mpia.de [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

2014-08-10

We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M{sub *} = 10{sup 8}-10{sup 9} M{sub ☉}) galaxies undergoing intense starburst episodes (M{sub *}/SFR ∼ 10-100 Myr). The sample is selected by [O III] or Hα emission line flux and equivalent width using near-infrared grism spectroscopy from the 3D-HST survey. High-resolution NIR spectroscopy is obtained with LBT/LUCI and VLT/X-SHOOTER. The [O III]/Hβ line ratio is high (≳ 5) and [N II]/Hα is always significantly below unity, which suggests a low gas-phase metallicity. We are able to determine gas-phase metallicities for seven of our objects using various strong-line methods, with values in the range 0.05-0.30 Z{sub ☉} and with a median of 0.15 Z{sub ☉}; for three of these objects we detect [O III] λ4363, which allows for a direct constraint on the metallicity. The velocity dispersion, as measured from the nebular emission lines, is typically ∼50 km s{sup –1}. Combined with the observed star-forming activity, the Jeans and Toomre stability criteria imply that the gas fraction must be large (f{sub gas} ≳ 2/3), consistent with the difference between our dynamical and stellar mass estimates. The implied gas depletion timescale (several hundred Myr) is substantially longer than the inferred mass-weighted ages (∼50 Myr), which further supports the emerging picture that most stars in low-mass galaxies form in short, intense bursts of star formation.

Gamma-ray line emission from 26Al produced by Wolf-Rayet stars

International Nuclear Information System (INIS)

Prantzos, N.; Casse, M.; Gros, M.; Arnould, M.

1985-08-01

The recent satellite observations of the 1.8 MeV line from the decay of 26 Al has given a new impetus to the study of the nucleosynthesis of 26 Al. In this communication we discuss the production and ejection of 26 Al by massive mass-losing stars (Of and WR stars), in the light of recent stellar models. We also derive the longitude distribution of the 26 Al gamma-ray line emission produced by the galactic collection of WR stars, based on various estimates of their radial distribution. This longitude profile provides i) a specific signature of massive stars on the background of other potential 26 Al sources, as novae, supernovae, certain red giants and possibly AGB stars and ii) a possible tool to improve the data analysis of the HEAO 3 and SMM experiments

Observations of radio emission in the 18 cm hydroxyl lines in the direction of Herbig-Haro objects and reflection nebulae

International Nuclear Information System (INIS)

Pashchenko, M.I.; Rudnitskij, G.M.

1980-01-01

In 1978 observations of Herbig-Haro objects and R associations in the 1665 and 1667 MHz main lines of the ground state of the OH molecule have been carried out at the Large radio telescope of the Nancay Radio Astronomy Station (France). Out of the 63 objects searched, the OH emission has been observed in 36 directions. In most cases, the observed line profiles have a simple singlepeak structure, with the line widths of 1-3 km/s. This emission most probably originates in interstellar dust clouds surrounding the Herbig-Haro objects and R associations. Some consequences of the results obtained are briefly discussed. Results of observations show that the quantity of strong maser radio sources near Herbig-Haro objects is not large

Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at Z greater than 1

Science.gov (United States)

vanderWel, A.; Straughn, A. N.; Rix, H.-W.; Finkelstein, S. L.; Koekemoer, A. M.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.;

Study of short-period RS Canum Venaticorum and W Ursae Majoris binary systems: The global nature of Hα

International Nuclear Information System (INIS)

Barden, S.C.

1985-01-01

I present the rotation versus emission characteristics of the Hα line for several short-period (P -5 ) and the Rossby number (the ratio between the rotational period and the convective time scale) is seen for those components showing emission. Such a correlation suggests that the Hα line is a good diagnostic for the study of the magnetic-related activity in late-type stellar systems. Plotting the L/sub Halpha//L/sub bol/ against a measure of the tidal amplitude of Scharlemann shows that the activity of the W UMa secondary components may be shut off by the tidal forces of the primaries. The shut-off appears in those components having a tidal amplitude > or approx. =0.02. It is, however, unclear whether the tidal damping of the differential rotation is the sole mechanism responsible for the shut-off of the Hα emission, as the activity damping may also be attributable to the contact nature of the W UMa systems

Detailed observations of NGC 4151 with IUE-III. Variability of the strong emission lines from 1978 February to 1980 May

International Nuclear Information System (INIS)

Ulrich, M.H.; Boksenberg, A.; Bromage, G.E.

1983-11-01

Observations of the variability of the three strong ultraviolet emission lines in the Seyfert galaxy NGC 4151 (CIV, CIII, and MgII) are used to study the structure of the broad line region and the nuclear energy source of this active galaxy. (author)

Broadening of the x-ray emission line due to the instrumental function of the double-crystal spectrometer

International Nuclear Information System (INIS)

Tochio, T.; Ito, Y.; Omote, K.

2002-01-01

The influence of the instrumental function on the Cu Kα 1 emission line was investigated for the case of a double-crystal spectrometer. The magnitude of broadening for both Si(220) and Si(440) was calculated for a Lorentzian emission line with the width of 1-5 eV; the broadening for Si(220) is 0.12-0.18 eV while that for Si(440) is only 0.015-0.043 eV. The former is too large to be neglected, so the correction for the instrumental function is important. The spectrum affected by the instrumental function seems to keep the shape of Lorentzian though its width is larger. The fact indicates that the Lorentzian fitting analysis is effective if the appropriate correction for width is done

RELATIVISTIC PLASMA AS THE DOMINANT SOURCE OF THE OPTICAL CONTINUUM EMISSION IN THE BROAD-LINE RADIO GALAXY 3C 120

International Nuclear Information System (INIS)

Leon-Tavares, J.; Lobanov, A. P.; Arshakian, T. G.; Chavushyan, V. H.; Doroshenko, V. T.; Sergeev, S. G.; Efimov, Y. S.; Nazarov, S. V.

2010-01-01

We report a relation between radio emission in the inner jet of the Seyfert galaxy 3C 120 and optical continuum emission in this galaxy. Combining the optical variability data with multi-epoch high-resolution very long baseline interferometry observations reveals that an optical flare rises when a superluminal component emerges into the jet, and its maxima is related to the passage of such component through the location of a stationary feature at a distance of ∼1.3 pc from the jet origin. This indicates that a significant fraction of the optical continuum produced in 3C 120 is non-thermal, and it can ionize material in a sub-relativistic wind or outflow. We discuss implications of this finding for the ionization and structure of the broad emission line region, as well as for the use of broad emission lines for determining black hole masses in radio-loud active galactic nucleus.

Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra

Energy Technology Data Exchange (ETDEWEB)

Lee, Yonghoon, E-mail: yhlee@mokpo.ac.kr [Department of Chemistry, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Ham, Kyung-Sik [Department of Food Engineering, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Han, Song-Hee [Division of Maritime Transportation System, Mokpo National Maritime University, Jeonnam 530-729 (Korea, Republic of); Yoo, Jonghyun, E-mail: jyoo@appliedspectra.com [Applied Spectra, Inc., 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Jeong, Sungho [School of Mechatronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

2014-11-01

We have investigated the discriminating power of the elements in edible sea salts using Laser-Induced Breakdown Spectroscopy (LIBS). For the ten different sea salts from South Korea, China, Japan, France, Mexico and New Zealand, LIBS spectra were recorded in the spectral range between 190 and 1040 nm, identifying the presence of Na, Cl, K, Ca, Mg, Li, Sr, Al, Si, Ti, Fe, C, O, N, and H. Intensity correlation analysis of the observed emission lines provided a valuable insight into the discriminating power of the different elements in the sea salts. The correlation analysis suggests that the elements with independent discrimination power can be categorized into three groups; those that represent dissolved ions in seawater (K, Li, and Mg), those that are associated with calcified particles (Ca and Sr), and those that are present in soils contained in the sea salts (Al, Si, Ti, and Fe). Classification models using a few emission lines selected based on the results from intensity correlation analysis and full broadband LIBS spectra were developed based on Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) and their performances were compared. Our results indicate that effective combination of a few emission lines can provide a dependable model for discriminating the edible sea salts and the performance is not much degraded from that based on the full broadband spectra. This can be rationalized by the intensity correlation results. - Highlights: • Broadband LIBS spectra of various edible sea salts were obtained. • Intensity correlation of emission lines of the elements in edible sea salts was analyzed. • The elements were categorized into three groups with independent discriminating power. • The effective combination of a few lines can provide dependable classification models.

CLASH: EXTREME EMISSION-LINE GALAXIES AND THEIR IMPLICATION ON SELECTION OF HIGH-REDSHIFT GALAXIES

International Nuclear Information System (INIS)

Huang, Xingxing; Wang, Junxian; Shu, Xinwen; Zheng, Wei; Ford, Holland; Lemze, Doron; Moustakas, John; Van der Wel, Arjen; Zitrin, Adi; Frye, Brenda L.; Postman, Marc; Bradley, Larry; Coe, Dan; Bartelmann, Matthias; Benítez, Narciso; Broadhurst, Tom; Donahue, Megan; Infante, Leopoldo

2015-01-01

We utilize the Cluster Lensing And Supernova survey with Hubble observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y 105 ) and F125W (J 125 ), as the flux of the central bands could be enhanced by the presence of [O III] λλ4959, 5007 at redshifts of ∼0.93-1.14 and 1.57-1.79, respectively. The multiband observations help to constrain the equivalent widths (EWs) of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O III] λλ4959, 5007 EW of ≅ 3700 Å. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high EW can only be found in such faint galaxies. These EELGs can mimic a dropout feature similar to that of high-redshift galaxies and contaminate the color-color selection of high-redshift galaxies when the signal-to-noise ratio is limited or the band coverage is incomplete

CLASH: EXTREME EMISSION-LINE GALAXIES AND THEIR IMPLICATION ON SELECTION OF HIGH-REDSHIFT GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Huang, Xingxing; Wang, Junxian; Shu, Xinwen [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, Wei; Ford, Holland; Lemze, Doron [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Moustakas, John [Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211 (United States); Van der Wel, Arjen [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117, Heidelberg (Germany); Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Frye, Brenda L. [Steward Observatory/Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Postman, Marc; Bradley, Larry; Coe, Dan [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States); Bartelmann, Matthias [Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden (Netherlands); Benítez, Narciso [Instituto de Astrofísica de Andalucía (CSIC), C/Camino Bajo de Huétor 24, Granada E-18008 (Spain); Broadhurst, Tom [Department of Theoretical Physics, University of Basque Country UPV/EHU E-Bilbao (Spain); Donahue, Megan [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Infante, Leopoldo, E-mail: hxx@mail.ustc.edu.cn [Departamento de Astronoía y Astrofísica, Pontificia Universidad Católica de Chile, V. Mackenna 4860 Santiago 22 (Chile); and others

2015-03-01

We utilize the Cluster Lensing And Supernova survey with Hubble observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y {sub 105}) and F125W (J {sub 125}), as the flux of the central bands could be enhanced by the presence of [O III] λλ4959, 5007 at redshifts of ∼0.93-1.14 and 1.57-1.79, respectively. The multiband observations help to constrain the equivalent widths (EWs) of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O III] λλ4959, 5007 EW of ≅ 3700 Å. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high EW can only be found in such faint galaxies. These EELGs can mimic a dropout feature similar to that of high-redshift galaxies and contaminate the color-color selection of high-redshift galaxies when the signal-to-noise ratio is limited or the band coverage is incomplete.

Imaging and spectroscopic observations of a strange elliptical bubble in the northern arm of the spiral galaxy NGC 6946

OpenAIRE

Efremov, Yuri N.; Moiseev, Alexei V.

2016-01-01

NGC 6946, known as the Fireworks galaxy because of its high supernova rate and high star formation, is embedded in a very extended HI halo. Its northern spiral arm is well detached from the galactic main body. We found that this arm contains a large (~300 pc in size) Red Ellipse, named according to a strong contamination of the H-alpha emission line on its optical images. The ellipse is accompanied by a short parallel arc and a few others still smaller and less regular; a bright star cluster ...

Correcting for variable laser-target distances of laser-induced breakdown spectroscopy measurements with ChemCam using emission lines of Martian dust spectra

Energy Technology Data Exchange (ETDEWEB)

Melikechi, N.; Mezzacappa, A. [Optical Science Center for Applied Research, Delaware State University, Dover, DE (United States); Cousin, A.; Lanza, N.L. [Los Alamos National Laboratory, Los Alamos, NM (United States); Lasue, J. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Clegg, S.M. [Los Alamos National Laboratory, Los Alamos, NM (United States); Berger, G. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Wiens, R.C. [Los Alamos National Laboratory, Los Alamos, NM (United States); Maurice, S. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Tokar, R.L.; Bender, S. [Planetary Science Institute, Flagstaff, AZ (United States); Forni, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Breves, E.A.; Dyar, M.D. [Dept. of Astronomy, Mount Holyoke College, South Hadley, MA (United States); Frydenvang, J. [The Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Delapp, D. [Los Alamos National Laboratory, Los Alamos, NM (United States); Gasnault, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Newsom, H.; Ollila, A.M. [Earth and Planetary Sciences, University of New Mexico, Alburquerque, NM (United States); Lewin, E. [Institut des Sciences de la Terre, Universite Grenoble l-CNRS, Grenoble (France); and others

2014-06-01

As part of the Mars Science Laboratory, the ChemCam instrument acquires remote laser induced breakdown spectra at distances that vary between 1.56 m and 7 m. This variation in distance affects the intensities of the measured LIBS emission lines in non-trivial ways. To determine the behavior of a LIBS emission line with distance, it is necessary to separate the effects of many parameters such as laser energy, laser spot size, target homogeneity, and optical collection efficiency. These parameters may be controlled in a laboratory on Earth but for field applications or in space this is a challenge. In this paper, we show that carefully selected ChemCam LIBS emission lines acquired from the Martian dust can be used to build an internal proxy spectroscopic standard. This in turn, allows for a direct measurement of the effects of the distance of various LIBS emission lines and hence can be used to correct ChemCam LIBS spectra for distance variations. When tested on pre-launch LIBS calibration data acquired under Martian-like conditions and with controlled and well-calibrated targets, this approach yields much improved agreement between targets observed at various distances. This work lays the foundation for future implementation of automated routines to correct ChemCam spectra for differences caused by variable distance. - Highlights: • Selected Martian dust emission lines are used to correct for variable laser-target distances. • The correction model yields improved agreement between targets observed at various distances. • The impact of the model reduces the bias between predicted and actual compositions by as much as 70%. • When implemented, the model will yield spectral corrections for various ChemCam measurements. • This work is a foundation to perform novel stand-off LIBS measurements on Earth and other planets.

Relating Line Width and Optical Depth for CO Emission in the Large Mgellanic Cloud

Science.gov (United States)

Wojciechowski, Evan; Wong, Tony; Bandurski, Jeffrey; MC3 (Mapping CO in Molecular Clouds in the Magellanic Clouds) Team

2018-01-01

We investigate data produced from ALMA observations of giant molecular clouds (GMCs) located in the Large Magellanic Cloud (LMC), using 12CO(2–1) and 13CO(2–1) emission. The spectral line width is generally interpreted as tracing turbulent rather than thermal motions in the cloud, but could also be affected by optical depth, especially for the 12CO line (Hacar et al. 2016). We compare the spectral line widths of both lines with their optical depths, estimated from an LTE analysis, to evaluate the importance of optical depth effects. Our cloud sample includes two regions recently published by Wong et al. (2017, submitted): the Tarantula Nebula or 30 Dor, an HII region rife with turbulence, and the Planck cold cloud (PCC), located in a much calmer environment near the fringes of the LMC. We also include four additional LMC clouds, which span intermediate levels of star formation relative to these two clouds, and for which we have recently obtained ALMA data in Cycle 4.

Line-emission cross sections for the charge-exchange reaction between fully stripped carbon and atomic hydrogen in tokamak plasma

International Nuclear Information System (INIS)

Ida, K.; Kato, T.

1992-01-01

Line-emission cross sections of the charge-exchange reaction between fully stripped carbon and atomic hydrogen are measured in the energy range of 18 - 38 keV/amu in tokamak plasmas. The energy dependence of the emission cross sections for the transition of Δn = 8 - 7 and Δn = 7 - 6 and their ratios are compared with theoretical calculations. (author)

The H II regions of IC 1613

International Nuclear Information System (INIS)

Hodge, P.; Lee, M.G.; Gurwell, M.

1990-01-01

Narrow-band CCD H-alpha imaging of the Local Group irregular galaxy IC 1613 has revealed a total of 77 H II regions, five of which are complexes of several smaller emission regions. Positions, H-alpha luminosities, and sizes of these objects are tabulated. The H-alpha luminosity function has the same shape as that for more luminous galaxies, following a power law with an exponent of -1.6. The faintest H II regions are at the low-luminosity end of the generally observed luminosity function for H II regions in galaxies, with fluxes of only 10 to the 35th erg/sec. The size distribution has an exponential shape, as for other galaxies, with a size scale of 56 pc. The morphologies of different H II regions are discussed and compared to those in other galaxies. Published radio continuum maps compare well with the H-alpha emission distribution. The distribution of H I is also similar in the central areas to the H II with, however, a tendency for the H II regions to lie to one side of H I peaks. 31 refs

DENSITY WAVE KINEMATICS AND GIANT MOLECULAR ASSOCIATION FORMATION IN M51

NARCIS (Netherlands)

RAND, RJ

1993-01-01

New spectroscopic observations of the ionized gas (Halpha and [N II] lines) in M51 are combined with existing CO, H I, and Halpha data to look for kinematic evidence that the gas is responding to a spiral density wave. Possible mechanisms for the formation of the approximately 3 x 10(7) M. giant

The device for the poloidal profile measurement of H sub(α)-line emission by photodiode and its calibration

International Nuclear Information System (INIS)

Miura, Yukitoshi; Kasai, Satoshi; Tamai, Hiroshi; Hasegawa, Koichi

1985-11-01

The device for the poloidal profile measurement of H sub(α)-line emission has been equipped by photodiode (S1225-5BQ by HAMAMATSU PHOTONICS K.K.) and operational amplifier. The absolute efficiency was calibrated by using He-Ne laser. The device is constructed by 44 channels. The fast type of 8 channels is for the monitor of pellet abration profile. The slow type of 36 channels is for the poloidal profile measurement of H sub(α)-line emission from JFT-2M plasma. The rise time of the fast type and the slow type is about 2.8 μsec and about 350 μsec, respectively. The absolute efficiency of the fast type and the slow type is 72.7 V/mW and 18.2 V/μW, respectively. (author)

Photoionization Models of the H_2 Emission of the Narrow Line Region of AGNs

Science.gov (United States)

Aleman, I.; Gruenwald, R.

2011-05-01

The excitation mechanism of the narrow line region (NLR) of AGNs is still an open question. Excitation by UV radiation from O and B stars, x-rays from the central black hole, shock from supernovae or jets, or a combination of these mechanisms have been suggested. In the present work, we use photoionization models to study the excitation mechanisms of the H_2 infrared emission lines in the NLR. In the literature, analyzes of the H_2 emission have been done assuming that the molecules is present only in neutral regions (photodissociation regions, x-ray-dominated regions, or shocks; Veilleux et al. 1997, Krabbe et al. 2000, Rigopoulou et al. 2002, Rodriguez-Ardila et al. 2004, 2005, and Davies et al. 2005). However, they are not conclusive. In previous work (Aleman & Gruenwald 2004, 2011), we show that the H_2 emission from the ionized region of PNe can be significant for planetary nebulae (PNe) with hot central stars (T⋆ > 150000 K). Such stars produce copious amounts of high energy photons, which create an extended partially ionized region that favors the H_2 survival. The conditions in the NLR are similar to those in PNe with hot central stars, so we can expect that the H_2 emission might also be important. We obtain and analyze a grid of photoionization models for different NRL parameters. We study the resulting H_2 density and emission, as well as, the formation, destruction, excitation, and de-excitation mechanisms. The higher values observed for the H_2 1-0 S(1)/Brγ ratio cannot be reproduced by our models. The calculated ratios are between 10^-8 and 10^-1, while the observational ration can be as high as 10. The calculated ratio is strongly anti-correlated with the ionization parameter (U) and only models with U<10-3 result in ratios inside the observational range. We show that the NLR is an environment more hostile to the H_2 molecule than the ionized region of PNe. Another interesting result of our calculations is that the H_2 formation on grain surfaces

Sub-mm emission line deep fields: CO and [C II] luminosity functions out to z = 6

NARCIS (Netherlands)

Popping, Gergö; van Kampen, Eelco; Decarli, Roberto; Spaans, Marco; Somerville, Rachel S.; Trager, Scott C.

2016-01-01

Now that Atacama Large (Sub)Millimeter Array is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J =1-0 out to CO

Physical and morphological properties of z ~ 3 Lyman break galaxies: dependence on Lyα line emission

Science.gov (United States)

Pentericci, L.; Grazian, A.; Scarlata, C.; Fontana, A.; Castellano, M.; Giallongo, E.; Vanzella, E.

2010-05-01

Aims: We investigate the physical and morphological properties of Lyman break galaxies (LBGs) at redshift ~2.5 to ~3.5, to determine if and how they depend on the nature and strength of the Lyα emission. Methods: We selected U-dropout galaxies from the z-detected GOODS-MUSIC catalog by adapting the classical Lyman break criteria on the GOODS filter set. We kept only those galaxies with spectroscopic confirmation, mainly from VIMOS and FORS public observations. Using the full multi-wavelength 14-bands information (U to IRAC), we determined the physical properties of the galaxies through a standard spectral energy distribution fitting procedure with the updated Charlot & Bruzual (2009) templates. We also added other relevant observations of the GOODS field, i.e. the 24 μm observations from Spitzer/MIPS and the 2 MSec Chandra X-ray observations. Finally, using non parametric diagnostics (Gini, Concentration, Asymmetry, M20 and ellipticity), we characterized the rest-frame UV morphologies of the galaxies. We then analyzed how these physical and morphological properties correlate with the presence of the Lyα emission line in the optical spectra. Results: We find that unlike at higher redshift, the dependence of physical properties on the Lyα line is milder: galaxies without Lyα in emission tend to be more massive and dustier than the rest of the sample, but all other parameters, ages, star formation rates (SFR), X-ray emission and UV morphology do not depend strongly on the presence of the Lyα emission. A simple scenario where all LBGs have intrinsically high Lyα emission, but where the dust and neutral hydrogen content (which shapes the final appearance of the Lyα) depend on the mass of the galaxies, is able to reproduce the majority of the observed properties at z˜3. Some modification might be needed to account for the observed evolution of these properties with cosmic epoch, which is also discussed.

SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

Science.gov (United States)

Zhang, Kai; Yan, Renbin; Bundy, Kevin; Bershady, Matthew; Haffner, L. Matthew; Walterbos, René; Maiolino, Roberto; Tremonti, Christy; Thomas, Daniel; Drory, Niv; Jones, Amy; Belfiore, Francesco; Sánchez, Sebastian F.; Diamond-Stanic, Aleksandar M.; Bizyaev, Dmitry; Nitschelm, Christian; Andrews, Brett; Brinkmann, Jon; Brownstein, Joel R.; Cheung, Edmond; Li, Cheng; Law, David R.; Roman Lopes, Alexandre; Oravetz, Daniel; Pan, Kaike; Storchi Bergmann, Thaisa; Simmons, Audrey

2017-04-01

Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H II regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H II region models can only shift line ratios slightly relative to H II region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R23, N2 = [N II]/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H II region models that fail to describe the DIG.

Comparison of AI techniques to solve combined economic emission dispatch problem with line flow constraints

Energy Technology Data Exchange (ETDEWEB)

Jacob Raglend, I. [School of Electrical Sciences, Noorul Islam University, Kumaracoil 629 180 (India); Veeravalli, Sowjanya; Sailaja, Kasanur; Sudheera, B. [School of Electrical Sciences, Vellore Institute of Technology, Vellore 632 004 (India); Kothari, D.P. [FNAE, FNASC, SMIEEE, Vellore Institute of Technology University, Vellore 632 014 (India)

2010-07-15

A comparative study has been made on the solutions obtained using combined economic emission dispatch (CEED) problem considering line flow constraints using different intelligent techniques for the regulated power system to ensure a practical, economical and secure generation schedule. The objective of the paper is to minimize the total production cost of the power generation. Economic load dispatch (ELD) and economic emission dispatch (EED) have been applied to obtain optimal fuel cost of generating units. Combined economic emission dispatch (CEED) is obtained by considering both the economic and emission objectives. This bi-objective CEED problem is converted into single objective function using price penalty factor approach. In this paper, intelligent techniques such as genetic algorithm (GA), evolutionary programming (EP), particle swarm optimization (PSO), differential evolution (DE) are applied to obtain CEED solutions for the IEEE 30-bus system and 15-unit system. This proposed algorithm introduces an efficient CEED approach that obtains the minimum operating cost satisfying unit, emission and network constraints. The proposed algorithm has been tested on two sample systems viz the IEEE 30-bus system and a 15-unit system. The results obtained by the various artificial intelligent techniques are compared with respect to the solution time, total production cost and convergence criteria. The solutions obtained are quite encouraging and useful in the economic emission environment. The algorithm and simulation are carried out using Matlab software. (author)

Comparison of AI techniques to solve combined economic emission dispatch problem with line flow constraints

International Nuclear Information System (INIS)

Jacob Raglend, I.; Veeravalli, Sowjanya; Sailaja, Kasanur; Sudheera, B.; Kothari, D.P.

2010-01-01

A comparative study has been made on the solutions obtained using combined economic emission dispatch (CEED) problem considering line flow constraints using different intelligent techniques for the regulated power system to ensure a practical, economical and secure generation schedule. The objective of the paper is to minimize the total production cost of the power generation. Economic load dispatch (ELD) and economic emission dispatch (EED) have been applied to obtain optimal fuel cost of generating units. Combined economic emission dispatch (CEED) is obtained by considering both the economic and emission objectives. This bi-objective CEED problem is converted into single objective function using price penalty factor approach. In this paper, intelligent techniques such as genetic algorithm (GA), evolutionary programming (EP), particle swarm optimization (PSO), differential evolution (DE) are applied to obtain CEED solutions for the IEEE 30-bus system and 15-unit system. This proposed algorithm introduces an efficient CEED approach that obtains the minimum operating cost satisfying unit, emission and network constraints. The proposed algorithm has been tested on two sample systems viz the IEEE 30-bus system and a 15-unit system. The results obtained by the various artificial intelligent techniques are compared with respect to the solution time, total production cost and convergence criteria. The solutions obtained are quite encouraging and useful in the economic emission environment. The algorithm and simulation are carried out using Matlab software. (author)

WHT spectroscopy of emission-line gas around two separate quasars at z = 0.87

International Nuclear Information System (INIS)

Fabian, A.C.; Crawford, C.S.; Johnstone, R.M.; Hewett, P.C.; Allington-Smith, J.R.

1988-01-01

A report is given of observations made with the Faint Object Spectrograph on the 4.2-m William Herschel Telescope (WHT), in which the line emission of the fuzz around two separate quasars, which coincidentally both have redshifts z = 0.87, is detected and measured. These represent the most distant quasars for which the spectrum of the fuzz has been obtained. The oxygen line ratios we observe are similar to those of the lower-z quasar 3C48 (to which the present quasars show a strong similarity) and again imply a high gas density. If confined by surrounding hot gas, the pressure is so high that an intracluster medium is required. This suggests that the quasars lie in clusters or groups of galaxies. (author)

Using a New Infrared Si X Coronal Emission Line for Discriminating between Magnetohydrodynamic Models of the Solar Corona During the 2006 Solar Eclipse

Science.gov (United States)

Dima, Gabriel I.; Kuhn, Jeffrey R.; Mickey, Don; Downs, Cooper

2018-01-01

During the 2006 March 29 total solar eclipse, coronal spectropolarimetric measurements were obtained over a 6 × 6 R ⊙ field of view with a 1–2 μm spectral range. The data yielded linearly polarized measurements of the Fe XIII 1.075 μm, He I 1.083 μm, and for the first time, of the Si X 1.430 μm emission lines. To interpret the measurements, we used forward-integrated synthetic emission from two magnetohydrodynamic models for the same Carrington rotation with different heating functions and magnetic boundary conditions. Observations of the Fe XIII 1.075/Si X 1.430 line ratio allowed us to discriminate between two models of the corona, with the observations strongly favoring the warmer model. The observed polarized amplitudes for the Si X 1.430 μm line are around 7%, which is three times higher than the predicted values from available atomic models for the line. This discrepancy indicates a need for a closer look at some of the model assumptions for the collisional coefficients, as well as new polarized observations of the line to rule out any unknown systematic effect in the present data. All but two near-limb fibers show correlated bright He I 1.083 μm and H I 1.282 μm emission, which likely indicates cool prominence emission that is non-localized by the strongly defocused optics. One of the distant fibers located at 1.5 R ⊙ detected a weak He I 1.083 μm intensity signal consistent with previous eclipse measurements around 3 × 10‑7 {B}ȯ . However, given the limitations of these observations, it is not possible to completely remove contamination that is due to emission from prominence material that is not obscured by the lunar limb.

Simultaneous detection and analysis of optical and ultraviolet broad emission lines in quasars at z 2.2

Science.gov (United States)

Bisogni, S.; di Serego Alighieri, S.; Goldoni, P.; Ho, L. C.; Marconi, A.; Ponti, G.; Risaliti, G.

2017-06-01

We studied the spectra of six z 2.2 quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and the X-shooter's spectral coverage allow us to cover the rest of the spectral range 1200-7000 Å for the simultaneous detection of optical and ultraviolet lines emitted by the broad-line region. Simultaneous measurements, avoiding issues related to quasars variability, help us understand the connection between the different broad-line region line profiles generally used as virial estimators of black hole masses in quasars. The goal of this work is to compare the different emission lines for each object to check on the reliability of Hα, Mg II and C iv with respect to Hβ. Hα and Mg II linewidths correlate well with Hβ, while C iv shows a poorer correlation, due to the presence of strong blueshifts and asymmetries in the profile. We compared our sample with the only other two whose spectra were taken with the same instrument and for all examined lines our results are in agreement with the ones obtained with X-shooter at z 1.5-1.7. We finally evaluate C III] as a possible substitute of C iv in the same spectral range and find that its behaviour is more coherent with those of the other lines: we believe that, when a high quality spectrum such as the ones we present is available and a proper modelization with the Fe II and Fe III emissions is performed, it is more appropriate to use this line than that of C iv if not corrected for the contamination by non-virialized components. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programme 086.B-0320(A).The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/603/A1

Narrowband imaging of the Herbig-Haro object HH 46/47

International Nuclear Information System (INIS)

Raga, A.C.; Mateo, M.

1987-01-01

Narrow-band CCD images of the HH 46/47 system were obtained in the light of the H-alpha, forbidden N II 6583-A forbidden S II 6717-A and forbidden S II 6731-A emission lines. The images include HH 46, HH 47B, and HH 47A. A calibration for these images was carried out that makes it possible to calculate line ratios, and then use these line ratios as diagnostics of the physical conditions in the radiating gas. The study shows that the bright condensation HH 47A has a higher electron density and a lower excitation spectrum than the jet that joins this condensation to the central source. This result does not agree with the observations of other morphologically similar Herbig-Haro objects. 36 references

OPTICAL LINE EMISSION IN BRIGHTEST CLUSTER GALAXIES AT 0 < z < 0.6: EVIDENCE FOR A LACK OF STRONG COOL CORES 3.5 Gyr AGO?

International Nuclear Information System (INIS)

McDonald, Michael

2011-01-01

In recent years the number of known galaxy clusters beyond z ∼> 0.2 has increased drastically with the release of multiple catalogs containing >30,000 optically detected galaxy clusters over the range 0 0.3, hinting at an earlier epoch of strong cooling. We compare the evolution of emission-line nebulae to the X-ray-derived cool core (CC) fraction from the literature over the same redshift range and find overall agreement, with the exception that an upturn in the strong CC fraction is not observed at z > 0.3. The overall agreement between the evolution of CCs and optical line emission at low redshift suggests that emission-line surveys of galaxy clusters may provide an efficient method of indirectly probing the evolution of CCs and thus provide insights into the balance of heating and cooling processes at early cosmic times.

CONFIRMATION OF SMALL DYNAMICAL AND STELLAR MASSES FOR EXTREME EMISSION LINE GALAXIES AT z ∼ 2

Energy Technology Data Exchange (ETDEWEB)

Maseda, Michael V.; Van der Wel, Arjen; Da Cunha, Elisabete; Rix, Hans-Walter [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Pacifici, Camilla [Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of); Momcheva, Ivelina; Van Dokkum, Pieter; Nelson, Erica J. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Brammer, Gabriel B.; Grogin, Norman A.; Koekemoer, Anton M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Franx, Marijn; Fumagalli, Mattia; Patel, Shannon G. [Leiden Observatory, Leiden University, Leiden (Netherlands); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Kocevski, Dale D. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Lundgren, Britt F. [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States); Marchesini, Danilo [Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States); Skelton, Rosalind E. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa); Straughn, Amber N., E-mail: maseda@mpia.de [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); and others

2013-11-20

Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (∼50 km s{sup –1}) for a sample of 14 extreme emission line galaxies at redshifts 1.4 < z < 2.3. These measurements imply that the total dynamical masses of these systems are low (≲ 3 × 10{sup 9} M {sub ☉}). Their large [O III] λ5007 equivalent widths (500-1100 Å) and faint blue continuum emission imply young ages of 10-100 Myr and stellar masses of 10{sup 8}-10{sup 9} M {sub ☉}, confirming the presence of a violent starburst. The dynamical masses represent the first such determinations for low-mass galaxies at z > 1. The stellar mass formed in this vigorous starburst phase represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.

The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data.

Science.gov (United States)

Fan; Strauss; Gunn; Lupton; Carilli; Rupen; Schmidt; Moustakas; Davis; Annis; Bahcall; Brinkmann; Brunner; Csabai; Doi; Fukugita; Heckman; Hennessy; Hindsley; Ivezic; Knapp; Lamb; Munn; Pauls; Pier; Rockosi; Schneider; Szalay; Tucker; York

1999-12-01

We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

ELLERMAN BOMBS AT HIGH RESOLUTION. II. TRIGGERING, VISIBILITY, AND EFFECT ON UPPER ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Vissers, Gregal J. M.; Rouppe van der Voort, Luc H. M.; Rutten, Robert J., E-mail: g.j.m.vissers@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

2013-09-01

We use high-resolution imaging spectroscopy with the Swedish 1-m Solar Telescope (SST) to study the transient brightenings of the wings of the Balmer H{alpha} line in emerging active regions that are called Ellerman bombs. Simultaneous sampling of Ca II 8542 A with the SST confirms that most Ellerman bombs also occur in the wings of this line, but with markedly different morphology. Simultaneous images from the Solar Dynamics Observatory (SDO) show that Ellerman bombs are also detectable in the photospheric 1700 A continuum, again with differing morphology. They are also observable in 1600 A SDO images, but with much contamination from C IV emission in transition-region features. Simultaneous SST spectropolarimetry in Fe I 6301 A shows that Ellerman bombs occur at sites of strong-field magnetic flux cancellation between small bipolar strong-field patches that rapidly move together over the solar surface. Simultaneous SDO images in He II 304 A, Fe IX 171 A, and Fe XIV 211 A show no clear effect of the Ellerman bombs on the overlying transition region and corona. These results strengthen our earlier suggestion, based on H{alpha} morphology alone, that the Ellerman bomb phenomenon is a purely photospheric reconnection phenomenon.

THE REDSHIFT EVOLUTION OF OXYGEN AND NITROGEN ABUNDANCES IN EMISSION-LINE SDSS GALAXIES

International Nuclear Information System (INIS)

Thuan, Trinh X.; Pilyugin, Leonid S.; Zinchenko, Igor A.

2010-01-01

The oxygen and nitrogen abundance evolutions with redshift and galaxy stellar mass in emission-line galaxies from the Sloan Digital Sky Survey (SDSS) are investigated. This is the first such study for nitrogen abundances, and it provides an additional constraint for the study of the chemical evolution of galaxies. We have devised a criterion to recognize and exclude from consideration active galactic nuclei and star-forming galaxies with large errors in the line flux measurements. To select star-forming galaxies with accurate line fluxes measurements, we require that, for each galaxy, the nitrogen abundances derived with various calibrations based on different emission lines agree. Using this selection criterion, subsamples of star-forming SDSS galaxies have been extracted from catalogs of the Max-Planck-Institute for Astrophysics/Johns Hopkins University group. We found that the galaxies of highest masses, those with masses ∼>10 11.2 M sun , have not been enriched in both oxygen and nitrogen over the last ∼3 Gyr: they have formed their stars in the so distant past that these have returned their nucleosynthesis products to the interstellar medium before z = 0.25. The galaxies in the mass range from ∼10 11.0 M sun to ∼10 11.2 M sun do not show an appreciable enrichment in oxygen, but do show some enrichment in nitrogen: they also formed their stars before z = 0.25 but later in comparison to the galaxies of highest masses; these stars have not returned nitrogen to the interstellar medium before z = 0.25 because they have not had enough time to evolve. This suggests that stars with lifetimes of 2-3 Gyr, in the 1.5-2 M sun mass range, contribute to the nitrogen production. Finally, galaxies with masses ∼ 11 M sun show enrichment in both oxygen and nitrogen during the last 3 Gyr: they have undergone appreciable star formation and have converted up to ∼20% of their mass into stars over this period. Both oxygen and nitrogen enrichments increase with decreasing

Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

Energy Technology Data Exchange (ETDEWEB)

Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc' h, Émeric; Pannella, Maurilio; Schreiber, Corentin [CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Charlot, Stéphane; Lehnert, M. D.; Pacifici, Camilla [UPMC-CNRS, UMR 7095, Institut d' Astrophysique de Paris, F-75014 Paris (France); Trump, Jonathan R. [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Brinchmann, Jarle [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Dickinson, Mark, E-mail: stephanie.juneau@cea.fr [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2014-06-10

Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

International Nuclear Information System (INIS)

Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Pannella, Maurilio; Schreiber, Corentin; Charlot, Stéphane; Lehnert, M. D.; Pacifici, Camilla; Trump, Jonathan R.; Brinchmann, Jarle; Dickinson, Mark

2014-01-01

Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

Science.gov (United States)

Arnold, N. D.; Attig, J.; Banks, G.; Bechtold, R.; Beczek, K.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Biggs, J. A.; Borland, M.; Boerste, K.; Bosek, M.; Brzowski, W. R.; Budz, J.; Carwardine, J. A.; Castro, P.; Chae, Y.-C.; Christensen, S.; Clark, C.; Conde, M.; Crosbie, E. A.; Decker, G. A.; Dejus, R. J.; DeLeon, H.; Den Hartog, P. K.; Deriy, B. N.; Dohan, D.; Dombrowski, P.; Donkers, D.; Doose, C. L.; Dortwegt, R. J.; Edwards, G. A.; Eidelman, Y.; Erdmann, M. J.; Error, J.; Ferry, R.; Flood, R.; Forrestal, J.; Freund, H.; Friedsam, H.; Gagliano, J.; Gai, W.; Galayda, J. N.; Gerig, R.; Gilmore, R. L.; Gluskin, E.; Goeppner, G. A.; Goetzen, J.; Gold, C.; Gorski, A. J.; Grelick, A. E.; Hahne, M. W.; Hanuska, S.; Harkay, K. C.; Harris, G.; Hillman, A. L.; Hogrefe, R.; Hoyt, J.; Huang, Z.; Jagger, J. M.; Jansma, W. G.; Jaski, M.; Jones, S. J.; Keane, R. T.; Kelly, A. L.; Keyser, C.; Kim, K.-J.; Kim, S. H.; Kirshenbaum, M.; Klick, J. H.; Knoerzer, K.; Koldenhoven, R. J.; Knott, M.; Labuda, S.; Laird, R.; Lang, J.; Lenkszus, F.; Lessner, E. S.; Lewellen, J. W.; Li, Y.; Lill, R. M.; Lumpkin, A. H.; Makarov, O. A.; Markovich, G. M.; McDowell, M.; McDowell, W. P.; McNamara, P. E.; Meier, T.; Meyer, D.; Michalek, W.; Milton, S. V.; Moe, H.; Moog, E. R.; Morrison, L.; Nassiri, A.; Noonan, J. R.; Otto, R.; Pace, J.; Pasky, S. J.; Penicka, J. M.; Pietryla, A. F.; Pile, G.; Pitts, C.; Power, J.; Powers, T.; Putnam, C. C.; Puttkammer, A. J.; Reigle, D.; Reigle, L.; Ronzhin, D.; Rotela, E. R.; Russell, E. F.; Sajaev, V.; Sarkar, S.; Scapino, J. C.; Schroeder, K.; Seglem, R. A.; Sereno, N. S.; Sharma, S. K.; Sidarous, J. F.; Singh, O.; Smith, T. L.; Soliday, R.; Sprau, G. A.; Stein, S. J.; Stejskal, B.; Svirtun, V.; Teng, L. C.; Theres, E.; Thompson, K.; Tieman, B. J.; Torres, J. A.; Trakhtenberg, E. M.; Travish, G.; Trento, G. F.; Vacca, J.; Vasserman, I. B.; Vinokurov, N. A.; Walters, D. R.; Wang, J.; Wang, X. J.; Warren, J.; Wesling, S.; Weyer, D. L.; Wiemerslage, G.; Wilhelmi, K.; Wright, R.; Wyncott, D.; Xu, S.; Yang, B.-X.; Yoder, W.; Zabel, R. B.

2001-12-01

Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

CERN Document Server

Arnold, N D; Banks, G; Bechtold, R; Beczek, K; Benson, C; Berg, S; Berg, W; Biedron, S G; Biggs, J A; Boerste, K; Borland, M; Bosek, M; Brzowski, W R; Budz, J; Carwardine, J A; Castro, P; Chae, Y C; Christensen, S; Clark, C; Conde, M; Crosbie, E A; Decker, G A; Dejus, Roger J; Deleon, H; Den Hartog, P K; Deriy, B N; Dohan, D; Dombrowski, P; Donkers, D; Doose, C L; Dortwegt, R J; Edwards, G A; Eidelman, Y; Erdmann, M J; Error, J J; Ferry, R; Flood, R; Forrestal, J; Freund, H; Friedsam, H; Gagliano, J; Gai, W; Galayda, J N; Gerig, R; Gilmore, R L; Gluskin, E; Goeppner, G A; Goetzen, J; Gold, C; Grelick, A E; Hahne, M W; Hanuska, S; Harkay, K C; Harris, G; Hillman, A L; Hogrefe, R; Hoyt, J; Huang, Z; Jagger, J M; Jansma, W G; Jaski, M; Jones, S J; Keane, R T; Kelly, A L; Keyser, C; Kim, K J; Kim, S H; Kirshenbaum, M; Klick, J H; Knoerzer, K; Knott, M; Koldenhoven, R J; Labuda, S; Laird, R; Lang, J; Lenkszus, F R; Lessner, E S; Lewellen, J W; Li, Y; Lill, R M; Lumpkin, Alex H; Makarov, O A; Markovich, G M; McDowell, M; McDowell, W P; McNamara, P E; Meier, T; Meyer, D; Michalek, W; Milton, S V; Moe, H; Moog, E; Morrison, L; Nassiri, A; Noonan, J R; Otto, R; Pace, J; Pasky, S J; Penicka, J M; Pietryla, A F; Pile, G; Pitts, C; Power, J; Powers, T; Putnam, C C; Puttkammer, A J; Reigle, D; Reigle, L; Ronzhin, D; Rotela, E R; Russell, E F; Sajaev, Vadim; Sarkar, S; Scapino, J C; Schröder, K; Seglem, R A; Sereno, N S; Sharma, S K; Sidarous, J F; Singh, O; Smith, T L; Soliday, R; Sprau, G A; Stein, S J; Stejskal, B; Svirtun, V; Teng, L C; Theres, E; Thompson, K; Tieman, B J; Torres, J A; Trakhtenberg, E; Travish, G; Trento, G F; Vacca, J; Vasserman, I B; Vinokurov, N A; Walters, D R; Wang, J; Wang, X J; Warren, J; Wesling, S; Weyer, D L; Wiemerslage, G; Wilhelmi, K; Wright, R; Wyncott, D; Xu, S; Yang, B X; Yoder, W; Zabel, R B

2001-01-01

Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

VARIABILITY OF THE SiO THERMAL LINE EMISSION TOWARD THE YOUNG L1448-mm OUTFLOW

International Nuclear Information System (INIS)

Jimenez-Serra, I.; MartIn-Pintado, J.; RodrIguez-Franco, A.; Winters, J.-M.; Caselli, P.

2011-01-01

The detection of narrow SiO thermal emission toward young outflows has been proposed to be a signature of the magnetic precursor of C-shocks. Recent modeling of the SiO emission across C-shocks predicts variations in the SiO line intensity and line shape at the precursor and intermediate-velocity regimes in only a few years. We present high angular resolution (3.''8 x 3.''3) images of the thermal SiO J = 2→1 emission toward the L1448-mm outflow in two epochs (2004 November-2005 February, 2009 March-April). Several SiO condensations have appeared at intermediate velocities (20-50 km s -1 ) toward the redshifted lobe of the outflow since 2005. Toward one of the condensations (clump D), systematic differences of the dirty beams between 2005 and 2009 could be responsible for the SiO variability. At higher velocities (50-80 km s -1 ), SiO could also have experienced changes in its intensity. We propose that the SiO variability toward L1448-mm is due to a real SiO enhancement by young C-shocks at the internal working surface between the jet and the ambient gas. For the precursor regime (5.2-9.2 km s -1 ), several narrow and faint SiO components are detected. The narrow SiO components tend to be compact, transient and show elongated (bow-shock) morphologies perpendicular to the jet. We speculate that these features are associated with the precursor of C-shocks appearing at the interface of the new SiO components seen at intermediate velocities.

Coronal Physics and the Chandra Emission Line Project

Science.gov (United States)

Brickhouse, N. S.; Drake, J. J.

2000-01-01

With the launch of the Chandra X-ray Observatory, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources Capella, Procyon, and HR 1099 are providing not only invaluable calibration data, but also benchmarks for plasma spectral models. These models are needed to interpret data from stellar coronae, galaxies and clusters of galaxies, supernova, remnants and other astrophysical sources. They have been called into question in recent years as problems with understanding low resolution ASCA and moderate resolution Extreme Ultraviolet Explorer Satellite (EUVE) data have arisen. The Emission Line Project is a collaborative effort, to improve the models, with Phase I being the comparison of models with observed spectra of Capella, Procyon, and HR 1099. Goals of these comparisons are (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. A critical issue in exploiting the coronal data for these purposes is to understand the extent, to which common simplifying assumptions (coronal equilibrium, negligible optical depth) apply. We will discuss recent, advances in our understanding of stellar coronae, in this context.

New observations and models of circumstellar CO line emission of AGB stars in the Herschel SUCCESS programme

Science.gov (United States)

Danilovich, T.; Teyssier, D.; Justtanont, K.; Olofsson, H.; Cerrigone, L.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Castro-Carrizo, A.; García-Lario, P.; Marston, A.

2015-09-01

Context. Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy elements and dust grains for the interstellar medium. The mass-loss rate can be well traced by carbon monoxide (CO) line emission. Aims: We present new Herschel/HIFI and IRAM 30 m telescope CO line data for a sample of 53 galactic AGB stars. The lines cover a fairly large range of excitation energy from the J = 1 → 0 line to the J = 9 → 8 line, and even the J = 14 → 13 line in a few cases. We perform radiative transfer modelling for 38 of these sources to estimate their mass-loss rates. Methods: We used a radiative transfer code based on the Monte Carlo method to model the CO line emission. We assume spherically symmetric circumstellar envelopes that are formed by a constant mass-loss rate through a smoothly accelerating wind. Results: We find models that are consistent across a broad range of CO lines for most of the stars in our sample, i.e., a large number of the circumstellar envelopes can be described with a constant mass-loss rate. We also find that an accelerating wind is required to fit, in particular, the higher-J lines and that a velocity law will have a significant effect on the model line intensities. The results cover a wide range of mass-loss rates (~10-8 to 2 × 10-5 M⊙ yr-1) and gas expansion velocities (2 to 21.5 km s-1) , and include M-, S-, and C-type AGB stars. Our results generally agree with those of earlier studies, although we tend to find slightly lower mass-loss rates by about 40%, on average. We also present "bonus" lines detected during our CO observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Based on observations carried out with the IRAM 30 m Telescope. IRAM is

THE HERSCHEL COMPREHENSIVE (U)LIRG EMISSION SURVEY (HERCULES): CO LADDERS, FINE STRUCTURE LINES, AND NEUTRAL GAS COOLING

Energy Technology Data Exchange (ETDEWEB)

Rosenberg, M. J. F.; Van der Werf, P. P.; Israel, F. P.; Meijerink, R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Aalto, S. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-43994 Onsala (Sweden); Armus, L.; Díaz-Santos, T. [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Charmandaris, V. [Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, P. Penteli, 15236 Athens (Greece); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Ave SW, Washington, DC 20375 (United States); Gao, Y. [Purple Mountain Observatory, Chinese Academy of Sciences (CAS), 2 West Beijing Road, Nanjing 210008 (China); González-Alfonso, E. [Departamento de Fsica y Matemáticas, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Harris, A. I. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Henkel, C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 16, Bonn, D-53121 (Germany); Isaak, K. G. [Scientific Support Office, ESTEC/SRE-S, Keplerlaan 1, NL-2201 AZ Noordwijk (Netherlands); Kramer, C., E-mail: rosenberg@strw.leidenuniv.nl [Instituto Radioastronomía Milimétrica (IRAM), Av. Divina Pastora 7, Nucleo Central, E-18012 Granada (Spain); and others

2015-03-10

(Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 μm) luminosities (L {sub LIRG} > 10{sup 11} L {sub ☉} and L {sub ULIRG} > 10{sup 12} L {sub ☉}). The Herschel Comprehensive ULIRG Emission Survey (PI: van der Werf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (10{sup 11} L {sub ☉} ≤ L {sub IR} ≤ 10{sup 13} L {sub ☉}). With the Herschel Space Observatory, we observe [C II] 157 μm, [O I] 63 μm, and [O I] 145 μm line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 μm, and [C I] 609 μm with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 μm emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 μm ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 ≤ J {sub upp} ≤ 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important.

Autoionization spectral line shapes in dense plasmas

International Nuclear Information System (INIS)

Rosmej, F.B.; Hoffmann, D.H.H.; Faenov, A.Ya.; Pikuz, T.A.; Suess, W.; Geissel, M.

2001-01-01

The distortion of resonance line shapes due to the accumulation of a large number of satellite transitions is discovered by means of X-ray optical methods with simultaneous high spectral (λ/δλ≅8000) and spatial resolution (δx≅7 μm). Disappearance of the He α resonance line emission near the target surface is observed while Rydberg satellite intensity accumulates near the resonance line position. He β and He γ resonance line shapes are also shown to be seriously affected by opacity, higher-order line emissions from autoionizing states and inhomogeneous spatial emission. Opposite to resonance line emissions the He β satellites originate only from a very narrow spatial interval. New temperature and density diagnostics employing the 1s2131' and 1s3131'-satellites are developed. Moreover, even-J components of the satellite line emissions were resolved in the present high resolution experiments. Line transitions from the autoionizing states 1s2131' are therefore also proposed for space resolved Stark broadening analysis and local high density probing. Theorists are encouraged to provide accurate Stark broadening data for the transitions 1s2131 ' →1s 2 21+hv

ALMA INVESTIGATION OF VIBRATIONALLY EXCITED HCN/HCO{sup +}/HNC EMISSION LINES IN THE AGN-HOSTING ULTRALUMINOUS INFRARED GALAXY IRAS 20551−4250

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

2016-07-01

We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551−4250 at HCN/HCO{sup +}/HNC J = 3–2 lines at both vibrational ground ( v = 0) and vibrationally excited ( v {sub 2} = 1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v {sub 2} = 1f J = 4–3 emission line. In our ALMA Cycle 2 data, the HCN/HCO{sup +}/HNC J = 3–2 emission lines at v = 0 are clearly detected. The HCN and HNC v {sub 2} = 1f J = 3–2 emission lines are also detected, but the HCO{sup +} v {sub 2} = 1f J = 3–2 emission line is not. Given the high energy level of v {sub 2} = 1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5–35 μ m spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO{sup +} and HNC. The flux ratio and excitation temperature between v {sub 2} = 1f and v = 0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational ( J -level) excitation at v = 0 at least for HCN and HNC. The HCN-to-HCO{sup +} v = 0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO{sup +} flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO{sup +} abundance ratio and sufficient HCN excitation at up to J = 4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO{sup +}.

VUV emission spectra from binary rare gas mixtures near the resonance lines of Xe I and Kr I

CERN Document Server

Morozov, A; Gerasimov, G; Arnesen, A; Hallin, R

2003-01-01

Emission spectra of Xe-X (X = He, Ne, Ar and Kr) and of Kr-Y (Y = He, Ne and Ar) mixtures with low concentrations of the heavier gases (0.1-1%) and moderate total pressures (50-200 hPa) have been recorded near each of the two resonance lines of Xe and Kr in DC glow capillary discharges. The recorded intense emissions have narrow spectral profiles with FWHM of about 0.1 nm. The profiles are very similar in shape to profiles of known high resolution absorption spectra recorded at comparable gas pressures. A tentative identification of the emission structures is given, which involves transitions in heteronuclear molecules and quasimolecules between weakly-bound states.

40 CFR Table 12 to Subpart Wwww of... - Data Requirements for New and Existing Continuous Lamination Lines and Continuous Casting Lines...

Science.gov (United States)

2010-07-01

... Continuous Lamination Lines and Continuous Casting Lines Complying With a Lbs/Ton Organic HAP Emissions Limit... Requirements for New and Existing Continuous Lamination Lines and Continuous Casting Lines Complying With a Lbs... with a lbs/ton organic HAP emissions limit for continuous lamination lines and continuous casting lines...

A new beam emission polarimetry diagnostic for measuring the magnetic field line angle at the plasma edge of ASDEX Upgrade.

Science.gov (United States)

Viezzer, E; Dux, R; Dunne, M G

2016-11-01

A new edge beam emission polarimetry diagnostic dedicated to the measurement of the magnetic field line angle has been installed on the ASDEX Upgrade tokamak. The new diagnostic relies on the motional Stark effect and is based on the simultaneous measurement of the polarization direction of the linearly polarized π (parallel to the electric field) and σ (perpendicular to the electric field) lines of the Balmer line D α . The technical properties of the system are described. The calibration procedures are discussed and first measurements are presented.

Luminosity-velocity diagrams for Virgo Cluster spirals. I - Inner rotation curves

Science.gov (United States)

Woods, David; Fahlman, Gregory G.; Madore, Barry F.

1990-01-01

Optical rotation curves are presented for the innermost portions of nine spiral galaxies in the Virgo Cluster. The emission-line (H-alpha and forbidden N II) velocity data are to be used in combination with new CCD photometry to construct luminosity-velocity diagrams, in a continuing investigation of an apparent initial linear branch and its potential as a distance indicator. Compared to recent H I data, the present optical rotation curves generally show systematically steeper inner gradients. This effect is ascribed to the poorer resolution of the H I data and/or to holes in the gas distribution.

A line-of-sight electron cyclotron emission receiver for electron cyclotron resonance heating feedback control of tearing modes

DEFF Research Database (Denmark)

Oosterbeek, J.W.; Bürger, A.; Westerhof, E.

2008-01-01

An electron cyclotron emission (ECE) receiver inside the electron cyclotron resonance heating (ECRH) transmission line has been brought into operation. The ECE is extracted by placing a quartz plate acting as a Fabry-Perot interferometer under an angle inside the electron cyclotron wave (ECW) bea...

High-resolution H-band spectroscopy of Be stars with SDSS-III/apogee. I. New Be stars, line identifications, and line profiles

International Nuclear Information System (INIS)

Chojnowski, S. Drew; Majewski, Steven R.; Hall, Matthew; Beaton, Rachael; Burton, Adam; Damke, Guillermo; Wilson, John; Whelan, David G.; Wisniewski, John P.; Shetrone, Matthew; Eikenberry, Steve; Hasselquist, Sten; Holtzman, Jon A.; Brewington, Howard; Brinkmann, J.; Mészáros, Szabolcs; Nidever, David; Schneider, Donald P.; Zasowski, Gail; Bizyaev, Dmitry

2015-01-01

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has amassed the largest ever collection of multi-epoch, high-resolution (R∼22,500), H-band spectra for B-type emission line (Be) stars. These stars were targeted by APOGEE as telluric standard stars and subsequently identified via visual inspection as Be stars based on H i Brackett series emission or shell absorption in addition to otherwise smooth continua and occasionally non-hydrogen emission features. The 128/238 APOGEE Be stars for which emission had never previously been reported serve to increase the total number of known Be stars by ∼6%. Because the H band is relatively unexplored compared to other wavelength regimes, we focus here on identification of the H-band lines and analysis of the emission peak velocity separations (Δv p ) and emission peak intensity ratios (V/R) of the usually double-peaked H i and non-hydrogen emission lines. H i Br11 emission is found to preferentially form in the circumstellar disks at an average distance of ∼2.2 stellar radii. Increasing Δv p toward the weaker Br12–Br20 lines suggests these lines are formed interior to Br11. By contrast, the observed IR Fe ii emission lines present evidence of having significantly larger formation radii; distinctive phase lags between IR Fe ii and H i Brackett emission lines further supports that these species arise from different radii in Be disks. Several emission lines have been identified for the first time including C i 16895, a prominent feature in the spectra for almost a fifth of the sample and, as inferred from relatively large Δv p compared to the Br11–Br20, a tracer of the inner regions of Be disks. Emission lines at 15760 Å and 16781 Å remain unidentified, but usually appear along with and always have similar line profile morphology to Fe ii 16878. Unlike the typical metallic lines observed for Be stars in the optical, the H-band metallic lines, such as Fe ii 16878, never exhibit any evidence of

WEAK LINE QUASARS AT HIGH REDSHIFT: EXTREMELY HIGH ACCRETION RATES OR ANEMIC BROAD-LINE REGIONS?

International Nuclear Information System (INIS)

Shemmer, Ohad; Trakhtenbrot, Benny; Netzer, Hagai; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Lira, Paulina; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

2010-01-01

We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDSS J114153.34+021924.3 at z = 3.55 and SDSS J123743.08+630144.9 at z = 3.49. In both sources, we detect an unusually weak broad Hβ line and place tight upper limits on the strengths of their [O III] lines. Virial, Hβ-based black hole mass determinations indicate normalized accretion rates of L/L Edd =0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of Γ = 1.91 +0.24 -0.22 , which supports the virial L/L Edd determination in this source. Our results suggest that the weakness of the broad emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad emission line region properties.

AN UNBIASED 1.3 mm EMISSION LINE SURVEY OF THE PROTOPLANETARY DISK ORBITING LkCa 15

Energy Technology Data Exchange (ETDEWEB)

Punzi, K. M.; Kastner, J. H. [Center for Imaging Science, School of Physics and Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Hily-Blant, P.; Forveille, T. [UJF—Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, F-38041, Grenoble (France); Sacco, G. G. [INAF—Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze (Italy)

2015-06-01

The outer (>30 AU) regions of the dusty circumstellar disk orbiting the ∼2–5 Myr old, actively accreting solar analog LkCa 15 are known to be chemically rich, and the inner disk may host a young protoplanet within its central cavity. To obtain a complete census of the brightest molecular line emission emanating from the LkCa 15 disk over the 210–270 GHz (1.4–1.1 mm) range, we have conducted an unbiased radio spectroscopic survey with the Institute de Radioastronomie Millimétrique (IRAM) 30 m telescope. The survey demonstrates that in this spectral region, the most readily detectable lines are those of CO and its isotopologues {sup 13}CO and C{sup 18}O, as well as HCO{sup +}, HCN, CN, C{sub 2}H, CS, and H{sub 2}CO. All of these species had been previously detected in the LkCa 15 disk; however, the present survey includes the first complete coverage of the CN (2–1) and C{sub 2}H (3–2) hyperfine complexes. Modeling of these emission complexes indicates that the CN and C{sub 2}H either reside in the coldest regions of the disk or are subthermally excited, and that their abundances are enhanced relative to molecular clouds and young stellar object environments. These results highlight the value of unbiased single-dish line surveys in guiding future high-resolution interferometric imaging of disks.

EVOLUTION AND HYDRODYNAMICS OF THE VERY BROAD X-RAY LINE EMISSION IN SN 1987A

Energy Technology Data Exchange (ETDEWEB)

Dewey, D.; Canizares, C. R. [MIT Kavli Institute, Cambridge, MA 02139 (United States); Dwarkadas, V. V. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Haberl, F.; Sturm, R., E-mail: dd@space.mit.edu, E-mail: vikram@oddjob.uchicago.edu [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Garching D-85748 (Germany)

2012-06-20

Observations of SN 1987A by the Chandra High Energy Transmission Grating (HETG) in 1999 and the XMM-Newton Reflection Grating Spectrometer (RGS) in 2003 show very broad (v-b) lines with a full width at half-maximum (FWHM) of order 10{sup 4} km s{sup -1}; at these times the blast wave (BW) was primarily interacting with the H II region around the progenitor. Since then, the X-ray emission has been increasingly dominated by narrower components as the BW encounters dense equatorial ring (ER) material. Even so, continuing v-b emission is seen in the grating spectra suggesting that the interaction with H II region material is ongoing. Based on the deep HETG 2007 and 2011 data sets, and confirmed by RGS and other HETG observations, the v-b component has a width of 9300 {+-} 2000 km s{sup -1} FWHM and contributes of order 20% of the current 0.5-2 keV flux. Guided by this result, SN 1987A's X-ray spectra are modeled as the weighted sum of the non-equilibrium-ionization emission from two simple one-dimensional hydrodynamic simulations; this '2 Multiplication-Sign 1D' model reproduces the observed radii, light curves, and spectra with a minimum of free parameters. The interaction with the H II region ({rho}{sub init} Almost-Equal-To 130 amu cm{sup -3}, {+-} 15 Degree-Sign opening angle) produces the very broad emission lines and most of the 3-10 keV flux. Our ER hydrodynamics, admittedly a crude approximation to the multi-D reality, gives ER densities of {approx}10{sup 4} amu cm{sup -3}, requires dense clumps ( Multiplication-Sign 5.5 density enhancement in {approx}30% of the volume), and predicts that the 0.5-2 keV flux will drop at a rate of {approx}17% per year once no new dense ER material is being shocked.

Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants

NARCIS (Netherlands)

Hankemeier, Th.; Rozenbrand, J.; Abhadur, M.; Vreuls, J.J.; Brinkman, U.A.Th.

1998-01-01

A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC

Studying the complex spectral line profiles in the spectra of hot emission stars and quasars .

Science.gov (United States)

Danezis, E.; Lyratzi, E.; Antoniou, A.; Popović, L. Č.; Dimitrijević, M. S.

Some Hot Emission Stars and AGNs present peculiar spectral line profiles which are due to DACs and SACs phenomena. The origin and the mechanisms which are responsible for the creation of DACs/SACs is an important problem that has been studied by many researchers. This paper is a review of our efforts to study the origin and the mechanisms of these phenomena. At first we present a theoretic ad hoc picture for the structure of the plasma that surrounds the specific category of hot emission stars that present DACs or SACs. Then we present the mathematical model that we constructed, which is based on the properties of the above ad hoc theoretical structure. Finally, we present some results from our statistical studies that prove the consistency of our model with the classical physical theory.

On the Calculation of the Fe K-alpha Line Emissivity of Black Hole Accretion Disks

Energy Technology Data Exchange (ETDEWEB)

Krawczynski, H.; Beheshtipour, B., E-mail: krawcz@wustl.edu [Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, 1 Brookings Drive, CB 1105, St. Louis, MO 63130 (United States)

2017-11-01

Observations of the fluorescent Fe K α emission line from the inner accretion flows of stellar mass black holes in X-ray binaries and supermassive black holes in active galactic nuclei have become an important tool to study the magnitude and inclination of the black hole spin, and the structure of the accretion flow close to the event horizon of the black hole. Modeling spectral, timing, and soon also X-ray polarimetric observations of the Fe K α emission requires the calculation of the specific intensity in the rest frame of the emitting plasma. We revisit the derivation of the equation used for calculating the illumination of the accretion disk by the corona. We present an alternative derivation leading to a simpler equation, and discuss the relation to previously published results.

Infrared Space Observatory Observations of Far-Infrared Rotational Emission Lines of Water Vapor toward the Supergiant Star VY Canis Majoris

Science.gov (United States)

Neufeld, David A.; Feuchtgruber, Helmut; Harwit, Martin; Melnick, Gary J.

1999-06-01

We report the detection of numerous far-infrared emission lines of water vapor toward the supergiant star VY Canis Majoris. A 29.5-45 μm grating scan of VY CMa, obtained using the Short-Wavelength Spectrometer (SWS) of the Infrared Space Observatory at a spectral resolving power λ/Δλ of ~2000, reveals at least 41 spectral features due to water vapor that together radiate a total luminosity of ~25 Lsolar. In addition to pure rotational transitions within the ground vibrational state, these features include rotational transitions within the (010) excited vibrational state. The spectrum also shows the 2Π1/2(J=5/2)VY CMa were carried out in the instrument's Fabry-Perot mode for three water transitions: the 725-616 line at 29.8367 μm, the 441-312 line at 31.7721 μm, and the 432-303 line at 40.6909 μm. The higher spectral resolving power λ/Δλ of approximately 30,000 thereby obtained permits the line profiles to be resolved spectrally for the first time and reveals the ``P Cygni'' profiles that are characteristic of emission from an outflowing envelope. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the UK) with the participation of ISAS and NASA.

Orbit of the HDE 245770 system

International Nuclear Information System (INIS)

Aab, O.E.

1984-01-01

Spectroscopic observations of HDE 245770, the optical counterpart of the X-ray source A0535 + 26, obtained at 350-700 nm with dispersion 9, 14, or 28 A/mm using a 600-mm-focal-length camera on the main stellar spectrograph of the 6-m telescope of the Special Astrophysical Observatory at Nizhni Arkhyz during 1979-1981 are reported. The data are used to calculate radial velocities and orbital parameters based on both absorption and emission lines, and the results are compared in tables and graphs. In absorption, the system is found to have best-fit parameters P = about 35 d, K = about 35 km/s, V0 = about -5 km/s, e = 0.2, and f(M) = 0.15 solar mass. For P = 35 d, the emission-line velocities lead to unrealistic mass functions and e values of 0.6 for H-beta and 0.7 for H-alpha, indicating that these velocities are not associated with the (Be) optical component of the system. 15 references

A Solar-Pumped Fluorescence Model for Line-By-Line Emission Intensities in the B-X, A-X, and X-X Band Systems of 12C14N

Science.gov (United States)

Paganini, L.; Mumma, M. J.

2016-01-01

We present a new quantitative model for detailed solar-pumped fluorescent emission of the main isotopologue of CN. The derived fluorescence efficiencies permit estimation and interpretation of ro-vibrational infrared line intensities of CN in exospheres exposed to solar (or stellar) radiation. Our g-factors are applicable to astronomical observations of CN extending from infrared to optical wavelengths, and we compare them with previous calculations in the literature. The new model enables extraction of rotational temperature, column abundance, and production rate from astronomical observations of CN in the inner coma of comets. Our model accounts for excitation and de-excitation of rotational levels in the ground vibrational state by collisions, solar excitation to the A(sup 2)Pi(sub I) and B(sup 2)Sum(sup +) electronically excited states followed by cascade to ro-vibrational levels of X(sup 2)Sum(sup +), and direct solar infrared pumping of ro-vibrational levels in the X(sup 2)Sum(sup +) state. The model uses advanced solar spectra acquired at high spectral resolution at the relevant infrared and optical wavelengths and considers the heliocentric radial velocity of the comet (the Swings effect) when assessing the exciting solar flux for a given transition. We present model predictions for the variation of fluorescence rates with rotational temperature and heliocentric radial velocity. Furthermore, we test our fluorescence model by comparing predicted and measured line-by-line intensities for X(sup 2)Sum(sup +) (1-0) in comet C/2014 Q2 (Lovejoy), thereby identifying multiple emission lines observed at IR wavelengths.

Transition probabilities for lines of Cr II, Na II and Sb I by laser produced plasma atomic emission spectroscopy

International Nuclear Information System (INIS)

Gonzalez, A. M.; Ortiz, M.; Campos, J.

1995-01-01

Absolute transition probabilities for lines of CR II, Na II and Sb I were determined by emission spectroscopy of laser induced plasmas. the plasma was produced focusing the emission of a pulsed Nd-Yag laser on solid samples containing the atom in study. the light arising from the plasma region was collected by and spectrometer. the detector used was a time-resolved optical multichannel analyzer (OMA III EG and G). The wavelengths of the measured transitions range from 2000 sto 4100 A. The spectral resolution of the system was 0. 2 A. The method can be used in insulators materials as Cl Na crystals and in metallic samples as Al-Cr and Sn-Sn alloys. to avoid self-absorption effects the alloys were made with low Sb or Cr content. Relative transition probabilities have been determined from measurements of emission-line intensities and were placed on an absolute scale by using, where possible, accurate experimental lifetime values form the literature or theoretical data. From these measurements, values for plasma temperature (8000-24000 K), electron densities (∼∼ 10''16 cm ''-3) and self-absorption coefficients have been obtained. (Author) 56 refs

Transition probabilities for lines of Cr II, Na II and Sb I by laser produced plasma atomic emission spectroscopy

International Nuclear Information System (INIS)

Gonzalez, A.M.; Ortiz, M.; Campos, J.

1995-09-01

Absolute transition probabilities for lines of Cr II, Na II and Sb I were determined by emission spectroscopy of laser induced plasmas. The plasma was produced focusing the emission of a pulsed Nd-Yag laser on solid samples containing the atom in study. The light arising from the plasma region was collected by and spectrometer. the detector used was a time-resolved optical multichannel analyzer (OMA III EG and G). The wavelengths of the measured transitions range from 2000 to 4100 A. The spectral resolution of the system was 0.2 A. The method can be used in insulators materials as Cl Na crystals and in metallic samples as Al-Cr and Sn-Sb alloys. To avoid self-absorption effects the alloys were made with low Sb or Cr content. Relative transition probabilities have been determined from measurements of emission-line intensities and were placed on an absolute scale by using, where possible, accurate experimental lifetime values form the literature or theoretical data. From these measurements, values for plasma temperature (8000-24000K), electron densities (approx 10 ''16 cm''-3) and self-absorption coefficients have been obtained

X-ray spectral models of Galactic bulge sources - the emission-line factor

International Nuclear Information System (INIS)

Vrtilek, S.D.; Swank, J.H.; Kallman, T.R.

1988-01-01

Current difficulties in finding unique and physically meaningful models for the X-ray spectra of Galactic bulge sources are exacerbated by the presence of strong, variable emission and absorption features that are not resolved by the instruments observing them. Nine Einstein solid state spectrometer (SSS) observations of five Galactic bulge sources are presented for which relatively high resolution objective grating spectrometer (OGS) data have been published. It is found that in every case the goodness of fit of simple models to SSS data is greatly improved by adding line features identified in the OGS that cannot be resolved by the SSS but nevertheless strongly influence the spectra observed by SSS. 32 references

Detection of binaries in the core of the globular cluster M15 using calcium emission lines

Energy Technology Data Exchange (ETDEWEB)

Murphy, B W [Rijksuniversiteit Utrecht (Netherlands). Inst. of Astronomy; Rutten, R G.M. [Astronomical Inst. ' Anton Pannekoek' , Amsterdam (Netherlands); Callanan, P J [Oxford Univ. (UK). Dept. of Astrophysics; Seitzer, Patrick [Space Telescope Science Inst., Baltimore, MD (USA); Charles, P A [Oxford Univ. (UK). Dept. of Astrophysics Observatorio del Roque do los Muchachos, Santa Cruz de La Palma, Tenerife, Canary Islands (Spain); Cohn, H N; Lugger, P M [Indiana Univ., Bloomington, IN (USA). Dept. of Astronomy

1991-05-09

M12 is the prototypical collapsed-core globular cluster. Having undergone collapse, its core is believed now to be expanding, with energy for the re-expansion provided by binary stars, which turn gravitational potential energy into kinetic energy. Because these binary stars are generally more massive than single stars, they will have settled to the centre of the cluster. We report here that several of the stars at the core of M15 show Ca II H- and K-line emission characteristic of young, rapidly rotating stars and close binaries. We argue that the emission from M15 comes from primordial binaries, in which a period of spin-up has led to magnetic field generation by enhanced dynamo action, which in turn causes heating of the stellar chromospheres. If this interpretation is correct, the Ca H and K emission may provide an important diagnostic tool of the binary population in cluster cores, and thus of the cluster dynamics. (author).

Detection of binaries in the core of the globular cluster M15 using calcium emission lines

International Nuclear Information System (INIS)

Murphy, B.W.; Callanan, P.J.; Charles, P.A.; Cohn, H.N.; Lugger, P.M.

1991-01-01

M12 is the prototypical collapsed-core globular cluster. Having undergone collapse, its core is believed now to be expanding, with energy for the re-expansion provided by binary stars, which turn gravitational potential energy into kinetic energy. Because these binary stars are generally more massive than single stars, they will have settled to the centre of the cluster. We report here that several of the stars at the core of M15 show Ca II H- and K-line emission characteristic of young, rapidly rotating stars and close binaries. We argue that the emission from M15 comes from primordial binaries, in which a period of spin-up has led to magnetic field generation by enhanced dynamo action, which in turn causes heating of the stellar chromospheres. If this interpretation is correct, the Ca H and K emission may provide an important diagnostic tool of the binary population in cluster cores, and thus of the cluster dynamics. (author)

ASPIICS: a giant, white light and emission line coronagraph for the ESA proba-3 formation flight mission

Science.gov (United States)

Lamy, P. L.; Vivès, S.; Curdt, W.; Damé, L.; Davila, J.; Defise, J.-M.; Fineschi, S.; Heinzel, P.; Howard, Russel; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Zhukov, A.

2017-11-01

Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observations of the white light corona inside typically 2-2.5 solar radii (Rsun). Formation flying offers and elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at a distance of hundred meters [1, 2]. Such an instrument ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire) has been selected by the European Space Agency (ESA) to fly on its PROBA-3 mission of formation flying demonstration which is presently in phase B (Fig. 1). The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.04 solar radii from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to reach the chromosphere and the upper part of the spicules [3]. ASPIICS will perform (i) high spatial resolution imaging of the continuum K+F corona in photometric and polarimetric modes, (ii) high spatial resolution imaging of the E-corona in two coronal emission lines (CEL): Fe XIV and He I D3, and (iii) two-dimensional spectrophotometry of the Fe XIV emission line. ASPIICS will address the question of the coronal heating and the role of waves by characterizing propagating fluctuations (waves and turbulence) in the solar wind acceleration region and by looking for oscillations in the intensity and Doppler shift of spectral lines. The combined imaging and spectral diagnostics capabilities available with ASPIICS will allow mapping the velocity field of the corona both in the

The influence of Stark shift and plasma inhomogeneity on half width of self-absorbed line profiles in the plasma emission spectrum

International Nuclear Information System (INIS)

Catsalap, K.Yu.; Ershov-Pavlov, E.A.

2005-01-01

Emission spectral line profiles are commonly used for the evaluation of local plasma parameters. The plasma parameters and local line profiles are related in a rather simple way: e.g. at quadratic Stark broadening, the local line half widths and shifts are proportional to the electron density. For homogeneous optically thin plasmas, there is no difference in the line profiles of plasma emission and emissivity spectra. However for inhomogeneous source, the profiles are different due to spatial dependence of electron density and plasma temperature: profiles in the plasma emission are a superposition of different local ones. A transition from the recorded to local profiles is usually performed by tomography techniques. As the result, the measurement procedure is getting slower and additional errors occurs. For transparent plasmas, an approach was developed to evaluate local profiles from as recorded spectra using relations found by modeling. However, for semi-transparent plasmas the relation between the recorded and local profiles is more complicated one. With the optical thickness t increase, profile half width Δλ in the plasma emission spectrum changes much comparing to the profile half width Δλ 0 in the spectrum of optically thin plasma. The ratio t h =Δλ/Δλ 0 on τ for dispersion profile and homogeneous plasma can be written as t h =(-1-τ/ln((1+e -τ )/2)) 1/2 . When Δλ and τ are known, the function allows obtaining Δλ 0 , i. e. reducing the problem to the transparent plasma diagnostics. However, the plasma is nearly always inhomogeneous and the value t depends significantly on plasma inhomogeneity and on Stark parameters ratio d/w. Here, the dependence t(τ) for plasmas of different inhomogeneity rates has been obtained by the numerical simulation. The radiation transfer equation has been solved to calculate the spectral line profiles for LTE-plasma of known composition and distribution of temperature along the observation line. The temperature

POLYCYCLIC AROMATIC HYDROCARBON AND EMISSION LINE RATIOS IN ACTIVE GALACTIC NUCLEI AND STARBURST GALAXIES

International Nuclear Information System (INIS)

Sales, Dinalva A.; Pastoriza, M. G.; Riffel, R.

2010-01-01

We study the polycyclic aromatic hydrocarbon (PAH) bands, ionic emission lines, and mid-infrared continuum properties in a sample of 171 emission line galaxies taken from the literature plus 15 new active galactic nucleus (AGN) Spitzer spectra. We normalize the spectra at λ = 23 μm and grouped them according to the type of nuclear activity. The continuum shape steeply rises for longer wavelengths and can be fitted with a warm blackbody distribution of T ∼ 150-300 K. The brightest PAH spectral bands (6.2, 7.7, 8.6, 11.3, and 12.7 μm) and the forbidden emission lines of [Si II] 34.8 μm, [Ar II] 6.9 μm, [S III] 18.7 and 33.4 μm were detected in all the starbursts and in ∼80% of the Seyfert 2. Taking under consideration only the PAH bands at 7.7 μm, 11.3 μm, and 12.7 μm, we find that they are present in ∼80% of the Seyfert 1, while only half of this type of activity show the 6.2 μm and 8.6 μm PAH bands. The observed intensity ratios for neutral and ionized PAHs (6.2 μm/7.7 μm x 11.3 μm/7.7 μm) were compared to theoretical intensity ratios, showing that AGNs have higher ionization fraction and larger PAH molecules (≥180 carbon atoms) than SB galaxies. The ratio between the ionized (7.7 μm) and the neutral PAH bands (8.6 μm and 11.3 μm) are distributed over different ranges for AGNs and SB galaxies, suggesting that these ratios could depend on the ionization fraction, as well as on the hardness of the radiation field. The ratio between the 7.7 μm and 11.3 μm bands is nearly constant with the increase of [Ne III]15.5 μm/[Ne II] 12.8 μm, indicating that the fraction of ionized to neutral PAH bands does not depend on the hardness of the radiation field. The equivalent width of both PAH features show the same dependence (strongly decreasing) with [Ne III]/[Ne II], suggesting that the PAH molecules, emitting either ionized (7.7 μm) or neutral (11.3 μm) bands, may be destroyed with the increase of the hardness of the radiation field.

Probing the accretion flow and emission-line regions of M81, the nearest broad-lined low-luminosity AGN

Science.gov (United States)

Barth, Aaron

2017-08-01

The nucleus of M81 is an object of singular importance as a template for low-luminosity accretion flows onto supermassive black holes. We propose to obtain a complete, small-aperture, high S/N STIS UV/optical spectrum of the M81 nucleus and multi-filter WFC3 imaging covering the UV through near-IR. Such data have never previously been obtained with HST; the only prior archival UV/optical spectra of M81 have low S/N, incomplete wavelength coverage, and are strongly contaminated by starlight. Combined with new Chandra X-ray data, our proposed observations will comprise the definitive reference dataset on the spectral energy distribution of this benchmark low-luminosity AGN. These data will provide unique new constraints on the possible contribution of a truncated thin accretion disk to the AGN emission spectrum, clarifying a fundamental property of low-luminosity accretion flows. The data will additionally provide new insights into broad-line region structure and black hole mass scaling relationships at the lowest AGN luminosities, and spatially resolved diagnostics of narrow-line region excitation conditions at unprecedented spatial resolution to assess the impact of the AGN on the ionization state of the gas in the host galaxy bulge.

Anisotropic electron velocity distribution in an ECR helium plasma as determined from polarization of emission lines

International Nuclear Information System (INIS)

Iwamae, A; Sato, T; Horimoto, Y; Inoue, K; Fujimoto, T; Uchida, M; Maekawa, T

2005-01-01

A helium plasma is produced by electron-cyclotron resonance heating in a cusp-configuration magnetic field. Several neutral helium lines are found polarized in the direction perpendicular to the magnetic field; the maximum polarization degree exceeds 10%. The polarization degree and intensity of the emission lines yield, respectively, the alignment and population of the upper levels. The population-alignment collisional-radiative model is developed, and the experimental result is interpreted in terms of an anisotropic electron velocity distribution; it is of a Saturn-type with the central thermal component of 14 eV and the 'ring' component displaced by 9.2 eV from the central component. The relative number of 'ring' electrons is 40%. (letter to the editor)

Investigations on burning efficiency and exhaust emission of in-line type emulsified fuel system

Energy Technology Data Exchange (ETDEWEB)

Tseng, Y.K. [National Chinyi University of Technology (Taiwan). Dept. of Mechanical Engineering; Cheng, H.C. [Point Environmental Protection Technology Company Limited (Taiwan)

2011-07-28

In this research, the burning efficiency as well as exhaust emission of a new water-in-oil emulsified fuel system was studied. This emulsified system contains two core processes, the first one is to mix 97% water with 3% emulsifier by volume, and get the milk-like emulsified liquid, while the second one is to compound the milk-like emulsified liquid with heavy oil then obtain the emulsified fuel. In order to overcome the used demulsification problem during in reserve or in transport, this system was designed as a made and use in-line type. From the results of a series of burning tests, the fuel saving can be 8--15%. Also, from the comparison of decline for the heat value and total energy output of emulsified fuel, one can find that the water as the dispersed phase in the combustion process will lead to a micro-explosion as well as the water gas effect, both can raise the combustion temperature and burning efficiency. By comparing the waste gas emission of different types of emulsified fuel, one can know that, the CO2 emission reduces approximately 14%, and NOx emission reduces above 46%, meaning the reduction of the exhaust gas is truly effective. From the exhaust temperature of tail pipe, the waste heat discharge also may reduce 27%, it is quite advantageous to the global warming as well as earth environmental protection.

Be discs in coplanar circular binaries: Phase-locked variations of emission lines

Science.gov (United States)

Panoglou, Despina; Faes, Daniel M.; Carciofi, Alex C.; Okazaki, Atsuo T.; Baade, Dietrich; Rivinius, Thomas; Borges Fernandes, Marcelo

2018-01-01

In this paper, we present the first results of radiative transfer calculations on decretion discs of binary Be stars. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and this can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Some orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way to identifying binaries and to constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star.

Heavy impurity transport in the TFR tokamak. Comparison of line emission with numerical simulations

International Nuclear Information System (INIS)

1982-10-01

Heavy element ion line emissions have been simulated with a numerical code using two adjustable, independent of radius, parameters in the flux density expression: an anomalous diffusion coefficient Dsub(A) and an inward convective velocity Vsub(A). Previously reported results on the laser blow-off injection of V, Cr, and Ni have thus been interpreted. The quasi-stationary phase of ohmically-heated high-density (nsub(e)(0)approximately1.5x10 14 cm -3 ) discharges has also been simulated, thus allowing the plasma ''chemical'' composition and the radiated power to be calculated

SUZAKU OBSERVATION OF STRONG FLUORESCENT IRON LINE EMISSION FROM THE YOUNG STELLAR OBJECT V1647 ORI DURING ITS NEW X-RAY OUTBURST

International Nuclear Information System (INIS)

Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Richmond, Michael; Weintraub, David A.

2010-01-01

The Suzaku X-ray satellite observed the young stellar object (YSO) V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in 2008 August. During the 87 ks observation with a net exposure of 40 ks, V1647 Ori showed a high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other YSOs. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT ∼ 5 keV). It also shows a fluorescent iron Kα line with a remarkably large equivalent width (EW) of ∼600 eV. Such a large EW suggests that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron Kα line, so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.

Spatial distribution of FIR rotationally excited CH+ and OH emission lines in the Orion Bar PDR.

Science.gov (United States)

Parikka, A; Habart, E; Bernard-Salas, J; Goicoechea, J R; Abergel, A; Pilleri, P; Dartois, E; Joblin, C; Gerin, M; Godard, B

2017-03-01

The methylidyne cation (CH + ) and hydroxyl (OH) are key molecules in the warm interstellar chemistry, but their formation and excitation mechanisms are not well understood. Their abundance and excitation are predicted to be enhanced by the presence of vibrationally excited H 2 or hot gas (~500-1000 K) in photodissociation regions with high incident FUV radiation field. The excitation may also originate in dense gas (> 10 5 cm -3 ) followed by nonreactive collisions with H 2 , H, and electrons. Previous observations of the Orion Bar suggest that the rotationally excited CH + and OH correlate with the excited CO, a tracer of dense and warm gas, and formation pumping contributes to CH + excitation. Our goal is to examine the spatial distribution of the rotationally excited CH + and OH emission lines in the Orion Bar in order to establish their physical origin and main formation and excitation mechanisms. We present spatially sampled maps of the CH + J=3-2 transition at 119.8 µm and the OH Λ-doublet at 84 µm in the Orion Bar over an area of 110″×110″ with Herschel (PACS). We compare the spatial distribution of these molecules with those of their chemical precursors, C + , O and H 2 , and tracers of warm and dense gas (high-J CO). We assess the spatial variation of CH + J=2-1 velocity-resolved line profile at 1669 GHz with Herschel HIFI spectrometer observations. The OH and especially CH + lines correlate well with the high-J CO emission and delineate the warm and dense molecular region at the edge of the Bar. While notably similar, the differences in the CH + and OH morphologies indicate that CH + formation and excitation are strongly related to the observed vibrationally excited H 2 . This, together with the observed broad CH + line widths, indicates that formation pumping contributes to the excitation of this reactive molecular ion. Interestingly, the peak of the rotationally excited OH 84 µm emission coincides with a bright young object, proplyd 244

THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT

Energy Technology Data Exchange (ETDEWEB)

Hayes, Matthew [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Oestlin, Goeran; Duval, Florent; Guaita, Lucia; Melinder, Jens; Sandberg, Andreas [Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Schaerer, Daniel [CNRS, IRAP, 14, avenue Edouard Belin, F-31400 Toulouse (France); Verhamme, Anne; Orlitova, Ivana [Geneva Observatory, University of Geneva, 51 Chemin des Maillettes, CH-1290 Versoix (Switzerland); Mas-Hesse, J. Miguel; Oti-Floranes, Hector [Centro de Astrobiologia (CSIC-INTA), Departamento de Astrofisica, POB 78, 28691 Villanueva de la Canada (Spain); Adamo, Angela [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Atek, Hakim [Laboratoire d' Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire, CH-1290 Sauverny (Switzerland); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Herenz, E. Christian [Leibniz-Institut fuer Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Kunth, Daniel [Institut d' Astrophysique de Paris, UMR 7095 CNRS and UPMC, 98 bis Bd Arago, F-75014 Paris (France); Laursen, Peter, E-mail: matthew@astro.su.se [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2013-03-10

We report on new imaging observations of the Lyman alpha emission line (Ly{alpha}), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Ly{alpha}, H{alpha}, and the far ultraviolet continuum. We show that Ly{alpha} is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20% radius, R{sub P20}, Ly{alpha} radii are larger than those of H{alpha} by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Ly{alpha}-to-FUV radii is 2.9. This suggests that much of the Ly{alpha} light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Ly{alpha} compared to H{alpha}, {xi}{sub Ly{alpha}} = R {sup Ly{alpha}}{sub P20}/R {sup H{alpha}}{sub P20}, we find {xi}{sub Ly{alpha}} to be uncorrelated with total Ly{alpha} luminosity. However, {xi}{sub Ly{alpha}} is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Ly{alpha} photons throughout the interstellar medium and drive a large extended Ly{alpha} halo.

High-resolution Laboratory Measurements of Coronal Lines near the Fe IX Line at 171 Å

Science.gov (United States)

Beiersdorfer, Peter; Träbert, Elmar

2018-02-01

We present high-resolution laboratory measurements in the spectral region between 165 and 175 Å that focus on the emission from various ions of C, O, F, Ne, S, Ar, Fe, and Ni. This wavelength region is centered on the λ171 Fe IX channel of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, and we place special emphasis on the weaker emission lines of Fe IX predicted in this region. In general, our measurements show a multitude of weak lines missing in the current databases, where the emission lines of Ni are probably most in need of further identification and reclassification. We also find that the wavelengths of some of the known lines need updating. Using the multi-reference Møller–Plesset method for wavelength predictions and collisional-radiative modeling of the line intensities, we have made tentative assignments of more than a dozen lines to the spectrum of Fe IX, some of which have formerly been identified as Fe VII, Fe XIV, or Fe XVI lines. Several Fe features remain unassigned, although they appear to be either Fe VII or Fe X lines. Further work will be needed to complete and correct the spectral line lists in this wavelength region.

Optical imagery and spectrophotometry of CTB 80

Science.gov (United States)

Hester, J. Jeff; Kulkarni, Shrinivas R.

1989-01-01

Narrow-band imagery and spectrophotometry of the central region of CTB 80 are presented. The images show weak forbidden O III and ubiquitous filamentary forbidden S II and H-alpha emission from the extended radio lobes in which the core is embedded. The data indicate that the extended component is shock heated. Balmer line-dominated emission is observed around the perimeter of the core. Assuming that the volume of the radio shell is similar to the volume of the thermal shell, it is found that a magnetic field of about 600 microG and a cosmic-ray proton-to-electron ratio of about 200 are required to explain the pressure and synchrotron volume emissivity in the radio shell. It is suggested that the optical emission form the core of CTB 80 arises behind shocks which are being driven into a magnetized thermal plasma by the confined relativistic wind from PSR 1951+32.

ALFA: an automated line fitting algorithm

Science.gov (United States)

Wesson, R.

2016-03-01

I present the automated line fitting algorithm, ALFA, a new code which can fit emission line spectra of arbitrary wavelength coverage and resolution, fully automatically. In contrast to traditional emission line fitting methods which require the identification of spectral features suspected to be emission lines, ALFA instead uses a list of lines which are expected to be present to construct a synthetic spectrum. The parameters used to construct the synthetic spectrum are optimized by means of a genetic algorithm. Uncertainties are estimated using the noise structure of the residuals. An emission line spectrum containing several hundred lines can be fitted in a few seconds using a single processor of a typical contemporary desktop or laptop PC. I show that the results are in excellent agreement with those measured manually for a number of spectra. Where discrepancies exist, the manually measured fluxes are found to be less accurate than those returned by ALFA. Together with the code NEAT, ALFA provides a powerful way to rapidly extract physical information from observations, an increasingly vital function in the era of highly multiplexed spectroscopy. The two codes can deliver a reliable and comprehensive analysis of very large data sets in a few hours with little or no user interaction.

Optical design of visible emission line coronagraph on Indian space solar mission Aditya-L1

Science.gov (United States)

Raj Kumar, N.; Raghavendra Prasad, B.; Singh, Jagdev; Venkata, Suresh

2018-03-01

The ground based observations of the coronal emission lines using a coronagraph are affected by the short duration of clear sky and varying sky transparency. These conditions do not permit to study small amplitude variations in the coronal emission reliably necessary to investigate the process or processes involved in heating the coronal plasma and dynamics of solar corona. The proposed Visible Emission Line Coronagraph (VELC) over comes these limitations and will provide continuous observation 24 h a day needed for detailed studies of solar corona and drivers for space weather predictions. VELC payload onboard India's Aditya-L1 space mission is an internally occulted solar coronagraph for studying the temperature, velocity, density and heating of solar corona. To achieve the proposed science goals, an instrument which is capable of carrying out simultaneous imaging, spectroscopy and spectro-polarimetric observations of the solar corona close to the solar limb is required. VELC is designed with salient features of (a) Imaging solar corona at 500 nm with an angular resolution of 5 arcsec over a FOV of 1.05Ro to 3Ro (Ro:Solar radius) (b) Simultaneous multi-slit spectroscopy at 530.3 nm [Fe XIV],789.2 nm [Fe XI] and 1074.7 nm [Fe XIII] with spectral dispersion of 28mÅ, 31mÅ and 202mÅ per pixel respectively, over a FOV of 1.05Ro to 1.5Ro. (c) Multi-slit dual beam spectro-polarimetry at 1074.7 nm. All the components of instrument have been optimized in view of the scientific objectives and requirements of space payloads. In this paper we present the details of optical configuration and the expected performance of the payload.

Optical design of visible emission line coronagraph on Indian space solar mission Aditya-L1

Science.gov (United States)

Raj Kumar, N.; Raghavendra Prasad, B.; Singh, Jagdev; Venkata, Suresh

2018-04-01

The ground based observations of the coronal emission lines using a coronagraph are affected by the short duration of clear sky and varying sky transparency. These conditions do not permit to study small amplitude variations in the coronal emission reliably necessary to investigate the process or processes involved in heating the coronal plasma and dynamics of solar corona. The proposed Visible Emission Line Coronagraph (VELC) over comes these limitations and will provide continuous observation 24 h a day needed for detailed studies of solar corona and drivers for space weather predictions. VELC payload onboard India's Aditya-L1 space mission is an internally occulted solar coronagraph for studying the temperature, velocity, density and heating of solar corona. To achieve the proposed science goals, an instrument which is capable of carrying out simultaneous imaging, spectroscopy and spectro-polarimetric observations of the solar corona close to the solar limb is required. VELC is designed with salient features of (a) Imaging solar corona at 500 nm with an angular resolution of 5 arcsec over a FOV of 1.05Ro to 3Ro (Ro:Solar radius) (b) Simultaneous multi-slit spectroscopy at 530.3 nm [Fe XIV],789.2 nm [Fe XI] and 1074.7 nm [Fe XIII] with spectral dispersion of 28mÅ, 31mÅ and 202mÅ per pixel respectively, over a FOV of 1.05Ro to 1.5Ro. (c) Multi-slit dual beam spectro-polarimetry at 1074.7 nm. All the components of instrument have been optimized in view of the scientific objectives and requirements of space payloads. In this paper we present the details of optical configuration and the expected performance of the payload.

Fluorescent H{sub 2} Emission Lines from the Reflection Nebula NGC 7023 Observed with IGRINS

Energy Technology Data Exchange (ETDEWEB)

Le, Huynh Anh N.; Pak, Soojong; Lee, Hye-In [School of Space Research, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104 (Korea, Republic of); Kaplan, Kyle; Mace, Gregory; Pavel, Michael; Jaffe, Daniel T. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Lee, Sungho; Jeong, Ueejeong; Chun, Moo-Young; Yuk, In-Soo; Hwang, Narae; Kim, Kang-Min; Park, Chan; Oh, Jae Sok; Yu, Young Sam; Park, Byeong-Gon; Minh, Young Chol [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Oh, Heeyoung [Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Pyo, Tae-Soo, E-mail: huynhanh7@khu.ac.kr, E-mail: soojong@khu.ac.kr [Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences (NINS), 650 North Aohoku Place, Hilo, HI 96720 (United States)

2017-05-20

We have analyzed the temperature, velocity, and density of H{sub 2} gas in NGC 7023 with a high-resolution near-infrared spectrum of the northwestern filament of the reflection nebula. By observing NGC 7023 in the H and K bands at R ≃ 45,000 with the Immersion GRating INfrared Spectrograph, we detected 68 H{sub 2} emission lines within the 1″ × 15″ slit. The diagnostic ratio of 2-1 S(1)/1-0 S(1) is 0.41−0.56. In addition, the estimated ortho-to-para ratio (OPR) is 1.63−1.82, indicating that the H{sub 2} emission transitions in the observed region arise mostly from gas excited by UV fluorescence. Gradients in the temperature, velocity, and OPR within the observed area imply motion of the photodissociation region (PDR) relative to the molecular cloud. In addition, we derive the column density of H{sub 2} from the observed emission lines and compare these results with PDR models in the literature covering a range of densities and incident UV field intensities. The notable difference between PDR model predictions and the observed data, in high rotational J levels of ν = 1, is that the predicted formation temperature for newly formed H{sub 2} should be lower than that of the model predictions. To investigate the density distribution, we combine pixels in 1″ × 1″ areas and derive the density distribution at the 0.002 pc scale. The derived gradient of density suggests that NGC 7023 has a clumpy structure, including a high clump density of ∼10{sup 5} cm{sup −3} with a size smaller than ∼5 × 10{sup −3} pc embedded in lower-density regions of 10{sup 3}–10{sup 4} cm{sup −3}.

Near-infrared spectrophotometry of eight 3CR radiogalaxies: the first detections of [O III]500.7 and [S III]953.2 emission lines in galaxies with z > 1

International Nuclear Information System (INIS)

Rawlings, Steve; Lacy, Mark

1991-01-01

We present the results of near-IR spectrophotometry of eight 3CR radiogalaxies with redshifts in the range 0.256≤z≤1.575. The narrow [O III]500.7 emission line was detected in 3C13 (z = 1.351), and the narrow [S III]953.2 emission line in 3C79 (z = 0.256), in the northern near-IR knot of 3C356 (z = 1.079) and marginally in 3C368 (z=1.132). We show that narrow-line emission can sometimes account for a substantial fraction of the broad-band near-IR flux arising from the substructures of high-z radiogalaxies, but that this fraction is strongly dependent on, and therefore a valuable probe of, physical conditions within the substructures. (author)

New upper limit to the coronal line emission from the T Tauri star RU Lupi

Energy Technology Data Exchange (ETDEWEB)

Gahm, G F [Stockholm Observatory (Sweden); Lago, M T.V.T. [Universidade do Porto (Portugal). Grupo de Matematica Aplicada; Penston, M V [ESTEC, European Space Agency, Villafranca Satellite Tracking Station, Madrid, (Spain)

1981-05-01

A high dispersion AAT spectrogram sets an upper limit on the (Fe x) emission line lambda 6374.5 A in the T Tauri star RU Lupi. The intensity of any 10/sup 6/ K corona in this star is less than 600 times that of the Sun compared to a chromosphere and transition region of 3 x 10/sup 3/ to 2 x 10/sup 5/ K gas 10/sup 6/ times stronger than the Sun's. The important theoretical implications are noted.

Displacement of emission lines from the ArII ion in a dense plasma

International Nuclear Information System (INIS)

Simard, P.A.

1982-01-01

A spectroscopic study of the emission from an argon plasma produced by a small theta-pinch is described. The electron density in the plasma is very high and the temperature relatively cool. Values obtained for these quantities are Nsub(e) approxiiately equal to 6 x 10 19 cm 3 and Tsub(e) approximately equal to 3.6 eV. Wavelengths of many ArII lines have been measured between 2700 and 5000 A. Many of these lines exhibit small shifts to the blue or to the red but others show large red shifts. Particularly significant are the multiplets 4p 4 P-4d 4 P, 4p 4 P-5s 4 P and 4p 4 S-4d 4 P where the measured shifts are about 6.0 +-0.8 cm -1 . These shifts have been interpreted as plasma polarization shifts. A plasma effect on the spin-orbit coupling in ArII has also been observed for the first time. A qqalitative analysis of these phenomena is given [fr

A catalog of pre-main-sequence emission-line stars with IRAS source associations

International Nuclear Information System (INIS)

Weintraub, D.A.

1990-01-01

To aid in finding premain-sequence (PMS) emission-line stars that might have dusty circumstellar environments, 361 PMS stars that are associated with 304 separate IRAS sources were identified. These stars include 200 classical T Tauri stars, 25 weak-lined (naked) T Tauri stars, 56 Herbig Ae/Be stars, six FU Orionis stars, and two SU Aurigae stars. All six of the FU Orionis stars surveyed by IRAS were detected. Of the PMS-IRAS Point Source Catalog (PSC) associations, 90 are new and are not noted in the PSC. The other 271 entries include 104 that are correctly identified in the PSC but have not yet appeared in the literature, 56 more that can be found in both the PSC and in the published and unpublished iterature, and 111 that are in the literature but not in the PSC. Spectral slope diagrams constructed from the 12-, 25-, and 60-micron flux densities reveal unique distributions for the different PMS subclasses; these diagrams may help identify the best candidate PMS stars for observations of circumstellar dust. 30 refs

SIMULTANEOUS ULTRAVIOLET AND OPTICAL EMISSION-LINE PROFILES OF QUASARS: IMPLICATIONS FOR BLACK HOLE MASS DETERMINATION

International Nuclear Information System (INIS)

Ho, Luis C.; Dong Xiaobo; Goldoni, Paolo; Ponti, Gabriele; Greene, Jenny E.

2012-01-01

The X-shooter instrument on the Very Large Telescope was used to obtain spectra of seven moderate-redshift quasars simultaneously covering the spectral range ∼3000 Å to 2.5 μm. At z ≈ 1.5, most of the prominent broad emission lines in the ultraviolet to optical region are captured in their rest frame. We use this unique data set, which mitigates complications from source variability, to intercompare the line profiles of C IV λ1549, C III] λ1909, Mg II λ2800, and Hα and evaluate their implications for black hole (BH) mass estimation. We confirm that Mg II and the Balmer lines share similar kinematics and that they deliver mutually consistent BH mass estimates with minimal internal scatter (∼<0.1 dex) using the latest virial mass estimators. Although no virial mass formalism has yet been calibrated for C III], this line does not appear promising for such an application because of the large spread of its velocity width compared to lines of both higher and lower ionization; part of the discrepancy may be due to the difficulty of deblending C III] from its neighboring lines. The situation for C IV is complex and, because of the limited statistics of our small sample, inconclusive. On the one hand, slightly more than half of our sample (4/7) have C IV line widths that correlate reasonably well with Hα line widths, and their respective BH mass estimates agree to within ∼0.15 dex. The rest, on the other hand, exhibit exceptionally broad C IV profiles that overestimate virial masses by factors of 2-5 compared to Hα. As C IV is widely used to study BH demographics at high redshifts, we urgently need to revisit our analysis with a larger sample.

A RADIAL VELOCITY TEST FOR SUPERMASSIVE BLACK HOLE BINARIES AS AN EXPLANATION FOR BROAD, DOUBLE-PEAKED EMISSION LINES IN ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

Liu, Jia; Halpern, Jules P. [Astronomy Department, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Eracleous, Michael [Department of Astronomy and Institute for Gravitation and The Cosmos, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

2016-01-20

One of the proposed explanations for the broad, double-peaked Balmer emission lines observed in the spectra of some active galactic nuclei (AGNs) is that they are associated with sub-parsec supermassive black hole (SMBH) binaries. Here, we test the binary broad-line region hypothesis through several decades of monitoring of the velocity structure of double-peaked Hα emission lines in 13 low-redshift, mostly radio-loud AGNs. This is a much larger set of objects compared to an earlier test by Eracleous et al. and we use much longer time series for the three objects studied in that paper. Although systematic changes in radial velocity can be traced in many of their lines, they are demonstrably not like those of a spectroscopic binary in a circular orbit. Any spectroscopic binary period must therefore be much longer than the span of the monitoring (assuming a circular orbit), which in turn would require black hole masses that exceed by 1–2 orders of magnitude the values obtained for these objects using techniques such as reverberation mapping and stellar velocity dispersion. Moreover, the response of the double-peaked Balmer line profiles to fluctuations of the ionizing continuum and the shape of the Lyα profiles are incompatible with an SMBH binary. The binary broad-line region hypothesis is therefore disfavored. Other processes evidently shape these line profiles and cause the long-term velocity variations of the double peaks.

HDE 229189 - A variable Ae star in the field of NGC 6910

International Nuclear Information System (INIS)

Halbedel, E.M.

1991-01-01

The star HDE 229189 (BD + 40 4145; in the field, though probably not a member, of the open cluster NGC 6910) has been found to exhibit large photometric changes in V magnitude over relatively short time scales. The total observed range was 0.416 V magnitude. An outburst in 1982 showed an even greater V range (Delta V = 1.66) and concomitant color changes. A coude spectrum of the star taken a week before a minor outburst showed emission at H-alpha but no other unusual lines. The star is likely an A3 (V)e star, an unusual object in itself (since stars as late as A3 seldom show emission at H-α), or else possibly a member of a binary system undergoing mass transfer between the members. 19 refs

Detection of CI line emission towards the oxygen-rich AGB star omi Ceti

Science.gov (United States)

Saberi, M.; Vlemmings, W. H. T.; De Beck, E.; Montez, R.; Ramstedt, S.

2018-05-01

We present the detection of neutral atomic carbon CI(3P1-3P0) line emission towards omi Cet. This is the first time that CI is detected in the envelope around an oxygen-rich M-type asymptotic giant branch (AGB) star. We also confirm the previously tentative CI detection around V Hya, a carbon-rich AGB star. As one of the main photodissociation products of parent species in the circumstellar envelope (CSE) around evolved stars, CI can be used to trace sources of ultraviolet (UV) radiation in CSEs. The observed flux density towards omi Cet can be reproduced by a shell with a peak atomic fractional abundance of 2.4 × 10-5 predicted based on a simple chemical model where CO is dissociated by the interstellar radiation field. However, the CI emission is shifted by 4 km s-1 from the stellar velocity. Based on this velocity shift, we suggest that the detected CI emission towards omi Cet potentially arises from a compact region near its hot binary companion. The velocity shift could, therefore, be the result of the orbital velocity of the binary companion around omi Cet. In this case, the CI column density is estimated to be 1.1 × 1019 cm-2. This would imply that strong UV radiation from the companion and/or accretion of matter between two stars is most likely the origin of the CI enhancement. However, this hypothesis can be confirmed by high-angular resolution observations.

Zero-phonon-line emission of single molecules for applications in quantum information processing

Science.gov (United States)

Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

2005-07-01

A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

The absorption effect of the Lα-line Supplement to the paper 'On the Correlation Between the Hα-line emission rate and the ablation rate of a hydrogen pellet in tokamak discharges' – Nuclear Fusion 24 (1984) 697

DEFF Research Database (Denmark)

Chang, C. T.; Thomsen, Kenneth

1985-01-01

Several assumptions made in a previous study of the correlation between the Hα-line emission rate and the ablation rate of a hydrogen pellet injected into a tokamak discharge showed that the emission layer of the ablatant as optically thin with respect to all levels of the principal quantum numbe...

Study of turbulent and shock heated IGM gas with emission line spectroscopy in the Taffy galaxies

Science.gov (United States)

Joshi, Bhavin; Appleton, Phil; Blanc, Guillermo; Guillard, Pierre; Freeland, Emily; Peterson, Bradley; Alatalo, Katherine

2018-01-01

We present our results from optical IFU observations of the Taffy system (UGC 12914/15); named so because of the radio emission that stretches between the two galaxies. The Taffy galaxies are a major merger pair of galaxies where two gas-rich spiral galaxies have collided face on and passed through each other. The pair presents an unusually low IR luminosity (L_FIR ~ 4.5 x 10^{10} L_solar) and SFR (~ 0.23 M_solar / yr) for a typical post merger system. It was also found from Spitzer and Chandra observations that the Taffy "bridge" between the galaxies contains large amounts of warm molecular Hydrogen, >4.5 x 10^8 M_solar at 150-175K, and also shows soft X-ray emission. These results hinted at shock heating as a likely mechanism for heating the large amounts of gas in the Taffy bridge and keeping it at these temperatures, after other sources of heating are ruled out. The data we present in this paper are from the VIRUS-P instrument (now called GCMS) on the Harlan J. Smith 2.7m telescope at McDonald Observatory. We detect ionized gas all throughout the Taffy galaxies and in the bridge between them. Interestingly, the ionized gas shows emission line profiles with two velocity components almost all throughout the system. We also show evidence, through line diagnostic (BPT) diagrams, that the velocity component with lower velocity is likely excited by star formation whereas the velocity component with higher velocity is likely excited by shocks. We also find evidence for post-starburst populations in parts of the Taffy system.

H2 emission from Herbig-Haro objects

International Nuclear Information System (INIS)

Elias, J.H.

1980-01-01

Molecular hydrogen emission lines have been detected in six Herbig-Haro objects. The line intensities suggest tha the H 2 emission arises in a moderate-density, shock-heated gas, consistent with evidence for a similar origin of the visible emission-line spectra in Herbig-Haro objects. Indirect arguments indicate that the typical H 2 line widths are less than 70 km s -1 and that typical helicentric radial velocities are no more than 30 km s -1 in magnitude

X-ray continuum and iron K emission line from the radio galaxy 3C 390.3

Science.gov (United States)

Inda, M.; Makishima, K.; Kohmura, Y.; Tashiro, M.; Ohashi, T.; Barr, P.; Hayashida, K.; Palumbo, G. G. C.; Trinchieri, G.; Elvis, M.

1994-01-01

X-ray properties of the radio galaxy 3C 390.3 were investigated using the European X-ray Observatory Satellite (EXOSAT) and Ginga satellites. Long-term, large-amplitude X-ray intensity changes were detected over a period extending from 1984 through 1991, and high-quality X-ray spectra were obtained especially with Ginga. The X-ray continuum spectra were described with power-law model with photon slope in the range 1.5-1.8, and the slope flattened as the 2-20 keV luminosity decreased by 40%. There was a first detection of the iron emission line from this source at the 90% confidence level. An upper limit was derived on the thermal X-ray component. X-ray emission mechanisms and possible origins of the long-term variation are discussed.

Broadband spectral study of the jet-disc emission in the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342

Science.gov (United States)

Ghosh, Ritesh; Dewangan, Gulab C.; Mallick, Labani; Raychaudhuri, Biplab

2018-06-01

We present a broadband spectral study of the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 based on multi-epoch observations performed with NuSTAR on 2014 March 15, and two simultaneous observations performed with Suzaku and Swift on 2009 July 26 and 2013 March 1. We found the presence of a strong soft X-ray excess emission, a broad but weak Fe line and hard X-ray excess emission. We used the blurred reflection (relxill) and the intrinsic disc Comptonization (optxagnf), two physically motivated models, to describe the broadband spectra and to disentangle the disk/corona and jet emission. The relxill model is mainly constrained by the strong soft X-ray excess although the model failed to predict this excess when fitted above 3{keV} and extrapolated to lower energies. The joint spectral analysis of the three datasets above 3{keV} with this model resulted in a high black hole spin (a > 0.9) and moderate reflection fraction R ˜ 0.5. The optxagnf model fitted to the two simultaneous datasets resulted in an excess emission in the UV band. The simultaneous UV-to-hard X-ray spectra of 1H 0323+342 are best described by a model consisting of a primary X-ray power-law continuum with Γ ˜ 1.8, a blurred reflection component with R ˜ 0.5, Comptonised disk emission as the soft X-ray excess, optical/UV emission from a standard accretion disk around a black hole of mass ˜107M⊙ and a steep power law (Γ ˜ 3 - 3.5) component, most likely the jet emission in the UV band. The fractional RMS variability spectra suggest that both the soft excess and the powerlaw component are variable in nature.

Discovery of a Possible Symbiotic Binary in the Large Magellanic Cloud

Science.gov (United States)

Mathew, Blesson; Reid, Warren A.; Mennickent, R. E.; Banerjee, D. P. K.

2017-12-01

We report the discovery of a possible symbiotic star, in the Large Magellanic Cloud (LMC). The object under consideration here, designated as RP 870, was detected during the course of a comprehensive H$\\alpha$ survey of the LMC by Reid & Parker (2012). The spectrum of RP 870 showed high ionization emission lines of He I, He II and [O III] and molecular absorption bands of TiO $\\lambda$$\\lambda$6180, 7100. The collective signatures of a hot component (high excitation/ionization lines) and of a cool component (TiO molecular bands) are seen in RP 870, from which we propose it as a symbiotic star. Since known symbiotic systems are rare in the LMC, possibly less than a dozen are known, we thought the present detection to be interesting enough to be reported.

Ion cyclotron emission by spontaneous emission

Energy Technology Data Exchange (ETDEWEB)

Da Costa, O [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Gresillon, D [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

1994-07-01

The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs.

Ion cyclotron emission by spontaneous emission

International Nuclear Information System (INIS)

Da Costa, O.; Gresillon, D.

1994-01-01

The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs

A silicon photo-multiplier signal readout using strip-line and waveform sampling for Positron Emission Tomography

Science.gov (United States)

Kim, H.; Chen, C.-T.; Eclov, N.; Ronzhin, A.; Murat, P.; Ramberg, E.; Los, S.; Kao, C.-M.

2016-09-01

A strip-line and waveform sampling based readout is a signal multiplexing method that can efficiently reduce the readout channels while fully exploiting the fast time characteristics of photo-detectors such as the SiPM. We have applied this readout method for SiPM-based time-of-flight (TOF) positron emission tomography (PET) detectors. We have prototyped strip-line boards in which 8 SiPMs (pitch 5.2 mm) are connected by using a single strip-line, and the signals appearing at the ends of the strip-line are acquired by using the DRS4 waveform sampler at a nominal sampling frequency of 1-5 GS/s. Experimental tests using laser and LYSO scintillator are carried out to assess the performance of the strip-line board. Each SiPM position, which is inferred from the arrival time difference of the two signals at the ends of the strip-line, is well identified with 2.6 mm FWHM resolution when the SiPMs are coupled to LYSO crystals and irradiated by a 22Na source. The average energy and coincidence time resolution corresponding to 511 keV photons are measured to be ∼32% and ∼510 ps FWHM, respectively, at a 5.0 GS/s DRS4 sampling rate. The results show that the sampling rate can be lowered to 1.5 GS/s without performance degradation. These encouraging initial test results indicate that the strip-line and waveform sampling readout method is applicable for SiPM-based TOF PET development.

Radial-velocity variations in Alpha Ori, Alpha Sco, and Alpha Her

International Nuclear Information System (INIS)

Smith, M.A.; Patten, B.M.; Goldberg, L.

1989-01-01

Radial-velocity observations of Alpha Ori, Alpha Sco A, and Alpha Her A are used to study radial-velocity periodicities in M supergiants. The data refer to several metallic lines in the H-alpha region and to H-alpha itself. It is shown that Alpha Ori and Alpha Sco A have cycle lengths of about 1 yr and semiamplitudes of 2 km/s. It is suggested that many semiregular red supergiant varibles such as Alpha Ori may be heading toward chaos. All three stars show short-term stochastic flucutations with an amplitude of 1-2 km/s. It is found that the long-term variability of H-alpha velocities may be a consequence of intermittent failed ejections. 58 refs

Computation and measurement of a plasma temperature using the emission lines of copper

International Nuclear Information System (INIS)

Sassi, M.; Pierre, L.; Benard, J.; Cahen, C.

1994-01-01

The use of copper emission lines for temperature measurement in plasma environments is presented. The article features the problems encountered with such a measurement method when used in a stationary and a non-stationary plasma. In the first case, we were concerned with the temperature measurements in the jet of a 2 MW industrial plasma torche. The plasma was stationary and the measurement geometry allowed the use of the Abel inversion method to recover the temperature profiles in the plasma jet. The limitations of the measurement method on the jet boundaries as well as the cooling of the plasma by entrainement of cold air are discussed. In the second case, a non-stationary plasma in a 1.4 MW electric furnace was studied. This study allowed to feature the role of the detector dynamics as related to the dynamics of the observed medium. The obtained measurements show only a probable temperature in the immediate proximity of the arc. Finally, we conclude on the validity of copper as a tracer and the use of spontaneous emission spectroscopy, and easy method to implement, compared to other sophisticated temperature measurement methods. (orig.)

Massive unseen companion of X Persei - emission contamination in the Balmer lines

Energy Technology Data Exchange (ETDEWEB)

Penrod, G.D.; Vogt, S.S.

1985-12-01

X Per is the optical counterpart of the pulsating X-ray source 4U 0352 + 30. Although nearly all observations of this system are consistent with a relatively simple model consisting of a normal O93-B0e star with a neutron star companion in a distant orbit, Hutchings et al. (1974) reported large-amplitude radial velocity variations with a 580-day period in the high-order Balmer absorption lines, which, if interpreted as orbital motion, imply the existence of a massive (more than 30 solar mass) unseen compansion, probably a black hole. High-quality Reticon spectra of the high-order Balmer lines have been obtained which show that the radial velocity variations reported by Hutchings et al. are spurious and are caused by asymmetric and variable emission components hiding in the absorption profiles. This result eliminates the necessity for postulating a massive, unseen secondary or tertiary star. All observed aspects of X Per now seem consistent with the Be + neutron star binary scenario. A previously reported 22.4-hr periodicity in the X-ray flux is explained in terms of nonradial g-mode pulsations of the Be star, which modulate the star's wind, and, hence, the accretion rate onto the neutron star. 21 references.

Massive unseen companion of X Persei - emission contamination in the Balmer lines

International Nuclear Information System (INIS)

Penrod, G.D.; Vogt, S.S.

1985-01-01

X Per is the optical counterpart of the pulsating X-ray source 4U 0352 + 30. Although nearly all observations of this system are consistent with a relatively simple model consisting of a normal O93-B0e star with a neutron star companion in a distant orbit, Hutchings et al. (1974) reported large-amplitude radial velocity variations with a 580-day period in the high-order Balmer absorption lines, which, if interpreted as orbital motion, imply the existence of a massive (more than 30 solar mass) unseen compansion, probably a black hole. High-quality Reticon spectra of the high-order Balmer lines have been obtained which show that the radial velocity variations reported by Hutchings et al. are spurious and are caused by asymmetric and variable emission components hiding in the absorption profiles. This result eliminates the necessity for postulating a massive, unseen secondary or tertiary star. All observed aspects of X Per now seem consistent with the Be + neutron star binary scenario. A previously reported 22.4-hr periodicity in the X-ray flux is explained in terms of nonradial g-mode pulsations of the Be star, which modulate the star's wind, and, hence, the accretion rate onto the neutron star. 21 references

Alfvén Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-induced Emission Line Broadening

Energy Technology Data Exchange (ETDEWEB)

Oran, R. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139 (United States); Landi, E.; Holst, B. van der; Sokolov, I. V.; Gombosi, T. I., E-mail: roran@mit.edu [Atmospheric, Oceanic and Atmospheric Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI, 48109 (United States)

2017-08-20

We test the predictions of the Alfvén Wave Solar Model (AWSoM), a global wave-driven magnetohydrodynamic (MHD) model of the solar atmosphere, against high-resolution spectra emitted by the quiescent off-disk solar corona. AWSoM incorporates Alfvén wave propagation and dissipation in both closed and open magnetic field lines; turbulent dissipation is the only heating mechanism. We examine whether this mechanism is consistent with observations of coronal EUV emission by combining model results with the CHIANTI atomic database to create synthetic line-of-sight spectra, where spectral line widths depend on thermal and wave-related ion motions. This is the first time wave-induced line broadening is calculated from a global model with a realistic magnetic field. We used high-resolution SUMER observations above the solar west limb between 1.04 and 1.34 R {sub ⊙} at the equator, taken in 1996 November. We obtained an AWSoM steady-state solution for the corresponding period using a synoptic magnetogram. The 3D solution revealed a pseudo-streamer structure transversing the SUMER line of sight, which contributes significantly to the emission; the modeled electron temperature and density in the pseudo-streamer are consistent with those observed. The synthetic line widths and the total line fluxes are consistent with the observations for five different ions. Further, line widths that include the contribution from the wave-induced ion motions improve the correspondence with observed spectra for all ions. We conclude that the turbulent dissipation assumed in the AWSoM model is a viable candidate for explaining coronal heating, as it is consistent with several independent measured quantities.

Spatial distribution of FIR rotationally excited CH+ and OH emission lines in the Orion Bar PDR⋆

Science.gov (United States)

Parikka, A.; Habart, E.; Bernard-Salas, J.; Goicoechea, J. R.; Abergel, A.; Pilleri, P.; Dartois, E.; Joblin, C.; Gerin, M.; Godard, B.

2016-01-01

Context The methylidyne cation (CH+) and hydroxyl (OH) are key molecules in the warm interstellar chemistry, but their formation and excitation mechanisms are not well understood. Their abundance and excitation are predicted to be enhanced by the presence of vibrationally excited H2 or hot gas (~500–1000 K) in photodissociation regions with high incident FUV radiation field. The excitation may also originate in dense gas (> 105 cm−3) followed by nonreactive collisions with H2, H, and electrons. Previous observations of the Orion Bar suggest that the rotationally excited CH+ and OH correlate with the excited CO, a tracer of dense and warm gas, and formation pumping contributes to CH+ excitation. Aims Our goal is to examine the spatial distribution of the rotationally excited CH+ and OH emission lines in the Orion Bar in order to establish their physical origin and main formation and excitation mechanisms. Methods We present spatially sampled maps of the CH+ J=3-2 transition at 119.8 µm and the OH Λ-doublet at 84 µm in the Orion Bar over an area of 110″×110″ with Herschel (PACS). We compare the spatial distribution of these molecules with those of their chemical precursors, C+, O and H2, and tracers of warm and dense gas (high-J CO). We assess the spatial variation of CH+ J=2-1 velocity-resolved line profile at 1669 GHz with Herschel HIFI spectrometer observations. Results The OH and especially CH+ lines correlate well with the high-J CO emission and delineate the warm and dense molecular region at the edge of the Bar. While notably similar, the differences in the CH+ and OH morphologies indicate that CH+ formation and excitation are strongly related to the observed vibrationally excited H2. This, together with the observed broad CH+ line widths, indicates that formation pumping contributes to the excitation of this reactive molecular ion. Interestingly, the peak of the rotationally excited OH 84 µm emission coincides with a bright young object, proplyd

Planck 2015 results. XXV. Diffuse low-frequency Galactic foregrounds

CERN Document Server

Ade, P.A.R.; Alves, M.I.R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.R.; Chiang, H.C.; Christensen, P.R.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Dickinson, C.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Ensslin, T.A.; Eriksen, H.K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Heraud, Y.; Gjerlow, E.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Helou, G.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leahy, J.P.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Orlando, E.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T.J.; Peel, M.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Reach, W.T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubino-Martin, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Stolyarov, V.; Stompor, R.; Strong, A.W.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vidal, M.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Watson, R.; Wehus, I.K.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-01-01

(abridged) We discuss the Galactic foreground emission between 20 and 100GHz based on observations by Planck/WMAP. The Commander component-separation tool has been used to separate the various astrophysical processes in total intensity. Comparison with RRL templates verifies the recovery of the free-free emission along the Galactic plane. Comparison of the high-latitude Halpha emission with our free-free map shows residuals that correlate with dust optical depth, consistent with a fraction (~30%) of Halpha having been scattered by high-latitude dust. We highlight a number of diffuse spinning dust morphological features at high latitude. There is substantial spatial variation in the spinning dust spectrum, with the emission peak ranging from below 20GHz to more than 50GHz. There is a strong tendency for the spinning dust component near many prominent HII regions to have a higher peak frequency, suggesting that this increase in peak frequency is associated with dust in the photodissociation regions around the n...

Quark nugget dark matter: no contradiction with 511 keV line emission from dwarf galaxies

Energy Technology Data Exchange (ETDEWEB)

Lawson, Kyle; Zhitnitsky, Ariel, E-mail: klawson@phas.ubc.ca, E-mail: arz@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C. V6T 1Z1 (Canada)

2017-02-01

The observed galactic 511 keV line has been interpreted in a number of papers as a possible signal of dark matter annihilation within the galactic bulge. If this is the case then it is possible that a similar spectral feature may be observed in association with nearby dwarf galaxies. These objects are believed to be strongly dark matter dominated and present a relatively clean observational target. Recently INTEGRAL observations have provided new constraints on the 511 keV flux from nearby dwarf galaxies [1] motivating further investigation into the mechanism by which this radiation may arise. In the model presented here dark matter in the form of heavy quark nuggets produces the galactic 511 keV emission line through interactions with the visible matter. It is argued that this type of interaction is not strongly constrained by the flux limits reported in [2].

High resolution measurements and modeling of auroral hydrogen emission line profiles

Directory of Open Access Journals (Sweden)

B. S. Lanchester

Full Text Available Measurements in the visible wavelength range at high spectral resolution (1.3 Å have been made at Longyearbyen, Svalbard (15.8 E,78.2 N during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wave-length of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.

Key words. Ionosphere (auroral ionosphere; particle precipitation – Magnetospheric physics (auroral phenomena

High resolution measurements and modeling of auroral hydrogen emission line profiles

Directory of Open Access Journals (Sweden)

B. S. Lanchester

2003-07-01

Full Text Available Measurements in the visible wavelength range at high spectral resolution (1.3 Å have been made at Longyearbyen, Svalbard (15.8 E,78.2 N during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wave-length of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.Key words. Ionosphere (auroral ionosphere; particle precipitation – Magnetospheric physics (auroral phenomena

Spectral classification of emission-line galaxies

International Nuclear Information System (INIS)

Veilleux, S.; Osterbrock, D.E.

1987-01-01

A revised method of classification of narrow-line active galaxies and H II region-like galaxies is proposed. It involves the line ratios which take full advantage of the physical distinction between the two types of objects and minimize the effects of reddening correction and errors in the flux calibration. Large sets of internally consistent data are used, including new, previously unpublished measurements. Predictions of recent photoionization models by power-law spectra and by hot stars are compared with the observations. The classification is based on the observational data interpreted on the basis of these models. 63 references

Study on the Extremely Low Frequency (ELF) Electromagnetic Field (EMF) emission from overhead High-Voltage Transmission Lines

International Nuclear Information System (INIS)

Parthasarathy, S.R.; Roha Tukimin; Wan Saffiey Wan Abdullah; Zulkifli Yusof; Mohd Azizi Mohd Jali

2016-01-01

The paper highlights the study on the Extremely Low Frequency (ELF) Electromagnetic Field (EMF) emission performed at an overhead 275-kV High-Voltage Transmission Lines. The study comprised of assessment at the transmission lines on 3 different cases and locations in Klang Valley, specifically on a vacant land near the transmission line, inside and around the house at the vicinity of the transmission line and the area directly under the transmission line. The instrument setup and measurement protocols during the assessment were adopted from standard measurement method and procedures stipulated under the Institute of Electrical and Electronics Engineers (IEEE) Standard. The results were compared with the standards recommended in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. The results showed that the measured field strengths are within the safety limit with the highest measured exposure was 10.8 % and 1.8 % of the permissible exposure limit for the electric and magnetic field respectively. Both the field strengths were found to drop significantly against distance from the transmission lines where closer distances showed higher field strengths. Furthermore, the study revealed that buildings and other object such as trees and shrubs screen out the electric field, resulting in a lower value at indoor measurements and near the stated objects. In addition, higher value of electric and magnetic field strengths were recorded when assessment was being done directly under the transmission line compared to the lateral measurement. (author)

Computer simulation of ICP spectra: A new tool for the study of excitation, emission, and line overlap

International Nuclear Information System (INIS)

Blades, M.W.; Burton, L.L.

1986-01-01

It is well known that the relatively high temperature of ICP sources provides an excitation environment relatively free from dissociation and vaporization interferences and, in addition, produces intense analyte line spectra and hence high analytical sensitivity. However, this feature also introduces the potential for spectral overlaps from sample concomitants. The degree to which an analyte spectral line intensity can be corrected for interfering spectral overlaps depends on many factors including spectrometer resolution, sample composition and ICP operating conditions. The authors have been using a computer program to assist them in the study of ICP analyte emission spectra. This program is being used to study the spectral distribution of line intensity information and also to do detailed investigations on spectral overlaps in complex sample mixtures. As input data the program uses tabulated wavelengths, transition probabilities (gA values), partition functions, excitation energies of the transitions, ionization energy, temperature, and Doppler and Stark linewidths

CONTINUUM OBSERVATIONS AT 350 MICRONS OF HIGH-REDSHIFT MOLECULAR EMISSION LINE GALAXIES

International Nuclear Information System (INIS)

Wu Jingwen; Evans, Neal J.; Dunham, Michael M.; Vanden Bout, Paul A.

2009-01-01

We report observations of 15 high-redshift (z = 1 - 5) galaxies at 350 μm using the Caltech Submillimeter Observatory and Submillimeter High Angular Resolution Camera II array detector. Emission was detected from eight galaxies, for which far-infrared luminosities, star formation rates (SFRs), total dust masses, and minimum source size estimates are derived. These galaxies have SFRs and star formation efficiencies comparable to other high-redshift molecular emission line galaxies. The results are used to test the idea that star formation in these galaxies occurs in a large number of basic units, the units being similar to star-forming clumps in the Milky Way. The luminosity of these extreme galaxies can be reproduced in a simple model with (0.9-30)x10 6 dense clumps, each with a luminosity of 5 x 10 5 L sun , the mean value for such clumps in the Milky Way. Radiative transfer models of such clumps can provide reasonable matches to the overall spectral energy distributions (SEDs) of the galaxies. They indicate that the individual clumps are quite opaque in the far-infrared. Luminosity-to-mass ratios vary over two orders of magnitude, correlating strongly with the dust temperature derived from simple fits to the SED. The gas masses derived from the dust modeling are in remarkable agreement with those from CO luminosities, suggesting that the assumptions going into both calculations are reasonable.

Neutrino-heated stars and broad-line emission from active galactic nuclei

Science.gov (United States)

Macdonald, James; Stanev, Todor; Biermann, Peter L.

1991-01-01

Nonthermal radiation from active galactic nuclei indicates the presence of highly relativistic particles. The interaction of these high-energy particles with matter and photons gives rise to a flux of high-energy neutrinos. In this paper, the influence of the expected high neutrino fluxes on the structure and evolution of single, main-sequence stars is investigated. Sequences of models of neutrino-heated stars in thermal equilibrium are presented for masses 0.25, 0.5, 0.8, and 1.0 solar mass. In addition, a set of evolutionary sequences for mass 0.5 solar mass have been computed for different assumed values for the incident neutrino energy flux. It is found that winds driven by the heating due to high-energy particles and hard electromagnetic radiation of the outer layers of neutrino-bloated stars may satisfy the requirements of the model of Kazanas (1989) for the broad-line emission clouds in active galactic nuclei.