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Sample records for carina nebula outflow

  1. Disentangling the outflow and protostars in HH 900 in the Carina Nebula

    CERN Document Server

    Reiter, Megan; Kiminki, Megan M; Bally, John; Anderson, Jay

    2015-01-01

    HH 900 is a peculiar protostellar outflow emerging from a small, tadpole-shaped globule in the Carina nebula. Previous H{\\alpha} imaging with HST/ACS showed an ionized outflow with a wide opening angle that is distinct from the highly collimated structures typically seen in protostellar jets. We present new narrowband near-IR [Fe II] images taken with the Wide Field Camera 3 on the Hubble Space Telescope that reveal a remarkably different structure than H{\\alpha}. In contrast to the unusual broad H{\\alpha} outflow, the [Fe II] emission traces a symmetric, collimated bipolar jet with the morphology and kinematics that are more typical of protostellar jets. In addition, new Gemini adaptive optics images reveal near-IR H$_2$ emission coincident with the H{\\alpha} emission, but not the [Fe II]. Spectra of these three components trace three separate and distinct velocity components: (1) H$_2$ from the slow, entrained molecular gas, (2) H{\\alpha} from the ionized skin of the accelerating outflow sheath, and (3) [Fe...

  2. A Tactile Carina Nebula

    Science.gov (United States)

    Grice, Noreen A.; Mutchler, M.

    2010-01-01

    Astronomy was once considered a science restricted to fully sighted participants. But in the past two decades, accessible books with large print/Braille and touchable pictures have brought astronomy and space science to the hands and mind's eye of students, regardless of their visual ability. A new universally-designed tactile image featuring the Hubble mosaic of the Carina Nebula is being presented at this conference. The original dataset was obtained with Hubble's Advanced Camera for Surveys (ACS) hydrogen-alpha filter in 2005. It became an instant icon after being infused with additional color information from ground-based CTIO data, and released as Hubble's 17th anniversary image. Our tactile Carina Nebula promotes multi-mode learning about the entire life-cycle of stars, which is dramatically illustrated in this Hubble mosaic. When combined with descriptive text in print and Braille, the visual and tactile components seamlessly reach both sighted and blind populations. Specific touchable features of the tactile image identify the shapes and orientations of objects in the Carina Nebula that include star-forming regions, jets, pillars, dark and light globules, star clusters, shocks/bubbles, the Keyhole Nebula, and stellar death (Eta Carinae). Visit our poster paper to touch the Carina Nebula!

  3. [Fe II] 1.64 um Features of Jets and Outflows from Young Stellar Objects in the Carina Nebula

    CERN Document Server

    Shinn, Jong-Ho; Lee, Jae-Joon; Lee, Ho-Gyu; Kim, Hyun-Jeong; Koo, Bon-Chul; Sung, Hwankyung; Chun, Moo Young; Lyo, A -Ran; Moon, Dae-Sik; Kyeong, Jaemann; Park, Byeong-Gon; Hur, Hyeonoh; Lee, Yong-Hyun

    2013-01-01

    We present [Fe II] 1.64 {\\mu}m imaging observations for jets and outflows from young stellar objects (YSOs) over the northern part (~ 24'x45') of the Carina Nebula, a massive star forming region. The observations were performed with IRIS2 of Anglo-Australian Telescope and the seeing was ~1.5"+-0.5". Eleven jet and outflow features are detected at eight different regions, and are named as Ionized Fe Objects (IFOs). One Herbig-Haro object candidate missed in Hubble Space Telescope H{\\alpha} observations is newly identified as HHc-16, referring our [Fe II] images. IFOs have knotty or longish shapes, and the detection rate of IFOs against previously identified YSOs is 1.4 %, which should be treated as a lower limit. Four IFOs show an anti-correlated peak intensities in [Fe II] and H{\\alpha}, where the ratio I([Fe II])/I(H{\\alpha}) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux, using two different methods. The jet-driving objects are identified for th...

  4. [Fe II] 1.64 μm FEATURES OF JETS AND OUTFLOWS FROM YOUNG STELLAR OBJECTS IN THE CARINA NEBULA

    International Nuclear Information System (INIS)

    We present [Fe II] 1.64 μm imaging observations for jets and outflows from young stellar objects (YSOs) over the northern part (∼24' × 45') of the Carina Nebula, a massive star-forming region. The observations were performed with IRIS2 of the Anglo-Australian Telescope and the seeing was ∼1.''5 ± 0.''5. Eleven jet and outflow features are detected at eight different regions and are termed ionized Fe objects (IFOs). One Herbig-Haro candidate that was missed in Hubble Space Telescope Hα observations is newly identified as HHc-16, referring to our [Fe II] images. IFOs have knotty or longish shapes, and the detection rate of IFOs against previously identified YSOs is 1.4%, which should be treated as a lower limit. Four IFOs show anti-correlated peak intensities in [Fe II] and Hα, where the ratio I([Fe II])/I(Hα) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux using two different methods. The jet-driving objects are identified for three IFOs (IFO-2, -4, and -7) for which we study the relations between the outflow mass loss rate and the YSO physical parameters from the radiative transfer model fitting. The ratios of the outflow mass loss rate over the disk accretion rate for IFO-4 and -7 are consistent with the previously reported values (10–2-10+1), while the ratio is higher for IFO-2. This excess may result from underestimating the disk accretion rate. The jet-driving objects are likely to be low- or intermediate-mass stars. Other YSO physical parameters, such as luminosity and age, show reasonable relations or trends

  5. A Smoking Gun in the Carina Nebula

    CERN Document Server

    Hamaguchi, Kenji; Ezoe, Yuichiro; Townsley, Leisa; Broos, Patrick; Gruendl, Robert; Vaidya, Kaushar; White, Stephen M; Strohmayer, Tod; Petre, Rob; Chu, You-Hua

    2009-01-01

    The Carina Nebula is one of the youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for ~30 years. The soft X-ray spectrum, consistent with kT ~128 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicate that it is a ~1e6-year-old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitor of the neutron star and massive stars in the Carina Nebula, in particular Eta Carinae, are coeval. This result suggests that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star may be responsible for remnants of high energy activity seen in multiple wavelengths.

  6. A Smoking Gun in the Carina Nebula

    Science.gov (United States)

    Hamaguchi, Kenji; Corcoran, Michael F.; Ezoe, Yuichiro; Townsley, Leisa; Broos, Patrick; Gruendl, Robert; Vaidya, Kaushar; White, Stephen M.; Petre, Rob; Chu, You-Hua

    2009-01-01

    The Carina Nebula is one of thc youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for approx.30 years. The soft X-ray spectrum. consistent with kT approx.130 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicate that it is a, approx. 10(exp 6)-year-old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitor of the neutron star and massive stars in the Carina Nebula, in particular (eta)Car, are coeval. This result demonstrates that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star would be responsible for remnants of high energy activity seen in multiple wavelengths.

  7. Forming Planets in the Hostile Carina Nebula

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    Can protoplanetary disks form and be maintained around low-mass stars in the harsh environment of a highly active, star-forming nebula? A recent study examines the Carina nebula to answer this question.Crowded ClustersStars are often born in clusters that contain both massive and low-mass stars. The most massive stars in these clusters emit far-ultraviolet and extreme-ultraviolet light that irradiates the region around them, turning the surrounding area into a hostile environment for potential planet formation.Planet formation from protoplanetary disks typically requires timescales of at least 12 million years. Could the harsh radiation from massive stars destroy the protoplanetary disks around low-mass stars by photoevaporation before planets even have a chance to form?Artists impression of a protoplanetary disk. Such disks can be photoevaporated by harsh ultraviolet light from nearby massive stars, causing the disk to be destroyed before planets have a chance to form within them. [ESO/L. Calada]Turning ALMA Toward CarinaA perfect case study for exploring hostile environments is the Carina nebula, located about 7500 lightyears away and home to nearly 100 O-type stars as well as tens of thousands of lower-mass young stars. The Carina population is ~14 Myr old: old enough to form planets within protoplanetary disks, but also old enough that photoevaporation could already have wreaked havoc on those disks.Due to the dense stellar populations in Carinas clusters, this is a difficult region to explore, but the Atacama Large Millimeter-submillimeter Array (ALMA) is up to the task. In a recent study, a team of scientists led by Adal Mesa-Delgado (Pontifical Catholic University of Chile) made use of ALMAs high spatial resolution to image four regions spaced throughout Carina, searching for protoplanetary disks.Detections and Non-DetectionsTwo evaporating gas globules in the Carina nebula, 104-593 and 105-600, that each contain a protoplanetary disk. The top panels are

  8. ONE-DIMENSIONAL DYNAMICAL MODELS OF THE CARINA NEBULA BUBBLE

    International Nuclear Information System (INIS)

    We have tested the two main theoretical models of bubbles around massive star clusters, Castor et al. and Chevalier and Clegg, against observations of the well-studied Carina nebula. The Castor et al. theory overpredicts the X-ray luminosity in the Carina bubble by a factor of 60 and expands too rapidly, by a factor of 4; if the correct radius and age are used, the predicted X-ray luminosity is even larger. In contrast, the Chevalier and Clegg model underpredicts the X-ray luminosity by a factor of 10. We modify the Castor et al. theory to take into account lower stellar wind mass-loss rates, radiation pressure, gravity, and escape of or energy loss from the hot shocked gas. We argue that energy is advected rather than radiated from the bubble. We undertake a parameter study for reduced stellar mass-loss rates and for various leakage rates and are able to find viable models. The X-ray surface brightness in Carina is highest close to the bubble wall, which is consistent with conductive evaporation from cold clouds. The picture that emerges is one in which the hot gas pressure is far below that found by dividing the time-integrated wind luminosity by the bubble volume; rather, the pressure in the hot gas is set by pressure equilibrium with the photoionized gas at T = 104 K. It follows that the shocked stellar winds are not dynamically important in forming the bubbles.

  9. The violent interstellar medium associated with the Carina Nebula

    International Nuclear Information System (INIS)

    We present a detailed study of the physical conditions and chemical composition of the interstellar medium in line to HD 93205, an 03V star embedded in the Great Carina Nebula. We have identified up to six components in the ultraviolet absorption lines, spanning a velocity range of 375 km s-1. The two main high-velocity components have been found to show different relative abundance patterns. The red-shifted component shows no depletion. For the blue-shifted component, the relative abundance pattern seems difficult to explain in terms of elements locked into grains; we tentatively attribute its composition to mixing with freshly synthetized material ejected by a recent supernova explosion. Among the two low-velocity components, one has been identified with the normal interstellar gas in the disk of the Galaxy. In this component we have measured column densities of interstellar CIV and SiIV, free from contamination by circumstellar material. The other low-velocity component has been identified with the approaching part of the expanding ionized nebula around the Carina OB associations. It consists of a dense HII region in which the two conspicuous OI fine-structure lines originate

  10. Kinematics of powerful jets from intermediate-mass protostars in the Carina nebula

    CERN Document Server

    Reiter, Megan

    2014-01-01

    We present measurements of proper motions and radial velocities of four powerful Herbig-Haro (HH) jets in the Carina nebula: HH 666, HH 901, HH 902, and HH 1066. Two epochs of Hubble Space Telescope (HST) imaging separated by a time baseline of ~4.4 years provide proper motions that allow us to measure the transverse velocities of the jets, while ground-based spectra sample their Doppler velocities. Together these yield full three-dimensional space velocities. Aside from HH 666, their identification as outflows was previously inferred only from morphology in images. Proper motions now show decisively that these objects are indeed jets, and confirm that the intermediate-mass protostars identified as the candidate driving sources for HH 666 and HH 1066 are indeed the origin of these outflows. The appearance of two new knots in the HH 1066 jet suggest recent (~35 yr) changes in the accretion rate, underscoring the variable nature of accretion and outflow in the formation of intermediate-mass stars. In fact, kine...

  11. A survey of irradiated pillars, globules, and jets in the Carina nebula

    International Nuclear Information System (INIS)

    We present wide-field, deep narrowband H2, Brγ, Hα, [S ii], [O iii], and broadband I- and K-band images of the Carina star formation region. The new images provide a large-scale overview of all the H2 and Brγ emission present in over a square degree centered on this signature star-forming complex. By comparing these images with archival Hubble Space Telescope and Spitzer images we observe how intense UV radiation from O and B stars affects star formation in molecular clouds. We use the images to locate new candidate outflows and identify the principal shock waves and irradiated interfaces within dozens of distinct areas of star-forming activity. Shocked molecular gas in jets traces the parts of the flow that are most shielded from the intense UV radiation. Combining the H2 and optical images gives a more complete view of the jets, which are sometimes only visible in H2. The Carina region hosts several compact young clusters, and the gas within these clusters is affected by radiation from both the cluster stars and the massive stars nearby. The Carina Nebula is ideal for studying the physics of young H ii regions and photodissociation region (PDR), as it contains multiple examples of walls and irradiated pillars at various stages of development. Some of the pillars have detached from their host molecular clouds to form proplyds. Fluorescent H2 outlines the interfaces between the ionized and molecular gas, and after removing continuum, we detect spatial offsets between the Brγ and H2 emission along the irradiated interfaces. These spatial offsets can be used to test current models of PDRs once synthetic maps of these lines become available.

  12. A survey of irradiated pillars, globules, and jets in the Carina nebula

    Energy Technology Data Exchange (ETDEWEB)

    Hartigan, P. [Rice University, Department of Physics and Astronomy, 6100 S. Main, Houston, TX 77521-1892 (United States); Reiter, M.; Smith, N. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Bally, J. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States)

    2015-03-01

    We present wide-field, deep narrowband H{sub 2}, Brγ, Hα, [S ii], [O iii], and broadband I- and K-band images of the Carina star formation region. The new images provide a large-scale overview of all the H{sub 2} and Brγ emission present in over a square degree centered on this signature star-forming complex. By comparing these images with archival Hubble Space Telescope and Spitzer images we observe how intense UV radiation from O and B stars affects star formation in molecular clouds. We use the images to locate new candidate outflows and identify the principal shock waves and irradiated interfaces within dozens of distinct areas of star-forming activity. Shocked molecular gas in jets traces the parts of the flow that are most shielded from the intense UV radiation. Combining the H{sub 2} and optical images gives a more complete view of the jets, which are sometimes only visible in H{sub 2}. The Carina region hosts several compact young clusters, and the gas within these clusters is affected by radiation from both the cluster stars and the massive stars nearby. The Carina Nebula is ideal for studying the physics of young H ii regions and photodissociation region (PDR), as it contains multiple examples of walls and irradiated pillars at various stages of development. Some of the pillars have detached from their host molecular clouds to form proplyds. Fluorescent H{sub 2} outlines the interfaces between the ionized and molecular gas, and after removing continuum, we detect spatial offsets between the Brγ and H{sub 2} emission along the irradiated interfaces. These spatial offsets can be used to test current models of PDRs once synthetic maps of these lines become available.

  13. A Census of the Carina Nebula -- II. Energy Budget and Global Properties of the Nebulosity

    OpenAIRE

    Smith, Nathan; Brooks, Kate J.

    2007-01-01

    The first paper in this series took a direct census of energy input from the known OB stars in the Carina Nebula, and in this paper we study the global properties of the surrounding nebulosity. We find that the total IR luminosity of Carina is about 1.2E7 Lsun, accounting for only about 50-60% of the known stellar luminosity from Paper I. Similarly, the ionizing photon luminosity -- (abridged; many important details omitted). Synchronized star formation around the periphery of Carina provides...

  14. Simultaneous Production of Disk and Lobes: A Single-Wind MHD Model for the Eta Carinae Nebula

    CERN Document Server

    Matt, S

    2004-01-01

    The luminous blue variable Eta Carinae is surrounded by a complex and highly structured nebula of ejected material. The best-studied and axisymmetric components of this outflow consist of bipolar lobes (the ``homunculus'') and an equatorial ``skirt.'' Recent proper motion measurements suggest that the skirt was ejected at the same time as the lobes, contrary to the assumptions of all current theoretical models for the formation of the nebula (which use the skirt to collimate stellar winds into lobes). We present a magnetohydrodynamic (MHD) stellar wind model that produces an outflowing disk and bipolar lobes in a single, steady-state wind. The basic model consists of a wind from a rotating star with a rotation-axis-aligned dipole magnetic field. The azimuthal component of the magnetic field, generated by stellar rotation, compresses the wind toward the equator and also toward the rotation axis, simultaneously producing an outflowing disk and jet. We use numerical MHD simulations to study the wind for various ...

  15. H.E.S.S. observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gallant, Y A; Garrigoux, T; Gast, H; Gèrard, L; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Grondin, M -H; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; Montmerle, T

    2012-01-01

    The massive binary system Eta Carinae and the surrounding HII complex, the Carina Nebula, are potential particle acceleration sites from which very-high-energy (VHE; E > 100 GeV) \\gamma-ray emission could be expected. This paper presents data collected during VHE \\gamma-ray observations with the H.E.S.S. telescope array from 2004 to 2010, which cover a full orbit of Eta Carinae. In the 33.1-hour data set no hint of significant \\gamma-ray emission from Eta Carinae has been found and an upper limit on the \\gamma-ray flux of 7.7 x 10-13 ph cm-2 s-1 (99% confidence level) is derived above the energy threshold of 470 GeV. Together with the detection of high-energy (HE; 0.1 GeV > E > 100 GeV) \\gamma-ray emission by the Fermi-LAT up to 100 GeV, and assuming a continuation of the average HE spectral index into the VHE domain, these results imply a cut-off in the \\gamma-ray spectrum between the HE and VHE \\gamma-ray range. This could be caused either by a cut-off in the accelerated particle distribution or by severe \\...

  16. Bipolar Outflows and the Evolution of Stars

    OpenAIRE

    Frank, Adam

    1998-01-01

    Hypersonic bipolar outflows are a ubiquitous phenomena associated with both young and highly evolved stars. Observations of Planetary Nebulae, the nebulae surrounding Luminous Blue Variables such as $\\eta$ Carinae, Wolf Rayet bubbles, the circumstellar environment of SN 1987A and Young Stellar Objects all revealed high velocity outflows with a wide range of shapes. In this paper I review the current state of our theoretical understanding of these outflows. Beginning with Planetary Nebulae con...

  17. Collimated Outflows in the Stingray Nebula (He 3-1357)

    Science.gov (United States)

    Bobrowsky, M.; Sahu, K. C.; Parthasarathy, M.; Garcia-Lario, P.

    1997-12-01

    Observations over the past four decades have revealed significant changes in the spectrum of the Stingray Nebula (He 3-1357). Here we present HST images and spectra showing the most recent developments. In 1950, Henize saw only Hα in emission; but more recent observations by Parthasarathy et al. in 1992 showed strong forbidden lines consistent with a young planetary nebula. The spherically aberrated 1992 HST images, in which Bobrowsky first optically resolved the nebula, showed a compact nebula surrounding the central star. Nebular gas appeared most strongly concentrated in an ellipse with its major axis subtending 1.('') 6 from NE to SW. If this ellipse is actually a circular ring viewed obliquely, then our line of sight is inclined from the symmetry axis by 56deg . Above and below the ring of gas are two bubbles containing lower-density gas. At the tip of each bubble, there is a hole where the gas inside the bubbles has broken through and is now escaping. While images of focused jets have been obtained previously (Borkowski et al.), this is the first case where the nebular structure responsible for the focusing of an outflow can be clearly seen. The windblown appearance of the nebula is consistent with the blueshifted Si IV (1394-1403 Angstroms) and Al III (1855-1863 Angstroms) doublets observed by Parthasarathy et al. that indicated the presence of a strong stellar wind. The N V (1239-1243 Angstroms) to C IV (1548-1551 Angstroms) ratio has increased in recent years, consistent with a young nebula becoming increasingly ionized. Our new spectra reveal additional developments that show the real-time development of this young nebula. Finally, the new HST Planetary Camera images of the nebula show detailed structure indicating a much more complex object than previously known, including the presence of a companion star 0.('') from the central star.

  18. Chandra X-ray observation of the HII region Gum 31 in the Carina Nebula complex

    CERN Document Server

    Preibisch, T; Townsley, L; Broos, P; Ratzka, T

    2014-01-01

    (abridged) We used the Chandra observatory to perform a deep (70 ksec) X-ray observation of the Gum 31 region and detected 679 X-ray point sources. This extends and complements the X-ray survey of the central Carina nebula regions performed in the Chandra Carina Complex Project. Using deep near-infrared images from our recent VISTA survey of the Carina nebula complex, our Spitzer point-source catalog, and optical archive data, we identify counterparts for 75% of these X-ray sources. Their spatial distribution shows two major concentrations, the central cluster NGC 3324 and a partly embedded cluster in the southern rim of the HII region, but majority of X-ray sources constitute a rather homogeneously distributed population of young stars. Our color-magnitude diagram analysis suggests ages of ~1-2 Myr for the two clusters, whereas the distributed population shows a wider age range up to ~10 Myr. We also identify previously unknown companions to two of the three O-type members of NGC 3324 and detect diffuse X-ra...

  19. A Census of the Carina Nebula -- II. Energy Budget and Global Properties of the Nebulosity

    CERN Document Server

    Smith, Nathan

    2007-01-01

    The first paper in this series took a direct census of energy input from the known OB stars in the Carina Nebula, and in this paper we study the global properties of the surrounding nebulosity. We find that the total IR luminosity of Carina is about 1.2E7 Lsun, accounting for only about 50-60% of the known stellar luminosity from Paper I. Similarly, the ionizing photon luminosity -- (abridged; many important details omitted). Synchronized star formation around the periphery of Carina provides a strong case that star formation here was indeed triggered by stellar winds and UV radiation. This second generation appears to involve a cascade toward preferentially intermediate- and low-mass stars, but this may soon change when eta Car and its siblings explode. If the current reservoir of atomic and molecular gas can be tapped at that time, massive star formation may be rejuvinated around the periphery of Carina much as if it were a young version of Gould's Belt. Also, when these multiple SNe occur, the triggered se...

  20. On the 3D structure of the nebula around \\eta-Carinae

    CERN Document Server

    Lorenzo, Zaninetti

    2010-01-01

    The asymmetric shape of the nebula around $\\eta$-Carinae (Homunculus) can be explained by a spherical expansion in a non-homogeneous medium. Two models are analyzed: an exponential and an inverse power law dependence for the density as a function of distance from the equatorial plane. The presence of a medium with variable density along the polar direction progressively converts the original spherical shell into a bipolar nebula. In the case of the nebula around $\\eta$-Carinae, we know the time elapsed since the great outburst in 1840. An exact match between observed radii and velocities can be obtained by fine tuning the parameters involved, such as initial radius, initial velocity and the typical scale that characterizes the gradient in density. The observed radius and velocity of the Homunculus as a function of the polar angle in spherical coordinates can be compared with the corresponding simulated data by introducing the efficiency in a single or multiple directions. Once the 3D spatial structure of the ...

  1. Why a Single-Star Model Cannot Explain the Bipolar Nebula of Eta Carinae

    OpenAIRE

    Soker, Noam

    2004-01-01

    I examine the angular momentum evolution during the 1837-1856 Great Eruption of the massive star Eta Carinae. I find that the new estimate of the mass blown during that eruption implies that the envelope of Eta Car substantially spun-down during the 20 years eruption. Single-star models, most of which require the envelope to rotate close to the break-up velocity, cannot account for the bipolar nebula (the Homunculus) formed from matter expelled in that eruption. The kinetic energy and momentu...

  2. A Catalog of Chandra X-ray Sources in the Carina Nebula

    CERN Document Server

    Broos, Patrick S; Feigelson, Eric D; Getman, Konstantin V; Garmire, Gordon P; Preibisch, Thomas; Smith, Nathan; Babler, Brian L; Hodgkin, Simon; Indebetouw, Rémy; Irwin, Mike; King, Robert R; Lewis, Jim; Majewski, Steven R; McCaughrean, Mark J; Meade, Marilyn R; Zinnecker, Hans

    2011-01-01

    We present a catalog of ~14,000 X-ray sources observed by the ACIS instrument on the Chandra X-ray Observatory within a 1.42 square degree survey of the Great Nebula in Carina, known as the Chandra Carina Complex Project (CCCP). This study appears in a Special Issue of the ApJS devoted to the CCCP. Here, we describe the data reduction and analysis procedures performed on the X-ray observations, including calibration and cleaning of the X-ray event data, point source detection, and source extraction. The catalog appears to be complete across most of the field to an absorption-corrected total-band luminosity of ~10^{30.7} erg/s for a typical low-mass pre-main sequence star. Counterparts to the X-ray sources are identified in a variety of visual, near-infrared, and mid-infrared surveys. The X-ray and infrared source properties presented here form the basis of many CCCP studies of the young stellar populations in Carina.

  3. Image of the Eta Carinae Nebula Taken by the High Energy Astronomy Observatory (HEAO)-2

    Science.gov (United States)

    1979-01-01

    This image is an x-ray view of Eta Carinae Nebula showing bright stars taken with the High Energy Astronomy Observatory (HEAO)-2/Einstein Observatory. The Eta Carinae Nebula is a large and complex cloud of gas, crisscrossed with dark lanes of dust, some 6,500 light years from Earth. Buried deep in this cloud are many bright young stars and a very peculiar variable star. The HEAO-2, the first imaging and largest x-ray telescope built to date, was capable of producing actual photographs of x-ray objects. Shortly after launch, the HEAO-2 was nicknamed the Einstein Observatory by its scientific experimenters in honor of the centernial of the birth of Albert Einstein, whose concepts of relativity and gravitation have influenced much of modern astrophysics, particularly x-ray astronomy. The HEAO-2, designed and developed by TRW, Inc. under the project management of the Marshall Space Flight Center, was launched aboard an Atlas/Centaur launch vehicle on November 13, 1978.

  4. Extended Red Objects and Stellar Wind Bow Shocks in the Carina Nebula

    CERN Document Server

    Sexton, Remington O; Smith, Nathan; Babler, Brian L; Meade, Marilyn R; Rudolph, Alexander L

    2014-01-01

    We report the results of infrared photometry on 39 extended red objects (EROs) in the Carina Nebula, observed with the Spitzer Space Telescope. Most EROs are identified by bright, extended 8.0 um emission, which ranges from 10'' to 40'' in size, but our sample also includes 4 EROs identified by extended 24 um emission. Of particular interest are nine EROs associated with late O or early B-type stars and characterized by arc-shaped morphology, suggesting dusty, stellar-wind bow shocks. These objects are preferentially oriented towards the central regions of the Carina Nebula, suggesting that these bow shocks are generally produced by the interactions of OB winds with the bulk expansion of the H II region rather than high proper motion. We identify preferred regions of mid-infrared color space occupied by our bow shock candidates, which also contain bow shock candidates in M17 and RCW 49 but are well-separated from polycyclic aromatic hydrocarbon emission or circumstellar discs. Color cuts identify an additiona...

  5. Gaia-ESO Survey: Gas dynamics in the Carina Nebula through optical emission lines

    CERN Document Server

    Damiani, F; Magrini, L; Prisinzano, L; Mapelli, M; Micela, G; Kalari, V; Apellaniz, J Maiz; Gilmore, G; Randich, S; Alfaro, E; Flaccomio, E; Koposov, S; Klutsch, A; Lanzafame, A C; Pancino, E; Sacco, G G; Bayo, A; Carraro, G; Casey, A R; Costado, M T; Franciosini, E; Hourihane, A; Lardo, C; Lewis, J; Monaco, L; Morbidelli, L; Worley, C; Zaggia, S; Zwitter, T; Dorda, R

    2016-01-01

    We present observations from the Gaia-ESO Survey in the lines of H$\\alpha$, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV $>$50 km/s) gas emission. We show that gas giving rise to H$\\alpha$ and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around $\\eta$ Car, the Trumpler 14...

  6. Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.

    2016-06-01

    Aims: We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods: We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results: We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These "shells" are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey (program 188.B-3002).Full Tables 1-3 are only available at the CDS via anonymous ftp to http

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-01

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

  8. The Nature and Frequency of Outflows from Stars in the Central Orion Nebula Cluster

    CERN Document Server

    O'Dell, C R; Henney, W J; Peimbert, M; Garcia-Diaz, Ma T; Rubin, Robert H

    2015-01-01

    Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig-Haro objects known within the inner Orion Nebula. We find that the best-known Herbig-Haro shocks originate from a relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blue shifted because the redshifted outflows pass into the optically thick Photon Dominated Region behind the nebula. There are two regions from which optical outflow...

  9. Outflows, Dusty Cores, and a Burst of Star Formation in the North America and Pelican Nebulae

    CERN Document Server

    Bally, John; Probst, Ron; Reipurth, Bo; Shirley, Yancy L; Stringfellow, Guy S

    2014-01-01

    We present observations of near-infrared 2.12 micro-meter molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000 / IC 5070 / W80 HII region are among the most active sites of on-going star formation in the Solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionization front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80 degrees. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The `Gulf of Mexico' located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen ...

  10. The Carina Nebula and Gum 31 molecular complex - I. Molecular gas distribution, column densities, and dust temperatures

    Science.gov (United States)

    Rebolledo, David; Burton, Michael; Green, Anne; Braiding, Catherine; Molinari, Sergio; Wong, Graeme; Blackwell, Rebecca; Elia, Davide; Schisano, Eugenio

    2016-03-01

    We report high-resolution observations of the 12CO(1-0) and 13CO(1-0) molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of The Mopra Southern Galactic Plane CO Survey. We cover 8 deg2 from l = 285° to 290°, and from b = -1.5° to +0.5°. The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from 6.3 × 1020 to 1.4 × 1023 cm-2, while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a lognormal function for a limited range of column densities. A high-column-density tail is clearly evident for the gas column density distribution, which appears to be a common feature in regions with active star formation. There are regional variations in the fraction of the mass recovered by the CO emission lines with respect to the total mass traced by the dust emission. These variations may be related to changes in the radiation field strength, variation of the atomic to molecular gas fraction across the observed region, differences in the CO molecule abundance with respect to H2, and evolutionary stage differences of the molecular clouds that compose the Carina Nebula-Gum 31 complex.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-01

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

  13. Discovery of collimated bipolar outflows in the planetary nebula Th 2-A

    CERN Document Server

    Danehkar, Ashkbiz

    2015-01-01

    We present a comprehensive set of spatially resolved, integral field spectroscopic mapping of the Wolf-Rayet planetary nebula Th 2-A, obtained using the Wide Field Spectrograph on the Australian National University 2.3-m telescope. Velocity-resolved H$\\alpha$ channel maps with a resolution of 20 km s$^{-1}$ allow us to identify different kinematic components within the nebula. This information is used to develop a three-dimensional morpho-kinematic model of the nebula using the interactive kinematic modeling tool SHAPE. These results suggest that Th 2-A has a thick toroidal shell with an expansion velocity of 40 $\\pm$ 10 km s$^{-1}$, and a thin prolate ellipsoid with collimated bipolar outflows toward its axis reaching velocities in the range of 70-110 km s$^{-1}$, with respect to the central star. The relationship between its morpho-kinematic structure and peculiar [WO]-type stellar characteristics deserves further investigation.

  14. The first "water fountain" collimated outflow in a planetary nebula

    CERN Document Server

    Gomez, J F; Bendjoya, Ph; Rizzo, J R; Miranda, L F; Green, J A; Uscanga, L; Garcia-Garcia, E; Lagadec, E; Guerrero, M A; Ramos-Larios, G

    2014-01-01

    "Water fountains" (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-Asymptotic Giant Branch and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103--5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103-5754 is an evolved object, while the mid-IR spectrum displays unambiguous [NeII] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range ~75 km/s and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and k...

  15. THE SHAPING EFFECT OF COLLIMATED FAST OUTFLOWS IN THE EGG NEBULA

    International Nuclear Information System (INIS)

    We present high angular resolution observations of the HC3N J = 5-4 line from the Egg nebula, which is the archetype of proto-planetary nebulae (PPNs). We find that the HC3N emission in the approaching and receding portion of the envelope traces a clumpy hollow shell, similar to that seen in normal carbon-rich envelopes. Near the systemic velocity, the hollow shell is fragmented into several large blobs or arcs with missing portions correspond spatially to locations of previously reported high-velocity outflows in the Egg nebula. This provides direct evidence for the disruption of the slowly expanding envelope ejected during the AGB phase by the collimated fast outflows initiated during the transition to the PPN phase. From modeling the HC3N distribution, we could reproduce qualitatively the spatial kinematics of the HC3N J = 5-4 emission using a HC3N shell with two pairs of cavities cleared by the collimated high-velocity outflows along the polar direction and in the equatorial plane. We infer a relatively high abundance of HC3N/H2 ∼ 3 x 10-6 for an estimated mass-loss rate of 3 x 10-5 M sun yr-1 in the HC3N shell. The high abundance of HC3N and the presence of some weaker J = 5-4 emission in the vicinity of the central post-AGB star suggest an unusually efficient formation of this molecule in the Egg nebula.

  16. The Spectral Temperature of Optically Thick Outflows with Application to Light Echo Spectra from $\\eta$~Carinae's Giant Eruption

    CERN Document Server

    Owocki, Stanley P

    2016-01-01

    The detection by Rest et al. (2012) of light echoes from $\\eta$ Carinae has provided important new observational constraints on the nature of its 1840's era giant eruption. Spectra of the echoes suggest a relatively cool spectral temperature of about 5500K, lower than the lower limit of about 7000K suggested in the optically thick wind outflow analysis of Davidson (1987). This has lead to a debate about the viability of this steady wind model relative to alternative, explosive scenarios. Here we present an updated analysis of the wind outflow model using newer low-temperature opacity tabulations and accounting for the stronger mass loss implied by the $>$10 Msun mass now inferred for the Homunculus. A major conclusion is that, because of the sharp drop in opacity due to free electron recombination for $T<$6500K, a low temperature of about 5000K is compatible with, and indeed expected from, a wind with the extreme mass loss inferred for the eruption. Within a spherical gray model in radiative equilibrium, w...

  17. HST images of dark giants as dark matter: Part.I The black cocoon stars of Carina Nebula region

    International Nuclear Information System (INIS)

    In an evolutionary scenario, the existence of isolated dark giant objects known as Post M latest spectral type stars (1) (or black cocoon stars) are in the last stage of their life and, as extremely advanced old age objects, they cease to be stars. The photographic images of Carina nebula taken by the Hubble Space Telescope (HST) have been used to detect the post M-Iatest stars as dark silhouettes. The luminosity attenuation equation of M late stars (1), A = αS3, points out the baryonic dark matter envelopes the oldest red giants that produce earlier dark giants. This equation says that when the red giant star finishes to produce baryonic dark matter, the central star is extinguishing and transforms into dark giants and dusty globules that disperse cool gaseous matter into the interstellar space. These old dark objects have a size from 400 to 600 astronomical units (AU). The advanced dark giants, the dusty dark giants, might not contain a star within the molecular cloud that envelops it. In this case, the dark giants might produce the smaller and less massive dark globules of the Thackeray's globules type (less than 4 solar masses) where, Reupurth et al. (2) found that these globules are now in an advanced stage of disintegration and they found no evidence of star formation in any of these objects. The high-resolution of the Hubble images allows: The observation of isolated dark giants, dusty globules with central dark giants, the observation of partial eclipses or transiting of giant stars and the estimation of linear and angular diameters (ionised cocoons) of giant stellar objects. The dark giants of the image are identified them as objects with observed angular diameter. The large quantity of dark giants in a small sector of the sky suggests that they are densely populated (population stars III) and ubiquitous in the galactic disc. They can be located in isolated form or associated in dense Conglomerations of dark giants. At the same time, conglomerates of dark

  18. The triple-shell structure and collimated outflows of the planetary nebula NGC 6891

    CERN Document Server

    Guerrero, M; Manchado, A; Vázquez, R A

    1999-01-01

    Narrow-band H$\\alpha$ and [N {\\sc ii}] images and high-dispersion spatially-resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids with similar major to minor axial ratios, but different spatial orientations. The kinematical ages of the intermediate shell and halo are 4,800 and 28,000 years, respectively. The inter-shell time lapse is in good agreement with the evolutionary inter-pulse time lapse. A highly collimated outflow is observed to protrude from the tips of the major axis of the inner nebula and impact on the outer edge of the intermediate shell. Kinematics and excitation of this outflow provide conclusive evidence that it is deflected during the interaction with the outer edge of the intermediate shell. At the same time, both the kinematics and the morphology of the int...

  19. The Carina Nebula and Gum 31 molecular complex: I. Molecular gas distribution, column densities and dust temperatures

    CERN Document Server

    Rebolledo, David; Green, Anne; Braiding, Catherine; Molinari, Sergio; Wong, Graeme; Blackwell, Rebecca; Elia, Davide; Schisano, Eugenio

    2015-01-01

    We report high resolution observations of the $^{12}$CO$(1\\rightarrow0)$ and $^{13}$CO$(1\\rightarrow0)$ molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of the The Mopra Southern Galactic Plane CO Survey. We cover 8 deg$^2$ from $l = 285^{\\circ}$ to 290$^{\\circ}$, and from $b = -1.5^{\\circ}$ to +0.5$^{\\circ}$. The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from $6.3\\times\\ 10^{20}$ to $1.4\\times 10^{23}$ cm$^{-2}$, while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a log-normal function for a limited range of column densities. A high-column density tail is clearly evident for the gas column density dis...

  20. Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27

    CERN Document Server

    McCandliss, S R; Lupu, R E; Burgh, E B; Sembach, K; Kruk, J; Andersson, B G; Feldman, P D; Candliss, Stephan R. Mc; France, Kevin; Lupu, Roxana E.; Burgh, Eric B.; Sembach, Kenneth; Kruk, Jeffrey; Feldman, Paul D.

    2007-01-01

    High resolution spectroscopy with FUSE and STIS of atomic and molecular velocity stratification in the nebular outflow of M27 challenge models for the abundance kinematics in planetary nebulae. The simple picture of a very high speed (~ 1000 km/s), high ionization, radiation driven stellar wind surrounded by a slower (~ 10 km/s) mostly molecular outflow, with low ionization and neutral atomic species residing at the wind interaction interface, is not supported... We find ...there is a fast (33 -- 65 km/s) low ionization zone, surrounding a slower ( H_2^+ + e -> H(1s) + H (nl)), which ultimately produces fluorescence of Ha and Lya. In the optically thin limit at the inferred radius of the velocity transition we find dissociation of H_2 by stellar Lyc photons is an order of magnitude more efficient than spontaneous dissociation by far-UV photons. We suggest that the importance of this H_2 destruction process in HII regions has been overlooked.

  1. Multiple and Precessing Collimated Outflows in the Planetary Nebula IC 4634

    CERN Document Server

    Guerrero, M A; Riera, A; Velazquez, P F; Olguin, L; Vázquez, R; Chu, Y -H; Raga, A; Benitez, G

    2008-01-01

    With its remarkable double-S shape, IC 4634 is an archetype of point-symmetric planetary nebulae (PN). In this paper, we present a detailed study of this PN using archival HST WFPC2 and ground-based narrow-band images to investigate its morphology, and long-slit spectroscopic observations to determine its kinematics and to derive its physical conditions and excitation. The data reveal new structural components, including a distant string of knots distributed along an arc-like feature 40"-60" from the center of the nebula, a skin of enhanced [O III]/H-alpha ratio enveloping the inner shell and the double-S feature, and a triple-shell structure. The spatio-kinematical study also finds an equatorial component of the main nebula that is kinematically independent from the bright inner S-shaped arc. We have investigated in detail the bow shock-like features in IC 4634 and found that their morphological, kinematical and emission properties are consistent with the interaction of a collimated outflow with surrounding ...

  2. The peculiar isolated neutron star in the Carina Nebula - Deep XMM-Newton and ESO-VLT observations of 2XMM J104608.7-594306

    CERN Document Server

    Pires, Adriana Mancini; Turolla, Roberto; Schwope, Axel; Pilia, Maura; Treves, Aldo; Popov, Sergei B; Janot-Pacheco, Eduardo

    2012-01-01

    While fewer in number relative to the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) -- which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs) and central compact objects in supernova remnants (CCOs) -- represent a key element to understand the neutron star phenomenology. We report here on the results of an observational campaign aiming at studying the properties of the source 2XMM J104608.7-594306. Its evolutionary state is investigated by means of deep dedicated observations obtained with XMM-Newton, the ESO Very Large Telescope as well as on publicly available gamma-ray data from the Fermi and AGILE missions. The observations confirm previous expectations and further reveal a unique object. The source, likely within the Carina Nebula, shows a soft spectrum with absorption features and no magnetospheric emission. The optical counterpart is fainter than V=27 and no gamma-ray emission is significantly dete...

  3. The collimated outflows of the planetary nebula Hu1-2: proper motion and radial velocity measurements

    CERN Document Server

    Miranda, L F; Guerrero, M A; Riera, A

    2011-01-01

    Hu\\,1-2 is a planetary nebula that contains an isolated knot located northwestern of the main nebula, which could be related to a collimated outflow. We present a subsarcsecond H$\\alpha$+[N\\,{\\sc ii}] image and a high-resolution, long-slit spectrum of Hu\\,1-2 that allow us to identify the southeastern counterpart of the northwestern knot and to establish their high velocity ($>$ 340 km\\,s$^{-1}$), collimated bipolar outflow nature. The detection of the northwestern knot in POSS red plates allows us to carry out a proper motion analysis by combining three POSS red plates and two narrow-band H$\\alpha$+[N\\,{\\sc ii}] CCD images, with a time baseline of $\\simeq$ 57 yr. A proper motion of 20 $\\pm$ 6\\,mas\\,yr$^{-1}$ along position angle 312$^{\\circ}$ $\\pm$ 15$^{\\circ}$, and a dynamical age of 1375$^{+590}$\\llap{$_{-320}$}\\,yr are obtained for the bipolar outflow. The measured proper motion and the spatio-kinematical properties of the bipolar outflow yield a lower limit of 2.7\\,kpc for the distance to Hu\\,1-2.

  4. A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Preplanetary Nebula IRAS 22036+5306

    Science.gov (United States)

    Sahai, Raghvendra; Young, K.; Patel, N. A.; Sanchez Contreras, C.; Morris, M.

    2006-01-01

    We report high angular resolution (approx.1") CO J=3-2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (approx.10") CO and 13CO J=1-0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J=3-2 observations show the presence of a very fast (approx.220 km/s), highly collimated, massive (0.03 Solar Mass) bipolar outflow with a very large scalar momentum (about 10(exp 39) g cm/s), and the characteristic spatiokinematic structure of bow shocks at the tips of this outflow. The H(alpha) line shows an absorption feature blueshifted from the systemic velocity by approx.100 km/s, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I22036, as in most PPNs, cannot be driven by radiation pressure. We find an unresolved source of submillimeter (and millimeter-wave) continuum emission in I22036, implying a very substantial mass (0.02-0.04 Solar Mass) of large (radius > or approx.1 mm), cold ( or approx.4 Solar Mass) progenitor in which hot-bottom-burning has occurred.

  5. Hu1-2: a metal-poor bipolar planetary nebula with fast collimated outflows

    CERN Document Server

    Fang, Xuan; Miranda, Luis F; Riera, Angels; Velazquez, Pablo F; Raga, Alejandro C

    2015-01-01

    We present narrow-band optical and near-IR imaging and optical long-slit spectroscopic observations of Hu1-2, a Galactic planetary nebula (PN) with a pair of [N II]-bright, fast-moving (> 340 km/s) bipolar knots. Intermediate-dispersion spectra are used to derive physical conditions and abundances across the nebula, and high-dispersion spectra to study the spatio-kinematical structure. Generally Hu1-2 has high He/H (~0.14) and N/O ratios (~0.9), typical of Type I PNe. On the other hand, its abundances of O, Ne, S, and Ar are low as compared with the average abundances of Galactic bulge and disc PNe. The position-velocity maps can be generally described as an hour-glass shaped nebula with bipolar expansion, although the morphology and kinematics of the innermost regions cannot be satisfactorily explained with a simple, tilted equatorial torus. The spatio-kinematical study confines the inclination angle of its major axis to be within 10 degrees of the plane of sky. As in the irradiated bow-shocks of IC4634 and ...

  6. THE FIRST ''WATER FOUNTAIN'' COLLIMATED OUTFLOW IN A PLANETARY NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, José F.; Miranda, Luis F.; Guerrero, Martín A. [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Suárez, Olga; Bendjoya, Philippe; Lagadec, Eric [Laboratoire Lagrange, UMR 7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06304 Nice (France); Rizzo, J. Ricardo; García-García, Enrique [Centro de Astrobiología (INTA-CSIC), Ctra. M-108, km. 4, E-28850 Torrejón de Ardoz (Spain); Green, James A. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Uscanga, Lucero [Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Athens (Greece); Ramos-Larios, Gerardo [Instituto de Astronomía y Meteorología, Av. Vallarta No. 2602, Col. Arcos Vallarta, C.P. 44130 Guadalajara, Jalisco (Mexico)

    2015-02-01

    ''Water fountains'' (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-asymptotic giant branch (post-AGB) and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103–5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103–5754 is an evolved object, while the mid-IR spectrum displays unambiguous [Ne II] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range (≅ 75 km s{sup –1}) and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and kinematical distribution of the maser emission in this object are significantly different from those in other WFs. Moreover, the velocity distribution of the maser emission shows a ''Hubble-like'' flow (higher velocities at larger distances from the central star), consistent with a short-lived, explosive mass-loss event. This velocity pattern is not seen in other WFs (which are presumably in earlier evolutionary stages). We therefore suggest that we are witnessing a fundamental change of mass-loss processes in WFs, with water masers being pumped by steady jets in post-AGB stars, but tracing explosive/ballistic events as the object enters the PN phase.

  7. THE FIRST ''WATER FOUNTAIN'' COLLIMATED OUTFLOW IN A PLANETARY NEBULA

    International Nuclear Information System (INIS)

    ''Water fountains'' (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-asymptotic giant branch (post-AGB) and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103–5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103–5754 is an evolved object, while the mid-IR spectrum displays unambiguous [Ne II] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range (≅ 75 km s–1) and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and kinematical distribution of the maser emission in this object are significantly different from those in other WFs. Moreover, the velocity distribution of the maser emission shows a ''Hubble-like'' flow (higher velocities at larger distances from the central star), consistent with a short-lived, explosive mass-loss event. This velocity pattern is not seen in other WFs (which are presumably in earlier evolutionary stages). We therefore suggest that we are witnessing a fundamental change of mass-loss processes in WFs, with water masers being pumped by steady jets in post-AGB stars, but tracing explosive/ballistic events as the object enters the PN phase

  8. High-velocity collimated outflows in planetary nebulae NGC 6337, He 2-186, and K 4-47

    CERN Document Server

    Corradi, R L M; Villaver, E; Mampaso, A; Perinotto, M; Schwarz, H E; Zanin, C; Corradi, Romano L.M.; Goncalves, Denise R.; Villaver, Eva; Mampaso, Antonio; Perinotto, Mario; Schwarz, Hugo E.; Zanin, Caterina

    2000-01-01

    We have obtained narrow-band images and high-resolution spectra of the planetary nebulae NGC 6337, He 2-186, and K 4-47, with the aim of investigating the relation between their main morphological components and several low-ionization features present in these nebulae. The data suggest that NGC 6337 is a bipolar PN seen almost pole on, with polar velocities higher than 200 km/s. The bright inner ring of the nebula is interpreted to be the "equatorial" density enhancement. It contains a number of low-ionization knots and outward tails that we ascribe to dynamical instabilities leading to fragmentation of the ring or transient density enhancements due to the interaction of the ionization front with previous density fluctuations in the ISM. The lobes show a pronounced point-symmetric morphology and two peculiar low-ionization filaments whose nature remains unclear. The most notable characteristic of He 2-186 is the presence of two high-velocity (higher than 135 km/s) knots from which an S-shaped lane of emission...

  9. Sculpting an AGB Mass-Loss Envelope into a Bipolar Planetary Nebula: High-Velocity Outflows in V Hydrae

    CERN Document Server

    Sahai, Raghvendra; Hinkle, Kenneth

    2009-01-01

    We have carried out high-resolution spectroscopic observations of the carbon star V Hya, covering the 4.6 micron band of CO. These data, taken over 7 epochs, show that the circumstellar environment of V Hya consists of a complex high-velocity (HV) outflow containing at least six kinematic components with expansion velocities ranging between 70 and 120 km/s, together with a slow-moving normal outflow at about 10 km/s. Physical changes occur in the HV outflow regions on a time-scale as short as two days, limiting their extent to < ~ 10^{16} cm. The intrinsic line-width for each HV component is quite large (6-8 km/s) compared to the typical values (~1 km/s) appropriate for normal AGB circumstellar envelopes (CSEs), due to excess turbulence and/or large velocity gradients resulting from the energetic interaction of the HV outflow with the V Hya CSE. We have modelled the absorption features to set constraints on the temperature distribution in, and the mass ejection-rates for gas in the main HV components.

  10. Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

    Science.gov (United States)

    Portegies Zwart, S. F.; van den Heuvel, E. P. J.

    2016-03-01

    We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive third companion star, which is the current binary companion in the Eta Carinae system. We come to this conclusion by a combination of theoretical arguments supported by computer simulations using the Astrophysical Multipurpose Software Environment. According to this model the ˜90 M⊙ present primary star of the highly eccentric Eta Carinae binary system is the product of this merger, and its ˜30 M⊙ companion originally was the third star in the system. In our model, the Homunculus nebula was produced by an extremely enhanced stellar wind, energized by tidal energy dissipation prior to the merger, which enormously boosted the radiation-driven wind mass-loss. The current orbital plane is then aligned with the equatorial plane of the Homunculus, and the symmetric lobes are roughly aligned with the argument of periastron of the current Eta Carina binary. The merger itself then occurred in 1838, which resulted in a massive asymmetric outflow in the equatorial plane of the Homunculus. The 1843 outburst can in our model be attributed to the subsequent encounter when the companion star (once the outermost star in the triple system) plunges through the bloated envelope of the merger product, once when it passed periastron again. We predict that the system has an excess space velocity of order 50 km s-1 in the equatorial plane of the Homunculus. Our triple model gives a viable explanation for the high runaway velocities typically observed in LBVs.

  11. Waiting in the Wings: Reflected X-ray Emission from the Homunculus Nebula

    CERN Document Server

    Corcoran, M F; Gull, T R; Davidson, K; Petre, R; Hillier, D J; Smith, N; Damineli, A; Morse, J A; Walborn, N R; Verner, E; Collins, N; White, S; Pittard, J M; Weis, K; Bomans, D; Butt, Y

    2004-01-01

    We report the first detection of X-ray emission associated with the Homunculus Nebula which surrounds the supermassive star Eta Carinae. The emission is characterized by a temperature in excess of 100 MK, and is consistent with scattering of the time-delayed X-ray flux associated with the star. The nebular emission is bright in the northwestern lobe and near the central regions of the Homunculus, and fainter in the southeastern lobe. We also report the detection of an unusually broad Fe K fluorescent line, which may indicate fluorescent scattering off the wind of a companion star or some other high velocity outflow. The X-ray Homunculus is the nearest member of the small class of Galactic X-ray reflection nebulae, and the only one in which both the emitting and reflecting sources are distinguishable.

  12. THE CHANDRA CARINA COMPLEX PROJECT: DECIPHERING THE ENIGMA OF CARINA'S DIFFUSE X-RAY EMISSION

    International Nuclear Information System (INIS)

    We present a 1.42 deg2 mosaic of diffuse X-ray emission in the Great Nebula in Carina from the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer camera. After removing >14,000 X-ray point sources from the field, we smooth the remaining unresolved emission, tessellate it into segments of similar apparent surface brightness, and perform X-ray spectral fitting on those tessellates to infer the intrinsic properties of the X-ray-emitting plasma. By modeling faint resolved point sources, we estimate the contribution to the extended X-ray emission from unresolved point sources and show that the vast majority of Carina's unresolved X-ray emission is truly diffuse. Line-like correlated residuals in the X-ray spectral fits suggest that substantial X-ray emission is generated by charge exchange at the interfaces between Carina's hot, rarefied plasma and its many cold neutral pillars, ridges, and clumps.

  13. [Fe II] jets from intermediate-mass protostars in Carina

    CERN Document Server

    Reiter, Megan; Bally, John

    2016-01-01

    We present new HST/WFC3-IR narrowband [Fe II] images of protostellar jets in the Carina Nebula. Combined with 5 previously published sources, we have a sample of 18 jets and 2 HH objects. All of the jets we targeted with WFC3 show bright infrared [Fe II] emission, and a few H$\\alpha$ candidate jets are confirmed as collimated outflows based on the morphology of their [Fe II] emission. Continuum-subtracted images clearly separate jet emission from the adjacent ionization front, providing a better tracer of the collimated jet than H$\\alpha$ and allowing us to connect these jets with their embedded driving sources. The [Fe II] 1.64 $\\mu$m/H$\\alpha$ flux ratio measured in the jets is $\\gtrsim 5$ times larger than in the adjacent ionization fronts. The low-ionization jet core requires high densities to shield Fe$^+$ against further ionization by the FUV radiation from O-type stars in the H II region. High jet densities imply high mass-loss rates, consistent with the intermediate-mass driving sources we identify fo...

  14. Particle Acceleration in Relativistic Outflows

    Science.gov (United States)

    Bykov, Andrei; Gehrels, Neil; Krawczynski, Henric; Lemoine, Martin; Pelletier, Guy; Pohl, Martin

    2012-01-01

    In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae. We highlight the possible contributions of these sources to ultra-high-energy cosmic rays.

  15. Illuminating gas in-/outflows in the MUSE deepest fields: discovery of Ly-alpha nebulae around forming galaxies at z~3.3

    CERN Document Server

    Vanzella, E; Gronke, M; Karman, W; Caminha, G B; Dijkstra, M; Rosati, P; De Barros, S; Caputi, K; Grillo, C; Tozzi, P; Meneghetti, M; Mercurio, A; Gilli, R

    2016-01-01

    We report on the discovery of extended Ly-alpha nebulae at z~3.3 in the Hubble Ultra Deep Field (HUDF, ~ 40 kpc X 80 kpc) and behind the Hubble Frontier Fields galaxy cluster MACSJ0416 (~ 40kpc), spatially associated with groups of star-forming galaxies. VLT/MUSE integral field spectroscopy reveals a complex structure with a spatially-varying double peaked Ly-alpha emission. Overall, the spectral profiles of the two Ly-alpha nebulae are remarkably similar, both showing a prominent blue emission, more intense and slightly broader than the red peak. From the first nebula, located in the HUDF, no X-ray emission has been detected, disfavoring the possible presence of AGNs. Spectroscopic redshifts have been derived for 11 galaxies within two arcsec from the nebula and spanning the redshift range 1.037nebula, behind MACSJ0416, shows three aligned star-forming galaxies plausibly associated to the emitting gas. In both systems, the associated galaxies reveal possible intense rest-frame-optic...

  16. Fabry-Perot Kinematics of HH 202, 203-204 in the Orion Nebula Are they part of a Big Bipolar Outflow?

    CERN Document Server

    Rosado, M; Arias, L; Le Coarer, E; Rosado, Margarita; Fuente, Eduardo de la; Arias, Lorena

    2001-01-01

    We present a kinematic study of the Herbig-Haro objects HH 202, 203 and 204 using Halpha and [NII] Fabry-Perot velocity maps. For HH 202 we find new features that could belong to this HH object or that perhaps are associated with an outflow different from HH 202. Because of its high velocity (up to 100 km/seg) this outflow probably can be a HH flow not catalogued previously. Large internal motions are found in the fainter regions of HH 203-204, as well as evidence of transverse density gradients. We show that the apex of HH 204 is the zone of maximum velocity in agreement with bow shock models. From our studies, we find kinematic evidence that suggests that HH 203-204 and HH 202 are part of a single and large (approx 0.55 pc) HH flow.

  17. Revisiting 2D numerical models for the 19th century outbursts of η Carinae

    Science.gov (United States)

    González, R. F.; Villa, A. M.; Gómez, G. C.; de Gouveia Dal Pino, E. M.; Raga, A. C.; Cantó, J.; Velázquez, P. F.; de La Fuente, E.

    2010-02-01

    We present here new results of two-dimensional hydrodynamical simulations of the eruptive events of the 1840s (the great) and the 1890s (the minor) eruptions suffered by the massive star η Carinae (Car). The two bipolar nebulae commonly known as the Homunculus and the little Homunculus (LH) were formed from the interaction of these eruptive events with the underlying stellar wind. We assume here an interacting, non-spherical multiple-phase wind scenario to explain the shape and the kinematics of both Homunculi, but adopt a more realistic parametrization of the phases of the wind. During the 1890s eruptive event, the outflow speed decreased for a short period of time. This fact suggests that the LH is formed when the eruption ends, from the impact of the post-outburst η Car wind (that follows the 1890s event) with the eruptive flow (rather than by the collision of the eruptive flow with the pre-outburst wind, as claimed in previous models; González et al.). Our simulations reproduce quite well the shape and the observed expansion speed of the large Homunculus. The LH (which is embedded within the large Homunculus) becomes Rayleigh-Taylor unstable and develop filamentary structures that resemble the spatial features observed in the polar caps. In addition, we find that the interior cavity between the two Homunculi is partially filled by material that is expelled during the decades following the great eruption. This result may be connected with the observed double-shell structure in the polar lobes of the η Car nebula. Finally, as in previous work, we find the formation of tenuous, equatorial, high-speed features that seem to be related to the observed equatorial skirt of η Car.

  18. Birth and early evolution of a planetary nebula

    CERN Document Server

    Bobrowsky, M; Parthasarathy, M; García-Lario, P

    1998-01-01

    The final expulsion of gas by a star as it forms a planetary nebula --- the ionized shell of gas often observed surrounding a young white dwarf --- is one of the most poorly understood stages of stellar evolution. Such nebulae form extremely rapidly (about 100 years for the ionization) and so the formation process is inherently difficult to observe. Particularly puzzling is how a spherical star can produce a highly asymmetric nebula with collimated outflows. Here we report optical observations of the Stingray Nebula which has become an ionized planetary nebula within the past few decades. We find that the collimated outflows are already evident, and we have identified the nebular structure that focuses the outflows. We have also found a companion star, reinforcing previous suspicions that binary companions play an important role in shaping planetary nebulae and changing the direction of successive outflows.

  19. The Chandra Carina Complex Project View of Trumpler 16

    CERN Document Server

    Wolk, Scott J; Getman, Konstantin V; Feigelson, Eric D; Preibisch, Thomas; Townsley, Leisa K; Wang, Junfeng; Stassun, Keivan G; King, Robert R; McCaughrean, Mark J; Moffat, Anthony F J; Zinnecker, Hans

    2011-01-01

    Trumpler 16 is a well--known rich star cluster containing the eruptive supergiant $\\eta$ Carin\\ae\\ and located in the Carina star-forming complex. In the context of the Chandra Carina Complex Project, we study Trumpler 16 using new and archival X-ray data. A revised X-ray source list of the Trumpler 16 region contains 1232 X-ray sources including 1187 likely Carina members. These are matched to 1047 near-infrared counterparts detected by the HAWK-I instrument at the VLT allowing for better selection of cluster members. The cluster is irregular in shape. Although it is roughly circular, there is a high degree of sub-clustering, no noticeable central concentration and an extension to the southeast. The high--mass stars show neither evidence of mass segregation nor evidence of strong differential extinction. The derived power-law slope of the X-ray luminosity function for Trumpler 16 reveals a much steeper function than the Orion Nebula Cluster implying different ratio of solar- to higher-mass stars. We estimate...

  20. An Introduction to the Chandra Carina Complex Project

    CERN Document Server

    Townsley, Leisa K; Corcoran, Michael F; Feigelson, Eric D; Gagné, Marc; Montmerle, Thierry; Oey, M S; Smith, Nathan; Garmire, Gordon P; Getman, Konstantin V; Povich, Matthew S; Evans, Nancy Remage; Nazé, Yaël; Parkin, E R; Preibisch, Thomas; Wang, Junfeng; Wolk, Scott J; Chu, You-Hua; Cohen, David H; Gruendl, Robert A; Hamaguchi, Kenji; King, Robert R; Mac Low, Mordecai-Mark; McCaughrean, Mark J; Moffat, Anthony F J; Oskinova, L M; Pittard, Julian M; Stassun, Keivan G; ud-Doula, Asif; Walborn, Nolan R; Waldron, Wayne L; Churchwell, Ed; Nichols, J S; Owocki, Stanley P; Schulz, N S

    2011-01-01

    The Great Nebula in Carina provides an exceptional view into the violent massive star formation and feedback that typifies giant HII regions and starburst galaxies. We have mapped the Carina star-forming complex in X-rays, using archival Chandra data and a mosaic of 20 new 60ks pointings using the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer, as a testbed for understanding recent and ongoing star formation and to probe Carina's regions of bright diffuse X-ray emission. This study has yielded a catalog of properties of >14,000 X-ray point sources; >9800 of them have multiwavelength counterparts. Using Chandra's unsurpassed X-ray spatial resolution, we have separated these point sources from the extensive, spatially-complex diffuse emission that pervades the region; X-ray properties of this diffuse emission suggest that it traces feedback from Carina's massive stars. In this introductory paper, we motivate the survey design, describe the Chandra observations, and present some simple results, pr...

  1. Opening the Treasure Chest: A Newborn Star Cluster Emerges from its Dust Pillar in Carina

    CERN Document Server

    Smith, N; Bally, J; Smith, Nathan; Stassun, Keivan G.; Bally, John

    2005-01-01

    We present detailed observations of the Treasure Chest, a compact nebula at the head of a dust pillar in the southern Carina nebula. This object is of interest because it is an example of a dense young cluster containing at least one massive star, the formation of which may have been triggered by feedback from the very massive stars in the Carina nebula, and possibly Eta Car itself. We investigate both the nebular and stellar content of the object. Near-IR emission-line images reveal a cavity inside the head of the dust pillar, which contains a dense cluster of young stars, while the observed spectrum of the nebula is consistent with an H II region ionized by an O9.5 V star. After subtracting contamination of field stars within the Carina nebula itself, we compare the cluster's color magnitude diagram with pre-main-sequence isochrones to derive a likely cluster age less than about 0.1 Myr. This is in reasonable agreement with the dynamical age of a few times 10^4 yr for the expanding nebular cavity, indicatin...

  2. HH 666: Different kinematics from H{\\alpha} and [Fe II] emission provide a missing link between jets and outflows

    CERN Document Server

    Reiter, Megan; Kiminki, Megan M; Bally, John

    2015-01-01

    HH 666 is an externally irradiated protostellar outflow in the Carina Nebula for which we present new near-IR [Fe II] spectra obtained with the FIRE spectrograph at Magellan Observatory. Earlier H{\\alpha} and near-IR [Fe II] imaging revealed that the two emission lines trace substantially different morphologies in the inner ~40" of the outflow. H{\\alpha} traces a broad cocoon that surrounds the collimated [Fe II] jet that extends throughout the parent dust pillar. New spectra show that this discrepancy extends to their kinematics. Near-IR [Fe II] emission traces steady, fast velocities of +/- 200 km/s from the eastern and western limbs of the jet. We compare this to a previously published H{\\alpha} spectrum that reveals a Hubble-flow velocity structure near the jet-driving source. New, second-epoch HST/ACS H{\\alpha} images reveal the lateral spreading of the H{\\alpha} outflow lobe away from the jet axis. H{\\alpha} proper motions also indicate a sudden increase in the mass-loss rate ~1000 yr ago, while steady ...

  3. Magnetic fields in planetary nebulae and post-AGB nebulae

    CERN Document Server

    Sabin, L; Greaves, J S

    2007-01-01

    Magnetic fields are an important but largely unknown ingredient of planetary nebulae. They have been detected in oxygen-rich AGB and post-AGB stars, and may play a role in the shaping of their nebulae. Here we present SCUBA sub-millimeter polarimetric observations of four bipolar planetary nebulae and post-AGB stars, including two oxygen-rich and two carbon-rich nebulae, to determine the geometry of the magnetic field by dust alignment. Three of the four sources (NGC 7027, NGC 6537 and NGC 6302) present a well-defined toroidal magnetic field oriented along their equatorial torus or disk. NGC 6302 may also show field lines along the bipolar outflow. CRL 2688 shows a complex field structure, where part of the field aligns with the torus, whilst an other part approximately aligns with the polar outflow. It also presents marked asymmetries in its magnetic structure. NGC 7027 shows evidence for a disorganized field in the south-west corner, where the SCUBA shows an indication for an outflow. The findings show a cl...

  4. Spatial distribution and kinematics of the molecular material associated with $\\eta$ Carinae

    CERN Document Server

    Loinard, L; Serra, P; Menten, K; Zapata, L; Rodriguez, L

    2016-01-01

    Single-dish sub-millimeter observations have recently revealed the existence of a substantial, chemically peculiar, molecular gas component located in the innermost circumstellar environment of the very massive luminous blue variable star $\\eta$ Carinae. Here, we present 5$"$-resolution interferometric observations of the 1$\\rightarrow$0 rotational transition of hydrogen cyanide (HCN) obtained with the Australia Telescope Compact Array (ATCA) toward this star. The emission is concentrated in the central few arcseconds around $\\eta$ Carinae and shows a clear 150 km s$^{-1}$ velocity gradient running from west-north-west (blue) to east-south-east (red). Given the extent and location of this molecular material, we associate it with the complex of dusty arcs and knots seen in mid-infrared emission along the equatorial plane of the Homunculus nebula. The dust located in the central few arcseconds around $\\eta$ Carinae and the molecular component described here have most likely formed in situ, out of material expel...

  5. Birth and early evolution of a planetary nebula

    OpenAIRE

    Bobrowsky, M.; Sahu, K.C.; M. Parthasarathy; Garcia-Lario, P.

    1998-01-01

    The final expulsion of gas by a star as it forms a planetary nebula --- the ionized shell of gas often observed surrounding a young white dwarf --- is one of the most poorly understood stages of stellar evolution. Such nebulae form extremely rapidly (about 100 years for the ionization) and so the formation process is inherently difficult to observe. Particularly puzzling is how a spherical star can produce a highly asymmetric nebula with collimated outflows. Here we report optical observation...

  6. FUSE Observations of eta Carinae

    CERN Document Server

    Iping, R C; Gull, T R

    2004-01-01

    Eta Carinae was observed by FUSE through the LWRS (30 arcsec x30 arcsec) and HIRS (1.25 arcsec x 20 arcsec) apertures in March and April 2004. There are significant differences between the two spectra. About half of the LWRS flux appears to be due to two B-type stars near the edge of the LWRS aperture, 14 arcsec from eta Carinae. The HIRS spectrum (LiF1 channel) therefore reveals the intrinsic FUV spectrum of eta Carinae without this stellar contamination. The HIRS spectrum contains strong interstellar H2 having high rotational excitation (up to J=8). Most of the atomic species with prominent ISM features (C II, Fe II, Ar I, P II, etc) also have strong blue-shifted absorption to v= ~ -580 km/s that is associated with expanding debris from the 1840 eruption.

  7. Speckle observations of eta Carinae

    International Nuclear Information System (INIS)

    Speckle observations of the central star-like object in eta Carinae with the AAT have shown that it is an unresolved (7 Lsun. Most likely it is a single star of approx. 100 Msun. No evidence of any binary component with a separation of between 0.03-0.9 arcsec has been found. (author)

  8. Interferometric observations of eta Carinae with VINCI/VLTI

    CERN Document Server

    Kervella, P

    2006-01-01

    Context: The bright star eta Carinae is the most massive and luminous star in our region of the Milky Way. Though it has been extensively studied using many different techniques, its physical nature and the mechanism that led to the creation of the Homunculus nebula are still debated. Aims: We aimed at resolving the central engine of the eta Carinae complex in the near-infrared on angular scales of a few milliarcseconds. Methods: We used the VINCI instrument of the VLTI to recombine coherently the light from two telescopes in the K band. Results: We report a total of 142 visibility measurements of eta Car, part of which were analyzed by Van Boekel et al. (2003). These observations were carried out on projected baselines ranging from 8 to 112 meters in length, using either two 0.35 m siderostats or two 8-meter Unit Telescopes. These observations cover the November 2001 - January 2004 period. Conclusions: The reported visibility data are in satisfactory agreement with the recent results obtained with AMBER/VLTI...

  9. Atlantic CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    R. Steinfeldt

    2010-01-01

    Full Text Available Water column data of carbon and carbon-relevant parameters have been collected and merged into a new database called CARINA (CARbon IN the Atlantic. In order to provide a consistent data set, all data have been examined for systematic biases and adjusted if necessary (secondary quality control (QC. The CARINA data set is divided into three regions: the Arctic/Nordic Seas, the Atlantic region and the Southern Ocean. Here we present the CFC data for the Atlantic region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113 as well as carbon tetrachloride (CCl4. The methods applied for the secondary quality control, a crossover analyses, the investigation of CFC ratios in the ocean and the CFC surface saturation are presented. Based on the results, the CFC data of some cruises are adjusted by a certain factor or given a "poor'' quality flag.

  10. Stingray Nebula

    Science.gov (United States)

    1996-01-01

    This Wide Field and Planetary Camera 2 image captures the infancy of the Stingray nebula (Hen-1357), the youngest known planetary nebula. In this image, the bright central star is in the middle of the green ring of gas. Its companion star is diagonally above it at 10 o'clock. A spur of gas (green) is forming a faint bridge to the companion star due to gravitational attraction. The image also shows a ring of gas (green) surrounding the central star, with bubbles of gas to the lower left and upper right of the ring. The wind of material propelled by radiation from the hot central star has created enough pressure to blow open holes in the ends of the bubbles, allowing gas to escape. The red curved lines represent bright gas that is heated by a 'shock' caused when the central star's wind hits the walls of the bubbles. The nebula is as large as 130 solar systems, but, at its distance of 18,000 light-years, it appears only as big as a dime viewed a mile away. The Stingray is located in the direction of the southern constellation Ara (the Altar). The colors shown are actual colors emitted by nitrogen (red), oxygen (green), and hydrogen (blue).

  11. The Stingray nebula: watching the rapid evolution of a newly born planetary nebula.

    Science.gov (United States)

    Bobrowsky, M.; Sahu, K. C.; Parthasarathy, M.; García-Lario, Pedro

    The formation and early evolution of planetary nebulae represent one of the most poorly understood phases of stellar evolution ( Kwok, 1987; Maddox, 1995). One of the youngest, the Stingray Nebula (He3-1357) ( Henize, 1967; Henize, 1976), shows all the tell-tale signs of a newly born planetary nebula: it has become ionized only within the past few decades ( Parthasarathy et al., 1993); the mass-loss from the central star has ceased within the past few years; and the central star is becoming hotter and fainter as expected from a star on its way to becoming a DA white dwarf ( Parthasarathy et al., 1995). The Stingray Nebula thus provides the ideal laboratory for examining the early structure and evolution of this class of objects. Images of the Stingray Nebula, obtained with the Hubble Space Telescope, show for the first time that its multiple expulsions of matter are focused by an equatorial ring and bubbles of gas located on opposite sides of the ring ( Bobrowsky et al., 1995). The position angle of the outflows has changed, possibly as a result of precessional motion induced by the presence of a companion star. This is consistent with the precessing jet model by Livio & Pringle (1996). Indeed, we have reported the discovery of a companion star in the Stingray Nebula ( Bobrowsky et al., 1998). Finally, we present evidence of the companion star dynamically distorting the gas in this newly-born planetary nebula.

  12. Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

    CERN Document Server

    Zwart, Simon Portegies

    2015-01-01

    We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive third companion star, which is the current binary companion in the Eta Carinae system. We come to this conclusion by a combination of theoretical arguments supported by computer simulations using the Astrophysical Multipurpose Software Environment. According to this model the $\\sim 90$\\,\\MSun\\, present primary star of the highly eccentric Eta Carinae binary system is the product of this merger, and its $\\sim 30$\\,\\MSun\\, companion originally was the third star in the system. In our model the Homunculus nebula was produced by an extremely enhanced stellar wind, energized by tidal energy dissipation prior to the merger, which enormously boosted the radiation-driven wind mass-loss. The current orbital plane is then align...

  13. Chemical evolution of the solar nebula: A new model

    Science.gov (United States)

    Trivedi, B. M. P.

    1984-01-01

    The common notion of a hot solar nebula from which meteoritic minerals condensed is not supported by theories of star formation. A model is developed which can give the same sequence of condensation without recourse to hot solar nebula. In this model, the solar nebula was formed from the matter ejected by the Sun during its T Tauri phase and the chemical condensation took place in this outflowing matter. Isotopic anomalies and the unique minerals found in meteorites may be explained by this model.

  14. CARINA alkalinity data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    A. Velo

    2009-08-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic.

    These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values.

    Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg−1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  15. CARINA: nutrient data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2009-07-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic. These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004. Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  16. A PHOTOMETRICALLY AND MORPHOLOGICALLY VARIABLE INFRARED NEBULA IN L483

    International Nuclear Information System (INIS)

    We present narrow and broad K-band observations of the Class 0/I source IRAS 18148-0440 that span 17 years. The infrared nebula associated with this protostar in the L483 dark cloud is both morphologically and photometrically variable on a timescale of only a few months. This nebula appears to be an infrared analog to other well known optically visible variable nebulae associated with young stars, such as Hubble's Variable Nebula. Along with Cepheus A, this is one of the first large variable nebulae to be found that is only visible in the infrared. The variability of this nebula is most likely due to changing illumination of the cloud rather than any motion of the structure in the nebula. Both morphological and photometric changes are observed on a timescale only a few times longer than the light crossing time of the nebula, suggesting very rapid intrinsic changes in the illumination of the nebula. Our narrowband observations also found that H2 knots are found nearly twice as far to the east of the source as to its west, and that H2 emission extends farther east of the source than the previously known CO outflow.

  17. Pulsar Wind Nebulae Modeling

    CERN Document Server

    Bucciantini, N

    2013-01-01

    Pulsar Wind Nebulae (PWNe) are ideal astrophysical laboratories where high energy relativistic phenomena can be investigated. They are close, well resolved in our observations, and the knowledge derived in their study has a strong impact in many other fields, from AGNs to GRBs. Yet there are still unresolved issues, that prevent us from a full clear understanding of these objects. The lucky combination of high resolution X-ray imaging and numerical codes to handle the outflow and dynamical properties of relativistic MHD, has opened a new avenue of investigation that has lead to interesting progresses in the last years. Despite all of this, we do not understand yet how particles are accelerated, and the functioning of the pulsar wind and pulsar magnetosphere, that power PWNe. I will review what is now commonly known as the MHD paradigm, and in particular I will focus on various approaches that have been and are currently used to model these systems. For each I will highlight its advantages, limitations, and de...

  18. Source Contamination in X-ray Studies of Star-Forming Regions: Application to the Chandra Carina Complex Project

    CERN Document Server

    Getman, Konstantin V; Feigelson, Eric D; Townsley, Leisa K; Povich, Matthew S; Garmire, Gordon P; Montmerle, Thierry; Yonekura, Yoshinori; Fukui, Yasuo

    2011-01-01

    We describe detailed simulations of X-ray-emitting populations to evaluate the levels of contamination by both Galactic and extragalactic X-ray sources unrelated to a star-forming region under study. For Galactic contaminations, we consider contribution from main-sequence stars and giants (not including cataclysmic variables and other classes of accretion-driven X-ray binary systems) as they make the dominant contribution at the position of the Carina Nebula. The simulations take into consideration a variety of technical factors involving a Galactic population synthesis model, stellar X-ray luminosity functions, Chandra telescope response, source detection methodology, and possible spatial variations in the X-ray background and absorption through molecular clouds. When applied to the 1.42 square-degree field of the Chandra Carina Complex Project (CCCP), the simulations predict ~5000 contaminating sources (1 source per square arcminute of the survey), evenly distributed across the field. The results of the sim...

  19. The three-dimensional structure of the Eta Carinae Homunculus

    CERN Document Server

    Steffen, W; Madura, T I; Groh, J H; Gull, T R; Mehner, A; Corcoran, M F; Damineli, A; Hamaguchi, K

    2014-01-01

    We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae, as mapped by new ESO VLT/X-Shooter observations of the H2 $\\lambda=2.12125$ micron emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) off-planar protrusions in the equatorial region from each lobe at longitudinal (~55 degrees) and latitudinal (10-20 degrees) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (~110 degrees) is similar to the angular extent of each polar trench (~130 degrees) and nearly equal to the opening angle of the wind-wind collision cavity (~110 degrees). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We con...

  20. Nordic Seas total alkalinity data in CARINA

    Directory of Open Access Journals (Sweden)

    A. Olsen

    2009-08-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the total alkalinity (ALK data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 21 had ALK data. The data from 6 of these were found to be of low quality and should not be used. Of the others, 3 were found to be biased low and were subject to adjustment. Thus the final CARINA data product contains ALK data from 15 cruises from the Nordic Seas, and these data appear consistent to ±3 μmol kg−1.

  1. Early-type PMS and MS objects in M16 and the Carina star-forming regions

    OpenAIRE

    Martayan, Christophe; Floquet, Michele; Fremat, Yves; Hubert, Anne-Marie; Neiner, Coralie; Baade, Dietrich; Fabregat, Juan

    2009-01-01

    Thanks to a variety of pertinent wide-angle facilities (WFI-slitless mode, VLT-FLAMES (Pasquini et al. 2002), SPITZER, 2MASS) it is possible to comprehensively study the nature of early-type objects in star-forming regions like the Eagle Nebula and Carina on large spatial scales. In them, the young open clusters NGC 6611, Trumpler 14, Trumpler 15, Trumpler 16, and their vicinities are of particular interest. With the WFI in its slitless mode (Baade et al. 1999), one can reliably and with litt...

  2. A spectral and spatial analysis of eta Carinae's diffuse X-ray emission using CHANDRA

    CERN Document Server

    Weis, K; Bomans, D J; Davidson, K; Weis, Kerstin; Corcoran, Michael F.; Bomans, Dominik J.; Davidson, Kris

    2004-01-01

    The luminous unstable star (star system) eta Carinae is surrounded by an optically bright bipolar nebula, the Homunculus and a fainter but much larger nebula, the so-called outer ejecta. As images from the EINSTEIN and ROSAT satellites have shown, the outer ejecta is also visible in soft X-rays, while the central source is present in the harder X-ray bands. With our CHANDRA observations we show that the morphology and properties of the X-ray nebula are the result of shocks from fast clumps in the outer ejecta moving into a pre-existing denser circumstellar medium. An additional contribution to the soft X-ray flux results from mutual interactions of clumps within the ejecta. Spectra extracted from the CHANDRA data yield gas temperatures kT of 0.6-0.76 keV. The implied pre-shock velocities of 670-760 km/s are within the scatter of the velocities we measure for the majority of the clumps in the corresponding regions. Significant nitrogen enhancements over solar abundances are needed for acceptable fits in all pa...

  3. Unveiling shocks in planetary nebulae

    CERN Document Server

    Guerrero, M A; Medina, J J; Luridiana, V; Miranda, L F; Riera, A; Velázquez, P F

    2013-01-01

    The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O III]/Halpha. To investigate the occurrence of shocks in planetary nebulae (PNe), we have used all narrowband [O III] and Halpha images of PNe available in the HST archive to build their [O III]/Halpha ratio maps and to search for regions where this ratio is enhanced. Regions with enhanced [O III]/Halpha emission ratio can be ascribed to two different types of morphological structures: bow-shock structures produced by fast collimated outflows and thin skins enveloping expanding nebular shells. Both collimated outflows and expanding shells are therefore confirmed to generate shocks in PNe. We also find regions with depressed values of the [O III]/Halpha ratio which are found mostly around density bounded PNe, where the local contribution of [N II] emission into the F656N Halpha filter cannot be neglected.

  4. Emission lines in the long period Cepheid l Carinae

    Science.gov (United States)

    Boehm-Vitense, Erika; Love, Stanley G.

    1991-01-01

    For the Cepheid (l) Carinae with a pulsation period of 35.5 days we have studied the emission line fluxes as a function of pulsational phase in order to find out whether we see chromosphere and transition layer emission or whether we see emission due to an outward moving shock. All emission lines show a steep increase in flux shortly before maximum light suggestive of a shock moving through the surface layers. The large ratio of the C IV to C II line fluxes shows that these are not transition layer lines. During maximum light the large ratio of the C IV to C II line fluxes also suggests that we see emission from a shock with velocities greater than 100 km/sec such that C IV emission can be excited. With such velocities mass outflow appears possible. The variations seen in the Mg II line profiles show that there is an internal absorption over a broad velocity band independent of the pulsational phase. We attribute this absorption to a circumstellar 'shell'. This 'shell' appears to be seen also as spatially extended emission in the O I line at 1300 angstrom, which is probably excited by resonance with Ly beta.

  5. X-ray Observations of Planetary Nebulae

    OpenAIRE

    Guerrero, M. A.; Chu, Y.-H.; Gruendl, R A

    2003-01-01

    Planetary nebulae (PNe) are an exciting addition to the zoo of X-ray sources. Recent Chandra and XMM-Newton observations have detected diffuse X-ray emission from shocked fast winds in PN interiors as well as bow-shocks of fast collimated outflows impinging on the nebular envelope. Point X-ray sources associated with PN central stars are also detected, with the soft X-ray (>0.5 keV) emission from instability shocks in the fast stellar wind itself or from a low-mass companion's coronal activit...

  6. Light echoes reveal an unexpectedly cool Eta Carinae during its 19th-century Great Eruption

    CERN Document Server

    Rest, A; Walborn, N R; Smith, N; Bianco, F B; Chornock, R; Welch, D L; Howell, D A; Huber, M E; Foley, R J; Fong, W; Sinnott, B; Bond, H E; Smith, R C; Toledo, I; Minniti, D; Mandel, K

    2011-01-01

    Eta Carinae (Eta Car) is one of the most massive binary stars in the Milky Way. It became the second-brightest star in the sky during its mid-19th century "Great Eruption," but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique among known astronomical transients in that it exceeded the Eddington luminosity limit for 10 years. Because it is only 2.3 kpc away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that in its 19th century eruption, Eta Car ejected more than 10 M_solar in an event that had 10% of the energy of a typical core-collapse supernova without destroying the star. Here we report the discovery of light echoes of Eta Carinae which appear to be from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km/s, in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-G5 supergiant spectra, which ha...

  7. Molecular clouds in the Carina arm

    Science.gov (United States)

    Cohen, R. S.; Grabelsky, D. A.; May, J.; Alvarez, H.; Bronfman, L.; Thaddeus, P.

    1985-01-01

    From a new survey of the 2.6 mm line of CO in the southern Milky Way, 37 molecular clouds were identified along the Carina arm from l = 282 deg to 336 deg with masses generally greater than 10 to the 5th solar mass. The clouds lie approximately every 700 pc along a spiral segment that is nearly 25 kpc long and has a pitch of about 10 deg. The total mass of these clouds is 40 x 10 to the 6th solar mass, or rougly 1 x 10 to the 6th solar mass each on average. The abrupt tangent point in molecular clouds at l = 280 deg and the characteristic loop structure in the l-v diagram are unmistakable evidence of a CO spiral arm in Carina. This arm apparently connects with the northern hemisphere Sagittarius arm to form a single 10 deg spiral which extends more than two-thirds of the way around the Galaxy.

  8. CARINA oxygen data in the Atlantic Ocean

    OpenAIRE

    Stendardo, I.; Gruber, N.; A. Körtzinger

    2009-01-01

    In the CARINA (Carbon dioxide in the Atlantic Ocean) project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC) procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the c...

  9. Nordic Seas total alkalinity data in CARINA

    OpenAIRE

    Olsen, A.

    2009-01-01

    Water column data of inorganic carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biase...

  10. Nordic Seas dissolved oxygen data in CARINA

    OpenAIRE

    Falck, E.; Olsen, A.

    2009-01-01

    Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the r...

  11. Superluminous supernovae: No threat from Eta Carinae

    CERN Document Server

    Thomas, Brian C; Fields, Brian D; Anthony-Twarog, Barbara J

    2007-01-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of ~10^44 Joules. It was proposed that the progenitor may have been a massive evolved star similar to Eta Carinae, which resides in our own galaxy at a (poorly determined) distance of ~2.5 kpc. Eta Carinae appears ready to detonate, and in fact had an outburst in 1843. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma Ray Burst oriented toward the Earth, Eta Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over ~10^4 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possib...

  12. The filamentary Multi-Polar Planetary Nebula NGC 5189

    CERN Document Server

    Sabin, L; López, J A; García-Díaz, Ma T; Ramos-Larios, G

    2012-01-01

    We present a set of optical and infrared images combined with long-slit, medium and high dispersion spectra of the southern planetary nebula (PN) NGC 5189. The complex morphology of this PN is puzzling and has not been studied in detail so far. Our investigation reveals the presence of a new dense and cold infrared torus (alongside the optical one) which probably generated one of the two optically seen bipolar outflows and which might be responsible for the twisted appearance of the optical torus via an interaction process. The high-resolution MES-AAT spectra clearly show the presence of filamentary and knotty structures as well as three expanding bubbles. Our findings therefore suggest that NGC 5189 is a quadrupolar nebula with multiple sets of symmetrical condensations in which the interaction of outflows has determined the complex morphology.

  13. THE FILAMENTARY MULTI-POLAR PLANETARY NEBULA NGC5189

    Directory of Open Access Journals (Sweden)

    L. Sabin

    2012-01-01

    Full Text Available We present a set of optical and infrared images combined with long-slit, medium and high dispersion spectra of the southern planetary nebula (PN NGC5189. The complex morphology of this PN is puzzling and has not been studied in detailed so far. Our investigation reveals the presence of a new dense and cold infrared torus (alongside the optical one which probably generated one of the two optically seen bipolar outflows and which might be responsible for the twisted appearance of the optical torus via an interaction process. The high-resolution MES-AAT spectra clearly show the presence of filamentary and knotty structures as well as three expanding bubbles. Our findings therefore suggest that NGC5189 is a quadrupolar nebula with multiple sets of symmetrical condensations in which the interaction of outflows has determined its complex morphology.

  14. Outflows, jets and shocks in the orion nebula

    Directory of Open Access Journals (Sweden)

    C. R. O`Dell

    2000-01-01

    Full Text Available El c umulo de estrellas j ovenes asociadas a la Nebulosa de Ori on es un buen laboratorio para el estudio de los plasmas. Vemos cinco tipos de ujos y choques. Los ujos de foto-ablaci on de los proplyds m as cercanos a 1Ori C forman choques cuasi estacionarios con el viento de la estrella. Se observan micro-chorros con escalas menores a 103 AU en 20 estrellas peque~nas. Los chorros aislados, con altas velocidades y escalas cercanas a 104 AU, son comunes pero menos numerosos. Tambi en se ven choques cuando los chorros golpean al gas nebular ionizado o al gas neutro del fondo. El tipo de objeto nal es el choque estacionario formado por la interacci on del viento estelar, generado durante la formaci on del disco, con el gas ambiental que uye hacia afuera de la nebulosa.

  15. Nordic Seas nutrients data in CARINA

    Directory of Open Access Journals (Sweden)

    J. Olafsson

    2010-09-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, Atlantic, and Southern Ocean have been assembled and the collection merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments, the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, and for model validation. The Arctic Mediterranean Seas is the collective term for the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the nutrients (nitrate, phosphate, and silicate data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 33 had nutrients data. The nitrate data from 4 of these appeared to be of so poor quality that they should not be used, for phosphate this number is 7 and for silicate it is 3. We also recommend that the nitrate data from 4 of the cruises should be adjusted, for phosphate and silicate only data from one cruise should be adjusted. The final data appears consistent to 5% based on evaluation of deep data. For nitrate this corresponds to 0.6 μmol kg−1, and for phosphate and silicate it corresponds to 0.04 and 0.6 μmol kg−1, respectively.

  16. Integral-field spectroscopy of GM 1-29 Nebula and PV Cep star

    International Nuclear Information System (INIS)

    Results of the integral field spectroscopy of the GM 1-29 nebula and its source star PV Cep on the 2.6m telescope of the Byurakan observatory are presented. The structure and kinematics of the emission collimated outflow, directed along the nebula axis, are studied. The variations of the radial velocity and the intensity of the absorption component of the Hα line in the spectrum of the nebula are revealed and studied. This effect is interpreted as the result of the stellar wind anisotropy in the distances of the several stellar radii, where this absorption is formed

  17. η Carinae Baby Homunculus uncovered by ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Zulema; Beaklini, Pedro P. B. [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, R. do Matão 1226, Cidade Universitária, CEP 05508-900 São Paulo, SP (Brazil); Falceta-Gonçalves, Diego, E-mail: zulema.abraham@iag.usp.br [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, R. Arlindo Bettio 1000, 03828-000 São Paulo, SP (Brazil)

    2014-08-20

    We report observations of η Carinae obtained with ALMA in the continuum of 100, 230, 280, and 660 GHz in 2012 November, with a resolution that varied from 2.''88 to 0.''45 for the lower and higher frequencies, respectively. The source is not resolved, even at the highest frequency; its spectrum is characteristic of thermal bremsstrahlung of a compact source, but different from the spectrum of optically thin wind. The recombination lines H42α, He42α, H40α, He40α, H50β, H28α, He28α, H21α, and He21α were also detected, and their intensities reveal non-local thermodynamic equilibrium effects. We found that the line profiles could only be fit by an expanding shell of dense and ionized gas, which produces a slow shock in the surroundings of η Carinae. Combined with fittings to the continuum, we were able to constrain the shell size, radius, density, temperature, and velocity. The detection of the He recombination lines is compatible with the high-temperature gas and requires a high-energy ionizing photon flux, which must be provided by the companion star. The mass-loss rate and wind velocity, necessary to explain the formation of the shell, are compatible with an luminous blue variable eruption. The position, velocity, and physical parameters of the shell coincide with those of the Weigelt blobs. The dynamics found for the expanding shell correspond to matter ejected by η Carinae in 1941 in an event similar to that which formed the Little Homunculus; for that reason, we called the new ejecta the 'Baby Homunculus'.

  18. Chandra Observations of Outflows from PSR J1509-5850

    CERN Document Server

    Klingler, Noel; Rangelov, Blagoy; Pavlov, George G; Posselt, Bettina; Ng, C -Y

    2016-01-01

    PSR J1509-5850 is a middle-aged pulsar with the period P ~ 89 ms, spin-down power Edot = 5.1 x 10^35 erg/s, at a distance of about 3.8 kpc. We report on deep Chandra X-ray Observatory observations of this pulsar and its pulsar wind nebula (PWN). In addition to the previously detected tail extending up to 7' southwest from the pulsar (the southern outflow), the deep images reveal a similarly long, faint diffuse emission stretched toward the north (the northern outflow) and the fine structure of the compact nebula (CN) in the pulsar vicinity. The CN is resolved into two lateral tails and one axial tail pointing southwest (a morphology remarkably similar to that of the Geminga PWN), which supports the assumption that the pulsar moves towards the northeast. The luminosities of the southern and northern outflows are about 1 x 10^33 and 4 x 10^32 erg/s, respectively. The spectra extracted from four regions of the southern outflow do not show any softening with increasing distance from the pulsar. The lack of synchr...

  19. QU Carinae: Supernova Ia in the making?

    CERN Document Server

    Kafka, Stella; Williams, Bob

    2012-01-01

    Variable NaI absorption lines have been reported in a number of type Ia supernovae (SNeIa). The presence of this circumstellar material suggests that cataclysmic variables (CVs) with a giant donor star may be the progenitors of these SNeIa (Patat et al. 2007). We present echelle spectra of the CV QU Carinae which strengthen the connection between CVs of the V Sge class, the Accretion Wind Evolution scenario, variable wind features, variable NaI absorption, and SNIa. This thread not only provides insight into the spectral peculiarities of QU Car, but also links SNeIa as a class with their parent systems.

  20. ALMA OBSERVATIONS OF THE COLDEST PLACE IN THE UNIVERSE: THE BOOMERANG NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, R. [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States); Vlemmings, W. H. T. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Huggins, P. J. [Physics Department, New York University, 4 Washington Place, New York, NY 10003 (United States); Nyman, L.-Å. [Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile); Gonidakis, I., E-mail: raghvendra.sahai@jpl.nasa.gov [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Marsfield NSW 2122 (Australia)

    2013-11-10

    The Boomerang Nebula is the coldest known object in the universe, and an extreme member of the class of pre-planetary nebulae, objects which represent a short-lived transitional phase between the asymptotic giant branch and planetary nebula evolutionary stages. Previous single-dish CO (J = 1-0) observations (with a 45'' beam) showed that the high-speed outflow in this object has cooled to a temperature significantly below the temperature of the cosmic background radiation. Here we report the first observations of the Boomerang Nebula with ALMA in the CO J = 2-1 and J = 1-0 lines to resolve the structure of this ultra-cold nebula. We find a central hourglass-shaped nebula surrounded by a patchy, but roughly round, cold high-velocity outflow. We compare the ALMA data with visible-light images obtained with the Hubble Space Telescope and confirm that the limb-brightened bipolar lobes seen in these data represent hollow cavities with dense walls of molecular gas and dust producing both the molecular-emission-line and scattered-light structures seen at millimeter and visible wavelengths. The large diffuse biconical shape of the nebula seen in the visible wavelength range is likely due to preferential illumination of the cold, high-velocity outflow. We find a compact source of millimeter-wave continuum in the nebular waist—these data, together with sensitive upper limits on the radio continuum using observations with ATCA, indicate the presence of a substantial mass of very large (millimeter-sized) grains in the waist of the nebula. Another unanticipated result is the detection of CO emission regions beyond the ultra-cold region which indicate the re-warming of the cold gas, most likely due to photoelectric grain heating.

  1. Cool gaseous nebulae

    CERN Document Server

    Shaver, P A; Pottasch, S R

    1979-01-01

    The electron temperatures of diffuse gaseous nebulae have long been thought to be close to 10/sup 4/K. Much lower temperatures were derived from some of the early radio continuum and recombination line work, but these were generally considered to be wrong for a variety of reasons. While there is little doubt that the bright nebulae do indeed have temperatures of approximately 8000-9000K, there are strong indications that some nebulae of lower densities have much lower temperatures, nebulae were made in order to determine electron temperatures in the absence of such effects as collisional de-excitation, stimulated emission, and pressure broadening. Several of these nebulae have been found to have temperatures below 5000K and for two of them which are discussed (RCW94 and G339.1-0.2) absolute upper limits of approximately 4700 K are imposed by the line widths alone. (11 refs).

  2. Modelling the Central Constant Emission X-ray component of η Carinae

    Science.gov (United States)

    Russell, Christopher M. P.; Corcoran, Michael F.; Hamaguchi, Kenji; Madura, Thomas I.; Owocki, Stanley P.; Hillier, D. John

    2016-05-01

    The X-ray emission of η Carinae shows multiple features at various spatial and temporal scales. The central constant emission (CCE) component is centred on the binary and arises from spatial scales much smaller than the bipolar Homunculus nebula, but likely larger than the central wind-wind collision region between the stars as it does not vary over the ˜2-3 month X-ray minimum when it can be observed. Using large-scale 3D smoothed particle hydrodynamics (SPH) simulations, we model both the colliding-wind region between the stars, and the region where the secondary wind collides with primary wind ejected from the previous periastron passage. The simulations extend out to one hundred semimajor axes and make two limiting assumptions (strong coupling and no coupling) about the influence of the primary radiation field on the secondary wind. We perform 3D radiative transfer calculations on the SPH output to synthesize the X-ray emission, with the aim of reproducing the CCE spectrum. For the preferred primary mass-loss rate dot{M}_A≈ 8.5× 10^{-4} M_{⊙} yr-1, the model spectra well reproduce the observation as the strong- and no-coupling spectra bound the CCE observation for longitude of periastron ω ≈ 252°, and bound/converge on the observation for ω ≈ 90°. This suggests that η Carinae has moderate coupling between the primary radiation and secondary wind, that both the region between the stars and the comoving collision on the backside of the secondary generate the CCE, and that the CCE cannot place constraints on the binary's line of sight. We also discuss comparisons with common X-ray fitting parameters.

  3. CARINA oxygen data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    I. Stendardo

    2009-12-01

    Full Text Available In the CARINA (Carbon dioxide in the Atlantic Ocean project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i the region is not subject to substantial temporal variability, and (ii the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen dataset has 103414 oxygen samples from 9491 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted dataset. Of the data included in the adjusted dataset, 20% were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency, the resulting product is well suited to produce an improved climatology or to study long-term changes in the oxygen content of the ocean. However, the adjusted dataset is not necessarily better suited than the unadjusted data to

  4. The Rings Around the Egg Nebula

    Science.gov (United States)

    Harpaz, Amos; Rappaport, Saul; Soker, Noam

    1997-01-01

    We present an eccentric binary model for the formation of the proto-planetary nebula CRL 2688 (the Egg Nebula) that exhibits multiple concentric shells. Given the apparent regularity of the structure in the Egg Nebula, we postulate that the shells are caused by the periodic passages of a companion star. Such an orbital period would have to lie in the range of 100-500 yr, the apparent time that corresponds to the spacing between the rings. We assume, in this model, that an asymptotic giant branch (AGB) star, which is the origin of the matter within the planetary nebula, loses mass in a spherically symmetric wind. We further suppose that the AGB star has an extended atmosphere (out to approximately 10 stellar radii) in which the outflow speed is less than the escape speed; still farther out, grains form and radiation pressure accelerates the grains along with the trapped gas to the escape speed. Once escape speed has been attained, the presence of a companion star will not significantly affect the trajectories of the matter leaving in the wind and the mass loss will be approximately spherically symmetric. On the other hand, if the companion star is sufficiently close that the Roche lobe of the AGB star moves inside the extended atmosphere, then the slowly moving material will be forced to flow approximately along the critical potential surface (i.e., the Roche lobe) until it flows into the potential lobe of the companion star. Therefore, in our model, the shells are caused by periodic cessations of the isotropic wind rather than by any periodic enhancement in the mass-loss process. We carry out detailed binary evolution calculations within the context of this scenario, taking into account the nuclear evolution and stellar wind losses of the giant as well as the effects of mass loss and mass transfer on the evolution of the eccentric binary orbit. From the initial binary parameters that we find are required to produce a multiple concentric shell nebula and the known

  5. Pulsar Wind Nebulae in the SKA era

    CERN Document Server

    Gelfand, J D; Ng, C -Y; Hessels, J W T; Stappers, B; Roberts, M S E; Possenti, A

    2015-01-01

    Neutron stars lose the bulk of their rotational energy in the form of a pulsar wind: an ultra-relativistic outflow of predominantly electrons and positrons. This pulsar wind significantly impacts the environment and possible binary companion of the neutron star, and studying the resultant pulsar wind nebulae is critical for understanding the formation of neutron stars and millisecond pulsars, the physics of the neutron star magnetosphere, the acceleration of leptons up to PeV energies, and how these particles impact the interstellar medium. With the SKA1 and the SKA2, it could be possible to study literally hundreds of PWNe in detail, critical for understanding the many open questions in the topics listed above.

  6. The San Pedro M\\'artir Kinematic Catalogue of Galactic Planetary Nebulae

    CERN Document Server

    López, J A; García-Díaz, M T; Clark, D M; Meaburn, J; Riesgo, H; Steffen, W; Lloyd, M

    2011-01-01

    The San Pedro M\\'artir kinematic catalogue of galactic planetary nebulae provides spatially resolved, long-slit Echelle spectra for about 600 planetary nebulae. The data are presented wavelength calibrated and corrected for heliocentric motion. For most objects multiple spectra have been acquired and images with accurate slit positions on the nebulae are also presented for each object. This is the most extensive and homogeneous single source of data concerning the internal kinematics of the ionized nebular material in planetary nebulae. Data can be retrieved for individual objects or selected by groups that share some common characteristics, such as by morphological classes, galactic population, binary cores, presence of fast outflows, etc. The catalogue is available through the world wide web at http://kincatpn.astrosen.unam.mx .

  7. Nordic Seas and Arctic Ocean CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    E. Jeansson

    2010-02-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters have been retrieved from a large number of cruises and collected into a new database called CARINA (CARbon IN the Atlantic. These data have been merged into three sets of files, one for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. The first part of the CARINA database consists of three files, one for each CARINA region, containing the original, non-adjusted cruise data sets, including data quality flags for each measurement. These data have then been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the second part of the CARINA data product. This consists of three files, one for each CARINA region, which contain adjustments to the original data values based on recommendations from the CARINA QC procedures, along with calculated and interpolated values for some missing parameters.

    Here we present an overview of the QC of the CFC data for the AMS region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113, as well as carbon tetrachloride (CCl4. The Arctic Mediterranean Seas is comprised of the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. For the secondary QC of the CFCs we used a combination of tools, including the evaluation of depth profiles and CFC ratios, surface saturations and a crossover analysis. This resulted in a multiplicative adjustment of data from some cruises, while other data were flagged to be of questionable quality, which excluded them from the final data product.

  8. Atlantic Ocean CARINA data: overview and salinity adjustments

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2009-08-01

    Full Text Available Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. Arctic, Atlantic and Southern Ocean. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report details of the secondary QC for salinity for this data set. Procedures of quality control – including crossover analysis between stations and inversion analysis of all crossover data – are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal accuracy of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004, and is now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  9. Atlantic Ocean CARINA data: overview and salinity adjustments

    Energy Technology Data Exchange (ETDEWEB)

    Tanhua, T. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Steinfeldt, R. [University of Bremen, Bremen, Germany; Key, Robert [Princeton University; Brown, P. [University of East Anglia, Norwich, United Kingdom; Gruber, N. [ETH Zurich, Switzerland; Wanninkhof, R. [Atlantic Oceanographic & Meteorological Laboratory, NOAA; Perez, F.F. [Instituto de Investigaciones Marinas de Vigo, CSIC, Vigo, Spain; Kortzinger, A. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Velo, A. [Instituto de Investigaciones Marinas de Vigo, CSIC, Vigo, Spain; Schuster, U. [University of East Anglia, Norwich, United Kingdom; Van Heuven, S. [University of Groningen, The Netherlands; Bullister, J.L. [NOAA Pacific Marine Environmental Laboratory; Stendardo, I. [ETH Zurich, Switzerland; Hoppema, M. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; Olsen, Are [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Kozyr, Alexander [ORNL; Pierrot, D. [Cooperative Institute of Marine and Atmospheric Sciences, U. Miami; Schirnick, C. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Wallace, D.W.R. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany

    2010-01-01

    Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30 S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control) for salinity for this data set. Procedures of quality control including crossover analysis between stations and inversion analysis of all crossover data are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally was well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, oceanic carbon inventories

  10. Massive molecular outflows

    OpenAIRE

    Beuther, H.; Schilke, P.; Menten, K. M.; Walmsley, C. M.; Sridharan, T. K.; Wyrowski, F.

    2001-01-01

    We present a mapping study of massive molecular outflows in 26 high-mass star-forming regions at 11'' spatial resolution. Bipolar morpholgy is found in 80% of the sources and the collimation is higher than previously thought. Additionally, we find that well known low-mass correlations continue up to the high-mass regime, and accretion rates are around 10^(-4) Msun/yr rising as high as 10^(-3) Msun/yr. A tight correlation between the outflow and the core mass is established, implying that the ...

  11. Suzaku Discovery of Twin Thermal Plasma from the Tornado Nebula

    CERN Document Server

    Sawada, Makoto; Koyama, Katsuji; Oka, Tomoharu

    2011-01-01

    The Tornado nebula (G357.7-0.1) is a mysterious radio source with bright "head" and faint "tail" located in the direction of the Galactic center (GC) region. We here report the discovery of two diffuse X-ray sources at the head and tail of the Tornado with the Suzaku satellite. We found emission lines from highly ionized atoms in the two sources. The spectra are reproduced by an optically thin thermal plasma with a common temperature of 0.6-0.7 keV. The interstellar absorption (NH) of these sources are the same and are slightly larger than that of the GC distance. Since the estimated distance using the NH value is consistent with the radio observation of the Tornado, these X-ray sources are likely associated with the Tornado nebula. The twin-plasma morphology at the both ends of the Tornado suggests that the system is a bipolar/outflow source.

  12. A wind-shell interaction model for multipolar planetary nebulae

    CERN Document Server

    Steffen, W; Esquivel, A; Garcia-Segura, G; Garcia-Diaz, Ma T; Lopez, J A; Magnor, M

    2013-01-01

    We explore the formation of multipolar structures in planetary and pre-planetary nebulae from the interaction of a fast post-AGB wind with a highly inhomogeneous and filamentary shell structure assumed to form during the final phase of the high density wind. The simulations were performed with a new hydrodynamics code integrated in the interactive framework of the astrophysical modeling package SHAPE. In contrast to conventional astrophysical hydrodynamics software, the new code does not require any programming intervention by the user for setting up or controlling the code. Visualization and analysis of the simulation data has been done in SHAPE without external software. The key conclusion from the simulations is that secondary lobes in planetary nebulae, such as Hubble 5 and K3-17, can be formed through the interaction of a fast low-density wind with a complex high density environment, such as a filamentary circumstellar shell. The more complicated alternative explanation of intermittent collimated outflow...

  13. Outflows and Shock Chemistry

    Science.gov (United States)

    Tafalla, M.

    2016-05-01

    Bipolar outflows result from the supersonic ejection of material by a protostar, and constitute one of the most characteristic signposts of stellar birth. They also provide ideal targets to test chemical models, and can serve as templates for more complex systems of galactic and extragalactic astronomy where supersonic interactions between gas components take place.

  14. Metallicity and Quasar Outflows

    CERN Document Server

    Wang, Huiyuan; Yuan, Weimin; Wang, Tinggui

    2012-01-01

    Correlations are investigated of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the CIV line (Wang et al. 2011), with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey. We find that most of the line ratios of other ions to CIV prominently increases with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of dominant coolant, CIV line, decreases and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using SiIV+OIV]/CIV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicitiy and the outflow strength of quasars over a wide range of 1.7 to 6.9 times solar abundance. Our result implies that the metallicity plays an important role in the formation of quasar outflows, likely via affecting outflow acceleration. This ...

  15. Modelling the Central Constant Emission X-ray component of eta Carinae

    CERN Document Server

    Russell, Christopher M P; Hamaguchi, Kenji; Madura, Thomas I; Owocki, Stanley P; Hillier, D John

    2016-01-01

    The X-ray emission of $\\eta$ Carinae shows multiple features at various spatial and temporal scales. The central constant emission (CCE) component is centred on the binary and arises from spatial scales much smaller than the bipolar Homunculus nebula, but likely larger than the central wind--wind collision region between the stars as it does not vary over the $\\sim$2-3 month X-ray minimum when it can be observed. Using large-scale 3D smoothed particle hydrodynamics (SPH) simulations, we model both the colliding-wind region between the stars, and the region where the secondary wind collides with primary wind ejected from the previous periastron passage. The simulations extend out to one hundred semimajor axes and make two limiting assumptions (strong coupling and no coupling) about the influence of the primary radiation field on the secondary wind. We perform 3D radiative transfer calculations on the SPH output to synthesize the X-ray emission, with the aim of reproducing the CCE spectrum. For the preferred pr...

  16. Latitude-dependent effects in the stellar wind of Eta Carinae

    CERN Document Server

    Smith, N; Gull, T R; Ishibashi, K; Hillier, J; Smith, Nathan; Davidson, Kris; Gull, Theodore R.; Ishibashi, Kazunori; Hillier, John

    2003-01-01

    The Homunculus reflection nebula around eta Carinae provides a rare opportunity to observe the spectrum of a star from multiple latitudes. We present STIS spectra of several positions in the Homunculus, showing directly that eta Car has an aspherical stellar wind. P Cygni absorption in Balmer lines depends on latitude, with high velocities and strong absorption near the poles. Stronger absorption at high latitudes is surprising, and it suggests higher mass flux toward the poles, perhaps resulting from radiative driving with equatorial gravity darkening on a rotating star. Reflected profiles of He I lines are more puzzling, offering clues to the wind geometry and ionization structure. During eta Car's high-excitation state in March 2000, the wind was fast and dense at the poles, with higher ionization at low latitudes. Older STIS data obtained since 1998 reveal that this global stellar-wind geometry changes during eta Car's 5.5 year cycle, and may suggest that this star's spectroscopic events are shell ejectio...

  17. Physical Structure of Planetary Nebulae. I. The Owl Nebula

    CERN Document Server

    Guerrero, M A; Manchado, A; Kwitter, K B

    2003-01-01

    The Owl Nebula is a triple-shell planetary nebula with the outermost shell being a faint bow-shaped halo. We have obtained deep narrow-band images and high-dispersion echelle spectra in the H-alpha, [O III], and [N II] emission lines to determine the physical structure of each shell in the nebula. These spatio-kinematic data allow us to rule out hydrodynamic models that can reproduce only the nebular morphology. Our analysis shows that the inner shell of the main nebula is slightly elongated with a bipolar cavity along its major axis, the outer nebula is a filled envelope co-expanding with the inner shell at 40 km/s, and the halo has been braked by the interstellar medium as the Owl Nebula moves through it. To explain the morphology and kinematics of the Owl Nebula, we suggest the following scenario for its formation and evolution. The early mass loss at the TP-AGB phase forms the halo, and the superwind at the end of the AGB phase forms the main nebula. The subsequent fast stellar wind compressed the superwi...

  18. VLT Images the Horsehead Nebula

    Science.gov (United States)

    2002-01-01

    fine HST image - a new infrared view by VLT and ISAAC of this area was published last month, cf. PR 25/01. Such structures are only temporary as they are being constantly eroded by the expanding region of ionized gas and are destroyed on timescales of typically a few thousand years. The Horsehead as we see it today will therefore not last forever and minute changes will become observable as the time passes. The surroundings To the east of the Horsehead (at the bottom of this image) there is ample evidence for star formation in the Lynds 1630 dark cloud . Here, the reflection nebula NGC 2023 surrounds the hot B-type star HD 37903 and some Herbig Haro objects are found which represent high-speed gas outflows from very young stars with masses of around a solar mass. The HII region to the west (top of picture) is ionized by the strong radiation from the bright star Sigma Orionis , located just below the southernmost star in Orion's Belt. The chain of dust and molecular clouds are part of the Orion A and B regions (also known as Orion's `sword' ). Other images of the Horsehead Nebula The Horsehead Nebula is a favourite object for amateur astrophotographers and large numbers of images are available on the WWW. Due to its significant extension and the limited field-of-view of some professional telescopes, fewer photographs are available from today's front-line facilities, except from specialized wide-field instruments like Schmidt telescopes, etc. The links below point to a number of prominent photos obtained elsewhere and some contain further useful links to other sites with more information about this splendid sky area. "Astronomy Picture of the Day" : http://antwrp.gsfc.nasa.gov/apod/ap971025.html Hubble Heritage image : http://hubble.stsci.edu/news_.and._views/pr.cgi?2001%2B12 INT Wide-Field image : http://www.ing.iac.es/PR/science/horsehead.htm NOT image : http://www.not.iac.es/new/general/photos/astronomical/ NOAO Wide-Field image : http

  19. The radio source around Eta Carinae

    Science.gov (United States)

    White, S. M.; Duncan, R. A.; Lim, J.; Nelson, G. J.; Drake, S. A.; Kundu, M. R.

    1994-01-01

    We present high spatial resolution radio observations of the peculiar southern star Eta Carinae, made with the Australian Telescope. The images, at 8 and 9 GHz with a resolution of 1.0 arcsec show a source of dimension 10 arcsec and total flux of 0.7 Jy dominated by a strong central peak. The radio emission is unpolarized and offers no support to models which invoke degenerate stars or more exotic objects within the core of Eta Car. In these data we find no evidence for more than one energy source in the core with arcsecond separations as some infrared observations have suggested. Several levels of structure are evident in the radio image, which shows symmetry on the larger scales. Conventional formulae for stellar wind radio sources give a mass loss rate of order 3 x 10(exp -4) Solar Mass/yr based on the radio flux in the central peak, which yields a wind momentum flux of order 20% of the momentum flux available from the star's radiation field. The radio emission at these frequencies is consistent with thermal emission from gas flowing away from a 'luminous blue variable' star (LBV) Eta Car is probably the brightest thermal stellar wind radio source in the sky.

  20. Galactic Structure Toward the Carina Tangent

    CERN Document Server

    Kaltcheva, N

    2012-01-01

    This investigation presents a photometric study of the Galactic structure toward the Carina arm tangent. The field is located between 280 deg and 286 deg galactic longitude and -4 deg to 4 deg galactic latitude. All currently available uvbybeta data is used to obtain homogeneous color excesses and distances for more than 260 stars of spectral types O to G. We present revised distances and average extinction for the open clusters and cluster candidates NGC 3293, NGC 3114, Loden 46 and Loden 112. The cluster candidate Loden 112 appears to be a very compact group at a true distance modulus of 11.06 +\\- 0.11 (s.e.) (1629 +84,-80 pc), significantly closer than previous estimates. We found other OB stars at that same distance and, based on their proper motions, suggest a new OB association at coordinates 282 deg < l < 285 deg, -2 deg < b < 2 deg. Utilizing BV photometry and spectral classification of the known O-type stars in the very young open cluster Wd 2 we provide a new distance estimate of 14.13 +...

  1. Gemini GMOS and WHT SAURON integral-field spectrograph observations of the AGN-driven outflow in NGC 1266

    NARCIS (Netherlands)

    Davis, Timothy A.; Krajnovic, Davor; McDermid, Richard M.; Bureau, Martin; Sarzi, Marc; Nyland, Kristina; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Cappellari, Michele; Crocker, Alison; Davies, Roger L.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M.

    2012-01-01

    We use the Spectrographic Areal Unit for Research on Optical Nebulae and Gemini Multi-Object Spectrograph integral-field spectrographs to observe the active galactic nucleus (AGN) powered outflow in NGC?1266. This unusual galaxy is relatively nearby (D = 30?Mpc), allowing us to investigate the proce

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  3. Galaxy Outflows Without Supernovae

    CERN Document Server

    Sur, Sharanya; Ostriker, Eve C

    2016-01-01

    High surface density, rapidly star-forming galaxies are observed to have $\\approx 50-100\\,{\\rm km\\,s^{-1}}$ line-of-sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly-compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds $\\approx 35\\,{\\rm km\\...

  4. Super-Acceleration in the Flaring Crab Nebula

    Energy Technology Data Exchange (ETDEWEB)

    Tavani, Marco, E-mail: marco.tavani@inaf.it

    2013-10-15

    The Crab Nebula continues to surprise us. The Crab system (energized by a very powerful pulsar at the center of the Supernova Remnant SN1054) is known to be a very efficient particle “accelerator” which can reach PeV energies. Today, new surprising data concerning the gamma-ray flares produced by the Crab Nebula challenge models of particle acceleration. The total energy flux from the Crab has been considered for many decades substantially stable at X-ray and gamma-ray energies. However, this paradigm was shattered by the AGILE discovery and Fermi confirmation in September 2010 of transient gamma-ray emission from the Crab. Indeed, we can state that four major flaring gamma-ray episodes have been detected by AGILE and Fermi during the period mid-2007/2012. During these events, transient particle acceleration occurs in a regime which apparently violates the MHD conditions and synchrotron cooling constraints. This fact justifies calling “super-acceleration” the mechanism which produces the “flaring Crab phenomenon”. Radiation between 50 MeV and a few GeV is emitted with a quite hard spectrum within a short timescale (hours-days), with no obvious relation with simultaneous optical and X-ray emissions in the inner Nebula. “Super-acceleration” implies overcoming synchrotron cooling by strong (and “parallel”) electric fields most likely produced by magnetic field reconnection within the pulsar wind outflow. This acceleration appears to be very efficient and, remarkably, limited by radiation reaction. It is not clear at the moment where in the Nebula this phenomenon occurs. An intense observational program is now focused on the Crab Nebula to resolve its most challenging mystery.

  5. Super-Acceleration in the Flaring Crab Nebula

    International Nuclear Information System (INIS)

    The Crab Nebula continues to surprise us. The Crab system (energized by a very powerful pulsar at the center of the Supernova Remnant SN1054) is known to be a very efficient particle “accelerator” which can reach PeV energies. Today, new surprising data concerning the gamma-ray flares produced by the Crab Nebula challenge models of particle acceleration. The total energy flux from the Crab has been considered for many decades substantially stable at X-ray and gamma-ray energies. However, this paradigm was shattered by the AGILE discovery and Fermi confirmation in September 2010 of transient gamma-ray emission from the Crab. Indeed, we can state that four major flaring gamma-ray episodes have been detected by AGILE and Fermi during the period mid-2007/2012. During these events, transient particle acceleration occurs in a regime which apparently violates the MHD conditions and synchrotron cooling constraints. This fact justifies calling “super-acceleration” the mechanism which produces the “flaring Crab phenomenon”. Radiation between 50 MeV and a few GeV is emitted with a quite hard spectrum within a short timescale (hours-days), with no obvious relation with simultaneous optical and X-ray emissions in the inner Nebula. “Super-acceleration” implies overcoming synchrotron cooling by strong (and “parallel”) electric fields most likely produced by magnetic field reconnection within the pulsar wind outflow. This acceleration appears to be very efficient and, remarkably, limited by radiation reaction. It is not clear at the moment where in the Nebula this phenomenon occurs. An intense observational program is now focused on the Crab Nebula to resolve its most challenging mystery

  6. Atomic hydrogen in planetary nebulae

    International Nuclear Information System (INIS)

    The authors searched for neutral atomic hydrogen associated with 22 planetary nebulae and three evolved stars in the 21 cm line at the Arecibo Observatory. Objects whose radial velocities permitted discrimination from Galactic H I were chosen for observation. Hydrogen was detected in absorption from IC 4997. From the measurements new low limits are derived to the mass of atomic hydrogen associated with the undetected nebulae. Radio continuum observations were also made of several of the nebulae at 12.6 cm. The authors reexamine previous measurements of H I in planetary nebulae, and present the data on a consistent footing. The question of planetary nebula distances is considered at length. Finally, implications of the H I measurements for nebular evolution are discussed and it is suggested that atomic hydrogen seen in absorption was expelled from the progenitor star during the final 1000 yr prior to the onset of ionization. 68 references

  7. Detection of the compressed primary stellar wind in eta Carinae

    CERN Document Server

    Teodoro, M; Gull, T R; Corcoran, M F; Hamaguchi, K

    2013-01-01

    A series of three HST/STIS spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe II] and [Ni II] emissions moving outward from eta Carinae. We identify these arcs with the shell-like structures, seen in the 3D hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.

  8. The Star Formation History of the Carina Dwarf Galaxy

    CERN Document Server

    Hurley-Keller, D A; Nemec, J; Hurley-Keller, Denise; Mateo, Mario; Nemec, James

    1998-01-01

    We have analyzed deep B and V photometry of the Carina dwarf spheroidal reaching below the old main-sequence turnoff to about V = 25. Using simulated color-magnitude diagrams to model a range of star formation scenarios, we have extracted a detailed, global star formation history. Carina experienced three significant episodes of star formation at about 15 Gyr, 7 Gyr, and 3 Gyr. Contrary to the generic picture of galaxy evolution, however, the bulk of star formation, at least 50%, occured during the episode 7 Gyr ago, which may have lasted as long as 2 Gyr. For unknown reasons, Carina formed only 10-20% of its stars at an ancient epoch and then remained quiescent for more than 4 Gyr. The remainder (~30%) formed relatively recently, only 3 Gyr ago. Interest in the local population of dwarf galaxies has increased lately due to their potential importance in the understanding of faint galaxy counts. We surmise that objects like Carina, which exhibits the most extreme episodic behavior of any of the dwarf spheroida...

  9. Atlantic Ocean CARINA data: overview and salinity adjustments

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2010-02-01

    Full Text Available Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean. The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control for salinity for this data set. Procedures of quality control – including crossover analysis between stations and inversion analysis of all crossover data – are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example

  10. The CARINA Satellite Mission to Study the Lower Thermosphere

    Science.gov (United States)

    Bernhardt, P. A.; Siefring, C. L.; Gatling, G.; Oppenheimer, P.

    2015-12-01

    The Naval Research Laboratory has constructed two satellites called CARINA to fly below the F-Layer ionosphere for a period of 45 to 60 days. The Space Plasma Mission will study (1) HF radio propagation in the ionosphere, (2) sporadic-E layer characterization, and (3) global imaging of F-Layer ionosphere. The CARINA spacecraft will be launched in 2016 into a 51.6° inclination orbit that has in initial insertion of 178 km by 284 km. The instruments on CARINA are (1) Electric Field Receiver (EFI) measuring electrostatic and electromagnetic waves in the MF/HF Band (3 to 13 MHz), (2) Ram Langmuir Probe (RLP) measuring the electron concentration in the 102 to 106 cm-3 range and the (3) Orbiting GPS Receiver (OGR) to record TEC in the F-Layer above the satellite. The six areas of research are (a) Sporadic-E/Intermediate Layers and TIDs with a focus on ionospheric structures below orbit and large scale bottomside fluctuations in the F-Layer, (b) global assimilation for using the CARINA OGR and RLP observations as drivers for data driven ionospheric models such as GAIM, IDA3D, etc., (c) HF propagation and radio scintillations to determine the impact of the bottomside ionosphere on HF ray trajectories for SuperDARN, ionosondes, etc., and to determine the effects of ionospheric irregularities and UHF/L-Band scintillation on GPS, etc., (d) lightning and ocean waves to directly measure lightning EM pulses and determine their impact on the ionosphere as well as derive ocean wave height spectrum from HF surface wave scatter, (e) Langmuir waves excited by photoelectrons during the daytime and high power HF transmitters, and (f) satellite drag with thermosphere/mesospheric density updates determined by orbit measurements and reentry modeling of drag coefficients. CARINA will employ ground HF beacon transmitters, incoherent scatter radars, and other instrumented satellites such as the Canadian ePOP/CASSIPE spacecraft for coordinated observations. By staying in orbit for an

  11. Protostellar outflow-driven turbulence

    CERN Document Server

    Matzner, C D

    2007-01-01

    Protostellar outflows crisscross the regions of star cluster formation, stirring turbulence and altering the evolution of the forming cluster. We model the stirring of turbulent motions by protostellar outflows, building on an observation that the scaling law of supersonic turbulence implies a momentum cascade analogous to the energy cascade in Kolmogorov turbulence. We then generalize this model to account for a diversity of outflow strengths, and for outflow collimation, both of which enhance turbulence. For a single value of its coupling coefficient the model is consistent with turbulence simulations by Li & Nakamura and, plausibly, with observations of the NGC 1333 cluster-forming region. Outflow-driven turbulence is strong enough to stall collapse in cluster-forming regions for several crossing times, relieving the mismatch between star formation and turbulent decay rates. The predicted line-width-size scaling implies radial density indices between -1 and -2 for regions supported by outflow-driven tu...

  12. Magnetic propeller outflows

    OpenAIRE

    Lovelace, R. V. E.; Romanova, M. M.; Bisnovatyi-Kogan, G. S.

    1998-01-01

    A model is developed for magnetic `propeller'-driven outflows which cause a rapidly rotating magnetized star accreting from a disk to spin-down. Energy and angular momentum lost by the star goes into expelling most of the accreting disk matter. The theory gives an expression for the effective Alfven radius $R_A$ (where the inflowing matter is effectively stopped) which depends on the mass accretion rate, the star's mass and magnetic moment, and the star's rotation rate. The model points to a ...

  13. The Tarantula Nebula

    Science.gov (United States)

    2004-01-01

    NASA's new Spitzer Space Telescope, formerly known as the Space Infrared Telescope Facility, has captured in stunning detail the spidery filaments and newborn stars of the Tarantula Nebula, a rich star-forming region also known as 30 Doradus. This cloud of glowing dust and gas is located in the Large Magellanic Cloud, the nearest galaxy to our own Milky Way, and is visible primarily from the Southern Hemisphere. This image of an interstellar cauldron provides a snapshot of the complex physical processes and chemistry that govern the birth - and death - of stars.At the heart of the nebula is a compact cluster of stars, known as R136, which contains very massive and young stars. The brightest of these blue supergiant stars are up to 100 times more massive than the Sun, and are at least 100,000 times more luminous. These stars will live fast and die young, at least by astronomical standards, exhausting their nuclear fuel in a few million years.The Spitzer Space Telescope image was obtained with an infrared array camera that is sensitive to invisible infrared light at wavelengths that are about ten times longer than visible light. In this four-color composite, emission at 3.6 microns is depicted in blue, 4.5 microns in green, 5.8 microns in orange, and 8.0 microns in red. The image covers a region that is three-quarters the size of the full moon.The Spitzer observations penetrate the dust clouds throughout the Tarantula to reveal previously hidden sites of star formation. Within the luminescent nebula, many holes are also apparent. These voids are produced by highly energetic winds originating from the massive stars in the central star cluster. The structures at the edges of these voids are particularly interesting. Dense pillars of gas and dust, sculpted by the stellar radiation, denote the birthplace of future generations of stars.The Spitzer image provides information about the composition of the material at the edges of the voids. The surface layers closest to the

  14. Sanduleak's Star (LMC Anonymous) - Its similarity in the far-ultraviolet with the luminous object Eta Carinae and SN 1987A

    International Nuclear Information System (INIS)

    Low-resolution IUE SWP spectra of the peculiar object LMC Anonymous (Sanduleak's Star) indicates strong evidence for CNO-processed nebula in the vicinity of the star. The far-UV spectrum of LMC Anonymous closely resembles that of the S Condensation of Eta Carinae. The similarity between LMC Anonymous and the S Condensation is apparent from the absolute intensity of the N V, semiforbidden N IV, and semiforbidden N III emission lines compared with the reduced strength of C IV or semiforbidden C III emission. IUE spectra of the S Condensation and SN 1987A may provide important clues concerning the nature of LMC Anonymous, which indicates departures from normal cosmic abundances of nitrogen relative to carbon that are extreme. This may suggest that carbon envelope burning and dredge-up occurred simultaneously during the helium-burning stage. 25 refs

  15. Sanduleak's Star (LMC Anonymous) - Its similarity in the far-ultraviolet with the luminous object Eta Carinae and SN 1987A

    Science.gov (United States)

    Michalitsianos, A. G.; Kafatos, M.; Shore, S. N.

    1989-01-01

    Low-resolution IUE SWP spectra of the peculiar object LMC Anonymous (Sanduleak's Star) indicates strong evidence for CNO-processed nebula in the vicinity of the star. The far-UV spectrum of LMC Anonymous closely resembles that of the S Condensation of Eta Carinae. The similarity between LMC Anonymous and the S Condensation is apparent from the absolute intensity of the N V, semiforbidden N IV, and semiforbidden N III emission lines compared with the reduced strength of C IV or semiforbidden C III emission. IUE spectra of the S Condensation and SN 1987A may provide important clues concerning the nature of LMC Anonymous, which indicates departures from normal cosmic abundances of nitrogen relative to carbon that are extreme. This may suggest that carbon envelope burning and dredge-up occurred simultaneously during the helium-burning stage.

  16. 3D Radiative Transfer in Eta Carinae: The SimpleX Radiative Transfer Algorithm Applied to 3D SPH Simulations of Eta Car's Colliding Winds

    Science.gov (United States)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.

    2014-04-01

    At the heart of the spectacular bipolar Homunculus nebula lies an extremely luminous (5*10^6 L_sun) colliding wind binary with a highly eccentric (e ~ 0.9), 5.54-year orbit and a total mass ~ 110 M_sun. Our closest (D ~ 2.3 kpc) and best example of a pre-hypernova environment, Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions, stellar wind-wind collisions, and massive star evolution. In order to improve our knowledge of the system, we need to generate synthetic observations and compare them with the already available and future HST/STIS data. We present initial results from full 3D radiative transfer post-processing of 3D SPH hydrodynamical simulations of the interacting winds of Eta Carinae. We use SimpleX algorithm to obtain the ionization fractions of hydrogen and helium, this results in ionization maps of both species that constrain the regions where these lines can form. These results will allow us to put constraints on the number of ionizing photons coming from the companion. This construction of synthetic observations allows us to obtain insight into the highly complex 3D flows in Eta, from the shape of the ionized volume and its resulting optical/spectral appearance.

  17. Observations of feedback from radio-quiet quasars - II. Kinematics of ionized gas nebulae

    Science.gov (United States)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.; Nesvadba, Nicole P. H.; Liu, Xin

    2013-12-01

    The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around 11 luminous, obscured, radio-quiet quasars at z ˜ 0.5 out to ˜15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III] λ5007 Å emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80 per cent of the emission as high as 103 km s-1) combined with relatively small velocity difference across them (from 90 to 520 km s-1) point towards wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km s-1, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly towards outer parts of the nebulae (by 3 per cent kpc-1 on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find dot{E}_kin between 4 × 1044 and 3 × 1045 erg s-1 and dot{M} between 2 × 103 and 2 × 104 M⊙ yr-1. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ˜2 per cent. We report four new candidates for `superbubbles' - outflows that may have broken out of the denser regions of the host galaxy.

  18. The Carina Project IX: On Hydrogen and Helium Burning Variables

    Science.gov (United States)

    Coppola, G.; Marconi, M.; Stetson, P. B.; Bono, G.; Braga, V. F.; Ripepi, V.; Dall'Ora, M.; Musella, I.; Buonanno, R.; Fabrizio, M.; Ferraro, I.; Fiorentino, G.; Iannicola, G.; Monelli, M.; Nonino, M.; Thévenin, F.; Walker, A. R.

    2015-11-01

    We present new multiband (UBVI) time-series data of helium burning variables in the Carina dwarf spheroidal galaxy. The current sample includes 92 RR Lyrae—six of them are new identifications—and 20 Anomalous Cepheids, one of which is new identification. The analysis of the Bailey diagram shows that the luminosity amplitude of the first overtone component in double-mode variables is located along the long-period tail of regular first overtone variables, while the fundamental component is located along the short-period tail of regular fundamental variables. This evidence further supports the transitional nature of these objects. Moreover, the distribution of Carina double-mode variables in the Petersen diagram (P1/P0 versus P0) is similar to metal-poor globulars (M15, M68), to the dwarf spheroidal Draco, and to the Galactic Halo. This suggests that the Carina old stellar population is metal-poor and affected by a small spread in metallicity. We use trigonometric parallaxes for five field RR Lyrae stars to provide an independent estimate of the Carina distance using the observed reddening free Period-Wesenheit [PW, (BV)] relation. Theory and observations indicate that this diagnostic is independent of metallicity. We found a true distance modulus of μ = 20.01 ± 0.02 (standard error of the mean) ± 0.05 (standard deviation) mag. We also provided independent estimates of the Carina true distance modulus using four predicted PW relations (BV, BI, VI, BVI) and we found: μ = (20.08 ± 0.007 ± 0.07) mag, μ = (20.06 ± 0.006 ± 0.06) mag, μ = (20.07 ± 0.008 ± 0.08) mag, and μ = (20.06 ± 0.006 ± 0.06) mag. Finally, we identified more than 100 new SX Phoenicis stars that together with those already known in the literature (340) make Carina a fundamental laboratory for constraining the evolutionary and pulsation properties of these transitional variables.

  19. X-ray Star Clusters in the Carina Complex

    CERN Document Server

    Feigelson, Eric D; Townsley, Leisa K; Broos, Patrick S; Povich, Matthew S; Garmire, Gordon P; King, Robert R; Montmerle, Thierry; Preibisch, Thomas; Smith, Nathan; Stassun, Keivan G; Wang, Junfeng; Wolk, Scott; Zinnecker, Hans

    2011-01-01

    The distribution of young stars found in the Chandra Carina Complex Project (CCCP) is examined for clustering structure. X-ray surveys are advantageous for identifying young stellar populations compared to optical and infrared surveys in suffering less contamination from nebular emission and Galactic field stars. The analysis is based on smoothed maps of a spatially complete subsample of about 3000 brighter X-ray sources classified as Carina members, and about 10,000 stars from the full CCCP sample. The principal known clusters are recovered, and some additional smaller groups are identified. No rich embedded clusters are present, although a number of sparse groups are found. The CCCP reveals considerable complexity in clustering properties. The Trumpler 14 and 15 clusters have rich stellar populations in unimodal, centrally concentrated structures several parsecs across. Non-spherical internal structure is seen, and large-scale low surface density distributions surround these rich clusters. Trumpler 16, in c...

  20. IRS Spectral Maps of Photoevaporative Columns in M16, Carina, and the Galactic Center

    Science.gov (United States)

    Cotera, Angela; Healy, Kevin; Hester, Jeff; Sellgren, Kris; Simpson, Janet; Stolovy, Susan

    2008-03-01

    Photoevaporated columns of dust and gas - also called elephant trunks, pillars or fingers - are found in the periphery of H II regions, and have been observed within the Galaxy, the SMC and the LMC. These features are sites of current star formation, but the question remains whether the columns persist because stars formed in the denser regions prior to interactions with the UV radiation and stellar winds of nearby massive stars, or because of core collapse resulting from these interactions. Mapping the distribution of the physical states of the dust and gas in these columns is a necessary step towards understanding the possible star formation mechanisms within these dynamic objects. We propose to obtain IRS spectral maps of columns within M 16, the Carina nebula, and the Galactic center (GC) to understand the effects on these pillars from different stellar populations and initial conditions, and to better understand star formation in the GC. Within the spectral range of the high resolution IRS modes (9.9-37.2 micron) there are a wealth of molecular, atomic and PAH emission lines that will enable us to determine the excitation state, dust and gas temperatures, and probe the shock characteristics within the columns. Using the IRS spectral mapping mode, in conjunction with the CUBISM tool and the CLOUDY H II region model code, we will be able to construct detailed maps of the accessible emission lines and derived parameters for each column. IRS mapping of elephant trunks has not been done to date, yet provides a wealth of information unobtainable for the foreseeable future once Cycle 5 is completed.

  1. Volumetric Image Guidance Using Carina vs Spine as Registration Landmarks for Conventionally Fractionated Lung Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Lavoie, Caroline; Higgins, Jane; Bissonnette, Jean-Pierre [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada); Le, Lisa W. [Department of Biostatistics, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9 (Canada); Sun, Alexander; Brade, Anthony; Hope, Andrew; Cho, John [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada); Bezjak, Andrea, E-mail: andrea.bezjak@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada)

    2012-12-01

    Purpose: To compare the relative accuracy of 2 image guided radiation therapy methods using carina vs spine as landmarks and then to identify which landmark is superior relative to tumor coverage. Methods and Materials: For 98 lung patients, 2596 daily image-guidance cone-beam computed tomography scans were analyzed. Tattoos were used for initial patient alignment; then, spine and carina registrations were performed independently. A separate analysis assessed the adequacy of gross tumor volume, internal target volume, and planning target volume coverage on cone-beam computed tomography using the initial, middle, and final fractions of radiation therapy. Coverage was recorded for primary tumor (T), nodes (N), and combined target (T+N). Three scenarios were compared: tattoos alignment, spine registration, and carina registration. Results: Spine and carina registrations identified setup errors {>=}5 mm in 35% and 46% of fractions, respectively. The mean vector difference between spine and carina matching had a magnitude of 3.3 mm. Spine and carina improved combined target coverage, compared with tattoos, in 50% and 34% (spine) to 54% and 46% (carina) of the first and final fractions, respectively. Carina matching showed greater combined target coverage in 17% and 23% of fractions for the first and final fractions, respectively; with spine matching, this was only observed in 4% (first) and 6% (final) of fractions. Carina matching provided superior nodes coverage at the end of radiation compared with spine matching (P=.0006), without compromising primary tumor coverage. Conclusion: Frequent patient setup errors occur in locally advanced lung cancer patients. Spine and carina registrations improved combined target coverage throughout the treatment course, but carina matching provided superior combined target coverage.

  2. Volumetric Image Guidance Using Carina vs Spine as Registration Landmarks for Conventionally Fractionated Lung Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To compare the relative accuracy of 2 image guided radiation therapy methods using carina vs spine as landmarks and then to identify which landmark is superior relative to tumor coverage. Methods and Materials: For 98 lung patients, 2596 daily image-guidance cone-beam computed tomography scans were analyzed. Tattoos were used for initial patient alignment; then, spine and carina registrations were performed independently. A separate analysis assessed the adequacy of gross tumor volume, internal target volume, and planning target volume coverage on cone-beam computed tomography using the initial, middle, and final fractions of radiation therapy. Coverage was recorded for primary tumor (T), nodes (N), and combined target (T+N). Three scenarios were compared: tattoos alignment, spine registration, and carina registration. Results: Spine and carina registrations identified setup errors ≥5 mm in 35% and 46% of fractions, respectively. The mean vector difference between spine and carina matching had a magnitude of 3.3 mm. Spine and carina improved combined target coverage, compared with tattoos, in 50% and 34% (spine) to 54% and 46% (carina) of the first and final fractions, respectively. Carina matching showed greater combined target coverage in 17% and 23% of fractions for the first and final fractions, respectively; with spine matching, this was only observed in 4% (first) and 6% (final) of fractions. Carina matching provided superior nodes coverage at the end of radiation compared with spine matching (P=.0006), without compromising primary tumor coverage. Conclusion: Frequent patient setup errors occur in locally advanced lung cancer patients. Spine and carina registrations improved combined target coverage throughout the treatment course, but carina matching provided superior combined target coverage.

  3. HUBBLE'S PLANETARY NEBULA GALLERY

    Science.gov (United States)

    2002-01-01

    [Top left] - IC 3568 lies in the constellation Camelopardalis at a distance of about 9,000 light-years, and has a diameter of about 0.4 light-years (or about 800 times the diameter of our solar system). It is an example of a round planetary nebula. Note the bright inner shell and fainter, smooth, circular outer envelope. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Top center] - NGC 6826's eye-like appearance is marred by two sets of blood-red 'fliers' that lie horizontally across the image. The surrounding faint green 'white' of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the center of the green oval) drives a fast wind into older material, forming a hot interior bubble which pushes the older gas ahead of it to form a bright rim. (The star is one of the brightest stars in any planetary.) NGC 6826 is 2,200 light- years away in the constellation Cygnus. The Hubble telescope observation was taken Jan. 27, 1996 with the Wide Field and Planetary Camera 2. Credits: Bruce Balick (University of Washington), Jason Alexander (University of Washington), Arsen Hajian (U.S. Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence, Italy), Patrizio Patriarchi (Arcetri Observatory, Italy) and NASA [Top right ] - NGC 3918 is in the constellation Centaurus and is about 3,000 light-years from us. Its diameter is about 0.3 light-year. It shows a roughly spherical outer envelope but an elongated inner balloon inflated by a fast wind from the hot central star, which is starting to break out of the spherical envelope at the top and bottom of the image. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Bottom left] - Hubble 5 is a striking example of a 'butterfly' or bipolar (two-lobed) nebula. The heat generated by fast winds causes

  4. CARINA TCO2 data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    R. Wanninkhof

    2010-01-01

    Full Text Available Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, Atlantic and Southern Ocean have been retrieved and merged in a new data base: the CARINA (CARbon IN the Atlantic Project. These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. Secondary quality control, which involved objective study of data in order to quantify systematic differences in the reported values, was performed for the pertinent parameters in the CARINA data base. Systematic biases in the data have been corrected in the data products. The products are three merged data files with measured, adjusted and interpolated data of all cruises for each of the three CARINA regions (Arctic, Atlantic and Southern Ocean. Ninety-eight cruises were conducted in the "Atlantic" defined as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we report the details of the secondary QC which was done on the total dissolved inorganic carbon (TCO2 data and the adjustments that were applied to yield the final data product in the Atlantic. Procedures of quality control – including crossover analysis between stations and inversion analysis of all crossover data – are briefly described. Adjustments were applied to TCO2 measurements for 17 of the cruises in the Atlantic Ocean region. With these adjustments, the CARINA data base is consistent both internally as well as with GLODAP data, an oceanographic data set based on the WOCE Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, regional oceanic carbon inventories, uptake rates and model validation.

  5. CARINA TCO2 data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    R. Wanninkhof

    2010-07-01

    Full Text Available Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged in a new data base: the CARINA (CARbon IN the Atlantic Project. These data have gone through rigorous quality control (QC procedures so as to improve the quality and consistency of the data as much as possible. Secondary quality control, which involved objective study of data in order to quantify systematic differences in the reported values, was performed for the pertinent parameters in the CARINA data base. Systematic biases in the data have been tentatively corrected in the data products. The products are three merged data files with measured, adjusted and interpolated data of all cruises for each of the three CARINA regions (Arctic Mediterranean Seas, Atlantic and Southern Ocean. Ninety-eight cruises were conducted in the "Atlantic" defined as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we report the details of the secondary QC which was done on the total dissolved inorganic carbon (TCO2 data and the adjustments that were applied to yield the final data product in the Atlantic. Procedures of quality control – including crossover analysis between stations and inversion analysis of all crossover data – are briefly described. Adjustments were applied to TCO2 measurements for 17 of the cruises in the Atlantic Ocean region. With these adjustments, the CARINA data base is consistent both internally as well as with GLODAP data, an oceanographic data set based on the WOCE Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, regional oceanic carbon inventories, uptake rates and model validation.

  6. Overview of the Nordic Seas CARINA data and salinity measurements

    Directory of Open Access Journals (Sweden)

    A. Olsen

    2009-11-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas include the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least ±0.005.

  7. Overview of the Nordic Seas CARINA data and salinity measurements

    Directory of Open Access Journals (Sweden)

    R. M. Key

    2009-07-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least 0.05.

  8. DETECTION OF THE COMPRESSED PRIMARY STELLAR WIND IN {eta} CARINAE

    Energy Technology Data Exchange (ETDEWEB)

    Teodoro, M.; Madura, T. I.; Gull, T. R. [Astrophysics Science Division, Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Corcoran, M. F.; Hamaguchi, K., E-mail: mairan.teodoro@nasa.gov [CRESST and X-ray Astrophysics Laboratory, Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-08-10

    A series of three Hubble Space Telescope/Space Telescope Imaging Spectrograph spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe II] and [Ni II] emissions moving outward from {eta} Carinae. We identify these arcs with the shell-like structures, seen in the three-dimensional hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.

  9. Overview of the Nordic Seas CARINA data and salinity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Are [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Key, Robert [Princeton University; Jeansson, Emil [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Falck, E. [University of Bergen, Bergen, Norway; Olafsson, J. [Marine Research Institute, Reykjavik, Iceland; Van Heuven, S. [University of Groningen, The Netherlands; Skjelvan, I. [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Omar, A.M. [University of Bergen, Bergen, Norway; Olsson, K.A. [University of Gothenburg, Sweden; Anderson, L.G. [University of Gothenburg, Sweden; Jutterström, S. [University of Gothenburg, Sweden; Rey, F. [Institute of Marine Research, Bergen, Norway; Johannessen, T. [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Bellerby, R.G.J. [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Bullister, J.L. [NOAA Pacific Marine Environmental Laboratory; Pfeil, B. [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Lin, X. [Princeton University; Kozyr, Alexander [ORNL; Schirnick, C. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Tanhua, T. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Wallace, D.W.R. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany

    2009-01-01

    Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS), the Atlantic (ATL) and the Southern Ocean (SO).With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas include the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summaries the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least 0.005.

  10. Learning About the Magnetar Swift J1834.9-0846 from its Wind Nebula

    CERN Document Server

    Granot, Jonathan; Younes, George; Gelfand, Josef; Harding, Alice; Kouveliotou, Chryssa; Baring, Matthew G

    2016-01-01

    The first wind nebula around a magnetar was recently discovered in X-rays around Swift~J1834.9$-$0846. We study this magnetar's global energetics and the properties of its particle wind or outflows. At a distance of $\\sim4\\;$kpc, Swift~J1834.9$-$0846 is located at the center of the supernova remnant (SNR) W41 whose radius is $\\sim 19\\;$pc, an order of magnitude larger than that of the X-ray nebula ($\\sim2\\;$pc). The association with SNR W41 suggests a common age of $\\sim5-100\\;$kyr, while its spin-down age is $4.9$~kyr. A small natal kick velocity may partly explain why a wind nebula was detected around this magnetar but not around other magnetars, most of which appear to have larger kick velocities and may have exited their birth SNR. We find that the GeV and TeV source detected by Fermi/LAT and H.E.S.S., respectively, of radius $\\sim11\\;$pc is most likely of hadronic origin. The dynamics and internal structure of the nebula are examined analytically to explain the nebula's current properties. Its size may n...

  11. Protoplanetary Disks in the Hostile Environment of Carina

    Science.gov (United States)

    Mesa-Delgado, A.; Zapata, L.; Henney, W. J.; Puzia, T. H.; Tsamis, Y. G.

    2016-07-01

    We report the first direct imaging of protoplanetary disks in the star-forming region of Carina, the most distant massive cluster in which disks have been imaged. Using the Atacama Large Millimeter/sub-millimeter Array (ALMA), the disks are observed around two young stellar objects (YSOs) that are embedded inside evaporating gaseous globules and exhibit jet activity. The disks have an average radius of 60 au and total masses of 30 and 50 {M}{Jup}. Given the measured masses, the minimum timescale required for planet formation (∼1–2 Myr) and the average age of the Carina population (∼1–4 Myr), it is plausible that young planets are present or their formation is currently ongoing in these disks. The non-detection of millimeter emission above the 4σ threshold (∼ 7{M}{Jup}) in the core of the massive cluster Trumpler 14, an area containing previously identified proplyd candidates, suggests evidence for rapid photo-evaporative disk destruction in the cluster’s harsh radiation field. This would prevent the formation of giant gas planets in disks located in the cores of Carina’s dense subclusters, whereas the majority of YSO disks in the wider Carina region remain unaffected by external photoevaporation.

  12. Dwarf Cepheids in the Carina Dwarf Spheroidal Galaxy

    CERN Document Server

    Mateo, M; Nemec, J; Mateo, Mario; Hurley-Keller, Denise; Nemec, James

    1998-01-01

    We have discovered 20 dwarf Cepheids (DC) in the Carina dSph galaxy from the analysis of individual CCD images obtained for a deep photometric study of the system. These short-period pulsating variable stars are by far the most distant (~100 kpc) and faintest (V ~ 23.0) DCs known. The Carina DCs obey a well-defined period-luminosity relation, allowing us to readily distinguish between overtone and fundamental pulsators in nearly every case. Unlike RR Lyr stars, the pulsation mode turns out to be uncorrelated with light-curve shape, nor do the overtone pulsators tend towards shorter periods compared to the fundamental pulsators. Using the period-luminosity (PL) relations from Nemec et al. (1994 AJ, 108, 222) and McNamara (1995, AJ, 109, 1751), we derive (m-M)_0 = 20.06 +/- 0.12, for E(B-V) = 0.025 and [Fe/H] = -2.0, in good agreement with recent, independent estimates of the distance/reddening of Carina. The error reflects the uncertainties in the DC distance scale, and in the metallicity and reddening of Cari...

  13. The Carina Project IX: on Hydrogen and helium burning variables

    CERN Document Server

    Coppola, G; Stetson, P B; Bono, G; Braga, V F; Ripepi, V; Dall'Ora, M; Musella, I; Buonanno, R; Fabrizio, M; Ferraro, I; Fiorentino, G; Iannicola, G; Monelli, M; Nonino, M; Thévenin, F; Walker, R

    2015-01-01

    We present new multi-band (UBVI) time-series data of helium burning variables in the Carina dwarf spheroidal galaxy. The current sample includes 92 RR Lyrae-six of them are new identifications-and 20 Anomalous Cepheids, one of which is new identification. The analysis of the Bailey diagram shows that the luminosity amplitude of the first overtone component in double-mode variables is located along the long-period tail of regular first overtone variables, while the fundamental component is located along the short-period tale of regular fundamental variables. This evidence further supports the transitional nature of these objects. Moreover, the distribution of Carina double-mode variables in the Petersen diagram (P_1/P_0 vs P_0) is similar to metal-poor globulars (M15, M68), to the dwarf spheroidal Draco and to the Galactic Halo. This suggests that the Carina old stellar population is metal-poor and affected by a small spread in metallicity. We use trigonometric parallaxes for five field RR Lyrae stars to provi...

  14. Scaling ultraviolet outflows in Seyferts

    OpenAIRE

    Stoll, R.; S Mathur; Krongold, Y.; Nicastro, F.

    2009-01-01

    X-ray and UV absorbing outflows are frequently seen in AGN and have been cited as a possible feedback mechanism. Whether or not they can provide adequate feedback depends on how massive they are and how much energy they carry, but it depends in a more fundamental way upon whether they escape the potential of the black hole. If the outflows have reached their asymptotic velocity when we observe them, then all of these properties critically depend on the radius of the outflow: a value which is ...

  15. The Trifid Nebula: Stellar Sibling Rivalry

    Science.gov (United States)

    2001-01-01

    A zoom into the Trifid Nebula starts with ground-based observations and ends with a Hubble Space Telescope (HST) image. Another HST image shows star formation in the nebula and the video concludes with a ground-based image of the Trifid Nebula.

  16. Contraction of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Rawal, J.J. (Nehru Planetarium, Bombay (India))

    1984-10-01

    The concept of Roche limit is applied to the Laplacian theory of the origin of the solar system to study the contraction of a spherical gas cloud (solar nebula). In the process of contraction of the solar nebula, it is assumed that the phenomenon of supersonic turbulent convection is operative and brings about the halt at various stages of contraction. It is found that the radius of the contracting solar nebula follows the Titius-Bode law. The consequences of the relation are also discussed. The aim is to attempt to explain, on the basis of the concept of Roche limit, the distribution of planets in the solar system and try to understand the physics underlying it.

  17. Energy exchanges in reconnection outflows

    CERN Document Server

    Lapenta, Giovanni; Newman, Davd L; Markidis, Stefano

    2016-01-01

    Reconnection outflows are highly energetic directed flows that interact with the ambient plasma or with flows from other reconnection regions. Under these conditions the flow becomes highly unstable and chaotic, as any flow jets interacting with a medium. We report here massively parallel simulations of the two cases of interaction between outflow jets and between a single outflow with an ambient plasma. We find in both case the development of a chaotic magnetic field, subject to secondary reconnection events that further complicate the topology of the field lines. The focus of the present analysis is on the energy balance. We compute each energy channel (electromagnetic, bulk, thermal, for each species) and find where the most energy is exchanged and in what form. The main finding is that the largest energy exchange is not at the reconnection site proper but in the regions where the outflowing jets are destabilized.

  18. Ultraviolet spectra of planetary nebulae

    International Nuclear Information System (INIS)

    Features observed in infrared spectra suggest that certain very low excitation (VLE) nebulae have low C/O abundance ratios (Cohen and Barlow 1980; Aitken and Roche 1982). Fluxes in the multiplets [O II] lambda 2470 and C II] lambda 2326 have been measured for the VLE nebula He He 2-131 = HD 138403 using IUE high-dispersion spectra. An analysis similar to that of Harrington et al. (1980) for IC 418 gives C/O = 0.3 for He 2-131, compared with C/O = 1.3 for IC 418 and 0.6 for the Sun. (author)

  19. Scaling ultraviolet outflows in Seyferts

    CERN Document Server

    Stoll, R; Krongold, Y; Nicastro, F

    2009-01-01

    X-ray and UV absorbing outflows are frequently seen in AGN and have been cited as a possible feedback mechanism. Whether or not they can provide adequate feedback depends on how massive they are and how much energy they carry, but it depends in a more fundamental way upon whether they escape the potential of the black hole. If the outflows have reached their asymptotic velocity when we observe them, then all of these properties critically depend on the radius of the outflow: a value which is difficult to measure. The tightest limit on the distance of an X-ray warm absorber from the ionizing source is that of Krongold et al. (2007) for NGC 4051. We use NGC 4051 to model other observed UV outflows, and find that on the whole they may not provide meaningful feedback. The outflow velocities are below or just above the escape velocity of the black hole. This may be because they are not yet fully accelerated, or the duty cycle of high-velocity outflows may be small. Another possibility is that they may only provide...

  20. Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment

    CERN Document Server

    Smith, N; Smith, Nathan; Morse, Jon A.

    2004-01-01

    We present optical spectra of the ionized `Outer Ejecta' of Eta Carinae that reveal differences in chemical composition at various positions. In particular, young condensations just outside the dusty Homunculus Nebula show strong nitrogen lines and little or no oxygen -- but farther away, nitrogen lines weaken and oxygen lines become stronger. The observed variations in the apparent N/O ratio may signify either that the various blobs were ejected with different abundances, or more likely, that the more distant condensations are interacting with normal-composition material. The second hypothesis is supported by various other clues involving kinematics and X-ray emission, and would suggest that Eta Car is enveloped in a ``cocoon'' deposited by previous stellar-wind mass loss. In particular, all emission features where we detect strong oxygen lines are coincident with or outside the soft X-ray shell. In either case, the observed abundance variations suggest that Eta Car's ejection of nitrogen-rich material is a ...

  1. Early-type PMS and MS objects in M16 and the Carina star-forming regions

    CERN Document Server

    Martayan, Christophe; Fremat, Yves; Hubert, Anne-Marie; Neiner, Coralie; Baade, Dietrich; Fabregat, Juan

    2009-01-01

    Thanks to a variety of pertinent wide-angle facilities (WFI-slitless mode, VLT-FLAMES (Pasquini et al. 2002), SPITZER, 2MASS) it is possible to comprehensively study the nature of early-type objects in star-forming regions like the Eagle Nebula and Carina on large spatial scales. In them, the young open clusters NGC 6611, Trumpler 14, Trumpler 15, Trumpler 16, and their vicinities are of particular interest. With the WFI in its slitless mode (Baade et al. 1999), one can reliably and with little extra effort discriminate in thousands of spectra between intrinsic circumstellar emission as in HBe/Ae stars and diffuse interstellar line emission. The only bias results from the need of the equivalent width and absolute strength of the line emission to be sufficient for detection. VLT-FLAMES spectra combined with infrared data from SPITZER and 2MASS permit the nature of the objects with and without emission-lines to be derived. Following this approach, we report on the discovery and classification of new Herbig Be/A...

  2. Spitzer Space Telescope IRS Spectral Mapping of Photoionized Columns in M16 and the Carina HII Regions

    Science.gov (United States)

    Cotera, Angela; Simpson, J. P.; Sellgren, K.; Stolovy, S. R.

    2013-01-01

    Photoevaporated columns of dust and gas - also called elephant trunks, pillars or fingers - are found in the periphery of many H II regions. They have been observed within the Galaxy, the SMC and the LMC. These features are thought to be sites of current star formation, but the question remains whether the columns persist because stars formed in the denser regions prior to interactions with the UV radiation and stellar winds of nearby massive stars, or because of core collapse resulting from these interactions. We have obtained Spitzer IRS spectral maps of three columns within M 16 and three columns within the Carina nebula, to test our understanding of the impact on these transitory features of differing stellar populations and initial conditions. We use the wealth of molecular, atomic and PAH emission lines located within the spectral range of the high resolution IRS modes (9.9-37.2 micron) to determine the excitation state, dust and gas temperatures, and probe the shock characteristics within the columns as a function of location. Using the IRS spectral mapping mode, in conjunction with the CUBISM tool and the CLOUDY H II region model code, we have constructed detailed maps of the accessible emission lines and derived parameters for each column. Mapping the distribution of the physical states of the dust and gas in these columns is enhancing our understanding of the competing processes within these dynamic objects. The data presented here represent the only IRS spectral maps of photoionized pillars.

  3. Diagnostics of planetary nebulae plasma

    International Nuclear Information System (INIS)

    Starting with the pioneering Ambartsumian's papers, the problems of diagnostics of low density plasma of planetary nebulae are reviewed. We discuss both the early papers of Ambartsumian and the papers developing the methods of plasma diagnostics based on Ambartsumian's ideas. The diagnostics methods for both homogeneous and inhomogeneous nebular plasma are described

  4. Observations of Feedback from Radio-Quiet Quasars: II. Kinematics of Ionized Gas Nebulae

    CERN Document Server

    Liu, Guilin; Greene, Jenny E; Nesvadba, Nicole P H; Liu, Xin

    2013-01-01

    The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around eleven luminous, obscured, radio-quiet quasars at z~0.5 out to ~15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III]5007 emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80% of the emission as high as 1000 km/s combined with relatively small velocity difference across them (from 90 to 520 km/s) point toward wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km/s, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly toward outer parts of the nebulae (by 3% per kpc on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, s...

  5. A Magnetar Wind Nebula: the Spin-down-Powered Wind is not Enough

    Science.gov (United States)

    Gill, Ramandeep; Granot, Jonathan; Baring, Matthew G.; Gelfand, Joseph; Younes, George A.; Kargaltsev, Oleg; Kust Harding, Alice; Kouveliotou, Chryssa; Huppenkothen, Daniela

    2016-04-01

    Magnetars are a small class of slowly-rotating (P~2-12 s) highly magnetized (surface dipole fields ~10^{14}-10^{15} G) that show a variety of bursting activity, powered by the decay of their super-strong magnetic field. While many rotation-powered pulsars are surrounded by a pulsar wind nebula (PWN) powered by their spin-down MHD wind (the prime example being the Crab nebula), only now has the first magnetar wind nebula (MWN) been discovered in X-rays, around Swift J1834.9-0846. We have analyzed this system in detail to see what can be learned from it. We find good evidence that unlike normal PWNe, this MWN cannot be powered by its spin-down MHD wind alone. A considerable contribution to the MWN energy should come from a different source, most likely sporadic outflows associated with the magnetar's bursting activity. This suggests that the MWN may serve as a calorimeter, and provide a new and robust estimate for the magnetar's long-term mean energy output rate in outflows. We also discuss other interesting aspects of this system.

  6. Planetary nebulae and their mimics: the MASH-MEN Project

    CERN Document Server

    Boissay, Rozenn; Frew, David J; Bojicic, Ivan

    2012-01-01

    The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is about 3000, approximately twice the number known a decade ago. The new discoveries are a legacy of the recent availability of wide-field, narrowband imaging surveys, primarily in the light of H-alpha. The two most important are the AAO/UKST SuperCOSMOS H-alpha survey - SHS and the Isaac Newton photometric H-alpha survey - IPHAS, which are responsible for most of the new discoveries. A serious problem with previous PN catalogues is that several different kinds of astrophysical objects are able to mimic PN in some of their observed properties leading to significant contamination. These objects include H II regions and Stromgren zones around young O/B stars, reflection nebulae, Wolf-Rayet ejecta, supernova remnants, Herbig-Haro objects, young stellar objects, B[e] stars, symbiotic stars and outflows, late-type stars, cataclysmic variables, low redshift emission-line galaxies, and even image/detector flaws. PN catal...

  7. OUTFLOWS FROM EVOLVED STARS: THE RAPIDLY CHANGING FINGERS OF CRL 618

    International Nuclear Information System (INIS)

    Our ultimate goal is to probe the nature of the collimator of the outflows in the pre-planetary nebula CRL 618. CRL 618 is uniquely suited for this purpose owing to its multiple, bright, and carefully studied finger-shaped outflows east and west of its nucleus. We compare new Hubble Space Telescope images to images in the same filters observed as much as 11 yr ago to uncover large proper motions and surface brightness changes in its multiple finger-shaped outflows. The expansion age of the ensemble of fingers is close to 100 yr. We find strong brightness variations at the fingertips during the past decade. Deep IR images reveal a multiple ring-like structure of the surrounding medium into which the outflows propagate and interact. Tightly constrained three-dimensional hydrodynamic models link the properties of the fingers to their possible formation histories. We incorporate previously published complementary information to discern whether each of the fingers of CRL 618 are the results of steady, collimated outflows or a brief ejection event that launched a set of bullets about a century ago. Finally, we argue on various physical grounds that fingers of CRL 618 are likely to be the result of a spray of clumps ejected at the nucleus of CRL 618 since any mechanism that form a sustained set of unaligned jets is unprecedented

  8. OUTFLOWS FROM EVOLVED STARS: THE RAPIDLY CHANGING FINGERS OF CRL 618

    Energy Technology Data Exchange (ETDEWEB)

    Balick, Bruce [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Huarte-Espinosa, Martin [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Frank, Adam; Gomez, Thomas [Astronomy Department, University of Texas, Austin, TX 78731-2330 (United States); Alcolea, Javier [Observatorio Astronomico Nacional (IGN), E-28014 Madrid (Spain); Corradi, Romano L. M. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Vinkovic, Dejan, E-mail: balick@uw.edu, E-mail: martinHE@pas.rochester.edu, E-mail: afrank@pas.rochester.edu, E-mail: gomezt@astro.as.utexas.edu, E-mail: j.alcolea@oan.es, E-mail: rcorradi@iac.es, E-mail: vinkovic@pmfst.hr [Physics Department, University of Split, Teslina 12/III, HR-21000 Split (Croatia)

    2013-07-20

    Our ultimate goal is to probe the nature of the collimator of the outflows in the pre-planetary nebula CRL 618. CRL 618 is uniquely suited for this purpose owing to its multiple, bright, and carefully studied finger-shaped outflows east and west of its nucleus. We compare new Hubble Space Telescope images to images in the same filters observed as much as 11 yr ago to uncover large proper motions and surface brightness changes in its multiple finger-shaped outflows. The expansion age of the ensemble of fingers is close to 100 yr. We find strong brightness variations at the fingertips during the past decade. Deep IR images reveal a multiple ring-like structure of the surrounding medium into which the outflows propagate and interact. Tightly constrained three-dimensional hydrodynamic models link the properties of the fingers to their possible formation histories. We incorporate previously published complementary information to discern whether each of the fingers of CRL 618 are the results of steady, collimated outflows or a brief ejection event that launched a set of bullets about a century ago. Finally, we argue on various physical grounds that fingers of CRL 618 are likely to be the result of a spray of clumps ejected at the nucleus of CRL 618 since any mechanism that form a sustained set of unaligned jets is unprecedented.

  9. Eta Carinae and the Homunculus: A Physics Laboratory

    Science.gov (United States)

    Gull, Theodore R.; Fisher, Richard R. (Technical Monitor)

    2002-01-01

    The Luminous Blue Variable, Eta Carinae, and its ejecta, thrown out since the 1840s, are proving to be a very challenging system to explain. The > 100 solar mass central source (which is likely a binary system) is very complex with P-Cygni lines throughout the spectrum. Superimposed upon the stellar spectrum are many thousands of narrow absorption lines. Indeed we have found twenty different velocities between -140km/s and -580km/s with many lower levels well elevated above the ground states of numerous ions.

  10. Detection of He II 4686 in eta Carinae

    OpenAIRE

    J. E. Steiner; A. Damineli

    2004-01-01

    We report the detection of the emission line He II 4686 A in eta Carinae. The equivalent width of this line is ~100 mA along most of the 5.5-yr cycle and jumps to ~900 mA just before phase 1.0, followed by a brief disappearance. The similarity between the intensity variations of this line and of the X-ray light curve is remarkable, suggesting that they are physically connected. We show that the number of ionizing photons in the ultraviolet and soft X-rays, expected to be emitted in the shock ...

  11. Modelling the Radio Light Curve of Eta Carinae

    OpenAIRE

    Kashi, Amit; Soker, Noam

    2007-01-01

    We study the propagation of the ionizing radiation emitted by the secondary star in Eta Carinae. We find that a large fraction of this radiation is absorbed by the primary stellar wind, mainly after it encounters the secondary wind and passes through a shock wave. The amount of absorption depends on the compression factor of the primary wind in the shock wave. We build a model where the compression factor is limited by the magnetic pressure in the primary wind. We find that the variation of t...

  12. CARINA data synthesis project: pH data scale unification and cruise adjustments

    Directory of Open Access Journals (Sweden)

    A. Velo

    2010-05-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Artic Mediterranean Seas (AMS, Atlantic Ocean and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic Ocean.

    These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values. Systematic biases found in the data have been corrected in the data products, three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; AMS, Atlantic Ocean and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 59 reported pH measured values. All reported pH data have been unified to the Sea-Water Scale (SWS at 25 °C.

    Here we present details of the secondary QC of pH in the CARINA database and the scale unification to SWS at 25 °C. The pH scale has been converted for 36 cruises. Procedures of quality control, including crossover analysis between cruises and inversion analysis are described. Adjustments were applied to the pH values for 21 of the cruises in the CARINA dataset. With these adjustments the CARINA database is consistent both internally as well as with the GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal consistency of the CARINA pH data to be 0.005 pH units. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, for ocean acidification assessment and for model validation.

  13. Mediterranean Outflow Mixing and Dynamics

    Science.gov (United States)

    Price, James F.; O'Neil Baringer, Molly; Lueck, Rolf G.; Johnson, Gregory C.; Ambar, Isabel; Parrilla, Gregorio; Cantos, Alain; Kennelly, Maureen A.; Sanford, Thomas B.

    1993-02-01

    The Mediterranean Sea produces a salty, dense outflow that is strongly modified by entrainment as it first begins to descend the continental slope in the eastern Gulf of Cadiz. The current accelerates to 1.3 meters per second, which raises the internal Froude number above 1, and is intensely turbulent through its full thickness. The outflow loses about half of its density anomaly and roughly doubles its volume transport as it entrains less saline North Atlantic Central water. Within 100 kilometers downstream, the current is turned by the Coriolis force until it flows nearly parallel to topography in a damped geostrophic balance. The mixed Mediterranean outflow continues westward, slowly descending the continental slope until it becomes neutrally buoyant in the thermocline where it becomes an important water mass.

  14. Constraining the Turbulence Scale and Mixing of a Crushed Pulsar Wind Nebula

    Science.gov (United States)

    Ng, Chi Yung; Ma, Y. K.; Bucciantini, Niccolo; Slane, Patrick O.; Gaensler, Bryan M.; Temim, Tea

    2016-04-01

    Pulsar wind nebulae (PWNe) are synchrotron-emitting nebulae resulting from the interaction between pulsars' relativistic particle outflows and the ambient medium. The Snail PWN in supernova remnant G327.1-1.1 is a rare system that has recently been crushed by supernova reverse shock. We carried out radio polarization observations with the Australia Telescope Compact Array and found highly ordered magnetic field structure in the nebula. This result is surprising, given the turbulent environment expected from hydrodynamical simulations. We developed a toymodel and compared simple simulations with observations to constrain the characteristic turbulence scale in the PWN and the mixing with supernova ejecta. We estimate that the turbulence scale is about one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50-75%. The latter implies substantial mixing of the pulsar wind with the surrounding supernova ejecta.This work is supported by an ECS grant of the Hong Kong Government under HKU 709713P. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

  15. High Energy Studies of Pulsar Wind Nebulae

    CERN Document Server

    Slane, Patrick

    2008-01-01

    The extended nebulae formed as pulsar winds expand into their surroundings provide information about the composition of the winds, the injection history from the host pulsar, and the material into which the nebulae are expanding. Observations from across the electromagnetic spectrum provide constraints on the evolution of the nebulae, the density and composition of the surrounding ejecta, the geometry of the systems, the formation of jets, and the maximum energy of the particles in the nebulae. Here I provide a broad overview of the structure of pulsar wind nebulae, with specific examples that demonstrate our ability to constrain the above parameters. The association of pulsar wind nebulae with extended sources of very high energy gamma-ray emission are investigated, along with constraints on the nature of such high energy emission.

  16. Protoplanetary disks in the hostile environment of Carina

    CERN Document Server

    Mesa-Delgado, A; Henney, W J; Puzia, T H; Tsamis, Y G

    2016-01-01

    We report the first direct imaging of protoplanetary disks in the star-forming region of Carina, the most distant, massive cluster in which disks have been imaged. Using the Atacama Large Millimeter/sub-millimeter Array (ALMA), disks are observed around two young stellar objects (YSOs) that are embedded inside evaporating gaseous globules and exhibit jet activity. The disks have an average size of 120 AU and total masses of 30 and 50 M_Jup. Given the measured masses, the minimum timescale required for planet formation (~1-2 Myr) and the average age of the Carina population (~1-4 Myr), it is plausible that young planets are present or their formation is currently ongoing in these disks. The non-detection of millimeter emission above the 4sigma threshold (~7 M_Jup) in the core of the massive cluster Trumpler~14, an area containing previously identified proplyd candidates, suggest evidence for rapid photo-evaporative disk destruction in the cluster's harsh radiation field. This would prevent the formation of gia...

  17. SECULAR CHANGES IN ETA CARINAE'S WIND 1998–2011

    International Nuclear Information System (INIS)

    Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a timescale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude dependent, and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.

  18. Pulsar Wind Nebulae and Their Supernovae

    OpenAIRE

    Chevalier, Roger A.

    2003-01-01

    Young supernova remnants that contain pulsar wind nebulae provide diagnostics for both the inner part of the supernova and the interaction with the surrounding medium, providing an opportunity to relate these objects to supernova types. Among observed young nebulae, there is evidence for a range of supernova types, including Type IIP (Crab Nebula and SN 1054) and Type IIb/IIn/IIL (G292.0+1.8).

  19. Stars in the Tarantula Nebula

    Science.gov (United States)

    1999-01-01

    In the most active starburst region in the local universe lies a cluster of brilliant, massive stars, known to astronomers as Hodge 301. Hodge 301, seen in the lower right hand corner of this image, lives inside the Tarantula Nebula in our galactic neighbor, the Large Magellanic Cloud. This star cluster is not the brightest, or youngest, or most populous star cluster in the Tarantula Nebula, that honor goes to the spectacular R136. In fact, Hodge 301 is almost 10 times older than the young cluster R136. But age has its advantages; many of the stars in Hodge 301 are so old that they have exploded as supernovae. These exploded stars are blasting material out into the surrounding region at speeds of almost 200 miles per second. This high speed ejecta are plowing into the surrounding Tarantula Nebula, shocking and compressing the gas into a multitude of sheets and filaments, seen in the upper left portion of the picture. Hodge 301 contains three red supergiants - stars that are close to the end of their evolution and are about to go supernova, exploding and sending more shocks into the Tarantula. Also present near the center of the image are small, dense gas globules and dust columns where new stars are being formed today, as part of the overall ongoing star formation throughout the Tarantula region.

  20. Molecular outflows in starburst nuclei

    CERN Document Server

    Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.

  1. Molecular outflows in starburst nuclei

    Science.gov (United States)

    Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-08-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disk with mid-plane density n0 ˜ 200-1000 cm-3 and scale height z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that a SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  2. Knowledge Outflows from Foreign Subsidiaries

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf

    This paper analyzes the MNC subsidiaries’ trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we find that s...

  3. High Velocity Outflows in Quasars

    CERN Document Server

    Hidalgo, P R; Nestor, D; Shields, J; Hidalgo, Paola Rodriguez; Hamann, Fred; Nestor, Daniel; Shields, Joseph

    2007-01-01

    High velocity (HV) outflows are an important but poorly understood aspect of quasar/SMBH evolution. Outflows during the luminous accretion phase might play a critical role in "unveiling" young dusty AGN and regulating star formation in the host galaxies. Most quasar studies have focussed on the broad absorption lines (BALs). We are involved in a program to study a nearly unexplored realm of quasar outflow parameter space: HV winds with v>10,000 km/s up to v~0.2c but small velocity dispersions (narrow absorption lines), such that (Delta v)/v << 1. Narrow-line HV flows merit specific attention because they complement the BAL work and pose unique challenges for models of the wind acceleration, mass loss rates, launch radii, geometry, etc. We have selected the brightest quasars at 1.8outflow lines (CIV 1548 A) in existing SDSS spectra and followed up with monitoring observations to i) characterize, for the first time, the variability in a sample of absorbers spanning a ...

  4. Particle Transport in Young Pulsar Wind Nebulae

    OpenAIRE

    Tang, Xiaping; Chevalier, Roger A.

    2012-01-01

    The model for pulsar wind nebulae (PWNe) as the result of the magnetohydrodynamic (MHD) downstream flow from a shocked, relativistic pulsar wind has been successful in reproducing many features of the nebulae observed close to the central pulsars. However, observations of well-studied young nebulae like the Crab Nebula, 3C 58, and G21.5--0.9 do not show the toroidal magnetic field on a larger scale that might be expected in the MHD flow model; in addition, the radial variation of spectral ind...

  5. Molecular clouds in the Carina arm - the largest objects, associated regions of star formation, and the Carina arm in the Galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Grabelsky, D.A.; Cohen, R.S.; Bronfman, L.; Thaddeus, P.

    1988-08-01

    The Columbia CO survey of the southern Galactic plane is used to identify giant molecular clouds and cloud complexes in the Vela-Carina-Centaurus section of the Galaxy. Twenty-seven giant molecular clouds between l = 270 and 300 deg are catalogued and their heliocentric distances given. In addition, 16 clouds at l greater than 300 deg beyond the solar circle extend the catalog to include the very distant portion of the Carina arm. The most massive clouds in the catalog trace the Carina arm over 23 kpc in the plane of the Galaxy. The average mass of these objects is 1.4 x 10 to the 6th solar, and their average spacing along the arm is 700 pc. The composite distribution projected onto the Galactic plane of the largest molecular clouds in the Carina arm and of similarly massive clouds in the first and second quadrants strongly suggests that the Carina and Sagittarius arms form a single spiral arm about 40 kpc in length wrapping two-thirds of the way around the Galaxy. Descriptions of each cloud, including identification of associated star-forming regions, are presented in an appendix. 76 references.

  6. Molecular clouds in the Carina arm - The largest objects, associated regions of star formation, and the Carina arm in the Galaxy

    Science.gov (United States)

    Grabelsky, D. A.; Cohen, R. S.; Bronfman, L.; Thaddeus, P.

    1988-01-01

    The Columbia CO survey of the southern Galactic plane is used to identify giant molecular clouds and cloud complexes in the Vela-Carina-Centaurus section of the Galaxy. Twenty-seven giant molecular clouds between l = 270 and 300 deg are catalogued and their heliocentric distances given. In addition, 16 clouds at l greater than 300 deg beyond the solar circle extend the catalog to include the very distant portion of the Carina arm. The most massive clouds in the catalog trace the Carina arm over 23 kpc in the plane of the Galaxy. The average mass of these objects is 1.4 x 10 to the 6th solar, and their average spacing along the arm is 700 pc. The composite distribution projected onto the Galactic plane of the largest molecular clouds in the Carina arm and of similarly massive clouds in the first and second quadrants strongly suggests that the Carina and Sagittarius arms form a single spiral arm about 40 kpc in length wrapping two-thirds of the way around the Galaxy. Descriptions of each cloud, including identification of associated star-forming regions, are presented in an appendix.

  7. PTF10nvg: AN OUTBURSTING CLASS I PROTOSTAR IN THE PELICAN/NORTH AMERICAN NEBULA

    International Nuclear Information System (INIS)

    During a synoptic survey of the North American Nebula region, the Palomar Transient Factory (PTF) detected an optical outburst (dubbed PTF10nvg) associated with the previously unstudied flat or rising spectrum infrared source IRAS 20496+4354. The PTF R-band light curve reveals that PTF10nvg brightened by more than 5 mag during the current outburst, rising to a peak magnitude of RPTF ∼ 13.5 in 2010 September. Follow-up observations indicate that PTF10nvg has undergone a similar ∼5 mag brightening in the K band and possesses a rich emission-line spectrum, including numerous lines commonly assumed to trace mass accretion and outflows. Many of these lines are blueshifted by ∼175 km s-1 from the North American Nebula's rest velocity, suggesting that PTF10nvg is driving an outflow. Optical spectra of PTF10nvg show several TiO/VO band heads fully in emission, indicating the presence of an unusual amount of dense (>1010 cm-3), warm (1500-4000 K) circumstellar material. Near-infrared spectra of PTF10nvg appear quite similar to a spectrum of McNeil's Nebula/V1647 Ori, a young star which has undergone several brightenings in recent decades, and 06297+1021W, a Class I protostar with a similarly reached near-infrared emission line spectrum. While further monitoring is required to fully understand this event, we conclude that the brightening of PTF10nvg is indicative of enhanced accretion and outflow in this Class-I-type protostellar object, similar to the behavior of V1647 Ori in 2004-2005.

  8. An Interacting Binary System Powers Precessing Outflows of an Evolved Star

    CERN Document Server

    Boffin, Henri M J; Rauch, Thomas; Jones, David; Corradi, Romano L M; Napiwotzki, Ralf; Day-Jones, Avril C; Koeppen, Joachim

    2012-01-01

    Stars are generally spherical, yet their gaseous envelopes often appear non-spherical when ejected near the end of their lives. This quirk is most notable during the planetary nebula phase when these envelopes become ionized. Interactions among stars in a binary system are suspected to cause the asymmetry. In particular, a precessing accretion disk around a companion is believed to launch point-symmetric jets, as seen in the prototype Fleming 1. Our discovery of a post common-envelope binary nucleus in Fleming 1 confirms that this scenario is highly favorable. Similar binary interactions are therefore likely to explain these kinds of outflows in a large variety of systems.

  9. Revisiting 2D Numerical Models for the 19th century outbursts of $\\eta$ Carinae

    CERN Document Server

    González, R F; Gómez, G C; Pino, E M de Gouveia Dal; Raga, A C; Cantó, J; Velázquez, P F; de la Fuente, E

    2009-01-01

    We present here new results of two-dimensional hydrodynamical simulations of the eruptive events of the 1840s (the great) and the 1890s (the minor) eruptions suffered by the massive star $\\eta$ Car. The two bipolar nebulae commonly known as the Homunculus and the little Homunculus were formed from the interaction of these eruptive events with the underlying stellar wind. As in previous work (Gonzalez et al. 2004a, 2004b), we assume here an interacting, nonspherical multiple-phase wind scenario to explain the shape and the kinematics of both Homunculi, but adopt a more realistic parametrization of the phases of the wind. During the 1890s eruptive event, the outflow speed {\\it decreased} for a short period of time. This fact suggests that the little Homunculus is formed when the eruption ends, from the impact of the post-outburst $\\eta$ Car wind (that follows the 1890s event) with the eruptive flow (rather than by the collision of the eruptive flow with the pre-outburst wind, as claimed in previous models; Gonz...

  10. Irradiated Interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 Massive Star Formation Regions

    CERN Document Server

    Hartigan, P; Cleeves, L I

    2013-01-01

    Regions of massive star formation offer some of the best and most easily-observed examples of radiation hydrodynamics. Boundaries where fully-ionized H II regions transition to neutral/molecular photodissociation regions (PDRs) are of particular interest because marked temperature and density contrasts across the boundaries lead to evaporative flows and fluid dynamical instabilities that can evolve into spectacular pillar-like structures. When detached from their parent clouds, pillars become ionized globules that often harbor one or more young stars. H2 molecules at the interface between a PDR and an H II region absorb ultraviolet light from massive stars, and the resulting fluoresced infrared emission lines are an ideal way to trace this boundary independent of obscuring dust. This paper presents H2 images of four regions of massive star formation that illustrate different types of PDR boundaries. The Ara OB1 star formation region contains a striking long wall that has several wavy structures which are pres...

  11. A Herschel study of Planetary Nebulae

    CERN Document Server

    Van de Steene, G C; van Hoof, P A M; Lim, T L; Barlow, M J; Matsuura, M; Ueta, T

    2011-01-01

    We present Herschel PACS and SPIRE images of the dust shells around the planetary nebulae NGC 650, NGC 6853, and NGC 6720, as well as images showing the dust temperature in their shells. The latter shows a rich structure, which indicates that internal extinction in the UV is important despite the highly evolved status of the nebulae.

  12. 3-D structures of planetary nebulae

    CERN Document Server

    Steffen, Wolfgang

    2016-01-01

    Recent advances in the 3-D reconstruction of planetary nebulae are reviewed. We include not only results for 3-D reconstructions, but also the current techniques in terms of general methods and software. In order to obtain more accurate reconstructions, we suggest to extend the widely used assumption of homologous nebula expansion to map spectroscopically measured velocity to position along the line of sight.

  13. Narrow UV Absorption Line Outflows from Quasars

    CERN Document Server

    Hamann, Fred; Hidalgo, Paola Rodriguez; Capellupo, Daniel

    2012-01-01

    Narrow absorption line (NAL) outflows are an important yet poorly understood part of the quasar outflow phenomenon. We discuss one particular NAL outflow that has high speeds, time variability, and moderate ionizations like typical BAL flows, at an estimated location just ~5 pc from the quasar. It also has a total column density and line widths (internal velocity dispersions) ~100 times smaller than BALs, with no substantial X-ray absorption. We argue that radiative shielding (in the form of an X-ray/warm absorber) is not critical for the outflow acceleration and that the moderate ionizations occur in dense substructures that have an overall small volume filling factor in the flow. We also present new estimates of the overall incidence of quasar outflow lines; e.g., ~43% of bright quasars have a C IV NAL outflow while ~68% have a C IV outflow line of any variety (NAL, BAL, or mini-BAL).

  14. The Purple Haze of Eta Carinae: Binary-Induced Variability?

    CERN Document Server

    Smith, N; Collins, N R; Gull, T R; Smith, Nathan; Morse, Jon A.; Collins, Nicholas R.; Gull, Theodore R.

    2004-01-01

    Asymmetric variability in ultraviolet images of the Homunculus obtained with the Advanced Camera for Surveys/High Resolution Camera on the Hubble Space Telescope suggests that Eta Carinae is indeed a binary system. Images obtained before, during, and after the recent ``spectroscopic event'' in 2003.5 show alternating patterns of bright spots and shadows on opposite sides of the star before and after the event, providing a strong geometric argument for an azimuthally-evolving, asymmetric UV radiation field as one might predict in some binary models. The simplest interpretation of these UV images, where excess UV escapes from the secondary star in the direction away from the primary, places the major axis of the eccentric orbit roughly perpendicular to our line of sight, sharing the same equatorial plane as the Homunculus, and with apastron for the hot secondary star oriented toward the southwest of the primary. However, other orbital orientations may be allowed with more complicated geometries. Selective UV il...

  15. Detection of a Hot Binary Companion of $\\eta$ Carinae

    CERN Document Server

    Iping, R C; Gull, T R; Massa, D L; Hillier, D J; Iping, Rosina C.; Sonneborn, George; Gull, Theodore R.; Massa, Derck L.

    2005-01-01

    We report the detection of a hot companion of $\\eta$ Carinae using high resolution spectra (905 - 1180 \\AA) obtained with the Far Ultraviolet Spectroscopic Explorer (\\fuse) satellite. Observations were obtained at two epochs of the 2024-day orbit: 2003 June during ingress to the 2003.5 X-ray eclipse and 2004 April several months after egress. These data show that essentially all the far-UV flux from \\etacar shortward of \\lya disappeared at least two days before the start of the X-ray eclipse (2003 June 29), implying that the hot companion, \\etaB, was also eclipsed by the dense wind or extended atmosphere of \\etaA. Analysis of the far-UV spectrum shows that \\etaB is a luminous hot star. The \

  16. CO mapping of bipolar outflows

    International Nuclear Information System (INIS)

    We present CO J =2→1 mapping of the high velocity outflow zones NGC 1333, Cep A, K3-50, S 88B, NGC 2264, and NGC 6334V, NGC 6334B, a compact region of CO emission located within a very much more extended star-forming complex. For most of these sources, the present observations represent the highest resolution mapping so far obtained, and this leads to a variety of new insights into their spatial structures and kinematics

  17. Hot Outflows in Galaxy Clusters

    CERN Document Server

    Kirkpatrick, C C

    2015-01-01

    The gas-phase metallicity distribution has been analyzed for the hot atmospheres of 29 galaxy clusters using {\\it Chandra X-ray Observatory} observations. All host brightest cluster galaxies (BCGs) with X-ray cavity systems produced by radio AGN. We find high elemental abundances projected preferentially along the cavities of 16 clusters. The metal-rich plasma was apparently lifted out of the BCGs with the rising X-ray cavities (bubbles) to altitudes between twenty and several hundred kiloparsecs. A relationship between the maximum projected altitude of the uplifted gas (the "iron radius") and jet power is found with the form $R_{\\rm Fe} \\propto P_{\\rm jet}^{0.45}$. The estimated outflow rates are typically tens of solar masses per year but exceed $100 ~\\rm M_\\odot ~yr^{-1}$ in the most powerful AGN. The outflow rates are 10% to 20% of the cooling rates, and thus alone are unable to offset a cooling inflow. Nevertheless, hot outflows effectively redistribute the cooling gas and may play a significant role at ...

  18. Zinc abundances of planetary nebulae

    OpenAIRE

    Smith, Christina L.; Zijlstra, Albert A.; Dinerstein, Harriet L.

    2014-01-01

    Zinc is a useful surrogate element for measuring Fe/H as, unlike iron, it is not depleted in the gas phase media. Zn/H and O/Zn ratios have been derived using the [Zn IV] emission line at 3.625um for a sample of nine Galactic planetary nebulae, seven of which are based upon new observations using the VLT. Based on photoionization models, O/O++ is the most reliable ionisation correction factor for zinc that can readily be determined from optical emission lines, with an estimated accuracy of 10...

  19. Analysis of Carina Position as Surrogate Marker for Delivering Phase-Gated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Respiratory gating can mitigate the effect of tumor mobility in radiotherapy (RT) for lung cancer. Because the tumor is generally not visualized, external surrogates of tumor position are used to trigger respiration-gated RT. We evaluated the suitability of the carina position as a surrogate in respiration-gated RT. Methods and Materials: A total of 30 four-dimensional (4D) computed tomography (CT) scans from 14 patients with lung cancer were retrospectively analyzed. Both uncoached (free breathing) and audio-coached 4D-CT scans were acquired from 9 patients, and 12 uncoached 4D-CT scans were acquired from 5 other patients during a 2-4-week period of stereotactic RT. The repeat scans were co-registered. The carina position was identified on the coronal cut planes in all 4D-CT phases. The correlation between the carina position and the total lung volume for each phase was determined, and the reproducibility of the carina position was studied in the 5 patients with repeat uncoached 4D-CT scans. Results: The mean extent of carina motion in 21 uncoached scans was 5.3 ± 1.6 mm in the craniocaudal (CC), 2.3 ± 1.4 mm in the anteroposterior, and 1.5 ± 0.7 mm in the mediolateral direction. Audio coaching resulted in a twofold increase in carina mobility in all directions. The CC carina position correlated with changes in the total lung volume (R = 0.89 ± 0.14), but the correlation was better for the audio-coached than for the uncoached 4D-CT scans (R = 0.93 ± 0.08 vs. R = 0.85 ± 0.17; paired t test, p = 0.034). Preliminary data from the 5 patients indicated that the CC carina motion correlated better with tumor motion than did the motion of the diaphragm. Conclusions: The CC position of the carina correlated well with the total lung volume, indicating that the carina is a good surrogate for verifying the total lung volume during respiration-gated RT

  20. Imaging Planetary Nebulae with Herschel-PACS and SPIRE

    OpenAIRE

    van Hoof, P. A. M.; Exter, K. M.; Van de Steene, G. C.; Barlow, M.J.; Lim, T. L.; Sibthorpe, B.; Groenewegen, M. A. T.; Ueta, T.; Matsuura, M.; Blommaert, J. A. D. L.; M.Cohen; De Meester, W.; Gear, W. K.; Gomez, H. L.; Hargrave, P.C.

    2010-01-01

    In this paper we will discuss the images of Planetary Nebulae that have recently been obtained with PACS and SPIRE on board the Herschel satellite. This comprises results for NGC 650 (the little Dumbbell nebula), NGC 6853 (the Dumbbell nebula), and NGC 7293 (the Helix nebula).

  1. Polarization in Pulsar Wind Nebulae

    CERN Document Server

    Volpi, D; Amato, E; Bucciantini, N

    2009-01-01

    The main goal of our present work is to provide, for the first time, a simple computational tool that can be used to compute the brightness, the spectral index, the polarization, the time variability and the spectrum of the non-thermal light (both synchrotron and inverse Compton, IC) associated with the plasma dynamics resulting from given relativistic magnetohydrodynamics (RMHD) simulations. The proposed method is quite general, and can be applied to any scheme for RMHD and to all non-thermal emitting sources, e.g. pulsar wind nebulae (PWNe), and in particular to the Crab Nebula (CN) as in the present proceeding. Here only the linear optical and X-ray polarization that characterizes the PWNe synchrotron emission is analyzed in order to infer information on the inner bulk flow structure, to provide a direct investigation of the magnetic field configuration, in particular the presence and the strength of a poloidal component, and to understand the origin of some emitting features, such as the knot, whose origi...

  2. High-resolution CO observation of the carbon star CIT 6 revealing the spiral structure and a nascent bipolar outflow

    CERN Document Server

    Kim, Hyosun; Hirano, Naomi; Zhao-Geisler, Ronny; Trejo, Alfonso; Yen, Hsi-Wei; Taam, Ronald E; Kemper, Francisca; Kim, Jongsoo; Byun, Do-Young; Liu, Tie

    2015-01-01

    CIT 6 is a carbon star in the transitional phase from the asymptotic giant branch (AGB) to the protoplanetary nebulae (pPN). Observational evidences of two point sources in the optical, circumstellar arc segments in an HC$_3$N line emission, and a bipolar nebula in near-infrared provide strong support for the presence of a binary companion. Hence, CIT 6 is very attractive for studying the role of companions in the AGB-pPN transition. We have carried out high resolution $^{12}$CO $J=2-1$ and $^{13}$CO $J=2-1$ observations of CIT 6 with the Submillimeter Array combined with the Submillimeter Telescope (single-dish) data. The $^{12}$CO channel maps reveal a spiral-shell pattern connecting the HC$_3$N segments in a continuous form, and an asymmetric outflow corresponding to the near-infrared bipolar nebula. Rotation of the $^{12}$CO channel peak position may be related to the inner spiral winding and/or the bipolar outflow. An eccentric orbit binary is suggested for the presences of an anisotropic mass loss to th...

  3. Processing NASA Earth Science Data on Nebula Cloud

    Science.gov (United States)

    Chen, Aijun; Pham, Long; Kempler, Steven

    2012-01-01

    Three applications were successfully migrated to Nebula, including S4PM, AIRS L1/L2 algorithms, and Giovanni MAPSS. Nebula has some advantages compared with local machines (e.g. performance, cost, scalability, bundling, etc.). Nebula still faces some challenges (e.g. stability, object storage, networking, etc.). Migrating applications to Nebula is feasible but time consuming. Lessons learned from our Nebula experience will benefit future Cloud Computing efforts at GES DISC.

  4. Search for HH objects and emission stars in star formation regions. IV. New HH flows and HH objects related with cometary nebulae

    International Nuclear Information System (INIS)

    The results of the observations in the environments of the five cometary nebulae: MacC H12, MacC sH15, GM 1-14, RNO 33, Pars 17, are presented. This search was performed in the frames of the continuing survey of the new HH-objects in the star formation regions. Nine previously unknown HH-objects were found. Nearly all these objects belong to directed outflows, the sources of which are with high probability the central stars of the listed above nebulae. In the cases of MacC H12 and GM 1-14 the outflows have distinct bipolar structure. The position of the sources on J-H/H-K diagram is discussed

  5. PTF10nvg: An Outbursting Class I Protostar in the Pelican/North American Nebula

    CERN Document Server

    Covey, Kevin R; Miller, Adam A; Poznanski, Dovi; Cenko, S Bradley; Silverman, Jeffrey M; Bloom, Joshua S; Kasliwal, Mansi M; Fischer, William; Rayner, John; Rebull, Luisa M; Butler, Nathaniel R; Filippenko, Alexei V; Law, Nicholas M; Ofek, Eran O; Agueros, Marcel; Dekany, Richard G; Rahmer, Gustavo; Hale, David; Smith, Roger; Quimby, Robert M; Nugent, Peter; Jacobsen, Janet; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Khanh; McKenna, Dan; Kulkarni, Shrinivas R; Klein, Christopher

    2010-01-01

    During a synoptic survey of the North American Nebula region, the Palomar Transient Factory (PTF) detected an optical outburst (dubbed PTF10nvg) associated with the previously unstudied flat or rising spectrum infrared source IRAS 20496+4354. The PTF R-band light curve reveals that PTF10nvg brightened by more than 5 mag during the current outburst, rising to a peak magnitude of R~13.5 in 2010 Sep. Follow-up observations indicate PTF10nvg has undergone a similar ~5 mag brightening in the K band, and possesses a rich emission-line spectrum, including numerous lines commonly assumed to trace mass accretion and outflows. Many of these lines are blueshifted by ~175 km/s from the North American Nebula's rest velocity, suggesting that PTF10nvg is driving an outflow. Optical spectra of PTF10nvg show several TiO/VO bandheads fully in emission, indicating the presence of an unusual amount of dense (> 10^10 cm^-3), warm (1500-4000 K) circumstellar material. Near-infrared spectra of PTF10nvg appear quite similar to a spe...

  6. Fast, Low-ionization Emission Regions of the Planetary Nebula M2-42

    Science.gov (United States)

    Danehkar, A.; Parker, Q. A.; Steffen, W.

    2016-02-01

    Spatially resolved observations of the planetary nebula M2-42 (PN G008.2-04.8) obtained with the Wide Field Spectrograph on the Australian National University 2.3 m telescope have revealed the remarkable features of bipolar collimated jets emerging from its main structure. Velocity-resolved channel maps derived from the [N ii] λ6584 emission line disentangle different morphological components of the nebula. This information is used to develop a three-dimensional morpho-kinematic model, which consists of an equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion velocity of about 20 km s-1 is measured from the spectrum integrated over the main shell. However, the deprojected velocities of the jets are found to be in the range of 80-160 km s-1 with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 ± 125 cm-3, is five times lower than that of the main shell, 3150 cm-3, whereas their singly ionized nitrogen and sulfur abundances are about three times higher than those determined from the dense shell. The results indicate that the features of the collimated jets are typical of fast, low-ionization emission regions.

  7. Kinematics of Herbig-Haro Objects and Jets in the Orion Nebula

    CERN Document Server

    Rosado, M; Arias, L; Raga, A C; Le Coarer, E; Rosado, Margarita; Fuente, Eduardo de la; Arias, Lorena; Raga, Alejandro; Coarer, Ettiane Le

    2001-01-01

    We have surveyed the inner 5' of the Orion Nebula by means of Halpha and [NII] Fabry-Perot imaging spectroscopy to present a kinematical study of the Herbig-Haro objects in the nebula. The objects studied in this work are HH 202, 203, 204, 529, 269 and other associated features. For HH 202 we find new features that, because of their high velocities (up to 100 km/seg) indicate the presence of an outflow that probably is a HH flow not catalogued previously. HH 202 could be only a part of this larger outflow. Large internal motions are found in the fainter regions of HH 203-204, as well as evidence of transverse density gradients that could account for the asymmetry in the brightness distribution of HH 204. We report for the first time a high blueshifted velocity (-118 km/seg) associated with HH 204, and show that the apex of HH 204 is indeed the zone of maximum velocity, in agreement with bow shock models. We also studied the radial velocity field of HH 269 finding features associated with the HH object. From o...

  8. Fast, low-ionization emission regions of the planetary nebula M2-42

    CERN Document Server

    Danehkar, A; Steffen, W

    2016-01-01

    Spatially resolved observations of the planetary nebula M2-42 (PN G008.2-04.8) obtained with the Wide Field Spectrograph on the Australian National University 2.3 m telescope have revealed the remarkable features of bipolar collimated jets emerging from its main structure. Velocity-resolved channel maps derived from the [N II] $\\lambda$6584 emission line disentangle different morphological components of the nebula. This information is used to develop a three-dimensional morpho-kinematic model, which consists of an equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion velocity of about 20 km s$^{-1}$ is measured from the spectrum integrated over the main shell. However, the deprojected velocities of the jets are found to be in the range of 80-160 km s$^{-1}$ with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 $\\pm$ 125 cm$^{-3}$, is five times lower than that of the main shell, 3150 cm$^{-3}$, whereas their singly ionized nitrogen and ...

  9. High Velocity Outflows in the Orion Nebula Determined from Proper Motions

    Directory of Open Access Journals (Sweden)

    C. R. O`Dell

    2003-01-01

    Full Text Available Las imágenes del telescopio espacial Hubble son de resolución lo suficientemente alta que cuando se comparan las mas recientes con las que datan de diciembre de 1993, se pueden medir movimientos propios hasta unos 10km s-1. Tales observaciones muestran una gran riqueza de detalles y revelan múltiples sistemas de eyecciones de alta velocidad. Los movimientos propios son particularmente útiles para determinar el origen de las eyecciones. Estas revelan una eyección (HH 625 que se origina de la fuente molecular bipolar de alta velocidad en Orion-S. Quizá lo mas sorprendente es la evidencia de que la mayor parte de las eyecciones observadas en el óptico en Orion aparentemente se originan de una fuente localizada en 5:35:14.56 -5:23:54 (2000 que no posee una contraparte brillante en ninguna de las longitudes de onda observadas.

  10. From the ashes: JVLA observations of water fountain nebula candidates show the rebirth of IRAS 18455+0448

    CERN Document Server

    Vlemmings, W H T; van Langevelde, H J; Tafoya, D

    2014-01-01

    [abridged] The class of water fountain nebulae is thought to represent the stage of the earliest onset of collimated bipolar outflows during the post-Asymptotic Giant Branch phase. They thus play a crucial role in the study of the formation of bipolar Planetary Nebulae (PNe). To date, 14 water fountain nebulae have been identified. The identification of more sources in this unique stage of stellar evolution will enable us to study the origin of bipolar PNe morphologies in more detail. We present the results of seven sources observed with the JVLA that were identified as water fountain candidates in an Effelsberg 100m telescope survey of 74 AGB and early post-AGB stars. We find that our sample of water fountain candidates displays strong variability in their 22 GHz H2O maser spectra. The JVLA observations show an extended bipolar H2O maser outflow for one source, the OH/IR star IRAS 18455+0448. This source was previously classified as a 'dying' OH/IR star based on the exponential decrease of its 1612 MHz OH ma...

  11. Pulsar Wind Nebulae with Thick Toroidal Structure

    OpenAIRE

    Chevalier, Roger A.; Reynolds, Stephen P.

    2011-01-01

    We investigate a class of pulsar wind nebulae that show synchrotron emission from a thick toroidal structure. The best studied such object is the small radio and X-ray nebula around the Vela pulsar, which can be interpreted as the result of interaction of a mildly supersonic inward flow with the recent pulsar wind. Such a flow near the center of a supernova remnant can be produced in a transient phase when the reverse shock reaches the center of the remnant. Other nebulae with a thick toroida...

  12. A Minimum-Mass Extrasolar Nebula

    OpenAIRE

    Kuchner, Marc J.

    2004-01-01

    By analogy with the minimum-mass solar nebula, we construct a surface-density profile using the orbits of the 26 precise-Doppler planets found in multiple planet systems: Sigma = 2200 grams per square centimeter (a/1 AU)^- beta, where a is the circumstellar radius, and beta = 2.0 plus or minus 0.5. The minimum-mass solar nebula is consistent with this model, but the uniform-alpha accretion disk model is not. In a nebula with beta > 2, the center of the disk is the likely cradle of planet form...

  13. Worker Inflow, Outflow, and Churning

    OpenAIRE

    Ilmakunnas, Pekka; Maliranta, Mika

    2003-01-01

    Linked employer-employee data from the Finnish business sector is used in an analysis of worker turnover. The data is an unbalanced panel with over 219 000 observations in the years 1991-97. The churning (excess worker turnover), worker inflow (hiring), and worker outflow (separation) rates are explained by various plant and employee characteristics in type 2 Tobit models where the explanatory variables can have a different effect on the probability of the flow rates to be non-zero and on the...

  14. LIGHT ECHOES FROM η CARINAE'S GREAT ERUPTION: SPECTROPHOTOMETRIC EVOLUTION AND THE RAPID FORMATION OF NITROGEN-RICH MOLECULES

    International Nuclear Information System (INIS)

    We present follow-up optical imaging and spectroscopy of one of the light echoes of η Carinae's nineteenth century Great Eruption discovered by Rest et al. By obtaining images and spectra at the same light echo position between 2011 and 2014, we follow the evolution of the Great Eruption on a 3 yr timescale. We find remarkable changes in the photometric and spectroscopic evolution of the echo light. The i-band light curve shows a decline of ∼0.9 mag in ∼1 yr after the peak observed in early 2011 and a flattening at later times. The spectra show a pure-absorption early G-type stellar spectrum at peak, but a few months after peak the lines of the Ca II triplet develop strong P-Cygni profiles and we see the appearance of [Ca II] 7291, 7324 doublet in emission. These emission features and their evolution in time resemble those observed in the spectra of some Type IIn supernovae and supernova impostors. Most surprisingly, starting ∼300 days after peak brightness, the spectra show strong molecular transitions of CN at ≳ 6800 Å. The appearance of these CN features can be explained if the ejecta are strongly nitrogen enhanced, as is observed in modern spectroscopic studies of the bipolar Homunculus nebula. Given the spectroscopic evolution of the light echo, velocities of the main features, and detection of strong CN, we are likely seeing ejecta that contributes directly to the Homunculus nebula

  15. Propeller-driven Outflows and Disk Oscillations

    OpenAIRE

    Romanova, M. M.; Ustyugova, G. V.; Koldoba, A. V.; Lovelace, R. V. E.

    2005-01-01

    We report the discovery of propeller-driven outflows in axisymmetric magnetohydrodynamic simulations of disk accretion to rapidly rotating magnetized stars. Matter outflows in a wide cone and is centrifugally ejected from the inner regions of the disk. Closer to the axis there is a strong, collimated, magnetically dominated outflow of energy and angular momentum carried by the open magnetic field lines from the star. The ``efficiency'' of the propeller may be very high in the respect that mos...

  16. Explosive Outflows Powered by the Decay of Non-Hierarchical Multiple Systems of Massive Stars: Orion BN/KL

    CERN Document Server

    Bally, John; Moeckel, Nickolas; Burton, Michael G; Smith, Nathan; Frank, Adam; Nordlund, Ake

    2010-01-01

    The explosive BN/KL outflow emerging from OMC1 behind the Orion Nebula may have been powered by the dynamical decay of a non-hierarchical multiple system $\\sim$500 years ago that ejected the massive stars I, BN, and source n, with velocities of about 10 to 30 km s$^{-1}$. New proper motion measurements of H$_2$ features show that within the errors of measurement, the outflow originated from the site of stellar ejection. Combined with published data, these measurements indicate an outflow age of $\\sim$500 years, similar to the time since stellar ejection. The total kinetic energy of the ejected stars and the outflow is about 2 to $6 \\times 10^{47}$ ergs. It is proposed that the gravitational potential energy released by the formation of a short-period binary, most likely source I, resulted in stellar ejection and powered the outflow. A scenario is presented for the formation of a compact, non-hierarchical multiple star system, its decay into an ejected binary and two high-velocity stars, and launch of the outf...

  17. From stellar nebula to planetesimals

    CERN Document Server

    Marboeuf, Ulysse; Alibert, Yann; Cabral, Nahuel; Benz, Willy

    2014-01-01

    Solar and extrasolar comets and extrasolar planets are the subject of numerous studies in order to determine their chemical composition and internal structure. In the case of planetesimals, their compositions are important as they govern in part the composition of future planets. The present works aims at determining the chemical composition of icy planetesimals, believed to be similar to present day comets, formed in stellar systems of solar chemical composition. The main objective of this work is to provide valuable theoretical data on chemical composition for models of planetesimals and comets, and models of planet formation and evolution. We have developed a model that calculates the composition of ices formed during the cooling of the stellar nebula. Coupled with a model of refractory element formation, it allows us to determine the chemical composition and mass ratio of ices to rocks in icy planetesimals throughout in the protoplanetary disc. We provide relationships for ice line positions (for differen...

  18. Energetic outflows from young stars

    International Nuclear Information System (INIS)

    In our galaxy, stars are born in clouds of gas, bodies so cold they do not emit any radiation at the visible wavelengths. Moreover, the clouds are permeated by cosmic dust, so that the visible radiation emitted by new stars is absorbed. Radiation at the wavelengths of infrared waves and the shortest radio waves penetrate these clouds. With the development of new telescopes and equipment for the detection of radiation at those wavelengths, astronomers are now able to explore the dark clouds where stars are born. A prime probe of the conditions within star-forming clouds has turned out to be the molecule carbon monoxide (CO). In interstellar molecular clouds, CO molecules emit radiation at a wavelength of 2.6 mm. The study of such radiation has recently revealed a new and intriguing phenomena closely associated with the birth and early evolution of stars. When certain stars are in the earliest stages of their life, they appear to be associated with violent outflows of mass. In a number of instances, molecular gas is found to be flowing outward from around newly formed stars in two supersonic streams 1800 apart. The origin and nature of these energetic outflows is a mystery. (SC)

  19. Mapping dark nebulae in elliptical galaxies

    International Nuclear Information System (INIS)

    The Kitt Peak National Observatory video camera has been used on the 2.1-m telescope to provide imaging data for a survey of dark nebulae in 15 classical elliptical galaxies. Dark nebulae in ellipticals trace cool, dense interstellar matter and are potential sites for star formation. Spatial filtering techniques allow previously known dark nebulae in NGC 404, NGC 708, NGC 1052, NGC 4374, NGC 5363, and NGC 7052 to be readily mapped from the digital images. An extended dark nebular component is also found in NGC 5363. The majority of classical ellipticals in the sample, however, do not contain large dark nebulae. These observations are discussed in terms of processes which might control the amount and distribution of cool gas in elliptical galaxies. In particular, the presence of dust suggests that some of the gas has not been heated to the high temperatures characteristic of the X-ray emitting atmospheres that are found in many elliptical galaxies. 57 references

  20. Nonthermal Radiation of the Crab Nebula

    OpenAIRE

    Aharonian, F. A.; Atoyan, A. M.

    1998-01-01

    The radiation mechanisms contributing to formation of the nonthermal spectrum of the Crab Nebula, as well as the information that could be derived from future observations in different energy bands, are discussed.

  1. Circumstellar Nebulae in Young Supernova Remnants

    OpenAIRE

    Chu, Y.-H.

    2000-01-01

    Supernovae descendent from massive stars explode in media that have been modified by their progenitors' mass loss and UV radiation. The supernova ejecta will first interact with the circumstellar material shed by the progenitors at late evolutionary stages, and then interact with the interstellar material. Circumstellar nebulae in supernova remnants can be diagnosed by their small expansion velocities and high [N II]/H$\\alpha$ ratios. The presence of circumstellar nebulae appears ubiquitous a...

  2. Planetary nebulae abundances and stellar evolution

    OpenAIRE

    Pottasch, S. R.; Bernard-Salas, J.

    2006-01-01

    A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are the same as HII regions and early type star abundance gradients. The abundance of these elements predicted from these gradients at the distance of the Sun from the center are exactly the solar abundance. Sulfur is the exception to this; the reason for this...

  3. A low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling

    CERN Document Server

    Ural, Uğur; Read, Justin I; Walker, Matthew G

    2015-01-01

    Dark matter only simulations of galaxy formation predict many more subhalos around a Milky Way like galaxy than the number of observed satellites. Proposed solutions require the satellites to inhabit dark matter halos with masses between one to ten billion solar masses at the time they fell into the Milky Way. Here we use a modelling approach, independent of cosmological simulations, to obtain a preinfall mass of 360 (+380,-230) million solar masses for one of the Milky Way's satellites: Carina. This determination of a low halo mass for Carina can be accommodated within the standard model only if galaxy formation becomes stochastic in halos below ten billion solar masses. Otherwise Carina, the eighth most luminous Milky Way dwarf, would be expected to inhabit a significantly more massive halo. The implication of this is that a population of "dark dwarfs" should orbit the Milky Way: halos devoid of stars and yet more massive than many of their visible counterparts.

  4. The Carina Project. VIII. On the {\\alpha}-element abundances

    CERN Document Server

    Fabrizio, M; Bono, G; Primas, F; Thévenin, F; Stetson, P B; Cassisi, S; Buonanno, R; Coppola, G; da Silva, R O; Dall'Ora, M; Ferraro, I; Genovali, K; Gilmozzi, R; Iannicola, G; Marconi, M; Monelli, M; Romaniello, M; Walker, A R

    2015-01-01

    We have performed a new abundance analysis of Carina Red Giant (RG) stars from spectroscopic data collected with UVES (high resolution) and FLAMES/GIRAFFE (high and medium resolution) at ESO/VLT. The former sample includes 44 RGs, while the latter consists of 65 (high) and ~800 (medium resolution) RGs, covering a significant fraction of the galaxy's RG branch (RGB), and red clump stars. To improve the abundance analysis at the faint magnitude limit, the FLAMES/GIRAFFE data were divided into ten surface gravity and effective temperature bins. The spectra of the stars belonging to the same gravity/temperature bin were stacked. This approach allowed us to increase by at least a factor of five the signal-to-noise ratio in the faint limit (V>20.5mag). We took advantage of the new photometry index cU,B,I introduced by Monelli et al. (2014), as an age and probably a metallicity indicator, to split stars along the RGB. These two stellar populations display distinct [Fe/H] and [Mg/H] distributions: their mean Fe abund...

  5. Eta Carinae: At the Crossroads of becoming a Supernova

    Science.gov (United States)

    Gull, Theodore

    2007-01-01

    Since the 1840's, when Eta Carinae's visual magnitude rivaled Sirius, the brightest star in the night sky, astronomers have wondered what major event took place. Today with the Hubble Space Telescope Imaging Spectrograph, with CHANDRA X-ray spectroscopy and the Very Large Telescope spectrographs and interferometers, we have learned that over 12 solar masses of material was ejected at 500 to 700 km/s into interstellar space. This ejecta is quite different from the normal interstellar medium. It is rich in nitrogen, poor in oxygen and carbon. The dust properties are quite peculiar and many metals such as vanadium, strontium, cadmium are seen in both absorption against the central source, plus a number of molecules. The chemical and dust formation is likely dominated by nitrogen as we see H_2, CH, CH+, OH, NH, HCl and NH-3, but no CO. Other metals and molecules are being searched out in the FUSE, HST/STIS, VLT/UVES and VLT/CRIRES spectra. I will describe what we know about the massive binary stellar system, how it changes every 5.54 year in UV and X-ray output and how the massive ejecta responds in this astrophysical laboratory.

  6. A multispectral view of the periodic events in eta Carinae

    CERN Document Server

    Damineli, A; Corcoran, M F; Stahl, O; Groh, J H; Arias, J; Teodoro, M; Morrell, N; Gamen, R; Gonzalez, F; Leister, N V; Levato, H; Levenhagen, R S; Grosso, M; Colombo, J F Albacete; Wallerstein, G

    2007-01-01

    A full description of the 5.5-yr low excitation events in eta Carinae is presented. We show that they are not simple and brief, as thought before, but a combination of two components. The first, the `slow variation' component, is revealed by slow changes in the ionization level of circumstellar matter across the whole cycle and is caused by the gradual immersion of the secondary star in the wind of the primary. The second, the `collapse' component, is restricted to some months around the minimum, and is due to the immersion of the secondary deep in the primary wind. During this stage there is a general collapse of the wind-wind collision shock, and the Weigelt blobs are strongly shielded from high energy photons (E > 16 eV). High energy phenomena are sensitive only to the `collapse', low energy only to the `slow variation' and that of intermediate energy to both components. Simple eclipses and mechanisms effective only near periastron (e.g., shell ejection or accretion onto the secondary star) cannot account ...

  7. Accretion at the periastron passage of Eta Carinae

    CERN Document Server

    Kashi, Amit

    2016-01-01

    We present high resolution numerical simulations of the colliding wind system $\\eta$ Carinae, showing accretion onto the secondary star close to periastron passage. Our hydrodynamical simulations include self gravity and radiative cooling. The smooth stellar winds collide and develop instabilities, mainly the non-linear thin shell instability, and form filaments and clumps. We find that a few days before periastron passage the dense filaments and clumps flow towards the secondary as a result of its gravitational attraction, and reach the zone where we inject the secondary wind. We run our simulations for the conventional stellar masses, $M_1=120 ~\\rm{M_\\odot}$ and $M_2=30 ~\\rm{M_\\odot}$, and for a high mass model, $M_1=170 ~\\rm{M_\\odot}$ and $M_2=80 ~\\rm{M_\\odot}$, that was proposed to better fit the history of giant eruptions. As expected, the simulations results show that the accretion processes is more pronounced for a more massive secondary star.

  8. Molecular Hydrogen Outflows in W51

    OpenAIRE

    Hodapp, Klaus W.; Davis, Christopher J.

    2002-01-01

    We present the results of a deep search for the molecular hydrogen shock fronts associated with young stellar outflows in the giant molecular cloud and massive star forming region W51. A total of 14 outflows were identified, and a few of these were studied in detail with high-resolution imaging and spectroscopy.

  9. Hard X-ray identification of η Carinae and steadiness close to periastron

    Science.gov (United States)

    Leyder, J.-C.; Walter, R.; Rauw, G.

    2010-12-01

    Context. The colliding-wind binary η Carinae exhibits soft X-ray thermal emission that varies strongly around the periastron passage. It has been found to have non-thermal emission, thanks to its detection in hard X-rays using INTEGRAL and Suzaku, and also in γ-rays with AGILE and Fermi. Aims: This paper attempts to definitively identify η Carinae as the source of the hard X-ray emission, to examine how changes in the 2-10 keV band influence changes in the hard X-ray band, and to understand more clearly the mechanisms producing the non-thermal emission using new INTEGRAL observations obtained close to periastron passage. Methods: To strengthen the identification of η Carinae with the hard X-ray source, a long Chandra observation encompassing the INTEGRAL/ISGRI error circle was analysed, and all other soft X-ray sources (including the outer shell of η Carinae itself) were discarded as likely counter-parts. To expand the knowledge of the physical processes governing the X-ray lightcurve, new hard X-ray images of η Carinae were studied close to periastron, and compared to previous observations far from periastron. Results: The INTEGRAL component, when represented by a power law (with a photon index Γ of 1.8), would produce more emission in the Chandra band than observed from any point source in the ISGRI error circle apart from η Carinae, as long as the hydrogen column density to the ISGRI source is lower than NH ≲ 1024 cm-2. Sources with such a high absorption are very rare, thus the hard X-ray emission is very likely to be associated with η Carinae. The eventual contribution of the outer shell to the non-thermal component also remains fairly limited. Close to periastron passage, a 3-σ detection is achieved for the hard X-ray emission of η Carinae, with a flux similar to the average value far from periastron. Conclusions: Assuming a single absorption component for both the thermal and non-thermal sources, this 3-σ detection can be explained with a

  10. An Aboriginal Australian Record of the Great Eruption of Eta Carinae

    CERN Document Server

    Hamacher, Duane W

    2010-01-01

    We present evidence that the Boorong Aboriginal people of northwestern Victoria observed the Great Eruption of Eta ({\\eta}) Carinae in the nineteenth century and incorporated the event into their oral traditions. We identify this star, as well as others not specifically identified by name, using descriptive material presented in the 1858 paper by William Edward Stanbridge in conjunction with early southern star catalogues. This identification of a transient astronomical event supports the assertion that Aboriginal oral traditions are dynamic and evolving, and not static. This is the only definitive indigenous record of {\\eta} Carinae's outburst identified in the literature to date.

  11. An Aboriginal Australian Record of the Great Eruption of Eta Carinae

    Science.gov (United States)

    Hamacher, Duane W.; Frew, David J.

    2010-11-01

    We present evidence that the Boorong Aboriginal people of northwestern Victoria observed the Great Eruption of Eta Carinae in the nineteenth century and incorporated this event into their oral traditions. We identify this star, as well as others not specifically identified by name, using descriptive material presented in the 1858 paper by William Edward Stanbridge in conjunction with early southern star catalogues. This identification of a transient astronomical event supports the assertion that Aboriginal oral traditions are dynamic and evolving, and not static. This is the only definitive indigenous record of Eta Carinae's outburst identified in the literature to date.

  12. X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

    OpenAIRE

    Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore; Ishibashi, Kazunori; Pittard, Julian M.; Hillier, D. John; Damineli, Augusto; Davidson, Kris; Nielsen, Krister E.; Kober, Gladys Vieira

    2007-01-01

    We report the results of an X-ray observing campaign on the massive, evolved star Eta Carinae, concentrating on the 2003 X-ray minimum as seen by the XMM-Newton observatory. These are the first spatially-resolved X-ray monitoring observations of the stellar X-ray spectrum during the minimum. The hard X-ray emission, believed to be associated with the collision of Eta Carinae's wind with the wind from a massive companion star, varied strongly in flux on timescales of days, but not significantl...

  13. XMM-Newton Observations of the 2003 X-ray Minimum of Eta Carinae

    OpenAIRE

    Hamaguchi, K.; M. F. Corcoran; Gull, T.; White, N. E.; Damineli, A.; Davidson, K.

    2004-01-01

    The XMM-Newton X-ray observatory took part in the multi-wavelength observing campaign of the massive, evolved star Eta Carinae in 2003 during its recent X-ray minimum. This paper reports on the results of these observations, mainly from the aspect of spectral change. Hard X-ray emission from the point source of Eta Carinae was detected even during the minimum. During the minimum the observed flux above 3 keV was ~3e-12 ergs cm-2 s-1, which is about one percent of the flux before the minimum. ...

  14. The three dimensional dynamic structure of the inner Orion Nebula

    CERN Document Server

    O'Dell, C R; Abel, N P; Ferland, G J; Arthur, S J

    2008-01-01

    The three dimensional structure of the brightest part of the Orion Nebula is assessed in the light of published and new data. We find that the widely accepted model of a concave blister of ionized material needs to be altered in the southwest direction from the Trapezium, where we find that the Orion-S feature is a separate cloud of very optically thick molecules within the body of ionized gas, which is probably the location of the multiple embedded sources that produce the outflows that define the Orion-S star formation region. Evidence for this cloud comes from the presence of H2CO lines in absorption in the radio continuum and discrepancies in the extinction derived from radio-optical and optical only emission. We present an equilibrium Cloudy model of the Orion-S cloud, which successfully reproduces many observed properties of this feature. We also report the discovery of an open-sided shell of [O III] surrounding the Trapezium stars, revealed through emission line ratio images and the onset of radiation ...

  15. Submillimeter H2O masers in water-fountain nebulae

    CERN Document Server

    Tafoya, D; Vlemmings, W H T; Pérez-Sánchez, A F; Garay, G

    2013-01-01

    We report the first detection of submillimeter water maser emission toward water-fountain nebulae, which are post-AGB stars that exhibit high-velocity water masers. Using APEX we found emission of the ortho-H2O (1029-936) transition at 321.226 GHz toward three sources: IRAS 15445-5449, IRAS 18043-2116 and IRAS 18286-0959. Similarly to the 22 GHz masers, the submillimeter water masers are expanding with a velocity larger than that of the OH masers, suggesting that these masers also originate in fast bipolar outflows. While in IRAS 18043-2116 and IRAS 18286-0959, which figure among the sources with the fastest water masers, the velocity range of the 321 GHz masers coincides with that of the 22 GHz masers, the submillimeter masers of IRAS 15445-5449 appear in a different velocity range. This indicates that the 321 GHz and 22 GHz masers could be coexisting in the first two sources, but they are tracing different regions in the later one. The intensity of the submillimeter masers is comparable to that of the 22 GH...

  16. A Morpho-kinematic and Spectroscopic study of Bipolar Planetary Nebulae

    Science.gov (United States)

    Clyne, Niall

    2015-09-01

    hypersonic knotty outflow. As for M 2-9, Mz 3, and Hen 2-104, the expansion rates of their individual components are better constrained and fitted with a vector field to reveal their direction of motion. Both diagnostic diagrams show M 2-9 and Hen 2-104 to fall well within the category of having a symbiotic source, whereas Mz 3 borders the region of symbiotic and young planetary nebulae in the optical diagram but is located firmly in the symbiotic region of the NIR colour-colour diagram. With regards to Abell 14, it has been shown to be a highly-evolved bipolar nebula with a kinematical age of 19,400 ± 3480 yr for a distance of 4 kpc, and is a nebula with a very-low density, which further implies its evolved state.

  17. PHL 932: when is a planetary nebula not a planetary nebula?

    CERN Document Server

    Frew, David J; O'Toole, Simon J; Parker, Quentin A

    2009-01-01

    The emission nebula around the subdwarf B (sdB) star PHL 932 is currently classified as a planetary nebula (PN) in the literature. Based on a large body of multi-wavelength data, both new and previously published, we show here that this low-excitation nebula is in fact a small Stromgren sphere (HII region) in the interstellar medium around this star. We summarise the properties of the nebula and its ionizing star, and discuss its evolutionary status. We find no compelling evidence for close binarity, arguing that PHL 932 is an ordinary sdB star. We also find that the emission nebulae around the hot DO stars PG 0108+101 and PG 0109+111 are also Stromgren spheres in the ISM, and along with PHL 932, are probably associated with the same extensive region of high-latitude molecular gas in Pisces-Pegasus.

  18. OBSERVATIONS OF MOLECULAR OUTFLOW IN CAR 291.6-01.9

    Energy Technology Data Exchange (ETDEWEB)

    Saul, M. [School of Physics, University of New South Wales, NSW 2052 (Australia); Saul, L., E-mail: msaul@phys.unsw.edu.au, E-mail: luke.saul@space.unibe.ch [Physics Institute, University of Bern, Bern CH-3012 (Switzerland)

    2012-01-20

    We report the first observations of a dense molecular gas nebula and bipolar outflow in Car 291.6-01.9, showing characteristics of an embedded young stellar object (YSO). Using the Mopra radio telescope near Coonabarabaran, Australia, we image the kinematic structure of several emission features to examine physical properties within a molecular clump of mass {approx}3.2 {+-} 0.6 Multiplication-Sign 10{sup 3} M{sub Sun} in which a stellar cluster may be forming. Motivated by acquiring a more thorough understanding of star formation we ask what may have initiated collapse in the clump; observed outflow alignment is suggestive of {approx}1.0 pc distant massive star HD 308280 radiative-driven compression as a formation trigger for the dense core. An outflow derived age of <10{sup 6} years, together with significant C{sup 18}O and SO core depletion, support the case for the core as the host of an extremely YSO cluster.

  19. The Shaping of the Multipolar Pre-Planetary Nebula CRL 618 by Multi-directional Bullets

    CERN Document Server

    Huang, Po-Sheng; Moraghan, Anthony; Smith, Michael

    2016-01-01

    In order to understand the formation of the multipolar structures of the pre-planetary nebula (PPN) CRL 618, we perform 3D simulations using a multi-directional bullet model. The optical lobes of CRL 618 and fast molecular outflows at the tips of the lobes have been found to have similar expansion ages of ~ 100 yr. Additional fast molecular outflows were found near the source along the outflow axes with ages of ~ 45 yr, suggesting a second episode of bullet ejections. Thus, in our simulations, two episodes of bullet ejections are assumed. The shaping process is simulated using the ZEUS-3D hydrodynamics code that includes molecular and atomic cooling. In addition, molecular chemistry is also included to calculate the CO intensity maps. Our results show the following: (1) Multi-epoch bullets interacting with the toroidal dense core can produce the collimated multiple lobes as seen in CRL 618. The total mass of the bullets is ~ 0.034 solar mass, consistent with the observed high-velocity CO emission in fast mole...

  20. Zinc abundances of planetary nebulae

    CERN Document Server

    Smith, Christina L; Dinerstein, Harriet L

    2014-01-01

    Zinc is a useful surrogate element for measuring Fe/H as, unlike iron, it is not depleted in the gas phase media. Zn/H and O/Zn ratios have been derived using the [Zn IV] emission line at 3.625um for a sample of nine Galactic planetary nebulae, seven of which are based upon new observations using the VLT. Based on photoionization models, O/O++ is the most reliable ionisation correction factor for zinc that can readily be determined from optical emission lines, with an estimated accuracy of 10% or better for all targets in our sample. The majority of the sample is found to be sub-solar in [Zn/H]. [O/Zn] in half of the sample is found to be consistent with Solar within uncertainties, whereas the remaining half are enhanced in [O/Zn]. [Zn/H] and [O/Zn] as functions of Galactocentric distance have been investigated and there is little evidence to support a trend in either case.

  1. The Crab Nebula flaring activity

    Energy Technology Data Exchange (ETDEWEB)

    Montani, G., E-mail: giovanni.montani@frascati.enea.it [ENEA – C.R, UTFUS-MAG, via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Dipartimento di Fisica, Università di Roma “Sapienza”, p.le Aldo Moro 5, I-00185 Roma (Italy); Bernardini, M.G. [INAF – Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy)

    2014-12-12

    The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼10{sup 15} cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼10{sup 9}, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  2. ETHOS 1: A high latitude planetary nebula with jets forged by a post common envelope binary central star

    OpenAIRE

    Miszalski, B.; Corradi, R.L.M.; Boffin, H. M. J.; Jones, D.; Sabin, L.; Santander-García, M.; Rodríguez-Gil, P.; Rubio-Díez, M. M.

    2010-01-01

    We report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at $120\\pm10$ km/s and a close binary central star. The lightcurve observed with the Mercator telescope reveals an orbital period of 0.535 days and an extremely large amplitude (0.816 mag) due to irradiation of the compani...

  3. THE CARINA PROJECT. VI. THE HELIUM-BURNING VARIABLE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, G.; Marconi, M.; Ripepi, V.; Dall' Ora, M.; Musella, I. [INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Bono, G.; Buonanno, R. [Dipartimento di Fisica-Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma (Italy); Fabrizio, M. [INAF-Osservatorio Astronomico di Collurania, via M. Maggini, I-64100 Teramo (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Fiorentino, G. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Monelli, M. [Instituto de Astrofisica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Nonino, M. [INAF-Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-40131 Trieste (Italy); Thevenin, F. [Universite de Nice-Sophia Antipolis, Lab. Lagrange, UMR 7293, Observatoire de la Cote dAzur, BP 4229, F-06304 Nice (France); Walker, A. R., E-mail: coppola@na.astro.it [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile)

    2013-09-20

    We present new optical (BVI) time-series data for the evolved variable stars in the Carina dwarf spheroidal galaxy. The quality of the data and the observing strategy allowed us to identify 14 new variable stars. Eight out of the 14 are RR Lyrae (RRL) stars, 4 are Anomalous Cepheids (ACs), and 2 are geometrical variables. Comparison of the period distribution for the entire sample of RRLs with similar distributions in nearby dwarf spheroidal galaxies and in the Large Magellanic Cloud indicates that the old stellar populations in these systems share similar properties. This finding is also supported by the RRL distribution in the Bailey diagram. On the other hand, the period distribution and the Bailey diagram of ACs display significant differences among the above stellar systems. This evidence suggests that the properties of intermediate-age stellar populations might be affected both by environmental effects and structural parameters. We use the BV Period-Wesenheit (PW) relation of RRLs together with evolutionary prescriptions and find a true distance modulus of 20.09 {+-} 0.07 (intrinsic) {+-} 0.1 (statistical) mag that agrees quite well with similar estimates available in the literature. We identified four peculiar variables. Taking into account their position in the Bailey diagram and in the BV PW relation, two of them (V14 and V149) appear to be candidate ACs, while two (V158 and V182) might be peculiar RRLs. In particular, the variable V158 has a period and a V-band amplitude very similar to the low-mass RRL-RRLR-02792-recently identified by Pietrzynski et al. in the Galactic bulge.

  4. Hydroxyl Emission in the Westbrook Nebula

    Science.gov (United States)

    Strack, Angelica; Araya, Esteban; Ghosh, Tapasi; Arce, Hector G.; Lebron, Mayra E.; Salter, Christopher J.; Minchin, Robert F.; Pihlstrom, Ylva; Kurtz, Stan; Hofner, Peter; Olmi, Luca

    2016-06-01

    CRL 618, also known as the Westbrook Nebula, is a carbon-rich pre-planetary nebula. Hydroxyl (OH) transitions are typically not detected in carbon-rich late-type stellar objects, however observations conducted with the 305m Arecibo Telescope in 2008 resulted in the detection of 4765 MHz OH emission in CRL 618. We present results of observations carried out a few months after the original detection that confirm the line. This is the first detection of 4765 MHz OH emission (most likely a maser) in a pre-planetary nebula. Follow up observations conducted in 2015 resulted in non-detection of the 4765 MHz OH transition. This behavior is consistent with the high level of variability of excited OH lines that have been detected toward a handful of other pre-planetary nebulae. Our work supports that excited OH masers are short-lived during the pre-planetary nebula phase. We also conducted a search for other OH transitions from 1612 MHz to 8611 MHz with the Arecibo Telescope; we report no other detections at rms levels of ~5 mJy.This work has made use of the computational facilities donated by Frank Rodeffer to the WIU Astrophysics Research Laboratory. We also acknowledge support from M. & C. Wong RISE scholarships and a grant from the WIU College of Arts and Sciences.

  5. Accretion and plasma outflow from dissipationless discs

    OpenAIRE

    Bogovalov, Sergei; Kelner, Stanislav

    2008-01-01

    We consider an extreme case of disc accretion onto a gravitating centre when the viscosity in the disc is negligible. The angular momentum and the rotational energy of the accreted matter is carried out by a magnetized wind outflowing from the disc. The outflow of matter from the disc occurs due to the Blandford & Payne(1982) centrifugal mechanism. The disc is assumed to be cold. Accretion and outflow are connected by the conservation of the energy, mass and the angular momentum. The basic pr...

  6. AGN outflow feedback: Constraints from variability

    CERN Document Server

    Detmers, R G

    2009-01-01

    We present an overview on how variability can be used to constrain the location of the ionized outflow in nearby Active Galactic Nuclei using high-resolution X-ray spectroscopy. Without these constraints on the location of the outflow, the kinetic luminosity and mass loss rate can not be determined. We focus on the Seyfert 1 galaxy NGC 5548, which is arguably the best studied AGN on a timescale of 10 years. Our results show that frequent observations combined with long term monitoring, such as with the \\textit{Rossi X-ray Timing Explorer (RXTE)} satellite, are crucial to investigate the effects of these outflows on their surroundings.

  7. Sailing under the Magellanic Clouds: A DECam View of the Carina Dwarf

    CERN Document Server

    McMonigal, B; Lewis, G F; Irwin, M J; Battaglia, G; Ibata, R A; Martin, N F; McConnachie, A W; Guglielmo, M; Conn, A R

    2014-01-01

    We present deep optical photometry from the DECam imager on the 4m Blanco telescope of over 12 deg$^2$ around the Carina dwarf spheroidal, with complete coverage out to 1 degree and partial coverage extending out to 2.6 degrees. Using a Poisson-based matched filter analysis to identify stars from each of the three main stellar populations, old, intermediate, and young, we confirm the previously identified radial age gradient, distance, tidal radius, stellar radial profiles, relative stellar population sizes, ellipticity, and position angle. We find an angular offset between the three main elliptical populations of Carina, and find only tentative evidence for tidal debris, suggesting that past tidal interactions could not have significantly influenced the Carina dwarf. We detect stars in the vicinity of, but distinct to, the Carina dwarf, and measure their distance to be 46$\\pm$2 kpc. We determine this population to be part of the halo of the Large Magellanic Cloud at an angular radius of over 20 degrees. Due ...

  8. X-ray Gyrations of Eta Carinae, or, Is Presence of Evidence Evidence of Presence?

    CERN Document Server

    Corcoran, M F; Gull, T R; Damineli, A; Davidson, K

    2004-01-01

    We review the properties of the variable X-ray emission from the extremely massive star Eta Carinae concentrating on the last X-ray minimum, and briefly consider the possible role of a binary companion star on the observational properties of the system.

  9. Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

    NARCIS (Netherlands)

    S.F. Portegies Zwart; E.P.J. van den Heuvel

    2016-01-01

    We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive thi

  10. Outflows in Sodium Excess Objects

    CERN Document Server

    Park, Jongwon; Yi, Sukyoung K

    2015-01-01

    van Dokkum and Conroy revisited the unexpectedly strong Na I lines at 8200 A found in some giant elliptical galaxies and interpreted it as evidence for unusually bottom-heavy initial mass function. Jeong et al. later found a large population of galaxies showing equally-extraordinary Na D doublet absorption lines at 5900 A (Na D excess objects: NEOs) and showed that their origins can be different for different types of galaxies. While a Na D excess seems to be related with the interstellar medium (ISM) in late-type galaxies, smooth-looking early-type NEOs show little or no dust extinction and hence no compelling sign of ISM contributions. To further test this finding, we measured the doppler components in the Na D lines. We hypothesized that ISM would have a better (albeit not definite) chance of showing a blueshift doppler departure from the bulk of the stellar population due to outflow caused by either star formation or AGN activities. Many of the late-type NEOs clearly show blueshift in their Na D lines, wh...

  11. Monitoring the Orion Nebula Cluster

    Science.gov (United States)

    Reipurth, Bo

    The VYSOS (Variable Young Stars Optical Survey) project has at its disposal five small telescopes: a 5-inch and a 20-inch robotic optical imaging telescope in Hawaii funded by the NSF, and a 6-inch robotic optical imaging telescope, a 32-inch robotic infrared imaging telescope, and a 60-inch optical spectroscopic telescope in Chile, funded and operated from Germany. Through an agreement between the leaders of the two sites (B. Reipurth and R. Chini), it has been decided to devote a significant fraction of time on these facilities to a large Key Project, conducting a massive monitoring survey of the Orion Nebula Cluster. The vast data streams are being reduced through automated customized pipelines. The applicant seeks funding to employ a postdoc and an undergraduate assistant to work at the University of Hawaii and collaborate on the analysis of the data. Virtually all young stars are variable, with a wide range of amplitudes and characteristic timescales. This is mainly due to accretion shocks as material from circumstellar disks fall onto the stars along magnetic funnel flows, but also giant star spots, magnetic flares, occultations by orbiting dust condensations, and eclipses by companions can modulate the light from the nascent star. It is increasingly recognized that the rather static view of pre-main sequence evolution that has prevailed for many years is misleading, and that time-dependent phenomena may hold the key to an understanding of the way young stars grow and their circumstellar environments evolve. The VYSOS project is designed to bring sophisticated modern techniques to bear on the long neglected problem of variability in young solar type stars. To interpret the observations they will be compared to sophisticated MHD models of circumstellar disks around young stars. The Orion Nebula Cluster is the nearest rich region of star formation, and numerous, albeit heterogeneous, studies exist of the cluster members. The present study will provide the first

  12. The expansion of the Crab Nebula

    International Nuclear Information System (INIS)

    Using high-resolution radio observations from 1982 and 1987 the expansion of the synchrotron component of the Crab Nebula was measured, including a measurement of the expansion of the nebula's outer edge. The measurements show a rate of expansion similar to that obtained from optical data for the line-emitting filaments. It is shown that the synchrotron component of the Crab expands homologously and that its rate of expansion has accelerated since the supernova explosion. The data further suggest that the acceleration of the synchrotron component may be larger than that of the emission-line filaments which, if confirmed by future observations, implies that the relativistic gas is currently bursting through the net of filaments. The absence of deceleration allows the establishment of stringent upper limits on the density of gas into which the observed nebula is expanding. 19 refs

  13. Monitoring the Crab Nebula with LOFT

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2012-01-01

    From 2008-2010, the Crab Nebula was found to decline by 7% in the 15-50 keV band, consistently in Fermi GBM, INTEGRAL IBIS, SPI, and JEMX, RXTE PCA, and Swift BAT. From 2001-2010, the 15-50 keV flux from the Crab Nebula typically varied by about 3.5% per year. Analysis of RXTE PCA data suggests possible spectral variations correlated with the flux variations. I will present estimates of the LOFT sensitivity to these variations. Prior to 2001 and since 2010, the observed flux variations have been much smaller. Monitoring the Crab with the LOFT WFM and LAD will provide precise measurements of flux variations in the Crab Nebula if it undergoes a similarly active episode.

  14. Comparison of Spine, Carina, and Tumor as Registration Landmarks for Volumetric Image-Guided Lung Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To assess the feasibility, reproducibility, and accuracy of volumetric lung image guidance using different thoracic landmarks for image registration. Methods and Materials: In 30 lung patients, four independent observers conducted automated and manual image registrations on Day 1 cone-beam computed tomography data sets using the spine, carina, and tumor (720 image registrations). The image registration was timed, and the couch displacements were recorded. The intraclass correlation was used to assess reproducibility, and the Bland-Altman analysis was used to compare the automatic and manual matching methods. Tumor coverage (accuracy) was assessed through grading the tumor position after image matching against the internal target volume and planning target volume. Results: The image-guided process took an average of 1 min for all techniques, with the exception of manual tumor matching, which took 4 min. Reproducibility was greatest for automatic carina matching (intraclass correlation, 0.90-0.93) and lowest for manual tumor matching (intraclass correlation, 0.07-0.43) in the left-right, superoinferior, and anteroposterior directions, respectively. The Bland-Altman analysis showed no significant difference between the automatic and manual registration methods. The tumor was within the internal target volume 62% and 60% of the time and was outside the internal target volume, but within the planning target volume, 38% and 40% of the time after automatic spine and automatic carina matching, respectively. Conclusion: For advanced lung cancer, the spine or carina can be used equally for cone-beam computed tomography image registration without compromising target coverage. The carina was more reproducible than the spine, but additional analysis is required to confirm its validation as a tumor surrogate. Soft-tissue registration is unsuitable at present, given the limitations in contrast resolution and the high interobserver variability.

  15. Disk-Driven Outflows in AGNs

    CERN Document Server

    Koenigl, A

    2003-01-01

    Analysis of spectral absorption features has led to the identification of several distinct outflow components in AGNs. The outflowing gas is evidently photoionized by the nuclear continuum source and originates in the accretion flow toward the central black hole. The most likely driving mechanisms are continuum and line radiation pressure and magnetic stresses. The theoretical modeling of these outflows involves such issues as: (1) Which of the above mechanisms actually contributes in each case? (2) How is the gas uplifted from the underlying accretion disk? (3) How can the intense central continuum radiation be shielded to allow efficient radiative driving? (4) Is the outflow continuous or clumpy, and, if clumpy, what is the nature and dynamical state of the ``clouds''? This review summarizes recent theoretical and observational results that bear on these questions and outlines prospects for further progress.

  16. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    Science.gov (United States)

    Brambles, O J; Lotko, W; Zhang, B; Wiltberger, M; Lyon, J; Strangeway, R J

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence. PMID:21636770

  17. The expansion proper motions of the extraordinary giant lobes of the planetary nebula KjPn 8 revisited

    CERN Document Server

    Boumis, Panos

    2013-01-01

    The primary aim is to establish a firm value for the distance to the extraordinary planetary nebula KjPn 8. Secondary aims are to measure the ages of the three giant lobes of this object as well as estimate the energy in the eruption, that caused the most energetic outflow, for comparison with that of an intermediate luminosity optical transient (ILOT). For these purposes a mosaic of images in the Halpha+[N II] optical emission lines has been obtained with the new Aristarchos telescope in 2011 for comparison with the images of the KjPn 8 giant lobes present on the POSSI-R 1954 and POSSII-R 1991 plates. Expansion proper motions of features over this 57 yr baseline in the outflows are present. Using these, a firm distance to KjPn 8 of 1.8 +- 0.3 kpc has been derived for now the angle of the latest outflow to the sky has been established from HST imagery of the nebular core. Previously, the uncertain predictions of a bow-shock model were used for this purpose. The dynamical ages of the three separate outflows th...

  18. Temperature, salinity, nutrients, carbon, and other profile data collected worldwide as part of the CARINA project (NODC Accession 0057766)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CARINA (CARbon dioxide IN the Atlantic Ocean) data synthesis project is an international collaborative effort of the EU IP CARBOOCEAN, and US partners. It has...

  19. Molecular Outflows From the Protocluster, Serpens South

    CERN Document Server

    Nakamura, Fumitaka; Shimajiri, Yoshito; Tsukagoshi, Takashi; Higuchi, Aya E; Nishiyama, Shogo; Kawabe, Ryohei; Takami, Michihiro; Karr, Jennifer L; Gutermuth, Robert A; Wilson, Grant

    2011-01-01

    We present the results of CO ($J=3-2$) and HCO$^+$ ($J=4-3$) mapping observations toward a nearby embedded cluster, Serpens South, using the ASTE 10 m telescope. Our CO ($J=3-2$) map reveals that many outflows are crowded in the dense cluster-forming clump that can be recognized as a HCO$^+$ clump with a size of $\\sim$ 0.2 pc and mass of $\\sim$ 80 M$_\\odot$. The clump contains several subfragments with sizes of $\\sim$ 0.05 pc. By comparing the CO ($J=3-2$) map with the 1.1 mm dust continuum image taken by AzTEC on ASTE, we find that the spatial extents of the outflow lobes are sometimes anti-correlated with the distribution of the dense gas and some of the outflow lobes apparently collide with the dense gas. The total outflow mass, momentum, and energy are estimated at 0.6 $M_\\odot$, 8 $M_\\odot$ km s$^{-1}$, and 64 $M_\\odot$ km$^2$ s$^{-2}$, respectively. The energy injection rate due to the outflows is comparable to the turbulence dissipation rate in the clump, implying that the protostellar outflows can mai...

  20. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    OpenAIRE

    Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this positio...

  1. Evolution of the solar nebula. I. Nonaxisymmetric structure during nebula formation

    International Nuclear Information System (INIS)

    Numerical solutions of the equations of hydrodynamics, gravitation, and radiative transfer in three spatial dimensions are used to model the formation and time evolution of the early solar nebula in order to learn whether or not gravitational torques between nonaxisymmetric structures in the solar nebula can transport angular momentum rapidly enough to produce nebula clearing on astronomically indicated (10 to the 5 to 10 to the 7 yr) time scales. The models involve solutions for the collapse of spherical clouds with assumed initial density and rotation profiles onto protosuns of variable mass. Most of the models assume uniform initial density and rotation, and have variations in the initial parameters of cloud mass, cloud rotation rate, and protosun mass which are chosen to simulate a range of possible phases of early solar nebula evolution. The models show little tendency for directly forming small numbers of giant gaseous protoplanets through gaseous gravitational instability. 69 refs

  2. Eta Carinae in the Context of the Most Massive Stars

    Science.gov (United States)

    Gull, Theodore R.; Damineli, Augusto

    2009-01-01

    Eta Car, with its historical outbursts, visible ejecta and massive, variable winds, continues to challenge both observers and modelers. In just the past five years over 100 papers have been published on this fascinating object. We now know it to be a massive binary system with a 5.54-year period. In January 2009, Car underwent one of its periodic low-states, associated with periastron passage of the two massive stars. This event was monitored by an intensive multi-wavelength campaign ranging from -rays to radio. A large amount of data was collected to test a number of evolving models including 3-D models of the massive interacting winds. August 2009 was an excellent time for observers and theorists to come together and review the accumulated studies, as have occurred in four meetings since 1998 devoted to Eta Car. Indeed, Car behaved both predictably and unpredictably during this most recent periastron, spurring timely discussions. Coincidently, WR140 also passed through periastron in early 2009. It, too, is a intensively studied massive interacting binary. Comparison of its properties, as well as the properties of other massive stars, with those of Eta Car is very instructive. These well-known examples of evolved massive binary systems provide many clues as to the fate of the most massive stars. What are the effects of the interacting winds, of individual stellar rotation, and of the circumstellar material on what we see as hypernovae/supernovae? We hope to learn. Topics discussed in this 1.5 day Joint Discussion were: Car: the 2009.0 event: Monitoring campaigns in X-rays, optical, radio, interferometry WR140 and HD5980: similarities and differences to Car LBVs and Eta Carinae: What is the relationship? Massive binary systems, wind interactions and 3-D modeling Shapes of the Homunculus & Little Homunculus: what do we learn about mass ejection? Massive stars: the connection to supernovae, hypernovae and gamma ray bursters Where do we go from here? (future

  3. A Robust Measurement of the Mass Outflow Rate of the Galactic Outflow from NGC 6090

    Science.gov (United States)

    Chisholm, John; Tremonti, Christy A.; Leitherer, Claus; Chen, Yanmei

    2016-08-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si IV absorption lines to calculate the scaling of velocity (v), covering fraction (Cf), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: v~∝(1 - Ri/r)β (where Ri is the inner outflow radius). We find that the velocity (β=0.43) is consistent with an outflow driven by an r-2 force with the outflow radially accelerated, while the scaling of the covering fraction (Cf∝r-0.82) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of four weak metal lines and CLOUDY photoionization models to determine the outflow metallicity, the ionization correction, and the initial density of the outflow. Combining these values with the profile fitting, we find Ri = 63 pc, with most of the mass within 300 pc of the starburst. Finally, we find that the maximum mass outflow rate is 2.3 M⊙ yr-1 and the mass loading factor (outflow divided by the star formation rate) is 0.09, a factor of 10 lower than the value calculated using common assumptions for the geometry, metallicity and ionization structure of the outflow.

  4. The dynamic X-ray nebula powered by the pulsar B1259-63

    Energy Technology Data Exchange (ETDEWEB)

    Kargaltsev, Oleg; Volkov, Igor; Hare, Jeremy [George Washington University, Washington, DC 20052 (United States); Pavlov, George G. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16801 (United States); Durant, Martin, E-mail: kargaltsev@gwu.edu [Department of Medical Biophysics, University of Toronto, Toronto, ON, M5S 2J7 (Canada)

    2014-04-01

    We present observations of the eccentric γ-ray binary B1259-63/LS 2883 with the Chandra X-ray Observatory. The images reveal a variable, extended (about 4'', or ∼1000 times the binary orbit size) structure, which appears to be moving away from the binary with the velocity of 0.05 of the speed of light. The observed emission is interpreted as synchrotron radiation from relativistic particles supplied by the pulsar. However, the fast motion through the circumbinary medium would require the emitting cloud to be loaded with a large amount of baryonic matter. Alternatively, the extended emission can be interpreted as a variable extrabinary shock in the pulsar wind outflow launched near binary apastron. The resolved variable X-ray nebula provides an opportunity to probe pulsar winds and their interaction with stellar winds in a previously inaccessible way.

  5. Planetary Nebulae as Mass Tracers in Galaxies

    OpenAIRE

    Romanowsky, Aaron J.

    2006-01-01

    Planetary nebula are useful kinematic tracers of the stars in all galaxy types. I review recent observationally-driven developments in the study of galaxy mass profiles. These have yielded surprising results on spiral galaxy disk masses and elliptical galaxy halo masses. A key remaining question is the coupling between PNe and the underlying stellar populations.

  6. Spatial spectroscopic diagnostics of planetary nebulae. VI

    International Nuclear Information System (INIS)

    The numerical properties of the kernel function of the Fredholm integral equation of the first kind of spatial spectroscopic diagnostics of planetary nebulae, are studied and briefly discussed. Samples of some kernel functions are shown as three-dimensional axonometric figures. A simple reason is given for inherent limitations of the regularization techniques used. (author). 12 figs., 2 refs

  7. Molecular line mapping of (young) planetary nebulae

    Science.gov (United States)

    Bujarrabal, Valentín

    2016-07-01

    In this contribution, I will review recent results obtained from high-resolution observations of molecular emission of planetary nebulae in the millimeter and submillimeter waves, stressing the easy interpretation of the data and the great amount of quantitative results obtained from them. Radio interferometers have been shown to be very efficient in the observation of our objects and, particularly since the arrival of ALMA, the amount of results is becoming impressive. We will deal mainly with young planetary nebulae or protoplanetary nebulae, since, as we will see, molecular lines tend to be weak in evolved objects because of photodissociation. In relatively young nebulae, the molecular gas represents most of the nebular material and can be well observed in line emission in mm- and submm-waves. Those observations have yielded many quantitative and accurate results on the structure, dynamics, and physical conditions of this largely dominant nebular component. In more evolved sources, we can follow the evolution of the chemical composition, although the data become rare.

  8. Argon and neon in Galactic nebulae

    Science.gov (United States)

    Simpson, Janet P.; Bregman, Jesse D.; Dinerstein, H. L.; Lester, Dan F.; Rank, David M.; Witteborn, F. C.; Wooden, D. H.

    1995-01-01

    KAO observations of the 6.98 micron line of (Ar II), and KAO and ground-based observations of the 8.99 micron line of (Ar III) and the 12.8 micron line of (Ne II) are presented for a number of Galactic H II regions and planetary nebulae.

  9. INTERNAL PROPER MOTIONS IN THE ESKIMO NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    García-Díaz, Ma. T.; Gutiérrez, L.; Steffen, W.; López, J. A. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Km 103 Carretera Tijuana-Ensenada, 22860 Ensenada, B.C. (Mexico); Beckman, J., E-mail: tere@astro.unam.mx, E-mail: leonel@astro.unam.mx, E-mail: wsteffen@astro.unam.mx, E-mail: jal@astro.unam.mx, E-mail: jeb@iac.es [Instituto de Astrofísica de Canarias, La Laguna, Tenerife (Spain)

    2015-01-10

    We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695 yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a ''criss-cross'' mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3 kpc.

  10. Particle Transport in Young Pulsar Wind Nebulae

    CERN Document Server

    Tang, Xiaping

    2012-01-01

    The model for pulsar wind nebulae (PWNe) as the result of the magnetohydrodynamic (MHD) downstream flow from a shocked, relativistic pulsar wind has been successful in reproducing many features of the nebulae observed close to the central pulsars. However, observations of well-studied young nebulae like the Crab Nebula, 3C 58, and G21.5--0.9 do not show the toroidal magnetic field on a larger scale that might be expected in the MHD flow model; in addition, the radial variation of spectral index due to synchrotron losses is smoother than expected in the MHD flow model. We find that pure diffusion models can reproduce the basic data on nebular size and spectral index variation for the Crab, 3C 58, and G21.5--0.9. Most of our models use an energy independent diffusion coefficient; power law variations of the coefficient with energy are degenerate with variation in the input particle energy distribution index in the steady state, reflecting boundary case. Energy dependent diffusion is a possible reason for the sm...

  11. Identification of the Exciting Source of CO Outflow in the Star-Formation Region GGD 12-15

    Science.gov (United States)

    Sato, Yaeko; Tamura, Motohide; Kandori, Ryo; Nakajima, Yasushi; Kusakabe, Nobuhiko; Hashimoto, Jun; Kudo, Tomoyuki; Saito, Hiroo; Kitamura, Yoshimi; Kawamura, Akiko; Nishiyama, Shogo; Sunada, Kazuyoshi; Ueno, Munetaka

    2008-12-01

    We present results of near-infrared imaging polarimetry of the GGD 12-15 region with the IRSF 1.4m telescope and the SIRIUS camera/SIRPOL polarimeter and mid-infrared imaging with the AKARI telescope and the Infra-Red Camera (IRC). Two infrared sources, IRS9E and IRS9M near an H2O maser source situated on both sides around a VLA source (VLA7), have been believed to be two bipolar lobes associated with a massive CO outflow. However, our polarimetric observations have revealed that IRS9E is stellar-like, and not part of a reflection nebula. Furthermore, IRS9M itself is not stellar, but a bipolar nebula, extending north-south. Both polarization vector maps and polarized intensity images show that the true illuminating source, IRS9Mc, is not resolved, and is situated near the peak of the intensity image. Our astrometry also indicates that the position of IRS9Mc does not coincide with the water maser position, but rather coincides with the VLA7 position. We suggest that the unresolved illuminating source IRS9Mc is the true exciting source of the CO outflow, corresponding to amid-infrared source detected by AKARI with a lower spatial resolution. Fluxes of the newly identified source at 1 to 11μm were derived by separating contributions from nearby infrared sources; the spectral energy distribution is consistent with that of a class I/0 source.

  12. On the possible wind nebula of magnetar Swift J1834.9-0846: a magnetism-powered synchrotron nebula

    CERN Document Server

    Tong, H

    2016-01-01

    Recently, the magnetar Swift J1834.9$-$0846 is reported to have a possible wind nebula. It is shown that both the magnetar and its wind nebula are understandable in the wind braking scenario. The magnetar's rotational energy loss rate is not enough. The required particle luminosity should be about $10^{36} \\,\\rm erg \\,s^{-1}$ to $10^{38} \\,\\rm erg \\,s^{-1}$. It is obtained in three different approaches: considering wind braking of Swift J1834.9$-$0846; the spectral and spatial observations of the wind nebula; and an empirical upper bound on wind nebula X-ray luminosity. The nebula magnetic field is be about $10^{-4} \\,\\rm G$. The possible wind nebula of Swift J1834.9$-$0846 should be a magnetar wind nebula. It is powered by the magnetic energy release of the magnetar.

  13. Tearing the Veil: interaction of the Orion Nebula with its neutral environment

    CERN Document Server

    van der Werf, Paul P; O'Dell, C R

    2012-01-01

    We present HI 21cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.2"x5.7" and a velocity resolution of 0.77 km/s. Our data reveal HI absorption towards the radio continuum of the HII region, and HI emission arising from the Orion Bar photon-dominated region (PDR) and from the Orion-KL outflow. In the Orion Bar PDR, the HI signal peaks in the same layer as the H2 near-infrared vibrational line emission, in agreement with models of the photodissociation of H2. The gas temperature in this region is approximately 540K, and the HI abundance in the interclump gas in the PDR is 5-10% of the available hydrogen nuclei. Most of the gas in this region therefore remains molecular. Mechanical feedback on the Veil manifests itself through the interaction of ionized flow systems in the Orion Nebula, in particular the Herbig-Haro object HH202, with the Veil. These interactions give rise to prominent blueward velocity shifts of the gas in the Veil. The unambi...

  14. Evolution of Mass Outflow in Protostars

    CERN Document Server

    Watson, Dan M; Fischer, William J; Forrest, W J; Manoj, P; Megeath, S Thomas; Melnick, Gary J; Najita, Joan; Neufeld, David A; Sheehan, Patrick D; Stutz, Amelia M; Tobin, John J

    2015-01-01

    We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si II], [Fe II] and [S I] line emission, and 11 of these in far-infrared [O I] emission. We use the results to derive their mass outflow rates. Thereby we observe a strong correlation of mass outflow rates with bolometric luminosity, and with the inferred mass accretion rates of the central objects, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass-flow rates, the different classes of young stellar objects lie in the sequence Class 0 -- Class I/flat-spectrum -- Class II, indicating that the trend is an evolutionary sequence in which mass outflow and accretion rates decrease together with increasing age, while maintaining rough proportionality. The survey results include two which are key tests of magnetocentrifugal outflow-acceleration mechanisms: the distribution of the outflow/accretion branching ratio b, and limits on the distribution of...

  15. Bursty star formation feedback and cooling outflows

    CERN Document Server

    Suarez, Teresita; Peiris, Hiranya V; Slyz, Adrianne; Devriendt, Julien

    2016-01-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circumgalactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disk can be modelled as a rapidly moving bubble of hot gas at $\\mathrm{\\sim1\\;kpc}$ above disk, then ask what happens as it moves out further into the halo around the galaxy on $\\mathrm{\\sim 100\\;kpc}$ scales. To do this we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the 'burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in th...

  16. ETHOS 1: A high latitude planetary nebula with jets forged by a post common envelope binary central star

    CERN Document Server

    Miszalski, B; Boffin, H M J; Jones, D; Sabin, L; Santander-García, M; Rodríguez-Gil, P; Rubio-Díez, M M

    2010-01-01

    We report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at $120\\pm10$ km/s and a close binary central star. The lightcurve observed with the Mercator telescope reveals an orbital period of 0.535 days and an extremely large amplitude (0.816 mag) due to irradiation of the companion by a very hot pre-white dwarf. ETHOS 1 further strengthens the long suspected link between binary central stars of planetary nebulae (CSPN) and jets. INT IDS and VLT FORS spectroscopy of the CSPN reveals weak N III, C III and C IV emission lines seen in other close binary CSPN and suggests many CSPN with these weak emission lines are misclassified close binaries. We present VLT FORS imaging and Manchester Echelle Spectrometer long slit observations from which a kinematic model of the nebula is built. An unusual combina...

  17. Observations of Protostellar Outflow Feedback in Clustered Star Formation

    CERN Document Server

    Nakamura, Fumitaka

    2015-01-01

    We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects significantly the clump dynamics. On the other hand, for clumps with masses larger than about 200 M$_\\odot$, the outflow kinetic energy is significantly smaller than the clump gravitational energy. Since the majority of stars form in such clumps, we conclude that outflow feedback cannot destroy the whole parent clump. These characteristics of the outflow feedback support the scenario of slow star formation.

  18. Zooplankton in the Arctic outflow

    Science.gov (United States)

    Soloviev, K. A.; Dritz, A. V.; Nikishina, A. B.

    2009-04-01

    Climate changes in the Arctic cause the changes in the current system that may have cascading effect on the structure of plankton community and consequently on the interlinked and delicately balanced food web. Zooplankton species are by definition incapable to perform horizontal moving. Their transport is connected with flowing water. There are zooplankton species specific for the definite water masses and they can be used as markers for the different currents. That allows us to consider zooplankton community composition as a result of water mixing in the studied area. Little is known however about the mechanisms by which spatial and temporal variability in advection affect dynamics of local populations. Ice conditions are also very important in the function of pelagic communities. Melting time is the trigger to all "plankton blooming" processes, and the duration of ice-free conditions determines the food web development in the future. Fram Strait is one of the key regions for the Arctic: the cold water outflow comes through it with the East Greenland Current and meets warm Atlantic water, the West Spitsbergen Current, producing complicated hydrological situation. During 2007 and 2008 we investigated the structure functional characteristics of zooplankton community in the Fram Strait region onboard KV "Svalbard" (April 2007, April and May 2008) and RV "Jan Mayen" (May 2007, August 2008). This study was conducted in frame of iAOOS Norway project "Closing the loop", which, in turn, was a part of IPY. During this cruises multidisciplinary investigations were performed, including sea-ice observations, CTD and ADCP profiling, carbon flux, nutrients and primary production measurements, phytoplankton sampling. Zooplankton was collected with the Hydro-Bios WP2 net and MultiNet Zooplankton Sampler, (mouth area 0.25 m2, mesh size 180 um).Samples were taken from the depth strata of 2000-1500, 1500-1000, 1000-500,500-200, 200-100, 100-60, 60-30, 30-0 m. Gut fluorescence

  19. Investigating Cepheid $\\ell$ Carinae's Cycle-to-cycle Variations via Contemporaneous Velocimetry and Interferometry

    CERN Document Server

    Anderson, R I; Kervella, P; Breitfelder, J; LeBouquin, J -B; Eyer, L; Gallenne, A; Palaversa, L; Semaan, T; Saesen, S; Mowlavi, N

    2015-01-01

    Baade-Wesselink-type (BW) techniques enable geometric distance measurements of Cepheid variable stars in the Galaxy and the Magellanic clouds. The leading uncertainties involved concern projection factors required to translate observed radial velocities (RVs) to pulsational velocities and recently discovered modulated variability. We carried out an unprecedented observational campaign involving long-baseline interferometry (VLTI/PIONIER) and spectroscopy (Euler/Coralie) to search for modulated variability in the long-period (P $\\sim$ 35.5 d) Cepheid Carinae. We determine highly precise angular diameters from squared visibilities and investigate possible differences between two consecutive maximal diameters, $\\Delta_{\\rm{max}} \\Theta$. We characterize the modulated variability along the line-of-sight using 360 high-precision RVs. Here we report tentative evidence for modulated angular variability and confirm cycle-to-cycle differences of $\\ell$ Carinae's RV variability. Two successive maxima yield $\\Delta_{\\rm...

  20. Constraining the orbital orientation of Eta Carinae from H Paschen lines

    CERN Document Server

    Falceta-Goncalves, D

    2009-01-01

    During the past decade several observational and theoretical works provided evidences of the binary nature of Eta Carinae. Nevertheless, there is still no direct determination of the orbital parameters, and the different current models give contradictory results. The orbit is, in general, assumed to coincide with the Homunculus equator although the observations are not conclusive. Among all systems, Eta Carinae has the advantage that it is possible to observe both the direct emission of line transitions in the central source and its reflection by the Homunculus, which are dependent on the orbital inclination. In this work, we studied the orbital phase dependent hydrogen Paschen spectra reflected by the SE lobe of the Homunculus to constrain the orbital parameters of etaCar and determine its inclination with respect to the Homunculus axis. Assuming that the emission excess is originated in the wind-wind shock region we were able to model the latitude dependence of the spectral line profiles. For the first time...

  1. The threat to life from Eta Carinae and gamma ray bursts

    CERN Document Server

    Dar, Arnon; Dar, Arnon

    2001-01-01

    Eta Carinae, the most massive and luminous star known in our galaxy, is rapidly boiling matter off its surface. At any time its core could collapse into a black hole, which may result in a gamma-ray burst (GRB) that can devastate life on Earth. Auspiciously, recent observations indicate that the GRBs are narrowly beamed in cones along the rotational axis of the progenitor star. In the case of Eta Carinae the GRBs will not point to us, but will be ravaging to life on planets in our galaxy that happen to lie within the two beaming cones. The mean rate of massive life extinctions by jets from GRBs, per life-supporting planet in galaxies like ours, is once in 100 million years, comparable to the rate of major extinctions observed in the geological records of our planet. GRB extinctions also provide an answer to Fermi's question about alien visitors: ``Where are they?''

  2. The Abundance of Iron-Peak Elements and the Dust Composition in eta Carinae: Manganese

    Science.gov (United States)

    Bautista, M. A.; Melendez, M.; Hartman, H.; Gull, T. R.; Lodders, K.

    2010-01-01

    We study the chemical abundances of the Strontium Filament found in the ejecta of (eta) Carinae. In particular, we derive the abundances of iron-peak elements front spectra of their singly ionized ions present in the optical/IR spectra. In this paper we analyze the spectrum of Mn II using a new non-LTE model for this system. In constructing this models we carried out theoretical calculations of radiative transition rates and electron impact excitation rate coefficients. We find that relative to Ni the gas phase abundance ratio of Mn is roughly solar, similar to the Cr abundance but in contrast to the large enhancements in the abundances of Sc and Ti. NVe interpret this result as an indication of non-equilibrium condensation in the ejecta of (eta) Carinae.

  3. Outflows in Regions of Star Formation

    CERN Document Server

    Liseau, R

    2004-01-01

    The high spatial and spectral resolution offered by the new generation of infrared spectrometers at ESO is optimally suited for the observational study of outflows from young stellar objects. Models of interstellar shock waves would benefit from observations of spectrally resolved line profiles. This applies also to attempts of measuring the rotation rates of jets very close to their driving source, which in general suffer considerable extinction. Observations of forbidden lines of ionised iron, [Fe II], could be used to accomplish this. The possibility of using rotational lines of molecular hydrogen, H2, to study the temporal evolution of outflow and disk gas is discussed. Similarly, high resolution IR observations of fluorescent water lines, H2O, open up the possibility to access outflow and disk water.

  4. CARINA-Oxygen: a new high-quality oxygen database for the Atlantic Ocean

    OpenAIRE

    Stendardo, I.; Gruber, N.; A. Körtzinger

    2009-01-01

    In the CARINA project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC) procedures. In this paper, we present the dissolved oxygen measurements in the Atlantic region of the database and describe in detail the secondary QC procedures that aim to ensure optimal consistency between different cruises in order to permit studies of long-term change. The secondary QC is based on ...

  5. The CHANDRA HETGS X-ray Grating Spectrum of Eta Carinae

    Science.gov (United States)

    Corcoran, M. F.; Swank, J. H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; White, S.; Viotti, R.; Damineli, A.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.

  6. Eta Carinae's 2014.6 Spectroscopic Event: The Extraordinary He II and N II Features

    OpenAIRE

    Davidson, Kris; Mehner, Andrea; Humphreys, Roberta; Martin, John C.; Ishibashi, Kazunori

    2014-01-01

    Eta Carinae's spectroscopic events (periastron passages) in 2003, 2009, and 2014 differed progressively. He II 4687 and nearby N II multiplet 5 have special significance because they respond to very soft X-rays and the ionizing UV radiation field (EUV). HST/STIS observations in 2014 show dramatic increases in both features compared to the previous 2009.1 event. These results appear very consistent with a progressive decline in the primary wind density, proposed years ago on other grounds. If ...

  7. Wind influence on a coastal buoyant outflow

    Science.gov (United States)

    Whitney, Michael M.; Garvine, Richard W.

    2005-03-01

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

  8. Gas physical conditions and kinematics of the giant outflow Ou4

    CERN Document Server

    Corradi, Romano L M; Acker, Agnès; Greimel, Robert; Guillout, Patrick

    2014-01-01

    Ou4 is a recently discovered bipolar outflow with a projected size of more than one degree in the plane of the sky. It is apparently centred on the young stellar cluster -whose most massive representative is the triple system HR8119- inside the HII region Sh 2-129. The driving source, the nature, and the distance of Ou4 are not known. Deep narrow-band imagery of the whole nebula at arcsec resolution was obtained to study its morphology. Long-slit spectroscopy of the tips of the bipolar lobes was secured to determine the gas ionization mechanism, physical conditions, and line-of-sight velocities. An estimate of the proper motions at the tip of the south lobe using archival images is attempted. The existing multi-wavelength data for Sh 2-129 and HR 8119 are also comprehensively reviewed. The morphology of Ou4, its emission-line spatial distribution, line flux ratios, and the kinematic modelling adopting a bow-shock parabolic geometry, illustrate the expansion of a shock-excited fast collimated outflow. The radi...

  9. A submillimeter galaxy illuminating its circumgalactic medium: Ly-alpha scattering in a cold, clumpy outflow

    CERN Document Server

    Geach, J E; Alexander, D M; Blain, A W; Bremer, M; Chapin, E L; Chapman, S C; Clements, D L; Coppin, K E K; Dunlop, J S; Farrah, D; Jenness, T; Koprowski, M P; Michalowski, M J; Robson, E I; Scott, D; Smith, D J B; Spaans, M; Swinbank, A M; van der Werf, P

    2014-01-01

    We report the detection at 850um of the central source in SSA22-LAB1, the archetypal Lyman-alpha Blob (LAB), a 100kpc-scale radio-quiet emission-line nebula at z=3.1. The flux density of the source, $S_{850}=4.6\\pm1.1$mJy implies the presence of a galaxy, or group of galaxies, with a total luminosity of $L_{\\rm IR}\\approx10^{12}L_\\odot$. The position of an active source at the center of a ~50kpc-radius ring of linearly polarized Ly-alpha emission detected by Hayes et al. (2011) suggests that the central source is leaking Ly-alpha photons preferentially in the plane of the sky, which undergo scattering in HI clouds at large galactocentric radius. The Ly-alpha morphology around the submillimeter detection is reminiscent of biconical outflow, and the average Ly-alpha line profiles of the two `lobes' are dominated by a red peak, expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center. Taken together, these observations provide compelling evi...

  10. Imaging Scattered Light from the Youngest Protostars in L1448: Signatures of Outflows

    CERN Document Server

    Tobin, J J; Mundy, L G; Kwon, W; Hamidouche, M; Tobin, John J.; Looney, Leslie W.; Mundy, Lee G.; Kwon, Woojin; Hamidouche, Murad

    2007-01-01

    We present deep IRAC images that highlight the scattered light emission around many of the youngest protostars, the so-called Class 0 sources, in L1448. By comparison of the data with a Monte Carlo radiative transfer code \\citep{whitney2003a}, we demonstrate for the first time that the observed infrared light from these objects is consistent with scattered light from the central protostar. The scattered light escapes out the cavity, carved by molecular outflows, in the circumstellar envelope. In particular, we observe prominent scattered light nebulae associated with the Class 0 sources: L1448-mm, L1448 IRS 2, and 3B, as well as a Class I source: IRS 3A. We use a grid of models with probable protostellar properties to generate model spectral energy distributions (SEDs) and images for bands sensitive to this scattered light: J, H, Ks, and \\textit{Spitzer} IRAC bands. By simultaneously fitting SEDs and images of the outflow cavities, we are able to model geometric parameters, i.e. inclination angle and opening ...

  11. Episodic High Velocity Outflows from V899 Mon: A Constraint On The Outflow Mechanisms

    CERN Document Server

    Ninan, J P; Philip, N S

    2016-01-01

    We report the detection of large variations in the outflow wind velocity from a young eruptive star, V899 Mon during its ongoing high accretion outburst phase. Such large variations in the outflow velocity (from -722 km s$^{-1}$ to -425 km s$^{-1}$) have never been reported previously in this family of objects. Our continuous monitoring of this source shows that the multi-component, clumpy, and episodic high velocity outflows are stable in the time scale of a few days, and vary over the time scale of a few weeks to months. We detect significant decoupling in the instantaneous outflow strength to accretion rate. From the comparison of various possible outflow mechanisms in magnetospheric accretion of young stellar objects, we conclude magnetically driven polar winds to be the most consistent mechanism for the outflows seen in V899 Mon. The large scale fluctuations in outflow over the short period makes V899 Mon the most ideal source to constrain various magnetohydrodynamics (MHD) simulations of magnetospheric ...

  12. Episodic High-velocity Outflows from V899 Mon: A Constraint On The Outflow Mechanisms

    Science.gov (United States)

    Ninan, J. P.; Ojha, D. K.; Philip, N. S.

    2016-07-01

    We report the detection of large variations in the outflow wind velocity from a young eruptive star, V899 Mon, during its ongoing high accretion outburst phase. Such large variations in the outflow velocity (from ‑722 to ‑425 km s‑1) have never been reported previously in this family of objects. Our continuous monitoring of this source shows that the multi-component, clumpy, and episodic high velocity outflows are stable in the timescale of a few days, and vary over the timescale of a few weeks to months. We detect significant decoupling in the instantaneous outflow strength to accretion rate. From the comparison of various possible outflow mechanisms in magnetospheric accretion of young stellar objects, we conclude magnetically driven polar winds to be the most consistent mechanism for the outflows seen in V899 Mon. The large scale fluctuations in outflow over the short period makes V899 Mon the most ideal source to constrain various magnetohydrodynamics simulations of magnetospheric accretion. Based on observations made with the Southern African Large Telescope (SALT).

  13. Carina® and Esteem®: a systematic review of fully implantable hearing devices.

    Directory of Open Access Journals (Sweden)

    Janaina Oliveira Bentivi Pulcherio

    Full Text Available To review the outcomes of the fully implantable middle ear devices Carina and Esteem regarding the treatment of hearing loss.PubMed, Embase, Scielo, and Cochrane Library databases were searched.Abstracts of 77 citations were screened, and 43 articles were selected for full review. From those, 22 studies and two literature reviews in English directly demonstrating the results of Carina and Esteem were included.There were a total of 244 patients ranging from 18 to 88 years. One hundred and 10 patients were implanted with Carina and with 134 Esteem. There were registered 92 males and 67 females. Five studies provided no information about patients' age or gender. From the data available, the follow-up ranged from 2 to 29.4 months.The comparison of the results about word recognition is difficult as there was no standardization of measurement. The results were obtained from various sound intensities and different frequencies. The outcomes comparing to conventional HAs were conflicting. Nevertheless, all results comparing to unaided condition showed improvement and showed a subjective improvement of quality of life.There are still some problems to be solved, mainly related to device functioning and price. Due to the relatively few publications available and small sample sizes, we must be careful in extrapolating these results to a broader population. Additionally, none of all these studies represented level high levels of evidence (i.e. randomized controlled trials.

  14. Stellar populations in the Carina region: The Galactic plane at l = 291

    CERN Document Server

    Molina-Lera, J A; Gamen, R; Costa, E; Carraro, G

    2016-01-01

    Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. In many cases, these studies only concentrated on the central region or were not homogeneous. This latter aspect, in particular, is crucial because very different ages and distances for key clusters have been claimed in recent years. The aim of this work is to study in detail an area of the Galactic plane in Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of YSOs and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. We obtained photometric data for six young open clusters located in Carina at l = 291, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional infor...

  15. XMM-Newton Observations of the 2003 X-ray Minimum of Eta Carinae

    CERN Document Server

    Hamaguchi, K; Gull, T R; White, N E; Damineli, A; Davidson, K

    2004-01-01

    The XMM-Newton X-ray observatory took part in the multi-wavelength observing campaign of the massive, evolved star Eta Carinae in 2003 during its recent X-ray minimum. This paper reports on the results of these observations, mainly from the aspect of spectral change. Hard X-ray emission from the point source of Eta Carinae was detected even during the minimum. During the minimum the observed flux above 3 keV was ~3e-12 ergs cm-2 s-1, which is about one percent of the flux before the minimum. Changes in the spectral shape revealed two X-ray emission components in the central point source. One component is non-variable and has relatively cool plasma of kT~1 keV and moderate absorption, NH~5e22 cm-2. The plasma is probably located far from the star, possibly produced by the high speed polar wind from Eta Carinae. The other high temperature component has kT~5 keV and is strongly variable. This component shows an increase in the apparent column density from 5e22 cm-2 to 2e23 cm-2, probably originating near the hea...

  16. LMC SMP 64 - The youngest planetary nebula?

    International Nuclear Information System (INIS)

    The planetary nebula SMP 64 in the Large Magellanic Cloud is shown to possess several properties which set it apart from the general PN population. These are an extremely high central electron density, a strong radial density gradient, and a central star with a very low effective temperature, T(eff) = 31,500 K. However, the luminosity of the central star is 6400 solar luminosities, implying a core mass of 0.62 solar mass, typical of the Magellanic Cloud population of planetary nebulae. It is concluded that the central star of SMP 64 has only just reached a temperature high enough to ionize a portion of the material ejected during the asymptotic giant branch evolution of the central star. 25 refs

  17. Heat conduction fronts in planetary nebulae

    Science.gov (United States)

    Soker, Noam

    1994-01-01

    We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

  18. The theory of pulsar wind nebulae

    CERN Document Server

    Amato, E

    2013-01-01

    I review the current status of our theoretical understanding of Pulsar Winds and associated nebulae (PWNe). In recent years, axisymmetric models of pulsar winds with a latitude dependent energy flux have proved very successful at explaining the morphology of PWNe as seen in the X-rays. This success has prompted developments aimed at using multi-wavelength observations of these nebulae as a diagnostics of the hidden physics of the pulsar wind and of the mechanism(s) through which particles are accelerated in these sources. I will discuss these most recent developments in terms of the information that we infer from detailed comparison of simulated non-thermal emission with current observations.

  19. Star Formation in the Eagle Nebula

    CERN Document Server

    Oliveira, Joana M

    2008-01-01

    M16 (the Eagle Nebula) is a striking star forming region, with a complex morphology of gas and dust sculpted by the massive stars in NGC 6611. Detailed studies of the famous ``elephant trunks'' dramatically increased our understanding of the massive star feedback into the parent molecular cloud. A rich young stellar population (2 - 3 Myr) has been identified, from massive O-stars down to substellar masses. Deep into the remnant molecular material, embedded protostars, Herbig-Haro objects and maser sources bear evidence of ongoing star formation in the nebula, possibly triggered by the massive cluster members. M 16 is a excellent template for the study of star formation under the hostile environment created by massive O-stars. This review aims at providing an observational overview not only of the young stellar population but also of the gas remnant of the star formation process.

  20. Formation of iron sulphide in solar nebula

    Science.gov (United States)

    Kerridge, J. F.

    1976-01-01

    Noting that the iron sulfide in the Orgueil carbonaceous meteorite is an Fe-deficient monosulfide (pyrrhotite), it is suggested that such mineral chemistry is inconsistent with equilibrium condensation of the solar nebula and that the course of condensation may have been modified by kinetic effects. The effect of Ni on the reaction between Fe and S to produce FeS is examined, and possible reasons are considered for the fact that the cited meteorite differs in both crystal structure and Ni content from the predictions of equilibrium condensation. It is proposed that sulfide formation in the solar nebula may have been inhibited by sluggish diffusion, so that sulfur began to react with previously condensed troilite to form pyrrhotite. On this basis, observations of the Orgueil sulfides are shown to suggest that the course of solar-system condensation was modified by kinetic effects below about 700 K and that equilibrium may not have been achieved.

  1. Interstellar molecules - Formation in solar nebulae

    Science.gov (United States)

    Anders, E.

    1973-01-01

    Herbig's (1970) hypothesis that solar nebulae might be the principal source of interstellar grains and molecules is investigated. The investigation includes the determination of physical and chemical conditions in the early solar system. The production of organic compounds in the solar nebula is studied, and the compounds in meteorites are compared with those obtained in Miller-Urey and Fischer-Tropsch-type (FTT) reactions, taking into consideration aliphatic hydrocarbons, aromatic hydrocarbons, purines, pyrimidines, amino acids, porphyrins, and aspects of carbon-isotope fractionation. It is found that FTT reactions account reasonably well for all well-established features of organic matter in meteorites investigated. The distribution of compounds produced by FTT reactions is compared with the distribution of interstellar molecules. Biological implications of the results are considered.

  2. Direct photography of the Gum Nebula

    Science.gov (United States)

    Brandt, J. C.; Roosen, R. G.; Thompson, J.; Ludden, D. J.

    1976-01-01

    The paper discusses a series of wide-angle photographs taken of the Gum Nebula in the traditional region including H-alpha with the aid of a 40-cm and an 80-cm lens in both the red and the green. The photographs support the large dimensions (75 deg in galactic longitude by 40 deg in galactic latitude) of the Gum Nebula suggested earlier, and the appearance is consistent with an origin due to photons from a supernova outburst. The relatively high-density gas has cooled and is visible on the red plates. The low-density gas has remained at a high temperature and may be visible as diffuse emission on the green plates.

  3. Element Distributions In The Crab Nebula

    OpenAIRE

    Satterfield, T. J.; Katz, A. M.; Sibley, A. R.; G. M. MacAlpine; Uomoto, A.

    2012-01-01

    Images of the Crab Nebula have been obtained through custom interference filters which transmit emission from the expanding supernova remnant in HI, HeI, HeII, [CI], [NII], [OI], [SII], and [SIII] emission lines. We present both raw and flux-calibrated data. Arrays of 19,440 photoionization models, with extensive input abundance ranges, were matched pixel by pixel to the calibrated data in order to derive corresponding element abundance or mass-fraction distributions for helium, carbon, nitro...

  4. Planetary nebulae in the Small Magellanic Cloud

    Science.gov (United States)

    Ventura, P.; Stanghellini, L.; Di Criscienzo, M.; García-Hernández, D. A.; Dell'Agli, F.

    2016-08-01

    We analyse the planetary nebulae (PNe) population of the Small Magellanic Cloud (SMC), based on evolutionary models of stars with metallicities in the range 10-3 ≤ Z ≤ 4 × 10-3 and mass 0.9 M⊙ Cloud is explained on the basis of the diverse star formation history and age-metallicity relation of the two galaxies. The implications of this study for some still highly debated points regarding the AGB evolution are also commented.

  5. Environmental impact study of Orion Nebula dust

    International Nuclear Information System (INIS)

    In this paper, new high-quality extinction curves are presented for Theta-1 Ori A, C, and D, and Theta-2 Ori A and B, over the wavelength range 3300-6000 A. These are coupled with near-infrared and ultraviolet data to produce extinction curves from 0.12 to 3.5 microns. The Orion Nebula region is interesting in that most of the known processes of dust-grain growth, processing, and destruction may be operating nearly simultaneously in close proximity to one another. Each of these processes is considered with respect to the observed extinction curves and environmental conditions in the Orion Nebula and its associated molecular cloud. Plausible grain populations are fit to the observed extinction curves. A good fit to the average Theta Ori extinction curve can be obtained with: (1) a combination of larger than normal silicate grains produced through coagulation and accretion; (2) evaporation of volatile mantles; and (3) a reduction in the column density of small (smaller than 0.01 micron) grains responsible for the bump and far-ultraviolet extinction through differential acceleration due to radiation pressure and possible evaporation. It seems plausible to explain the observed peculiar extinction in the Orion Nebula simply by environmental effects on otherwise normal grains. 59 references

  6. Shocked molecular hydrogen towards the Tornado nebula

    CERN Document Server

    Lazendic, J S

    2004-01-01

    We present near-infrared and millimetre-line observations of the Tornado nebula (G357.7-0.1). We detected 2.12 micron_m H2 1-0 S(1) line emission towards the suspected site of interaction with a molecular cloud revealed by the presence of an OH(1720 MHz) maser. The distribution of the H2 emission is well correlated with the nonthermal radio continuum emission from the Tornado, and the velocity of the H2 emission spans over 100 km/s, which both imply that the H2 emission is shock excited. We also detected millimetre-lines from 12CO and 13CO transitions at the velocity of the maser, and mapped the distribution of the molecular cloud in a 2 \\times 2 arcmin^2 region around the maser. The peak of the molecular cloud aligns well with an indentation in the nebula's radio continuum distribution, suggesting that the nebula's shock is being decelerated at this location, which is consistent with the presence of the OH(1720 MHz) maser and shocked H2 emission at that location.

  7. Morphology and Composition of the Helix Nebula

    CERN Document Server

    Henry, R B C; Dufour, R J

    1999-01-01

    We present new narrow-band filter imagery in H-alpha and [N II] 6584 along with UV and optical spectrophotometry measurements from 1200 to 9600 Angstroms of NGC 7293, the Helix Nebula, a nearby, photogenic planetary nebula of large diameter and low surface brightness. Detailed models of the observable ionized nebula support the recent claim that the Helix is actually a flattened disk whose thickness is roughly one-third its diameter with an inner region containing hot, highly ionized gas which is generally invisible in narrow-band images. The outer visible ring structure is of lower ionization and temperature and is brighter because of a thickening in the disk. We also confirm a central star effective temperature and luminosity of 120,000K and 100L_sun, and we estimate a lower limit to the nebular mass to be 0.30M_sun. Abundance measurements indicate the following values: He/H=0.12 (+/-0.017), O/H=4.60x10^-4 (+/-0.18), C/O=0.87 (+/-0.12), N/O=0.54 (+/-0.14), Ne/O=0.33 (+/-0.04), S/O=3.22x10^-3 (+/-0.26), and ...

  8. High-energy radiation from the massive binary system Eta Carinae

    Science.gov (United States)

    Bednarek, W.; Pabich, J.

    2011-06-01

    Context. The most massive binary system Eta Carinae has been recently established as a gamma-ray source by the AGILE and Fermi-LAT detectors. The high energy spectrum of this gamma-ray source is very intriguing. It shows two clear components and a lack of any evidence of variability with the orbital period of the binary system. Aims: We consider different scenarios for the acceleration of particles (both electrons and hadrons) and the production of the high energy radiation in the model of stellar wind collisions within the binary system Eta Carinae with the aim to explain the gamma-ray observations and predict the behaviour of the source at very high gamma-ray energies. Methods: The gamma-ray spectra calculated in terms of the specific models are compared with the observations of Eta Carinae, and the neutrino spectra produced in hadronic models are confronted with the atmospheric neutrino background and the sensitivity of 1 km2 neutrino telescope. Results: We show that spectral features can be explained in terms of the stellar wind collision model between the winds of the companion stars in which the acceleration of particles occurs on both sides of the double shock structure. The shocks from the Eta Carinae star and the companion star can accelerate particles to different energies depending on the different conditions determined by the parameters of the stars. The lack of strong GeV gamma-ray variability with the period of the binary system can be also understood in terms of such a model. Conclusions: We predict that the gamma-ray emission features at energies above ~100 GeV will show significant variability (or its lack) depending on the acceleration and interaction scenario of particles accelerated within the binary system. For the hadronic models we predict the expected range of neutrino fluxes from the binary system Eta Carinae. This can be tested through observations with the large-scale neutrino telescopes, which will support or disprove the specific

  9. Stellar populations in the Carina region. The Galactic plane at l = 291°

    Science.gov (United States)

    Molina-Lera, J. A.; Baume, G.; Gamen, R.; Costa, E.; Carraro, G.

    2016-08-01

    Context. Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular, is crucial because very different ages and distances for key clusters have been claimed in recent years. Aims: The aim of this work is to study in detail an area of the Galactic plane in Carina, eastward η Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. Methods: We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l ~ 291°, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS. We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. Results: We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8 kpc and 2.8 kpc, with EB - V ~ 0.1 - 0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the

  10. The evolution of planetary nebulae VII. Modelling planetary nebulae of distant stellar systems

    CERN Document Server

    Schönberner, D; Sandin, C; Steffen, M

    2010-01-01

    By means of hydrodynamical models we do the first investigations of how the properties of planetary nebulae are affected by their metal content and what can be learned from spatially unresolved spectrograms of planetary nebulae in distant stellar systems. We computed a new series of 1D radiation-hydrodynamics planetary nebulae model sequences with central stars of 0.595 M_sun surrounded by initial envelope structures that differ only by their metal content. At selected phases along the evolutionary path, the hydrodynamic terms were switched off, allowing the models to relax for fixed radial structure and radiation field into their equilibrium state with respect to energy and ionisation. The analyses of the line spectra emitted from both the dynamical and static models enabled us to systematically study the influence of hydrodynamics as a function of metallicity and evolution. We also recomputed selected sequences already used in previous publications, but now with different metal abundances. These sequences w...

  11. Colors of reflection nebulae. I. Phase function effects in the Merope nebula

    International Nuclear Information System (INIS)

    The subject of color differences between reflection nebulae and their illuminating stars is reexamined in the light of developments of observational techniques, permitting accurate surface-brightness photometry over an expanded spectral region from the UV to the IR. Color-color diagrams for reflection nebulae can yield useful information about the wavelength dependence of the scattering properties of nebular dust without excessive sensitivity to the specific nebular geometry or the presence of multiple scattering, resulting in considerable savings in computational efforts. As an illustration, the color-difference method was applied to existing data for the Merope nebula, covering the spectral region 1550-5500 A. Strong evidence for a monotonically changing phase function of scattering at wavelengths less than or equal to 3500 A is found. The result is interpreted in the context of a plausible geometry for the Merope environment as providing support for a bimodal size distribution of nebular dust grains. 32 references

  12. Accretion, Outflows, and Winds of Magnetized Stars

    CERN Document Server

    Romanova, M M

    2016-01-01

    Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars...

  13. Propeller-driven Outflows and Disk Oscillations

    CERN Document Server

    Romanova, M M; Koldoba, A V; Lovelace, R V E

    2005-01-01

    We report the discovery of propeller-driven outflows in axisymmetric magnetohydrodynamic simulations of disk accretion to rapidly rotating magnetized stars. Matter outflows in a wide cone and is centrifugally ejected from the inner regions of the disk. Closer to the axis there is a strong, collimated, magnetically dominated outflow of energy and angular momentum carried by the open magnetic field lines from the star. The ``efficiency'' of the propeller may be very high in the respect that most of the incoming disk matter is expelled from the system in winds. The star spins-down rapidly due to the magnetic interaction with the disk through closed field lines and with corona through open field lines. Diffusive and viscous interaction between magnetosphere and the disk are important: no outflows were observed for very small values of the diffusivity and viscosity. These simulation results are applicable to the early stages of evolution of classical T Tauri stars and to different stages of evolution of cataclysmi...

  14. Left ventricular outflow obstruction and necrotizing enterocolitis

    Energy Technology Data Exchange (ETDEWEB)

    Allen, H.A.; Haney, P.J.

    1984-02-01

    Two neonates had unusually rapid development of necrotizing enterocolitis within 24 hours of birth. Both patients had decreased systemic perfusion secondary to aortic atresia. Onset of either clinical or radiographic manifestations of necrotizing enterocolitis in the first day of life should alert one to the possible presence of severe left ventricular outflow obstruction.

  15. CKVul: evolving nebula and three curious background stars

    OpenAIRE

    Hajduk, M.; van Hoof, P. A. M.; Zijlstra, A.A.

    2013-01-01

    We analyse the remnants of CK Vul (Nova Vul 1670) using optical imaging and spectroscopy. The imaging, obtained between 1991 and 2010, spans 5.6% of the life-time of the nebula. The flux of the nebula decreased during the last 2 decades. The central source still maintains the ionization of the innermost part of the nebula, but recombination proceeds in more distant parts of the nebula. Surprisingly, we discovered two stars located within 10 arcsec of the expansion centre of the radio emission...

  16. The Resolved Outflow from 3C 48

    Science.gov (United States)

    Shih, Hsin-Yi; Stockton, Alan

    2014-10-01

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

  17. THE TRIFID NEBULA: STELLAR SIBLING RIVALRY

    Science.gov (United States)

    2002-01-01

    This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from a nearby, massive star. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. Located about 9,000 light-years from Earth, the Trifid resides in the constellation Sagittarius. A stellar jet [the thin, wispy object pointing to the upper left] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a 'ticker tape,' telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a 'stalk' [the finger-like object] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or 'EGGs,' that were seen

  18. Accretion, winds and outflows in young stars

    Science.gov (United States)

    Günther, H. M.

    2013-02-01

    Young stars and planetary systems form in molecular clouds. After the initial radial infall an accretion disk develops. For classical T Tauri stars (CTTS, F-K type precursors) the accretion disk does not reach down to the central star, but it is truncated near the co-rotation radius by the stellar magnetic field. The inner edge of the disk is ionized by the stellar radiation, so that the accretion stream is funneled along the magnetic field lines. On the stellar surface an accretion shock develops, which is observed over a wide wavelength range as X-ray emission, UV excess, optical veiling and optical and IR emission lines. Some of the accretion tracers, e.g. Hα, can be calibrated to measure the accretion rate. This accretion process is variable on time scales of hours to years due to changing accretion rates, stellar rotation and reconfiguration of the magnetic field. Furthermore, many (if not all) accreting systems also drive strong outflows which are ultimately powered by accretion. However, the exact driving mechanism is still unclear. Several components could contribute to the outflows: slow, wide-angle disk winds, X-winds launched close to the inner disk rim, and thermally driven stellar winds. In any case, the outflows contain material of very different temperatures and speeds. The disk wind is cool and can have a molecular component with just a few tens of km s-1, while the central component of the outflow can reach a few 100 km s-1. In some cases the inner part of the outflow is collimated to a small-angle jet. These jets have an onion-like structure, where the inner components are consecutively hotter and faster. The jets can contain working surfaces, which show up as Herbig-Haro knots. Accretion and outflows in the CTTS phase do not only determine stellar parameters like the rotation rate on the main-sequence, they also can have a profound impact on the environment of young stars. This review concentrates on CTTS in near-by star forming regions where

  19. Enhanced gamma-ray activity from the Crab nebula

    Science.gov (United States)

    Buehler, R.; Ciprini, S.

    2016-01-01

    Preliminary LAT analysis indicates enhanced gamma-ray activity from the Crab nebula. The daily-averaged gamma-ray emission (E > 100 MeV) from the direction of the Crab Nebula has surpassed 4.0 x 10^-6 ph cm^-2 s^-1 five times in the last 12 days.

  20. Protostellar outflows with Smoothed Particle Magnetohydrodynamics (SPMHD)

    CERN Document Server

    Bürzle, Florian; Stasyszyn, Federico; Dolag, Klaus; Klessen, Ralf S

    2011-01-01

    The protostellar collapse of a molecular cloud core is usually accompanied by outflow phenomena. The latter are thought to be driven by magnetorotational processes from the central parts of the protostellar disc. While several 3D AMR/nested grid studies of outflow phenomena in collapsing magnetically supercritical dense cores have been reported in the literature, so far no such simulation has been performed using the Smoothed Particle Hydrodynamics (SPH) method. This is mainly due to intrinsic numerical difficulties in handling magnetohydrodynamics within SPH, which only recently were partly resolved. In this work, we use an approach where we evolve the magnetic field via the induction equation, augmented with stability correction and divergence cleaning schemes. We consider the collapse of a rotating core of one solar mass, threaded by a weak magnetic field initially parallel to the rotation axis so that the core is magnetically supercritical. We show, that Smoothed Particle Magnetohydrodynamics (SPMHD) is a...

  1. Hepatic venous outflow obstruction: Three similar syndromes

    Institute of Scientific and Technical Information of China (English)

    Ulas Darda Bayraktar; Soley Seren; Yusuf Bayraktar

    2007-01-01

    Our goal is to provide a detailed review of venoocclusive disease (VOD), Budd-Chiari syndrome (BCS),and congestive hepatopathy (CH), all of which results in hepatic venous outflow obstruction. This is the first article in which all three syndromes have been reviewed,enabling the reader to compare the characteristics of these disorders. The histological findings in VOD, BCS,and CH are almost identical: sinusoidal congestion and cell necrosis mostly in perivenular areas of hepatic acini which eventually leads to bridging fibrosis between adjacent central veins. Tender hepatomegaly with jaundice and ascites is common to all three conditions.However, the clinical presentation depends mostly on the extent and rapidity of the outflow obstruction.Although the etiology and treatment are completely different in VOD, BCS, and CH; the similarities in clinical manifestations and liver histology may suggest a common mechanism of hepatic injury and adaptation in response to increased sinusoidal pressure.

  2. Extracellular Matrix Turnover and Outflow Resistance

    OpenAIRE

    Kate E Keller; Mini, Aga; Bradley, John M.; Kelley, Mary J.; Acott, Ted S.

    2008-01-01

    Normal homeostatic adjustment of elevated intraocular pressure (IOP) involves remodeling the extracellular matrix (ECM) of the trabecular meshwork (TM). This entails sensing elevated IOP, releasing numerous activated proteinases to degrade existing ECM and concurrent biosynthesis of replacement ECM components. To increase or decrease IOP, the quantity, physical properties and/or organization of new components should be somewhat different from those replaced in order to modify outflow resistan...

  3. The formation of bipolar planetary nebulae

    OpenAIRE

    Mellema, Garrelt

    1997-01-01

    Using a radiation-hydrodynamics code I follow the formation of planetary nebulae around stars of different mass. Because a more massive central star evolves much faster than a lower mass one, it is to be expected that this will affect the formation of the PN. For the stars I use the evolutionary tracks for remnants with masses of 0.605 M0 and 0.836 M0, taken from Bloecker (1995). The AGB wind is assumed to be concentrated in a thin disk, which in models without evolving stars leads to the for...

  4. A large bubble around the Crab Nebula

    International Nuclear Information System (INIS)

    IRAS and 21 cm observations of the interstellar medium around the Crab nebula show evidence of a large bubble surrounded by a partial shell. If located at the canonical 2 kpc distance of the Crab pulsar, the shell is estimated to have a radius of about 90 pc and to contain about 50,000 solar masses of swept-up gas. The way in which interior conditions of this bubble can have important implications for observations of the Crab are described, and the fashion in which presupernova evolution of the pulsar progenitor has affected its local environment is described. 22 refs

  5. DLA kinematics and outflows from starburst galaxies

    CERN Document Server

    Razoumov, Alexei O

    2008-01-01

    We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses...

  6. Hot Electromagnetic Outflows I: Acceleration and Spectra

    CERN Document Server

    Russo, Matthew

    2013-01-01

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such the breakout of a gamma-ray burst jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pushed inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid...

  7. Magnotospheric imaging of high latitude ion outflows

    Directory of Open Access Journals (Sweden)

    D. E. Garrido

    Full Text Available High latitude ion outflows mostly consist of upward streaming O+ and He+ emanating from the ionosphere. At heights above 1000 km, these flows consist of cold and hot components which resonantly scatter solar extreme ultraviolet (EUV light, however, the ion populations respond differently to Doppler shifting resulting from the large relative velocities between the ions and the Sun. The possibility of optical detection of the Doppler effect on the scattering rate will be discussed for the O+ (83.4 nm ions. We have contrasted the EUV solar resonance images of these outflows by simulations of the 30.4 nm He+ and 83.4 nm O+ emissions for both quiet and disturbed geomagnetic conditions. Input data for the 1000 km level has been obtained from the EICS instrument aboard the Dynamics Explorer satellite. Our results show emission rates of 50 and 56 milli-Rayleighs at 30.4 nm for quiet and disturbed conditions and 65 and 75 milli-Rayleighs at 83.4 nm for quiet and disturbed conditions, respectively, obtained for a polar orbiting satellite and viewing radially outward. We also find that an imager at an equatorial distance of 9 RE or more is in a favourable position for detecting ion outflows, particularly when the plasmapause is depressed in latitude. However, an occultation disk is necessary to obscure the bright plasmaspheric emissions.

  8. CARINA-Oxygen: a new high-quality oxygen database for the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    I. Stendardo

    2009-08-01

    Full Text Available In the CARINA project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC procedures. In this paper, we present the dissolved oxygen measurements in the Atlantic region of the database and describe in detail the secondary QC procedures that aim to ensure optimal consistency between different cruises in order to permit studies of long-term change. The secondary QC is based on a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i the region not subject to substantial temporal variability, and (ii the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen database has 113005 oxygen samples from 9535 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted data base. Of the data included in the adjusted data base, 20% were adjusted with a mean adjustment of 2%.

  9. Assessing the internal consistency of the CARINA database in the Indian sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    C. Lo Monaco

    2010-02-01

    Full Text Available Carbon and carbon-relevant hydrographic and hydrochemical ancillary data from previously not publicly available cruises were retrieved and recently merged to a new data base, CARINA (CARbon IN the Atlantic. The initial North Atlantic project, an international effort for ocean carbon synthesis, was extended to include the Arctic Mediterranean Seas (Arctic Ocean and Nordic Seas and all three sectors of the Southern Ocean. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean. The present work focuses on data collected in the Indian sector (20° S–70° S; 30° E–150° E. The Southern Indian Ocean dataset covers the period 1992–2004 and includes seasonal repeated observations. Parameters including salinity, dissolved inorganic carbon (TCO2, total alkalinity (TA, oxygen, nitrate, phosphate and silicate were examined for cruise-to-cruise and overall consistency. In addition, data from an existing, quality controlled data base (GLODAP were introduced in the CARINA analysis to improve data coverage in the Southern Ocean. A global inversion was performed to synthesize the information deduced from objective comparisons of deep measurements (>1500 m at nearby stations (generally <220 km. The corrections suggested by the inversion were allowed to vary within a fixed envelope, thus accounting for ocean interior variability. The adjustments applied to CARINA data and those recommended for GLODAP data, in order to obtain a consistent merged dataset, are presented and discussed. The final outcome of this effort is a new quality controlled data base for TCO2 and other properties of the carbon system that can now be used to investigate the natural variability or stability of ocean chemistry and the accumulation of anthropogenic carbon. This data product also offers an important new synthesis of seasonal to decadal observations to validate ocean biogeochemical models in a region where available historical data were very

  10. The Present and Future of Planetary Nebula Research. A White Paper by the IAU Planetary Nebula Working Group

    CERN Document Server

    Kwitter, K B; Peña, M; Stanghellini, L; Corradi, R L M; DeMarco, O; Fang, X; Henry, R B C; Karakas, A I; Liu, X -W; López, J A; Manchado, A; Parker, Q A

    2014-01-01

    We present a summary of current research on planetary nebulae and their central stars, and related subjects such as atomic processes in ionized nebulae, AGB and post-AGB evolution. Future advances are discussed that will be essential to substantial improvements in our knowledge in the field.

  11. A Robust Measurement of the Mass Outflow Rate of the Galactic Outflow from NGC 6090

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei

    2016-01-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si~{\\sc IV} absorption lines to calculate the scaling of velocity (v), covering fraction (C$_f$), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: $v \\propto(1 -R_i/r )^\\beta$ (were R$_i$ is the inner outflow radius). We find that the velocity ($\\beta$=0.43) is consistent with an outflow driven by an r$^{-2}$ force, while the scaling of the covering fraction ($C_f \\propto r^{-0.82}$) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of fou...

  12. CARINA. A programme for experimental investigation of the irradiation behaviour of German reactor pressure vessel materials

    International Nuclear Information System (INIS)

    The proof of a sufficient safety margin against brittle fracture of the reactor pressure vessel (RPV) is an important part of the operational safety of nuclear power plants. The RPV safety assessment procedure applicable in Germany is described in KTA 3201.2 of the Nuclear Safety Standard Commission (KTA). In the recently completed research project CARINA (Characteristics of Irradiated German RPV Materials), the data base for pre-irradiated original RPV steels of German PWR construction lines was extended by comprehensive fracture toughness testing. The data obtained are a major contribution to the development of Master Curve applications to be integrated in German standards. (orig.)

  13. 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae's Inner Colliding Winds

    OpenAIRE

    Madura, Thomas I.; Clementel, Nicola; Gull, Theodore R.; Kruip, Chael J. H.; Paardekooper, Jan-Pieter

    2015-01-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 M_Sun), highly eccentric (e ~ 0.9) binary star system Eta Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF journal publication and the benefits of using 3D visualization and 3D printing as tools to analyze data from multidimensional numerical simulations. Using a consumer-grade 3D printer (Make...

  14. CARINA. A programme for experimental investigation of the irradiation behaviour of German reactor pressure vessel materials

    Energy Technology Data Exchange (ETDEWEB)

    Hein, Hieronymus; Keim, Elisabeth [AREVA GmbH, Erlangen (Germany); Bechler, Eduard [E.ON Kernkraft GmbH, Hannover (Germany); Efsing, Paal [Ringhals AB, Vaeroebacka (Sweden); Ganswind, Jens [VGB PowerTech e.V., Essen (Germany); Knobel, Rene [Kraftwerk Goesgen-Daeniken AG, Daeniken (Switzerland); Koenig, Guenter [EnBW Kernkraft GmbH, Neckarwestheim (Germany); Barreiro, Pablo [EnBW Kernkraft GmbH, Philippsburg (Germany); Widera, Martin [RWE Power AG, Essen (Germany); Jong, Andre de [N.V. EPZ Kerncentrale Borssele, Borssele (Netherlands)

    2013-06-01

    The proof of a sufficient safety margin against brittle fracture of the reactor pressure vessel (RPV) is an important part of the operational safety of nuclear power plants. The RPV safety assessment procedure applicable in Germany is described in KTA 3201.2 of the Nuclear Safety Standard Commission (KTA). In the recently completed research project CARINA (Characteristics of Irradiated German RPV Materials), the data base for pre-irradiated original RPV steels of German PWR construction lines was extended by comprehensive fracture toughness testing. The data obtained are a major contribution to the development of Master Curve applications to be integrated in German standards. (orig.)

  15. [TiII] and [NiII] emission from the strontium filament of eta Carinae

    OpenAIRE

    Bautista, M. A.; Hartman, H.; Gull, T. R.; Smith, N; Lodders, K.

    2006-01-01

    We study the nature of the [TiII] and [NiII] emission from the so-called strontium filament found in the ejecta of eta Carinae. To this purpose we employ multilevel models of the TiII and NiII systems which are used to investigate the physical condition of the filament and the excitation mechanisms of the observed lines. For the TiII ion, for which no atomic data was previously available, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coe...

  16. Eta Carinae's 2014.6 Spectroscopic Event: The Extraordinary He II and N II Features

    CERN Document Server

    Davidson, Kris; Humphreys, Roberta; Martin, John C; Ishibashi, Kazunori

    2014-01-01

    Eta Carinae's spectroscopic events (periastron passages) in 2003, 2009, and 2014 showed a progressive evolution in several respects. He II 4687 and nearby N II multiplet 5have special significance, because they are excited in unusual ways that sample very soft X-rays and the ionizing UV radiation field (EUV). HST/STIS observations in 2014 show dramatic increases in both compared to the previous 2009.1 event. These results appear very consistent with a progressive decline in the primary wind density, proposed years ago on other grounds. If material falls onto the companion star near periastron, the accretion rate may now have become too low to suppress the EUV

  17. The Lagoon Nebula and its Vicinity

    CERN Document Server

    Tothill, N F H; Stecklum, B; Kenworthy, M A

    2008-01-01

    The Lagoon Nebula is an HII region in the Sagittarius Arm, about 1.3 kpc away, associated with the young (1-3 Myr) open cluster NGC 6530, which contains several O stars and several dozen B stars. Lower-mass cluster members, detected by X-ray and H-alpha emission, and by near-IR excess, number more than a thousand. Myr-old star formation is traced by the optically-visible HII region and cluster; observations of infrared and submillimetre-wave emission, and of optical emission features, indicate ongoing star formation in several locations across the Lagoon. The most prominent of these are the Hourglass Nebula and M8E. Submillimetre-wave observations also reveal many clumps of dense molecular gas, which may form the next generation of stars. The complex structure of the region has been shaped by the interaction of the underlying molecular gas with multiple massive stars and episodes of star formation. NGC 6530 is the oldest component, with the newest stars found embedded in the molecular gas behind the cluster a...

  18. Planetary nebula progenitors that swallow binary systems

    CERN Document Server

    Soker, Noam

    2015-01-01

    I propose that some irregular `messy' planetary nebulae owe their morphologies to triple-stellar evolution where tight binary systems are tidally and frictionally destroyed inside the envelope of asymptotic giant branch (AGB) stars. The tight binary system might breakup with one star leaving the system. In an alternative evolution, one of the stars of the brook-up tight binary system falls toward the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process the drag inside the AGB envelope causes the tight binary system to merge. This releases gravitational energy within the AGB envelope, leading to a very asymmetrical envelope ejection, with an irregular and `messy' planetary nebula as a descendant. The evolution of the triple-stellar system before destruction can be in a full common envelope evolution (CEE) or in a grazing envelope evolution (GEE). Both before and after destruction the system might lunch pairs of opposite jets. One pronounced sig...

  19. IUE Tomography of the Rosette Nebula

    Science.gov (United States)

    van Buren, Dave

    We propose to obtain SWP and LWR spectra of a dozen 8th magnitude O and B stars associated with the Rosette Nebula in Monoceros for the purpose of determining the structure and kinematics of this HII region / stellar wind bubble. The ability to sense along numerous lines of sight will allow us to determine the detailed physical conditions which exist in the nebula, both inside the bubble and in the HII region exterior to it. This picture can then be compared in detail to the theory of stellar wind bubbles, HII region dynamics, photodissociation fronts and shock destruction of grains. The hot gas in the bubble has been detected in the soft x-rays by the Einstein satellite, so we anticipate a structure similar to that found by Castor, McCray and Weaver for adiabatic (non-radiative) stellar wind bubbles. Such adiabatic bubbles are ideal laboratories for the study of thermal conduction on astrophysical scales. While we will probably not be able to detect the conductive interface between the hot bubble interior and the swept up shell, we will be able to determine many properties of the bubble. These properties in turn will point to the Rosette's suitability as a cosmic laboratory for studying conductive interfaces with the Space Telescope. The energetics and mass balance of HII regions and stellar wind bubbles is important for a number of problems: the physical conditions in and near star forming regions; the structure and evolution of "superbubbles"; and galactic "ecology".

  20. FITTING PHOTOIONIZATION MODELS TO PLANETARY NEBULAE

    Directory of Open Access Journals (Sweden)

    J. Bohigas

    2009-01-01

    Full Text Available Good to excellent photoionization models based on the Cloudy code were obtained for 13 out of 19 spectra of planetary nebulae. The two most important assumptions are that the photoionizing continuum is a Rauch model star, with gravity set by the condition that the stellar mass must be 1 M , and density is constant and determined from the observed [S II]6717/6731 ratio. The temperature and luminosity of the central star, the inner radius of the nebula and the abundance of carbon are treated as free parameters in each model run, destined to obtain the best possible t to the relative intensities of He II 4686, [O III]5007 and [N II]6584. Observed and modeled nebular temperatures derived from [N II] (6548+6584 /5755 agree within 10%, but models usually underestimate temperatures found from [O III] (4959+5007 /4363, more so when the slit does not cover the in-depth extent of the ionized region. Helium, nitrogen, oxygen, neon, sulfur and argon model abundances are uncertain at the 15%, 15%, 10%, 7%, 30% and 7% level. It is shown that neon abundance in PNe has been consistently overestimated, and an alternative ionization correction factor is recommended.

  1. A HYPERSPECTRAL VIEW OF THE CRAB NEBULA

    International Nuclear Information System (INIS)

    We have obtained spatially resolved spectra of the Crab nebula in the spectral ranges 450-520 nm and 650-680 nm, encompassing the Hβ, [O III] λ4959, λ5007, Hα, [N II] λ6548, λ6584, and [S II] λ6717, λ6731 emission lines, with the imaging Fourier transform spectrometer SpIOMM at the Observatoire du Mont-Megantic's 1.6 m telescope. We first compare our data with published observations obtained either from a Fabry-Perot interferometer or from a long-slit spectrograph. Using a spectral deconvolution technique similar to the one developed by Cadez et al., we identify and resolve multiple emission lines separated by large Doppler shifts and contained within the rapidly expanding filamentary structure of the Crab. This allows us to measure important line ratios, such as [N II]/Hα, [S II]/Hα, and [S II] λ6717 /[S II] λ6731 of individual filaments, providing a new insight on the SE-NW asymmetry in the Crab. From our analysis of the spatial distribution of the electronic density and of the respective shocked versus photoionized gas components, we deduce that the skin-less NW region must have evolved faster than the rest of the nebula. Assuming a very simple expansion model for the ejecta material, our data provide us with a complete tridimensional view of the Crab.

  2. Radial velocities of Planetary Nebulae revisited

    Science.gov (United States)

    Vázquez, Roberto; Ayala, Sandra A.; Wendolyn Blanco Cárdenas, Mónica; Contreras, María E.; Gómez-Muñoz, Marco Antonio; Guillén, Pedro F.; Olguín, Lorenzo; Ramos-Larios, Gerardo; Sabin, Laurence; Zavala, Saúl A.

    2015-08-01

    We present a new determination of radial velocities of a sample of Galactic Planetary Nebulae (PNe) using a systematic method and the same instrumental setting: the long-slit high-dispersion Manchester Echelle Spectrograph (MES) on the 2.1-m telescope at the San Pedro Mártir Observatory (OAN-SPM; Mexico). This project was inspired by the work of Schneider et al. (1983, A&AS, 52, 399), which has been an important reference during the last decades. Radial velocities of gaseous nebulae can be obtained using the central wavelength of a Gaussian fit, even when there is an expansion velocity, as expected in PNe, but with not enough resolution to see a spectral line splitting. We have used the software SHAPE, a morpho-kinematic modeling and reconstruction tool for astrophysical objects (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to prove that non-uniform density or brightness, on an expanding shell, can lead to mistaken conclusions about the radial velocity. To determine radial velocities, we only use the spectral data in which a spectral line-splitting is seen, avoiding thus the problem of the possible biased one-Gaussian fit. Cases when this method is not recommended are discussed.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  3. Abundances in the Planetary Nebula IC 5217

    Science.gov (United States)

    Hyung, Siek; Aller, Lawrence H.; Feibelman, Walter A.; Lee, Woo-Baik; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    High resolution optical wavelength spectroscopic data were secured in the optical wavelengths, 3700A - 10,050A, for the planetary nebula IC 5217 with the Hamilton Echelle Spectrograph at Lick Observatory. These optical spectra have been analyzed along with the near-UV and UV archive data. Diagnostic analyses indicate a nebular physical condition with electron temperature of about 10,700 K (from the [O III] lines) and the density of N(sub epsilon) = 5000/cm. Ionic concentrations have been derived with the representative diagnostics, and with the aid of a photoionization model construction, we derived the elemental abundances. Contrary to the previous studies found in the literature, He and C appear to be depleted compared to the average planetary nebula and to the Sun (and S marginally so), while the remaining elements appear to be close to the average value. IC 5217 may have evolved from an O-rich progenitor and the central star temperature of IC 5217 is likely to be 92,000 K.

  4. The Stellar Populations of the Carina Dwarf Spheroidal Galaxy: I. a New Color-Magnitude Diagram for the Giant and Horizontal Branches

    OpenAIRE

    Smecker-Hane, T. A.; Stetson, P. B.; Hesser, J. E.; Lehnert, M. D.

    1994-01-01

    We report on the first in a series of studies of the Carina dwarf spheroidal galaxy, a nearby satellite of our Galaxy. Our two major results are: 1) precise BI photometry ($\\sigma_{B-I} \\simlt 0.05$ for $V \\simlt 22$) for 11,489 stars in the Carina field, and 2) the detection of two, morphologically distinct, horizontal branches, which confirms that star formation in Carina occurred in two well-separated episodes. The old horizontal branch and RR Lyrae instability strip belong to a > 10 Gyr s...

  5. Investigating the nature of the Fried Egg nebula: CO mm-line and optical spectroscopy of IRAS 17163-3907

    CERN Document Server

    Wallström, Sofia H J; Lagadec, E; Black, J H; Oudmaijer, R D; Justtanont, K; van Winckel, H; Zijlstra, A A

    2015-01-01

    Through CO mm-line and optical spectroscopy, we investigate the properties of the Fried Egg nebula IRAS 17163-3907, which has recently been proposed to be one of the rare members of the yellow hypergiant class. The CO J=2-1 and J=3-2 emission arises from a region within 20" of the star and is clearly associated with the circumstellar material. The CO lines show a multi-component asymmetrical profile, and an unexpected velocity gradient is resolved in the east-west direction, suggesting a bipolar outflow. This is in contrast with the apparent symmetry of the dust envelope as observed in the infrared. The optical spectrum of IRAS 17163-3907 between 5100 and 9000 {\\AA} was compared with that of the archetypal yellow hypergiant IRC+10420 and was found to be very similar. These results build on previous evidence that IRAS 17163-3907 is a yellow hypergiant.

  6. TEARING THE VEIL: INTERACTION OF THE ORION NEBULA WITH ITS NEUTRAL ENVIRONMENT

    International Nuclear Information System (INIS)

    We present H I 21 cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.''2 × 5.''7 and a velocity resolution of 0.77 km s–1. Our data reveal H I absorption in the Veil toward the radio continuum of the H II region, and H I emission arising from the Orion Bar photon-dominated region (PDR) and from the Orion-KL outflow. In the Orion Bar PDR, the H I signal peaks in the same layer as the H2 near-infrared vibrational line emission, in agreement with models of the photodissociation of H2. The gas temperature in this region is approximately 540 K, and the H I abundance in the interclump gas in the PDR is 5%-10% of the available hydrogen nuclei. Most of the gas in this region therefore remains molecular. Mechanical feedback on the Veil manifests itself through the interaction of ionized flow systems in the Orion Nebula, in particular the Herbig-Haro object HH 202, with the Veil. These interactions give rise to prominent blueward velocity shifts of the gas in the Veil. The unambiguous evidence for interaction of this flow system with the Veil shows that the distance between the Veil and the Trapezium stars needs to be revised downward to about 0.4 pc. The depth of the ionized cavity is about 0.7 pc, which is much smaller than the depth and the lateral extent of the Veil. Our results reaffirm the blister model for the M42 H II region, while also revealing its relation to the neutral environment on a larger scale.

  7. Imaging and high-resolution spectroscopy of the Planetary Nebula NGC 3242

    Science.gov (United States)

    Gómez-Muñoz, Marco Antonio; Wendolyn Blanco Cárdenas, Mónica; Vázquez, Roberto; Zavala, Saúl A.; Guillén, Pedro F.; Ayala, Sandra A.

    2015-08-01

    We present a high-resolution imaging and high-dispersion spectroscopy study of the complex morphological and kinematical structure of the planetary nebula NGC 3242. We analyze narrowband Hα, [O III] and [N II] images, addressing important morphological features: in the [O III] image we found one knot oriented to PA=-4°, in the [N II] image, three knots oriented at PA1=155°, PA2=+157°, and PA3=-45.5°, and in the Hα image, two bubbles in the internal region, one of them oriented toward SE and the other toward NW. Additionally we used the unsharp-masking technique and found faint structures in the halo that have not been studied before. These structures are presented in two pairs of arcs, one pair oriented toward PA=-35° and the other toward PA=140°. NGC 3242 is a morphologically rich PN with bubbles, asymmetrical outflows, and some knots in a double-shell nebular structure. Ground-based long-slit echelle spectra were obtained crossing NGC 3242 at twelve different positions to precisely determine kinematical features in the structure of the nebula. We obtain a systemic velocity of VLSR=-6.6 km/s. We have used the software SHAPE (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to reconstruct a 3D model of NGC 3242 which fits all our observational data. Preliminary results (deprojected velocities and kinematical ages) of all these structures will be presented.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  8. The planetary nebula Abell 48 and its [WN4] nucleus

    CERN Document Server

    Frew, David J; Parker, Q A; Stupar, M; Wachter, S; DePew, K; Danehkar, A; Fitzgerald, M F

    2013-01-01

    We have conducted a detailed multi-wavelength study of the peculiar planetary nebula Abell 48 and its central star. We present evidence for a new classification of the nucleus as a helium-rich, hydrogen-deficient star of type [WN4], one of only two currently known examples of its type. The evidence for either a massive WN or a low-mass [WN] interpretation is critically examined, and we firmly conclude that Abell 48 is a planetary nebula around an evolved low-mass star, rather than a Population I ejecta nebula. Importantly, the surrounding nebula has a morphology typical of planetary nebulae, and is not enriched in nitrogen, and thus not the 'peeled atmosphere' of a massive star. We estimate a distance of 1.6 kpc and a reddening, E(B-V) = 1.90 mag, the latter value clearly showing the nebula lies on the near side of the Galactic bar, and therefore cannot be a massive WN star. The planetary nebula has an ionized mass (0.3 M_sun) and electron density (740 cm^-3) typical of somewhat evolved objects. The observed ...

  9. VLT/FLAMES spectroscopy of Red Giant Branch stars in the Carina dwarf spheroidal galaxy

    CERN Document Server

    Lemasle, B; Tolstoy, E; Venn, K A; Shetrone, M D; Irwin, M J; de Boer, T J L; Starkenburg, E; Salvadori, S

    2011-01-01

    The ages of individual Red Giant Branch stars (RGB) can range from 1 Gyr old to the age of the Universe, and it is believed that the abundances of most chemical elements in their photospheres remain unchanged with time (those that are not affected by the 1st dredge-up). This means that they trace the ISM in the galaxy at the time the star formed, and hence the chemical enrichment history of the galaxy. CMD analysis has shown the Carina dwarf spheroidal (dSph) to have had an unusually episodic star formation history (SFH) which is expected to be reflected in the abundances of different chemical elements. We use the VLT-FLAMES spectrograph in HR mode (R~20000) to measure the abundances of several chemical elements in a sample of 35 RGB stars in Carina. We also combine these abundances with photometry to derive age estimates for these stars. This allows us to determine which of two distinct star formation (SF) episodes the stars in our sample belong to, and thus to define the relationship between SF and chemical...

  10. A FAST RADIO BURST IN THE DIRECTION OF THE CARINA DWARF SPHEROIDAL GALAXY

    International Nuclear Information System (INIS)

    We report the real-time discovery of a fast radio burst (FRB 131104) with the Parkes radio telescope in a targeted observation of the Carina dwarf spheroidal galaxy. The dispersion measure of the burst is 779 cm–3 pc, exceeding predictions for the maximum line-of-sight Galactic contribution by a factor of 11. The temporal structure of the burst is characterized by an exponential scattering tail with a timescale of 2.0−0.5+0.8 ms at 1582 MHz that scales as frequency to the power –4.4−1.8+1.6 (all uncertainties represent 95% confidence intervals). We bound the intrinsic pulse width to be <0.64 ms due to dispersion smearing across a single spectrometer channel. Searches in 78 hr of follow-up observations with the Parkes telescope reveal no additional sporadic emission and no evidence for associated periodic radio emission. We hypothesize that the burst is associated with the Carina dwarf galaxy. Follow-up observations at other wavelengths are necessary to test this hypothesis

  11. The Carina Project. X. On the kinematics of old and intermediate-age stellar populations

    CERN Document Server

    Fabrizio, M; Nonino, M; Lokas, E L; Ferraro, I; Iannicola, G; Buonanno, R; Cassisi, S; Coppola, G; Dall'Ora, M; Gilmozzi, R; Marconi, M; Monelli, M; Romaniello, M; Stetson, P B; Thévenin, F; Walker, A R

    2016-01-01

    We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2,200 low-resolution spectra collected with VIMOS at VLT. The targets are faint (20Carina stars. We found that the intermediate-age stellar component shows a well defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and -4 km s-1 when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbit...

  12. Global X-ray properties of the O and B stars in Carina

    CERN Document Server

    Naze, Y; Oskinova, L; Townsley, L K; Cohen, D; Corcoran, M F; Evans, N R; Gagne, M; Moffat, A F J; Pittard, J M; Rauw, G; ud-Doula, A; Walborn, N R

    2011-01-01

    The key empirical property of the X-ray emission from O stars is a strong correlation between the bolometric and X-ray luminosities. In the framework of the Chandra Carina Complex Project, 129 O and B stars have been detected as X-ray sources; 78 of those, all with spectral type earlier than B3, have enough counts for at least a rough X-ray spectral characterization. This leads to an estimate of the Lx/Lbol ratio for an exceptional number of 60 O stars belonging to the same region and triples the number of Carina massive stars studied spectroscopically in X-rays. The derived log(Lx/Lbol) is -7.26 for single objects, with a dispersion of only 0.21dex. Using the properties of hot massive stars listed in the literature, we compare the X-ray luminosities of different types of objects. In the case of O stars, the Lx/Lbol ratios are similar for bright and faint objects, as well as for stars of different luminosity classes or spectral types. Binaries appear only slightly harder and slightly more luminous in X-rays t...

  13. 3D printing meets computational astrophysics: deciphering the structure of η Carinae's inner colliding winds

    Science.gov (United States)

    Madura, T. I.; Clementel, N.; Gull, T. R.; Kruip, C. J. H.; Paardekooper, J.-P.

    2015-06-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (≳120 M⊙), highly eccentric (e ˜ 0.9) binary star system η Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF (Portable Document Format) journal publication and the benefits of using 3D visualization and 3D printing as tools to analyse data from multidimensional numerical simulations. Using a consumer-grade 3D printer (MakerBot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of η Carinae's inner (r ˜ 110 au) wind-wind collision interface at multiple orbital phases. The 3D prints and visualizations reveal important, previously unknown `finger-like' structures at orbital phases shortly after periastron (φ ˜ 1.045) that protrude radially outwards from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. thin-shell, Rayleigh-Taylor) that arise at the interface between the radiatively cooled layer of dense post-shock primary-star wind and the fast (3000 km s-1), adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unrecognized physical features highlight the important role 3D printing and interactive graphics can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.

  14. X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

    CERN Document Server

    Hamaguchi, K; Gull, T; Ishibashi, K; Pittard, J M; Hillier, D J; Damineli, A; Davidson, K; Nielsen, K E; Kober, G V; Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore; Ishibashi, Kazunori; Pittard, Julian M.; Damineli, Augusto; Davidson, Kris; Nielsen, Krister E.; Kober, Gladys Vieira

    2007-01-01

    We report the results of an X-ray observing campaign on the massive, evolved star Eta Carinae, concentrating on the 2003 X-ray minimum as seen by the XMM-Newton observatory. These are the first spatially-resolved X-ray monitoring observations of the stellar X-ray spectrum during the minimum. The hard X-ray emission, believed to be associated with the collision of Eta Carinae's wind with the wind from a massive companion star, varied strongly in flux on timescales of days, but not significantly on timescales of hours. The lowest X-ray flux in the 2-10 keV band seen by XMM-Newton was only 0.7% of the maximum seen by RXTE just before the X-ray minimum. The slope of the X-ray continuum above 5 keV did not vary in any observation, which suggests that the electron temperature of the hottest plasma associated with the stellar source did not vary significantly at any phase. Through the minimum, the absorption to the stellar source increased by a factor of 5-10 to NH ~3-4E23 cm-2. The thermal Fe XXV emission line show...

  15. The UV Scattering Halo of the Central Source Associated with Eta Carinae

    CERN Document Server

    Hillier, D J; Damineli, A; Gull, T R; Hamann, F W; Iping, R; Martin, J C; Nielsen, K; Smith, N; Sonneborn, G; Weis, K; Smith, Nathan

    2006-01-01

    We have made an extensive study of the UV spectrum of Eta Carinae, and find that we do not directly observe the star and its wind in the UV. Because of dust along our line of sight, the UV light that we observe arises from bound-bound scattering at large impact parameters. We obtain a reasonable fit to the UV spectrum by using only the flux that originates outside 0.033". This explains why we can still observe the primary star in the UV despite the large optical extinction -- it is due to the presence of an intrinsic coronagraph in the Eta Carinae system, and to the extension of the UV emitting region. It is not due to peculiar dust properties alone. We have computed the spectrum of the purported companion star, and show that it could only be directly detected in the UV spectrum preferentially in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectral region (912-1175 Ang.). However, we find no direct evidence for a companion star, with the properties indicated by X-ray studies and studies of the Weigelt b...

  16. 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae's Inner Colliding Winds

    CERN Document Server

    Madura, Thomas I; Gull, Theodore R; Kruip, Chael J H; Paardekooper, Jan-Pieter

    2015-01-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 M_Sun), highly eccentric (e ~ 0.9) binary star system Eta Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF journal publication and the benefits of using 3D visualization and 3D printing as tools to analyze data from multidimensional numerical simulations. Using a consumer-grade 3D printer (MakerBot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics (SPH) simulations of Eta Carinae's inner (r ~ 110 au) wind-wind collision interface at multiple orbital phases. The 3D prints and visualizations reveal important, previously unknown 'finger-like' structures at orbital phases shortly after periastron (phi ~ 1.045) that protrude radially outward from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. thin-shell, Rayleigh-Taylor) that arise a...

  17. SECULAR CHANGES IN ETA CARINAE'S WIND 1998-2011

    Energy Technology Data Exchange (ETDEWEB)

    Mehner, Andrea [ESO, Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile); Davidson, Kris; Humphreys, Roberta M. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Ishibashi, Kazunori [Global COE, Division of Particle Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Martin, John C. [Department of Physics and Astronomy, University of Illinois Springfield, Springfield, IL 62703 (United States); Ruiz, Maria Teresa [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago de Chile (Chile); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

    2012-05-20

    Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a timescale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude dependent, and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.

  18. New observations of the high-velocity outflows of the proto-planetary nebula hen 3-1475

    Directory of Open Access Journals (Sweden)

    A. Riera

    2002-01-01

    Full Text Available La nebulosa proto-planetaria Hen 3-1475 presenta un jet optico con un alto grado de colimaci on formado por una serie de condensaciones excitadas por ondas de choque. Las zonas internas del jet muestran alt simas velocidades radiales. En este trabajo presentamos el an alisis detallado de la estructura cinem atica y de las condiciones de excitaci on de las condensaciones en base a datos espectrosc opicos de alta resoluci on espectral y a las im agenes de alta resoluci on espacial obtenidas con el HST. Discutimos las semejanzas entre el jet de Hen 3-1475 y los jets HH. Ambos presentan per les extremadamente anchos con dos picos en emisi on, una disminuci on de las velocidades radiales con la distancia a la fuente central de forma escalonada, y en ambos se hallan velocidades tangenciales altas. La interpretaci on conjunta de estas propiedades apunta a la variabilidad temporal de la velocidad de eyecci on como mecanismo responsable de la formaci on de este jet.

  19. Gas physical conditions and kinematics of the giant outflow Ou4

    Science.gov (United States)

    Corradi, Romano L. M.; Grosso, Nicolas; Acker, Agnès; Greimel, Robert; Guillout, Patrick

    2014-10-01

    Context. The recently discovered bipolar outflow Ou4 has a projected size of more than one degree in the plane of the sky. It is apparently centred on the young stellar cluster - whose most massive representative is the triple system HR 8119 - inside the H ii region Sh 2-129. The driving source, the nature, and the distance of Ou4 are not known. Aims: The basic properties of Ou4 and its environment are investigated to shed light on the origin of this remarkable outflow. Methods: Deep narrow-band imagery of the whole nebula at arcsecond resolution was obtained to study the details of its morphology. Long-slit spectroscopy of the bipolar lobe tips was secured to determine the gas ionisation mechanism, physical conditions, and line-of-sight velocities. An estimate of the proper motions at the tip of the south lobe using archival plate images was attempted. The existing multi-wavelength data for Sh 2-129 and HR 8119 were also comprehensively reviewed. Results: The observed morphology of Ou4, its emission-line spatial distribution, line flux ratios, and the kinematic modelling developed adopting a bow-shock parabolic geometry, illustrate the expansion of a shock-excited fast collimated outflow. The observed radial velocities of Ou4 and its reddening are consistent with those of Sh 2-129 and HR 8119. The improved determination of the distance to HR 8119 (composed of two B0 V and one B0.5 V stars) and Sh 2-129 is 712 pc. We identify in WISE images at 22 μm an emission bubble of 5' radius (1 pc at the distance above) emitted by hot (107 K) dust grains, located inside the central part of Ou4 and corresponding to several [O iii] emission features of Ou4. Conclusions: The apparent position of Ou4 and the properties studied in this work are consistent with the hypothesis that Ou4 is located inside the Sh 2-129 H ii region, suggesting that it was launched some 90 000 yr ago by HR 8119. The outflow total kinetic energy is estimated to be ≈4 × 1047 ergs. However, we cannot

  20. X-ray Emission from the Guitar Nebula

    CERN Document Server

    Romani, R W; Yadigaroglu, I A; Romani, Roger W.; Cordes, James M.

    1997-01-01

    We have detected weak soft X-ray emission from the Pulsar Wind Nebula trailing the high velocity star PSR 2224+65 (the `Guitar Nebula'). This X-ray flux gives evidence of \\gamma~10^7 eV particles in the pulsar wind and constrains the properties of the post-shock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near equipartition values.

  1. Shock Waves in Outflows from Young Stars

    Science.gov (United States)

    Hartigan, Patrick

    This review focuses on physics of the cooling zones behind radiative shocks and the emission line diagnostics that can be used to infer physical conditions and mass loss rates in jets from young stars. Spatial separations of the cooling zones from the shock fronts, now resolvable with HST, and recent evidence for C-shocks have greatly increased our understanding of how shocks in outflows interact with the surrounding medium and with other material within the flow. By combining multiple epoch HST images, one can create `movies' of flows like those produced from numerical codes, and learn what kinds of instabilities develop within these systems.

  2. Iodine-131 monitoring in sewage plant outflow

    International Nuclear Information System (INIS)

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

  3. GGD 37: An Extreme Protostellar Outflow

    CERN Document Server

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

    2010-01-01

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

  4. The "Principes de Asturias" nebula: a new quadrupolar planetary nebula from the IPHAS survey

    CERN Document Server

    Mampaso, A; Viironen, K; Leisy, P; Greimel, R; Drew, J E; Barlow, M J; Frew, D J; Irwin, J; Morris, R A H; Parker, Q A; Phillipps, S; Rodriguez-Flores, E R; Zijlstra, A A

    2006-01-01

    The Isaac Newton Telescope Photometric H-alpha Survey (IPHAS) is currently mapping the Northern Galactic plane reaching to r'=20 mag with typically 1" resolution. Hundreds of Planetary Nebulae (PNe), both point-like and resolved, are expected to be discovered. We report on the discovery of the first new PN from this survey: it is an unusual object located at a large galactocentric distance and has a very low oxygen abundance. The nebula shows an intricate morphology: there is an inner ring surrounding the central star, bright inner lobes with an enhanced waist, and very faint lobular extensions reaching up to more than 100". We classify it as a quadrupolar PN, a rather unusual class of planetary showing two pairs of misaligned lobes. From long-slit spectroscopy we derive Te[NII] =12800+-1000K, Ne = 390+-40 cm-3, and chemical abundances typical of Peimbert's Type I nebulae (He/H =0.13, N/O =1.8) with an oxygen abundance of 12 + log(O/H)=8.17+-0.15. A kinematic distance of 7.0 kpc is derived, implying an unusua...

  5. Planetary Nebulae in Face-On Spiral Galaxies. II. Planetary Nebula Spectroscopy

    CERN Document Server

    Herrmann, Kimberly A

    2009-01-01

    As the second step in our investigation of the mass-to-light ratio of spiral disks, we present the results of a spectroscopic survey of planetary nebulae (PNe) in five nearby, low-inclination galaxies: IC 342, M74 (NGC 628), M83 (NGC 5236), M94 (NGC 4736), and M101 (NGC 5457). Using 50 setups of the WIYN/Hydra and Blanco/Hydra spectrographs, and 25 observations with the Hobby-Eberly Telescope's Medium Resolution Spectrograph, we determine the radial velocities of 99, 102, 162, 127, and 48 PNe, respectively, to a precision better than 15 km/s. Although the main purpose of this data set is to facilitate dynamical mass measurements throughout the inner and outer disks of large spiral galaxies, our spectroscopy has other uses as well. Here, we co-add these spectra to show that to first order, the [O III] and Balmer line ratios of planetary nebulae vary little over the top ~1.5 mag of the planetary nebula luminosity function. The only obvious spectral change occurs with [N II], which increases in strength as one p...

  6. Discovery of Relativistic Outflow in the Seyfert Galaxy Ark 564

    OpenAIRE

    Gupta, A; Mathur, S; Krongold, Y.; F. Nicastro

    2013-01-01

    We present \\chandra high energy transmission grating spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low velocity outflow components usually observed in Seyfert galaxies \\citep{Gupta2013}. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here we present identifications of the strongest lines as $K\\alpha$ transitions of \\oviin (two lines) and \\ovin at outflow ve...

  7. Cumulative neutrino background from quasar-driven outflows

    CERN Document Server

    Wang, Xiawei

    2016-01-01

    Quasar-driven outflows naturally account for the missing component of the extragalactic $\\gamma$-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic $\\gamma$-ray background data and derive a cumulative neutrino background of $\\sim10^{-7}\\,\\rm GeV\\,cm^{-2}\\,s^{-1}\\,sr^{-1}$ at neutrino energies $E_{\

  8. The spatio-kinematical structure and distance of the pre-planetary nebula IRAS 19134+2131

    CERN Document Server

    Imai, Hiroshi; Morris, Mark

    2007-01-01

    Using the VLBA, we have observed H2O maser emission in the pre-planetary nebula IRAS 19134+2131(I19134), in which the H2O maser spectrum has two groups of emission features separated in radial velocity by ~100 km/s. We also obtained optical images of I19134 with the HST to locate the bipolar reflection nebula in this source for the first time. The spatio-kinematical structure of the H2O masers indicates the existence of a fast, collimated (precessing) flow having a projected extent of ~140 mas and an expansion rate of ~1.9 mas/yr on the sky plane, which gives a dynamical age of only ~40 yr. The two detected optical lobes are also separated by ~150 mas in almost the same direction as that of the collimated flow. The good agreement between the extent and orientation of the H2O maser outflow and optical lobes suggests that the lobes have been recently formed along the collimated fast flow. The positions of all of the detected maser features have been measured with respect to the reference source J1925+2106 over ...

  9. IC10: the history of the nearest starburst galaxy through its Planetary Nebula and HII region populations

    Science.gov (United States)

    Magrini, Laura; Gonçalves, Denise R.

    2009-09-01

    We report the results of spectroscopic observations, obtained with the Gemini North Multi-Object Spectrograph, of nine planetary nebulae (PNe) and 15 HII regions located in the 5.5 × 5.5arcmin2 inner region of the nearby starburst galaxy IC10. Twelve new candidates PNe have been discovered during our pre-imaging phase. Nine of them have been spectroscopically confirmed. The direct availability of the electron temperature diagnostics in several nebulae allowed an accurate determination of the metallicity map of IC10 at two epochs: the present-time from HII regions and the old/intermediate-age from PNe. We found a non-homogeneous distribution of metals at both epochs, but similar average abundances were found for the two populations. The derived age-metallicity relation shows a little global enrichment interpreted as the loss of metals by supernova winds and to differential gas outflows. Finally, we analysed the production of oxygen - through the third dredge-up - in the chemical abundance patterns of the PN populations belonging to several dwarf irregular galaxies. We found that the third dredge-up of oxygen is a metallicity dependent phenomenon occurring mainly for 12 + log(O/H) arcetri.astro.it

  10. Morpho-kinematic analysis of the point-symmetric, bipolar planetary nebulae Hb 5 and K 3-17, a pathway to poly-polarity

    CERN Document Server

    López, J A; Steffen, W; Riesgo, H; Richer, M G

    2012-01-01

    The kinematics of the bipolar planetary nebulae Hb~5 and K 3-17 are investigated in detail by means of a comprehensive set of spatially resolved high spectral resolution, long-slit spectra. Both objects share particularly interesting characteristics, such as a complex filamentary, rosette-type nucleus, axial point-symmetry and very fast bipolar outflows. The kinematic information of Hb~5 is combined with {\\it HST} imagery to construct a detailed 3D model of the nebula using the code SHAPE. The model shows that the large scale lobes are growing in a non-homologous way. The filamentary loops in the core are proven to actually be secondary lobes emerging from what appears to be a randomly punctured, dense, gaseous core and the material that forms the point symmetric structure flows within the lobes with a distinct kinematic pattern and its interaction with the lobes has had a shaping effect on them. Hb~5 and K~3-17 may represent a class of fast evolving planetary nebulae that will develop poly-polar characterist...

  11. DISCOVERY OF RELATIVISTIC OUTFLOW IN THE SEYFERT GALAXY Ark 564

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, A.; Mathur, S. [Astronomy Department, Ohio State University, Columbus, OH 43210 (United States); Krongold, Y. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Nicastro, F., E-mail: agupta@astronomy.ohio-state.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2013-07-20

    We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as K{alpha} transitions of O VII (two lines) and O VI at outflow velocities of {approx}0.1c. These lines are detected at 6.9{sigma}, 6.2{sigma}, and 4.7{sigma}, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectral fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find E-dot (outflow)/L{sub bol} lower limit of {>=}0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved.

  12. Discovery of Relativistic Outflow in the Seyfert Galaxy Ark 564

    Science.gov (United States)

    Gupta, A.; Mathur, S.; Krongold, Y.; Nicastro, F.

    2013-07-01

    We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as Kα transitions of O VII (two lines) and O VI at outflow velocities of ~0.1c. These lines are detected at 6.9σ, 6.2σ, and 4.7σ, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectral fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find \\dot{E}(outflow)/L_{bol} lower limit of >=0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved.

  13. Suppression of galactic outflows by cosmological infall and circumgalactic medium

    Science.gov (United States)

    Singh, Priyanka; Rana, Sandeep; Bagla, Jasjeet S.; Nath, Biman B.

    2016-06-01

    We investigate the relative importance of two galactic outflow suppression mechanisms: (a) cosmological infall of the intergalactic gas on to the galaxy, and (b) the existence of a hot circumgalactic medium (CGM). Considering only radial motion, the infall reduces the speed of outflowing gas and even halts the outflow, depending on the mass and redshift of the galaxy. For star-forming galaxies, there exists an upper mass limit beyond which outflows are suppressed by the gravitational field of the galaxy. We find that infall can reduce this upper mass limit approximately by a factor of 2 (independent of the redshift). Massive galaxies (≳1012 M⊙) host large reservoir of hot, diffuse CGM around the central part of the galaxy. The CGM acts as a barrier between the infalling and outflowing gas and provides an additional source of outflow suppression. We find that at low redshifts (z ≲ 3.5), the CGM is more effective than the infall in suppressing the outflows. Together, these two processes give a mass range in which galaxies are unable to have effective outflows. We also discuss the impact of outflow suppression on the enrichment history of the galaxy and its environment.

  14. The Sulfur Abundance Anomaly in Planetary Nebulae

    CERN Document Server

    Henry, R B C; Kwitter, K B; Milingo, M B

    2006-01-01

    The failure of S and O abundances in most planetary nebulae to display the same strong direct correlation that is observed in extragalactic H II regions represents one of the most perplexing problems in the area of PN abundances today. Galactic chemical evolution models as well as large amounts of observational evidence from H II region studies support the contention that cosmic abundances of alpha elements such as O, Ne, S, Cl, and Ar increase together in lockstep. Yet abundance results from the Henry, Kwitter, & Balick (2004) database show a strong tendency for most PNe to have S abundances that are significantly less than expected from the observed level of O. One reasonable hypothesis for the sulfur anomaly is the past failure to properly measure the abundances of unseen ionization stages above S^+2. Future observations with Spitzer will allow us to test this hypothesis.

  15. High Energy Processes in Pulsar Wind Nebulae

    CERN Document Server

    Bednarek, W

    2006-01-01

    Young pulsars produce relativistic winds which interact with matter ejected during the supernova explosion and the surrounding interstellar gas. Particles are accelerated to very high energies somewhere in the pulsar winds or at the shocks produced in collisions of the winds with the surrounding medium. As a result of interactions of relativistic leptons with the magnetic field and low energy radiation (of synchrotron origin, thermal, or microwave background), the non-thermal radiation is produced with the lowest possible energies up to $\\sim$100 TeV. The high energy (TeV) gamma-ray emission has been originally observed from the Crab Nebula and recently from several other objects. Recent observations by the HESS Cherenkov telescopes allow to study for the first time morphology of the sources of high energy emission, showing unexpected spectral features. They might be also interpreted as due to acceleration of hadrons. However, theory of particle acceleration in the PWNe and models for production of radiation ...

  16. Atlas of monochromatic images of planetary nebulae

    CERN Document Server

    Weidmann, W A; Valdarenas, R R Vena; Ahumada, J A; Volpe, M G; Mudrik, A

    2016-01-01

    We present an atlas of more than one hundred original images of planetary nebulae (PNe). These images were taken in a narrow-band filter centred on the nebular emission of the [N II] during several observing campaigns using two moderate-aperture telescopes, at the Complejo Astron\\'omico El Leoncito (CASLEO), and the Estaci\\'on Astrof\\'isica de Bosque Alegre (EABA), both in Argentina. The data provided by this atlas represent one of the most extensive image surveys of PNe in [N II]. We compare the new images with those available in the literature, and briefly describe all cases in which our [N II] images reveal new and interesting structures.

  17. ISO Spectroscopy of Proto-Planetary Nebulae

    Science.gov (United States)

    Hrivnak, Bruce J.

    2000-01-01

    The goal of this program was to determine the chemical properties of the dust shells around protoplanetary nebulae (PPNs) through a study of their short-wavelength (6-45 micron) infrared spectra. PPNs are evolved stars in transition from the asymptotic giant branch to the planetary nebula stages. Spectral features in the 10 to 20 gm region indicate the chemical nature (oxygen- or carbon-rich), and the strengths of the features relate to the physical properties of the shells. A few bright carbon-rich PPNs have been observed to show PAH features and an unidentified 21 micron emission feature. We used the Infrared Space Observatory (ISO) to observe a sample of IRAS sources that have the expected properties of PPNs and for which we have accurate positions. Some of these have optical counterparts (proposal SWSPPN01) and some do not (SWSPPN02). We had previously observed these from the ground with near-infrared photometry and, for those with visible counterparts, visible photometry and spectroscopy, which we have combined with these new ISO data in the interpretation of the spectra. We have completed a study of the unidentified emission feature at 21 micron in eight sources. We find the shape of the feature to be the same in all of the sources, with no evidence of any substructure. The ratio of the emission peak to continuum ranges from 0.13 to 1.30. We have completed a study of seven PPNs and two other carbon-rich objects for which we had obtained ISO 2-45 micron observations. The unidentified emission features at 21 and 30 micron were detected in six sources, including four new detections of the 30 micron feature. This previously unresolved 30 micron feature was resolved and found to consist of a broad feature peaking at 27.2 micron (the "30 micron" feature) and a narrower feature peaking at 25.5 micron (the "26 micron" feature). This new 26 micron feature is detected in eight sources and is particularly strong in IRAS Z02229+6208 and 16594-4656. The unidentified

  18. Element Distributions In The Crab Nebula

    CERN Document Server

    Satterfield, T J; Sibley, A R; MacAlpine, G M; Uomoto, A

    2012-01-01

    Images of the Crab Nebula have been obtained through custom interference filters which transmit emission from the expanding supernova remnant in HI, HeI, HeII, [CI], [NII], [OI], [SII], and [SIII] emission lines. We present both raw and flux-calibrated data. Arrays of 19,440 photoionization models, with extensive input abundance ranges, were matched pixel by pixel to the calibrated data in order to derive corresponding element abundance or mass-fraction distributions for helium, carbon, nitrogen, oxygen, and sulfur. These maps show distinctive structure, and they illustrate regions of gas in which various stages of nucleosynthesis have apparently occurred, including the CNO-cycle, helium-burning, carbon-burning, and oxygen-burning. It is hoped that the calibrated observations and chemical abundance distribution maps will be useful for developing a better understanding of the precursor star evolution and the supernova explosive process.

  19. MHD models of Pulsar Wind Nebulae

    CERN Document Server

    Bucciantini, N

    2010-01-01

    Pulsar Wind Nebulae (PWNe) are bubbles or relativistic plasma that form when the pulsar wind is confined by the SNR or the ISM. Recent observations have shown a richness of emission features that has driven a renewed interest in the theoretical modeling of these objects. In recent years a MHD paradigm has been developed, capable of reproducing almost all of the observed properties of PWNe, shedding new light on many old issues. Given that PWNe are perhaps the nearest systems where processes related to relativistic dynamics can be investigated with high accuracy, a reliable model of their behavior is paramount for a correct understanding of high energy astrophysics in general. I will review the present status of MHD models: what are the key ingredients, their successes, and open questions that still need further investigation.

  20. Atlas of monochromatic images of planetary nebulae

    Science.gov (United States)

    Weidmann, W. A.; Schmidt, E. O.; Vena Valdarenas, R. R.; Ahumada, J. A.; Volpe, M. G.; Mudrik, A.

    2016-08-01

    We present an atlas of more than one hundred original images of planetary nebulae (PNe). These images were taken in a narrow-band filter centred on the nebular emission of the [N ii] during several observing campaigns using two moderate-aperture telescopes, at the Complejo Astronómico El Leoncito (CASLEO), and the Estación Astrofísica de Bosque Alegre (EABA), both in Argentina. The data provided by this atlas represent one of the most extensive image surveys of PNe in [N ii]. We compare the new images with those available in the literature, and briefly describe all cases in which our [N ii] images reveal new and interesting structures. The reduced images as 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/592/A103

  1. Lepton Acceleration in Pulsar Wind Nebulae

    CERN Document Server

    Baring, Matthew G

    2010-01-01

    Pulsar Wind Nebulae (PWNe) act as calorimeters for the relativistic pair winds emanating from within the pulsar light cylinder. Their radiative dissipation in various wavebands is significantly different from that of their pulsar central engines: the broadband spectra of PWNe possess characteristics distinct from those of pulsars, thereby demanding a site of lepton acceleration remote from the pulsar magnetosphere. A principal candidate for this locale is the pulsar wind termination shock, a putatively highly-oblique, ultra-relativistic MHD discontinuity. This paper summarizes key characteristics of relativistic shock acceleration germane to PWNe, using predominantly Monte Carlo simulation techniques that compare well with semi-analytic solutions of the diffusion-convection equation. The array of potential spectral indices for the pair distribution function is explored, defining how these depend critically on the parameters of the turbulent plasma in the shock environs. Injection efficiencies into the acceler...

  2. Quasar feedback revealed by giant molecular outflows

    CERN Document Server

    Feruglio, Chiara; Piconcelli, Enrico; Menci, Nicola; Aussel, Herve'; Lamastra, Alessandra; Fiore, Fabrizio

    2010-01-01

    In the standard scenario for galaxy evolution the transformation of young star-forming galaxies into red bulge-dominated spheroids, where star formation has been quenched, is often explained by invoking a strong negative feedback generated by accretion onto a central super-massive black hole. The depletion of gas resulting from quasar-driven outflows should eventually stop star-formation across the host galaxy and lead to the black hole "suicide" for starvation. Direct observational evidence for a major quasar feedback onto the host galaxy is still missing, since outflows previously observed in quasars are associated with the ionized component of the gas, which only accounts for a minor fraction of the total gas content, and typically occur in the central regions. We used the IRAM PdBI to observe the CO(1-0) transition in Mrk 231, the closest quasar known. We detect broad wings of the CO line, with velocities up to 750 km/s and spatially resolved on the kpc scale. Such broad CO wings trace a giant molecular o...

  3. Magnetospheric and Thermospheric Influence on Ionospheric Outflow

    Science.gov (United States)

    Garcia-Sage, K.; Moore, T. E.; Mitchell, E. J.; Olson, D. K.

    2013-12-01

    The Fast Auroral SnapshoT (FAST) small explorer has been used extensively to study ionospheric outflow. Past research has used particle and field data to examine the contemporaneous transfer of electromagnetic energy and particle flow downward from the magnetosphere and upward from the ionosphere. Single event studies published by Strangeway et al. [2005] and Brambles et al. [2011, Supporting Online Material] showed that downward electromagnetic energy and particle flow into the ionosphere are correlated with the upward flow of ions out of the ionosphere. It is expected, however, that this correlation will be affected by circumstances that are unique to each specific event, including but not limited to the outflow location (cusp or nightside), preconditioning due to prior geomagnetic activity, and thermospheric neutral densities. Although knowledge of the thermospheric neutral density is usually unavailable, data from the CHAllenging Minisatellite Payload (CHAMP) is able to provide insight into thermospheric populations at altitudes of about 400 km for a few select events. We expand on the previously-mentioned studies by looking at FAST particle and field data for additional events, and we further examine the influence of thermospheric neutral populations, based on CHAMP data.

  4. Accretion, winds and outflows in young stars

    CERN Document Server

    Günther, Hans Moritz

    2012-01-01

    Young stars and planetary systems form in molecular clouds. For classical T Tauri stars (CTTS, F-K type precursors) the accretion disk does not reach down to the central star, but it is truncated near the co-rotation radius. The inner edge of the disk is ionized by the stellar radiation, so that the accretion stream is funneled along the magnetic field lines. On the stellar surface an accretion shock develops, which is observed over a wide wavelength range as X-ray emission, UV excess, optical veiling and optical and IR emission lines. Some of the accretion tracers, e.g. H\\alpha, can be calibrated to measure the accretion rate. This accretion process is variable on time scales of hours to years due to changing accretion rates, stellar rotation and reconfiguration of the magnetic field. Furthermore, many accreting systems also drive strong outflows which are ultimately powered by accretion. Several components could contribute to the outflows: slow, wide-angle disk winds, X-winds launched close to the inner dis...

  5. Power spectra of outflow-driven turbulence

    CERN Document Server

    Moraghan, Anthony; Yoon, Suk-Jin

    2015-01-01

    We investigate the power spectra of outflow-driven turbulence through high-resolution three-dimensional isothermal numerical simulations where the turbulence is driven locally in real-space by a simple spherical outflow model. The resulting turbulent flow saturates at an average Mach number of ~2.5 and is analysed through density and velocity power spectra, including an investigation of the evolution of the solenoidal and compressional components. We obtain a shallow density power spectrum with a slope of ~-1.2 attributed to the presence of a network of localised dense filamentary structures formed by strong shock interactions. The total velocity power spectrum slope is found to be ~-2.0, representative of Burgers shock dominated turbulence model. The density weighted velocity power spectrum slope is measured as ~-1.6, slightly less than the expected Kolmogorov scaling value (slope of -5/3) found in previous works. The discrepancy may be caused by the nature of our real space driving model and we suggest ther...

  6. Disks and Outflows Around Young Stars

    Science.gov (United States)

    Beckwith, Steven; Staude, Jakob; Quetz, Axel; Natta, Antonella

    The subject of the book, the ubiquitous circumstellar disks around very young stars and the corresponding jets of outflowing matter, has recently become one of the hottest areas in astrophysics. The disks are thought to be precursors to planetary systems, and the outflows are thought to be a necessary phase in the formation of a young star, helping the star to get rid of angular momentum and energy as it makes its way onto the main sequence. The possible connections to planetary systems and stellar astrophysics makes these topics especially broad, appealing to generalists and specialists alike. The CD not only contains papers that could not be printed in the book but allows the authors to include a fair amount of data, often displayed as color images. The CD-ROM contains all the contributions printed in the corresponding book (Lecture Notes in Physics Vol. 465) and, in addition, those presented exclusively in digital form. Each contribution consists of a file in portable document format (PDF). The electronic version allows full-text searching within each file using Adobe's Acrobat Reader providing instructions for installation on Unix (Sun), PC and Macintosh computers, respectively. All contributions can be printed out; the color diagrams and color frames, which are printed in black and white in the book, can be viewed in color on screen.

  7. Multidimensional chemical modelling, II. Irradiated outflow walls

    CERN Document Server

    Bruderer, Simon; Doty, Steven D; van Dishoeck, Ewine F; Bourke, Tyler L

    2009-01-01

    Observations of the high-mass star forming region AFGL 2591 reveal a large abundance of CO+, a molecule known to be enhanced by far UV (FUV) and X-ray irradiation. In chemical models assuming a spherically symmetric envelope, the volume of gas irradiated by protostellar FUV radiation is very small due to the high extinction by dust. The abundance of CO+ is thus underpredicted by orders of magnitude. In a more realistic model, FUV photons can escape through an outflow region and irradiate gas at the border to the envelope. Thus, we introduce the first 2D axi-symmetric chemical model of the envelope of a high-mass star forming region to explain the CO+ observations as a prototypical FUV tracer. The model assumes an axi-symmetric power-law density structure with a cavity due to the outflow. The local FUV flux is calculated by a Monte Carlo radiative transfer code taking scattering on dust into account. A grid of precalculated chemical abundances, introduced in the first part of this series of papers, is used to ...

  8. Ionized Outflows from Compact Steep Spectrum Sources

    CERN Document Server

    Shih, Hsin-Yi; Kewley, Lisa

    2013-01-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10$^3$ to 10$^5$ years old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using GMOS on Gemini North. We fit the [\\ion{O}{3}] $\\lambda 5007$ line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of diffe...

  9. Accretion Disk Outflows from Compact Object Mergers

    Science.gov (United States)

    Metzger, Brian

    Nuclear reactions play a key role in the accretion disks and outflows associated with the merger of binary compact objects and the central engines of gamma-ray bursts and supernovae. The proposed research program will investigate the impact of nucleosynthesis on these events and their observable signatures by means of analytic calculations and numerical simulations. One focus of this research is rapid accretion following the tidal disruption of a white dwarf (WD) by a neutron star (NS) or black hole (BH) binary companion. Tidal disruption shreds the WD into a massive torus composed of C, O, and/or He, which undergoes nuclear reactions and burns to increasingly heavier elements as it flows to smaller radii towards the central compact object. The nuclear energy so released is comparable to that released gravitationally, suggesting that burning could drastically alter the structure and stability of the accretion flow. Axisymmetric hydrodynamic simulations of the evolution of the torus including nuclear burning will be performed to explore issues such as the mass budget of the flow (accretion vs. outflows) and its thermal stability (steady burning and accretion vs. runaway explosion). The mass, velocity, and composition of outflows from the disk will be used in separate radiative transfer calculations to predict the lightcurves and spectra of the 56Ni-decay powered optical transients from WD-NS/WD-BH mergers. The possible connection of such events to recently discovered classes of sub-luminous Type I supernovae will be assessed. The coalescence of NS-NS/NS-BH binaries also results in the formation of a massive torus surrounding a central compact object. Three-dimensional magnetohydrodynamic simulations of the long-term evolution of such accretion disks will be performed, which for the first time follow the effects of weak interactions and the nuclear energy released by Helium recombination. The nucleosynthetic yield of disk outflows will be calculated using a detailed

  10. The carbon budget in the outer solar nebula

    International Nuclear Information System (INIS)

    The compositional contrast between the giant-planet satellites and the significantly rockier Pluto/Charon system is indicative of different formation mechanisms; cosmic abundance calculations, in conjunction with an assumption of the Pluto/Charon system's direct formation from solar nebula condensates, strongly suggest that most of the carbon in the outer solar nebula was in CO form, in keeping with both the inheritance from the dense molecular clouds in the interstellar medium, and/or the Lewis and Prinn (1980) kinetic-inhibition model of solar nebula chemistry. Laboratory studies of carbonaceous chondrites and Comet Halley flyby studies suggest that condensed organic material, rather than elemental carbon, is the most likely candidate for the small percentage of the carbon-bearing solid in the outer solar nebula. 71 refs

  11. Radiation Transfer in the Cavity and Shell of Planetary Nebulae

    CERN Document Server

    Gray, M D; Zijlstra, A A

    2012-01-01

    We develop an approximate analytical solution for the transfer of line-averaged radiation in the hydrogen recombination lines for the ionized cavity and molecular shell of a spherically symmetric planetary nebula. The scattering problem is treated as a perturbation, using a mean intensity derived from a scattering-free solution. The analytical function was fitted to Halpha and Hbeta data from the planetary nebula NGC6537. The position of the maximum in the intensity profile produced consistent values for the radius of the cavity as a fraction of the radius of the dusty nebula: 0.21 for Halpha and 0.20 for Hbeta. Recovered optical depths were broadly consistent with observed optical extinction in the nebula, but the range of fit parameters in this case is evidence for a clumpy distribution of dust.

  12. Star Formation in the Orion Nebula I: Stellar Content

    CERN Document Server

    Muench, August; Hillenbrand, Lynne; Preibisch, Thomas

    2008-01-01

    The Orion Nebula is one of the most frequently observed nearby (<1 kiloparsec) star forming regions and, consequently, the subject of a large bibliography of observations and interpretation. The summary in this chapter is bounded spatially by the blister HII region, with sources beyond the central nebula that are part of the same dynamical clustering covered in other chapters in this book. Herein are discussed panchromatic observations of the massive OB stars, the general T Tauri population, the sub-stellar sources and variable stars within the Orion Nebula. First, a brief history of 400 years of observation of the Nebula is presented. As this history is marked clearly by revelations provided in each age of new technology, recent ultra-deep X-ray surveys and high resolution multi-epoch monitoring of massive binary systems and radio stars receive special attention in this review. Topics discussed include the kinematics, multiplicity, mass distribution, rotation, and circumstellar characteristics of the pre-...

  13. The Lexington Benchmarks for Numerical Simulations of Nebulae

    CERN Document Server

    Ferland, G; Contini, M; Harrington, J; Kallman, T; Netzer, H; Péquignot, D; Raymond, J; Rubin, R; Shields, G; Sutherland, R; Viegas, S

    2016-01-01

    We present the results of a meeting on numerical simulations of ionized nebulae held at the University of Kentucky in conjunction with the celebration of the 70th birthdays of Profs. Donald Osterbrock and Michael Seaton.

  14. Chemical composition of planetary nebulae : Including ISO results

    NARCIS (Netherlands)

    Pottasch, [No Value; Beintema, DA; Salas, JB; Feibelman, WA; Henney, WJ; Franco, J; Martos, M; Pena, M

    2002-01-01

    The method of determining abundances using Infrared Space Observatory spectra is discussed. The results for seven planetary nebula are given. Using these data, a preliminary discussion of their evolution is given.

  15. CCD observations of the polarization of the Crab Nebula

    International Nuclear Information System (INIS)

    CCD observations are used to map the intensity distribution and polarization of the optical synchrotron radiation of the Crab Nebula. The data indicate that the Crab Nebula has a large-scale magnetic field in which major variations generally occur over regions with sizes larger than 10 arcsec (0.1 pc). However, in the vicinity of the Crab pulsar, the polarization shows structure on a scale of a few arcsec. Evidence is found for a narrow depolarized channel extending from the pulsar to the region of the optical wisps in the synchrotron nebula. The results also confirm previous studies which show that the magnetic vectors of polarization are predominantly oriented parallel to the edges of the dark bays in the outer regions of the visible synchrotron nebulosity. This supports the suggestion that these regions of the Nebula are wrapped in magnetic field lines, and are therefore deficient in electrons capable of emitting synchrotron radiation. 33 refs

  16. Pulsar Wind Nebulae and Cosmic Rays: A Bedtime Story

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, A.

    2014-11-15

    The role pulsar wind nebulae play in producing our locally observed cosmic ray spectrum remains murky, yet intriguing. Pulsar wind nebulae are born and evolve in conjunction with SNRs, which are favored sites of Galactic cosmic ray acceleration. As a result they frequently complicate interpretation of the gamma-ray emission seen from SNRs. However, pulsar wind nebulae may also contribute directly to the local cosmic ray spectrum, particularly the leptonic component. This paper reviews the current thinking on pulsar wind nebulae and their connection to cosmic ray production from an observational perspective. It also considers how both future technologies and new ways of analyzing existing data can help us to better address the relevant theoretical questions. A number of key points will be illustrated with recent results from the VHE (E > 100 GeV) gamma-ray observatory VERITAS.

  17. New results on planetary nebula shaping and stellar binarity

    CERN Document Server

    De Marco, Orsola

    2010-01-01

    The question of what physical mechanisms shape planetary nebulae into their observed morphologies remains open. However, intensified efforts since the last meeting in this series, Asymmetrical Planetary Nebulae IV, in July 2007 have yielded some excellent results. In this review we concentrate on those developments that have taken place in the last three years, with emphasis on results obtained since the review by De Marco (2009).

  18. Spectroscopic Studies of Evolved Stars and Planetary Nebulae

    OpenAIRE

    Smith, Christina Louise

    2014-01-01

    Evolved stars and planetary nebulae are rich and varied sites of molecule and dust formation. These objects undergo dramatic mass loss which ultimately enriches the interstellar medium. In this thesis, a number of studies, outlined below, have been undertaken to better understand the chemical and physical properties of these diverse objects. A molecular line survey of a sample of evolved stars and planetary nebulae has been carried out using the Mopra radio telescope, Australia. Transitions w...

  19. Recombination Lines of CII in the Spectra of Planetary Nebulae

    OpenAIRE

    Sochi, Taha

    2010-01-01

    The current report presents the work to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. One of these targets contains 9 atomic terms while the other contains 26 terms. For each one of these targets, theoretical dat...

  20. Ly(alpha) Photolysis in the Primitive Solar Nebula

    Science.gov (United States)

    Gladstone, G. Randall

    1998-01-01

    This is the final report for the third year of work on this project. Our proposal was to quantitatively investigate the importance of photochemistry in the solar nebula. In the generally accepted theory for the chemical evolution of the primitive solar nebula, Prinn and Fegley argued that photochemistry is unimportant, and that thermochemistry controls the relative abundances of molecular species throughout the planet-forming region. They provided useful estimates of the chemical energy available to the solar nebula from a variety of sources, and established that even the small photolysis rate due to starlight is more important than the photolysis rate from direct sunlight (although small, the UV flux from starlight could have processed a non-negligible fraction of the solar nebula. The reason for this is that the opacity of the disk was so large that direct sunlight could only penetrate to 0.1 AU or so, despite the expectation that the protosun, if comparable to a T-Tauri star, would be emitting up to 104 more H I Ly(alpha) photons than the current sun. We developed a Monte Carlo resonance fine radiative transfer code, capable of accurately calculating the radiation field of H I Ly(alpha), He I 584 A, and He II 304 A emissions throughout the nebula and the nearby interstellar medium in which it is embedded. We applied the code to two appropriate models of the primitive solar nebula. Our model provided the photolysis rates of various species over the entire surface layer of the nebula, and from this we evaluated the importance of UV photochemistry due to backscattered solar UV resonance line emissions on different parts of the nebula. The results discussed below were presented.

  1. Ly(alpha) Photolysis in the Primitive Solar Nebula

    Science.gov (United States)

    Gladstone, G. Randall

    1998-01-01

    This is the final report for the third year of work on this project. Our proposal was to quantitatively investigate the importance of photochemistry in the solar nebula. In the generally accepted theory for the chemical evolution of the primitive solar nebula, Prinn and Fegley argued that photochemistry is unimportant, and that thermochemistry controls the relative abundances of molecular species throughout the planet-forming region. They provided useful estimates of the chemical energy available to the solar nebula from a variety of sources, and established that even the small photolysis rate due to starlight is more important than the photolysis rate from direct sunlight (although small, the UV flux from starlight could have processed a non-negligible fraction of the solar nebula. The reason for this is that the opacity of the disk was so large that direct sunlight could only penetrate to 0.1 AU or so, despite the expectation that the protosun, if comparable to a T-Tauri star, would be emitting up to 10(exp 4) more H I Ly(alpha) photons than the current sun. We developed a Monte Carlo resonance fine radiative transfer code, capable of accurately calculating the radiation field of H I Ly(alpha), He I 584 A, and He II 304 A emissions throughout the nebula and the nearby interstellar medium in which it is embedded. We applied the code to two appropriate models of the primitive solar nebula. Our model provided the photolysis rates of various species over the entire surface layer of the nebula, and from this we evaluated the importance of UV photochemistry due to backscattered solar UV resonance line emissions on different parts of the nebula. The results discussed below were presented.

  2. The spatial structure of planetary nebulae with binary nuclei

    International Nuclear Information System (INIS)

    The formation of the spatial structure of planetary nebulae with binary central stars is considered. It is shown that the main structure (the enhanced density area) has the form of an hour-glass or a toroid. The peripheral structure (a relatively fainter shell around the main structure) has the form of an ablate spheroid. If a planetary nebula is ionised incompletely, the observed form a peripheral structure can differ from the real form of an envelope

  3. Measurement of Outflow Facility Using iPerfusion.

    Directory of Open Access Journals (Sweden)

    Joseph M Sherwood

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

  4. The blue supergiant Sher 25 and its intriguing hourglass nebula

    CERN Document Server

    Hendry, M A; Skillman, E D; Evans, C J; Trundle, C; Lennon, D J; Crowther, P A; Hunter, I

    2008-01-01

    The blue supergiant Sher 25 is surrounded by an asymmetric, hourglass-shaped circumstellar nebula. Its structure and dynamics have been studied previously through high-resolution imaging and spectroscopy, and it appears dynamically similar to the ring structure around SN 1987A. Here we present long-slit spectroscopy of the circumstellar nebula around Sher 25, and of the background nebula of the host cluster NGC 3603. We perform a detailed nebular abundance analysis to measure the gas-phase abundances of oxygen, nitrogen, sulphur, neon and argon. The oxygen abundance in the circumstellar nebula (12 + log[O/H] = 8.61 +/- 0.13 dex) is similar to that in the background nebula (8.56 +/- 0.07), suggesting the composition of the host cluster is around solar. However, we confirm that the circumstellar nebula is very rich in nitrogen, with an abundance of 8.91 +/- 0.15, compared to the background value of 7.47 +/- 0.18. A new analysis of the stellar spectrum with the FASTWIND model atmosphere code suggests that the ph...

  5. Probing the Rosette Nebula Stellar Bubble with Faraday Rotation

    CERN Document Server

    Savage, Allison H; Fischer, Patrick D

    2012-01-01

    We report the results of Faraday rotation measurements of 23 background radio sources whose lines of sight pass through or close to the Rosette Nebula. The Rosette Nebula is an excellent candidate for studies of super bubbles associated with young star clusters. We made linear polarization measurements with the Karl G. Jansky Very Large Array (JVLA) at frequencies of 4.4GHz, 4.9GHz, and 7.7GHz. We are able to establish a background rotation measure in this part of the sky due to the Galaxy of +147 rad m^-2. Sources whose lines of sight pass through the nebula have an excess rotation measure of 50-750 rad m^-2, which we attribute to the plasma shell of the Rosette Nebula. We consider two simple plasma shell models and how they reproduce the magnitude and sign of the rotation measure, and its dependence on distance from the center of the nebula. These two models represent different modes of interaction of the Rosette Nebula star cluster with the surrounding interstellar medium. Both can reproduce the magnitude ...

  6. The Orion Nebula: Still Full of Surprises

    Science.gov (United States)

    2011-01-01

    This ethereal-looking image of the Orion Nebula was captured using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory, Chile. This nebula is much more than just a pretty face, offering astronomers a close-up view of a massive star-forming region to help advance our understanding of stellar birth and evolution. The data used for this image were selected by Igor Chekalin (Russia), who participated in ESO's Hidden Treasures 2010 astrophotography competition. Igor's composition of the Orion Nebula was the seventh highest ranked entry in the competition, although another of Igor's images was the eventual overall winner. The Orion Nebula, also known as Messier 42, is one of the most easily recognisable and best-studied celestial objects. It is a huge complex of gas and dust where massive stars are forming and is the closest such region to the Earth. The glowing gas is so bright that it can be seen with the unaided eye and is a fascinating sight through a telescope. Despite its familiarity and closeness there is still much to learn about this stellar nursery. It was only in 2007, for instance, that the nebula was shown to be closer to us than previously thought: 1350 light-years, rather than about 1500 light-years. Astronomers have used the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile to observe the stars within Messier 42. They found that the faint red dwarfs in the star cluster associated with the glowing gas radiate much more light than had previously been thought, giving us further insights into this famous object and the stars that it hosts. The data collected for this science project, with no original intention to make a colour image, have now been reused to create the richly detailed picture of Messier 42 shown here. The image is a composite of several exposures taken through a total of five different filters. Light that passed through a red filter as well as light from a filter that

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

    Indian Academy of Sciences (India)

    Santabrata Das; Sandip K. Chakrabarti

    2002-03-01

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

  8. Collective outflow from a small multiple stellar system

    International Nuclear Information System (INIS)

    The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M ☉, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H2 and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of two to three.

  9. Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei; Wofford, Aida; Lundgren, Britt

    2014-01-01

    We report on a sample of 51 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We calculate Si II kinematics and densities arising from warm gas entrained in galactic outflows. We use multi-wavelength ancillary data to estimate stellar masses (M$_\\ast$), star-formation rates (SFR), and morphologies. We derive significant correlations between outflow velocity and SFR$^{\\sim 0.1}$, M$_\\ast^{\\sim 0.1}$ and v$_\\text{circ}^{\\sim 1/2}$. Some mergers drive outflows faster than these relations prescribe, launching the outflow faster than the escape velocity. Calculations of the mass outflow rate reveal strong scaling with SFR$^{\\sim 1/2}$ and M$_\\ast^{\\sim 1/2}$. Additionally, mass-loading efficiency factors (mass outflow rate divided by SFR) scale approximately as M$_\\ast^{-1/2}$. Both the outflow velocity and mass-loading scaling suggest that these outflows are powered by supernovae, with only 0.7% of the total supernovae energy converted into the kinetic energ...

  10. Analysis of Co-spatial UV-optical STIS Spectra of Planetary Nebula NGC 3242

    CERN Document Server

    Miller, Timothy R; Balick, Bruce; Kwitter, Karen B; Dufour, Reginald J; Shaw, Richard A; Corradi, Romano L M

    2016-01-01

    This project sought to consider two important aspects of the planetary nebula NGC 3242 using new long-slit HST/STIS spectra. First, we investigated whether this object is chemically homogeneous by dividing the slit into different regions spatially and calculating the abundances of each region. The major result is that the elements of He, C, O, and Ne are chemically homogeneous within uncertainties across the regions probed, implying that the stellar outflow was well-mixed. Second, we constrained the stellar properties using photoionization models computed by CLOUDY and tested the effects of three different density profiles on these parameters. The three profiles tested were a constant density profile, a Gaussian density profile, and a Gaussian with a power law density profile. The temperature and luminosity were not affected significantly by the choice of density structure. The values for the stellar temperature and luminosity from our best fit model are 89.7$^{+7.3}_{-4.7}$kK and log(L/Lsol)=3.36$^{+0.28}_{-...

  11. A Keck High Resolution Spectroscopic Study of the Orion Nebula Proplyds

    CERN Document Server

    Henney, W J

    1999-01-01

    We present the results of spectroscopy of four bright proplyds in the Orion Nebula obtained at a velocity resolution of 6 km/s. After careful isolation of the proplyd spectra from the confusing nebular radiation, the emission line profiles are compared with those predicted by realistic dynamic/photoionization models of the objects. The spectral line widths show a clear correlation with ionization potential, which is consistent with the free expansion of a transonic, ionization-stratified, photoevaporating flow. Fitting models of such a flow simultaneously to our spectra and HST emission line imaging provides direct measurements of the proplyd size, ionized density and outflow velocity. These measurements confirm that the ionization front in the proplyds is approximately D-critical and provide the most accurate and robust estimate to date of the proplyd mass loss rate. Values of 0.7E-6 to 1.5E-6 Msun/year are found for our spectroscopic sample, although extrapolating our results to a larger sample of proplyds ...

  12. An asymmetric jet launching model for the protoplanetary nebula CRL 618

    CERN Document Server

    Velazquez, P F; Raga, A C; Toledo-Roy, J C

    2014-01-01

    We propose an asymmetrical jet ejection mechanism in order to model the mirror symmetry observed in the lobe distribution of some protoplanetary nebulae (pPNe), such as the pPN CRL 618. 3D hydrodynamical simulations of a precessing jet launched from an orbiting source were carried out including an alternation in the ejections of the two outflow lobes, depending on which side of the precessing accretion disk is hit by the accretion column from a Roche lobe-filling binary companion. Both synthetic optical emission maps and position-velocity (PV) diagrams were obtained from the numerical results with the purpose of carrying out a direct comparison with observations. Depending on the observer's point of view, multipolar morphologies are obtained which exhibit a mirror symmetry at large distances from the central source. The obtained lobe sizes and their spatial distribution are in good agreement with the observed morphology of the pPN CRL 618. We also obtain that the kinematic ages of the fingers are similar to t...

  13. Mid-infrared imaging of the bipolar planetary nebula M2-9 from SOFIA

    Energy Technology Data Exchange (ETDEWEB)

    Werner, M. W.; Sahai, R.; Davis, J.; Livingston, J. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91107 (United States); Lykou, F. [Institute for Astronomy, University of Vienna, Turkenschanzstrasse 17, A-1180, Vienna (Austria); DE Buizer, J. [USRA SOFIA Science Center, M/S 211-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Morris, M. R. [Division of Astronomy, P.O. Box 951547, UCLA, Los Angeles, CA 90095 (United States); Keller, L. [Department of Physics, Ithaca College, Ithaca, NY 14850 (United States); Adams, J.; Gull, G.; Henderson, C.; Herter, T.; Schoenwald, J., E-mail: Michael.W.Werner@jpl.nasa.gov [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)

    2014-01-10

    We have imaged the bipolar planetary nebula M2-9 using SOFIA's FORCAST instrument in six wavelength bands between 6.6 and 37.1 μm. A bright central point source, unresolved with SOFIA's ∼4''-5'' beam, is seen at each wavelength, and the extended bipolar lobes are clearly seen at 19.7 μm and beyond. The photometry between 10 and 25 μm is well fit by the emission predicted from a stratified disk seen at large inclination, as has been proposed for this source by Lykou et al. and by Smith and Gehrz. The principal new results in this paper relate to the distribution and properties of the dust that emits the infrared radiation. In particular, a considerable fraction of this material is spread uniformly through the lobes, although the dust density does increase at the sharp outer edge seen in higher resolution optical images of M2-9. The dust grain population in the lobes shows that small (<0.1 μm) and large (>1 μm) particles appear to be present in roughly equal amounts by mass. We suggest that collisional processing within the bipolar outflow plays an important role in establishing the particle size distribution.

  14. Mid-infrared imaging of the bipolar planetary nebula M2-9 from SOFIA

    International Nuclear Information System (INIS)

    We have imaged the bipolar planetary nebula M2-9 using SOFIA's FORCAST instrument in six wavelength bands between 6.6 and 37.1 μm. A bright central point source, unresolved with SOFIA's ∼4''-5'' beam, is seen at each wavelength, and the extended bipolar lobes are clearly seen at 19.7 μm and beyond. The photometry between 10 and 25 μm is well fit by the emission predicted from a stratified disk seen at large inclination, as has been proposed for this source by Lykou et al. and by Smith and Gehrz. The principal new results in this paper relate to the distribution and properties of the dust that emits the infrared radiation. In particular, a considerable fraction of this material is spread uniformly through the lobes, although the dust density does increase at the sharp outer edge seen in higher resolution optical images of M2-9. The dust grain population in the lobes shows that small (<0.1 μm) and large (>1 μm) particles appear to be present in roughly equal amounts by mass. We suggest that collisional processing within the bipolar outflow plays an important role in establishing the particle size distribution.

  15. On the implications of recent observations of the inner knot in the Crab nebula

    Science.gov (United States)

    Yuan, Yajie; Blandford, Roger D.

    2015-12-01

    Recent observations of the Crab nebula (Rudy et al.) have maintained its reputation for high-energy astrophysical enlightenment and its use as a test-bed for theories of the behaviour of magnetized, relativistic plasma. In particular, new observations of the inner knot located 0.65 arcsec SE from the pulsar confirm that it is compact, elongated transversely to the symmetry axis and curved concave towards the pulsar. 60 per cent polarization has been measured along the symmetry axis (Moran et al.). The knot does not appear to be involved in the gamma-ray flares. The new observations both reinforce the interpretation of the knot as dissipation of the pulsar wind at a strong shock and challenge the details of existing models of this process. In particular, it is argued that the compactness, high polarization, and curvature are difficult to reconcile with simple relativistic shock models. Alternative possibilities include deflection of the outflow ahead of the shock and spatial variation in which the knot is interpreted as a caustic. Some future observations are proposed and new theoretical investigations are suggested.

  16. On the Implications of Recent Observations of the Inner Knot in the Crab Nebula

    CERN Document Server

    Yuan, Yajie

    2015-01-01

    Recent observations of the Crab Nebula (Rudy et al 2015) have maintained its reputation for high energy astrophysical enlightenment and its use as a testbed for theories of the behaviour of magnetized, relativistic plasma. In particular, new observations of the inner knot located 0.65'' SE from the pulsar confirm that it is compact, elongated transversely to the symmetry axis and curved concave towards the pulsar. 60 percent polarization has been measured along the symmetry axis (Moran et al 2013). The knot does not appear to be involved in the gamma ray flares. The new observations both reinforce the interpretation of the knot as dissipation of the pulsar wind at a strong shock and challenge the details of existing models of this process. In particular, it is argued that the compactness, high polarization and curvature are difficult to reconcile with simple relativistic shock models. Alternative possibilities include deflection of the outflow ahead of the shock and spatial variation in which the knot is inte...

  17. Simulation of Breach Outflow for Earthfill Dam

    Science.gov (United States)

    Razad, Azwin Zailti Abdul; Sabri Muda, Rahsidi; Mohd Sidek, Lariyah; Azia, Intan Shafilah Abdul; Hanum Mansor, Faezah; Yalit, Ruzaimei

    2013-06-01

    Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

  18. FIRE simulations: galactic outflows and their consequences

    Science.gov (United States)

    Keres, Dusan; FIRE team

    2016-06-01

    We study gaseous outflows and their consequences in high-resolution galaxy formation simulations with explicit stellar feedback from the Feedback in Realistic Environments project. Collective, galaxy scale, effect of stellar feedback results in episodic ejections of large amount of gas and heavy elements into the circum-galactic medium. Gas ejection episodes follow strong bursts of star formation. Properties of galactic star formation and ejection episodes depend on galaxy mass and redshift and, together with gas infall and recycling, shape the evolution of the circum-galactic medium and galaxies. As a consequence, our simulated galaxies have masses, star formation histories and heavy element content in good agreement with the observed population of galaxies.

  19. Propeller outflows from an MRI disc

    CERN Document Server

    Lii, Patrick S; Ustyugova, Galina V; Koldoba, Alexander V; Lovelace, Richard V E

    2013-01-01

    We present the results of axisymmetric simulations of MRI-driven accretion onto a rapidly rotating, magnetized star accreting in the propeller regime. The stellar magnetosphere corotates with the star, forming a centrifugal barrier at the disc-magnetosphere boundary which inhibits matter accretion onto the star. Instead, the disc matter accumulates at the disc-magnetosphere interface and slowly diffuses into the inner magnetosphere where it picks up angular momentum and is quickly ejected from the system as an outflow. Due to the interaction of the matter with the magnetosphere, this wind is discontinuous and is launched as discrete plasmoids. If the ejection rate is lower than the disc accretion rate, the matter accumulates at the disc-magnetosphere boundary faster than it can be ejected. In this case, accretion onto the star proceeds through the episodic accretion instability in which episodes of matter accumulation are followed by simultaneous accretion and ejection. During the accretion phase of this inst...

  20. Simulation of Breach Outflow for Earthfill Dam

    International Nuclear Information System (INIS)

    Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

  1. Cluster Formation in Protostellar Outflow-Driven Turbulence

    CERN Document Server

    Li, Z Y; Li, Zhi-Yun; Nakamura, Fumitaka

    2006-01-01

    Most, perhaps all, stars go through a phase of vigorous outflow during formation. We examine, through 3D MHD simulation, the effects of protostellar outflows on cluster formation. We find that the initial turbulence in the cluster-forming region is quickly replaced by motions generated by outflows. The protostellar outflow-driven turbulence (``protostellar turbulence'' for short) can keep the region close to a virial equilibrium long after the initial turbulence has decayed away. We argue that there exist two types of turbulence in star-forming clouds: a primordial (or ``interstellar'') turbulence and a protostellar turbulence, with the former transformed into the latter mostly in embedded clusters such as NGC 1333. Since the majority of stars are thought to form in clusters, an implication is that the stellar initial mass function is determined to a large extent by the stars themselves, through outflows which individually limit the mass accretion onto forming stars and collectively shape the environments (de...

  2. The Implications of Extreme Outflows from Extreme Starbursts

    CERN Document Server

    Heckman, Timothy M

    2016-01-01

    Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We exploit the wide dynamic range provided by this new sample to determine scaling relations of outflow velocity with galaxy stellar mass (M*), circular velocity, star-formation rate (SFR), SFR/M*, and SFR/area. We argue that these results can be accommodated within the general interpretational framework we previously advocated, in which a population of ambient interstellar or circum-galactic clouds is accelerated by the combine...

  3. Searching for molecular outflows in Hyper-Luminous Infrared Galaxies

    CERN Document Server

    Calderón, D; Veilleux, S; Graciá-Carpio, J; Sturm, E; Lira, P; Schulze, S; Kim, S

    2016-01-01

    We present constraints on the molecular outflows in a sample of five Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet at 119 {\\mu}m. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ~1500 km/s. Our analysis shows that this system is in general agreement with previous results on Ultra-luminous Infrared Galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead the galaxy outflow likely arises from an embedded AGN.

  4. Analysis of the eclipsing binary ST Carinae using the SIMPLEX algorithm

    International Nuclear Information System (INIS)

    This work presents the analyses of two UBV data sets for the Algol binary ST Carinae, presenting a homogeneous study of all the data. The light-curve parameters for the system are derived using the Wilson-Devinney model (1917), with the SIMPLEX algorithm as an optimization procedure, and a mass ratio of q=0.54 is obtained. The primary has colors consistent with a B9.5 V primary, and the solution indicates that the secondary is an F subgiant (Te=6200 K) that fills its Roche lobe. The application of Kepler's law (using the observed period and the mass ratio determined in this investigation) indicates that the absolute dimensions for the components are normal for their respective classes. A description of SIMPLEX is given, and its advantages for the solution of eclipsing binary parameters are discussed. 19 refs

  5. Explosions Triggered by Violent Binary-Star Collisions: Application to Eta Carinae and other Eruptive Transients

    CERN Document Server

    Smith, Nathan

    2010-01-01

    This paper discusses a model where a violent periastron collision of stars in an eccentric binary system induces an eruption or explosion seen as a brief transient source, attributed to LBVs, SN impostors, or other transients. The key ingredient is that an evolved primary increases its photospheric radius on relatively short timescales, to a point where the radius is comparable to or larger than the periastron separation in an eccentric binary. In such a configuration, a violent and sudden collision would ensue, possibly leading to substantial mass ejection instead of a binary merger. Repeated periastral grazings in an eccentric system could quickly escalate to a catastrophic encounter, wherein the companion star actually plunges deep inside the photosphere of a bloated primary during periastron, as a result of the primary star increasing its own radius. This is motivated by the case of $\\eta$~Carinae, where such a collision must have occured if conventional estimates of the present-day orbit are correct, and...

  6. Scandium and Chromium in the Strontium Filament in the Homunculus of eta Carinae

    Science.gov (United States)

    Gull, T.R.; Melendez, M.; Baustista, M.A.; Ballance, C.; Hartman, H.; Lodders, K.; Martinez, M.

    2008-01-01

    We continue a systematic study of chemical abundances of the Strontium Filament found in the ejecta of eta Carinae. To this end we interpret the emission spectrum of Sc II and Cr II using multilevel non-LTE models of these systems. Since the atomic data for these ions was previously unavailable, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. The observed spectrum is emitted from a mostly neutral region with electron density of the order of 10(exp 7) cm (exp -3) and a temperature between 6000 and 7000 K. These conditions are consistent with our previous diagnostics from [Ni II], [Ti II], amd [Sr II]. The observed spectrum indicates an abundance of Sc relative Ni that more than 40 times the solar values, while the Cr/Ni abundance ratio is roughly solar. Various scenarios of depletion and dust destruction are suggested to explain such abnormal abundances.

  7. On the He II Emission In Eta Carinae and the Origin of Its Spectroscopic Events

    CERN Document Server

    Martin, J C; Humphreys, R M; Hillier, D J; Ishibashi, K

    2006-01-01

    We report Hubble Space Telescope (HST) observations of emission in Eta Carinae near 4680 {\\AA}, presumably He II 4687, which are not spatially resolved from the central star. The emission was not detected in the spectrum from 1998.0 to 2003.0, or after the spectroscopic event in 2003.5. It appeared in early 2003, rapidly grew to a larger brightness than the previous authors reported, and then disappeared suddenly near 2003.5. For several weeks the He II 4687 luminosity was too high to explain easily in most proposed models for Eta Car's spectroscopic events. According to our analyses, this feature appears most consistent with a wind-disturbance or mass-ejection type of model with relatively high gas densities. An unusual form of radiative excitation, making use of trapped He II 304 resonance photons, may have played a major role.

  8. LBVs AND THE NATURE OF THE S DOR CYCLES: THE CASE OF AG CARINAE

    Directory of Open Access Journals (Sweden)

    J. H. Groh

    2008-01-01

    Full Text Available Presentamos los resultados de un análisis espectroscópico detallado sobre 20 a~nos de observaciones de AG Carinae, usando el código de transferencia radiativa llamado CMFGEN. Entre las conclusiones de este trabajo, resaltamos la importancia de incluir efectos dependientes del tiempo en el análisis del ciclo completo de S Dor. Hemos obtenido que la tasa de pérdida de masa es aproximadamente constante durante las fases fras, implicando que las erupciones en los objetos de tipo S Dor comienzan bastante más temprano que durante el máximo observado en la curva de luz visual. Hemos determinado ademías que los ciclos S Dor son, en ultima instancia, consecuencia de un aumento/disminución del radio hidrostático en combinación con una pseudo-fotosfera.

  9. PARTICLE ACCELERATION IN THE EXPANDING BLAST WAVE OF η CARINA'S GREAT ERUPTION OF 1843

    International Nuclear Information System (INIS)

    Non-thermal hard X-ray and high-energy (HE; 1 MeV ≤ E ≤ 100 GeV) γ-ray emission in the direction of η Carina has been recently detected using the INTEGRAL, AGILE, and Fermi satellites. So far this emission has been interpreted in the framework of particle acceleration in the colliding wind region between the two massive stars. However, the existence of a very fast moving blast wave which originates in the historical 1843 'Great Eruption' provides an alternative particle acceleration site in this system. Here, we explore an alternate scenario and find that inverse Compton emission from electrons accelerated in the blast wave can naturally explain both the flux and spectral shape of the measured hard X-ray and HE γ-ray emission. This scenario is further supported by the lack of significant variability in the INTEGRAL and Fermi measured fluxes.

  10. Signatures of Chemical Evolution in Protostellar Nebulae

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha

    2011-01-01

    A decade ago observers began to take serious notice of the presence of crystalline silicate grains in the dust flowing away from some comets. While crystallinity had been seen in such objects previously, starting with the recognitions by Campins and Ryan (1990) that the 10 micron feature of Comet Halley resembled that of the mineral forsterite, most such observations were either ignored or dismissed as no path to explain such crystalline grains was available in the literature. When it was first suggested that an outward flow must be present to carry annealed silicate grains from the innermost regions of the Solar Nebula out to the regions where comets could form (Nuth, 1999; 2001) this suggestion was also dismissed because no such transport mechanism was known at the time. Since then not only have new models of nebular dynamics demonstrated the reality of long distance outward transport (Ciesla, 2007; 2008; 2009) but examination of older models (Boss, 2004) showed that such transport had been present but had gone unrecognized for many years. The most unassailable evidence for outward nebular transport came with the return of the Stardust samples from Comet Wild2, a Kuiper-belt comet that contained micron-scale grains of high temperature minerals resembling the Calcium-Aluminum Inclusions found in primitive meteorites (Zolensky et aI., 2006) that formed at T > 1400K. Now that outward transport in protostellar nebulae has been firmly established, a re-examination of its consequences for nebular gas is in order that takes into account both the factors that regulate both the outward flow as well as those that likely control the chemical composition of the gas. Laboratory studies of surface catalyzed reactions suggest that a trend toward more highly reduced carbon and nitrogen compounds in the gas phase should be correlated with a general increase in the crystallinity of the dust (Nuth et aI., 2000), but is such a trend actually observable? Unlike the Fischer-Tropsch or

  11. Consistency of cruise data of the CARINA database in the Atlantic sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    M. Hoppema

    2009-12-01

    Full Text Available Initially a North Atlantic project, the CARINA carbon synthesis was extended to include the Southern Ocean. Carbon and relevant hydrographic and geochemical ancillary data from cruises all across the Arctic Mediterranean Seas, Atlantic and Southern Ocean were released to the public and merged into a new database as part of the CARINA synthesis effort. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean, including 11 from the Atlantic sector. The variables from all Southern Ocean cruises, including dissolved inorganic carbon (TCO2, total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency in one collective effort. Seawater pH and chlorofluorocarbons (CFCs are also part of the database, but the pH quality control (QC is described in another Earth System Science Data publication, while the complexity of the Southern Ocean physics and biogeochemistry prevented a proper QC analysis of the CFCs. The area-specific procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data (i.e. secondary QC, are briefly described here for the Atlantic sector of the Southern Ocean. Data from an existing, quality controlled database (GLODAP were used as a reference for our computations – however, the reference data were included into the analysis without applying the recommended GLODAP adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises. The suggested corrections by the inversion analysis were allowed to vary within a fixed envelope, thus accounting for natural variability. The percentage of cruises adjusted ranged from 31% (for nitrate to 54% (for phosphate depending on the variable.

  12. [Ti II] and [Ni II] Emission from the Strontium Filament of eta Carinae

    Science.gov (United States)

    Bautista, M. A.; Hartman, H.; GUll, T. R.; Smith, N.; Lodders, K.

    2007-01-01

    We study the nature of the [Ti II] and [Ni II] emission from the so-called strontium filament found in the ejecta of eta Carinae. To this purpose we employ multilevel models of the Ti II and Ni II systems which are used to investigate the physical condition of the filament and the excitation mechanisms of the observed lines. For the Ti II ion, for which no atomic data was previously available, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. It is found that the observed spectrum is consistent with the lines being excited in a mostly neutral region with an electron density of the order of 10(exp 7) per cubic centimeter and a temperature around 6000 K. In analyzing three observations with different slit orientations recorded between March 2000 and November 2001 we find line ratios that change among various observations, in a way consistent with changes of up to an order of magnitude in the strength of the continuum radiation field. These changes result from different samplings of the extended filament, due to the different slit orientations used for each observation, and yield clues on the spatial extent and optical depth of the filament. The observed emission indicates a large Ti/Ni abundance ratio relative to solar abundances. It is suggested that the observed high Ti/Ni ratio in gas is caused by dust-gas fractionation processes and does not reflect the absolute Ti/Ni ratio in the ejecta of eta Carinae. We study the condensation chemistry of Ti, Ni and Fe within the filament and suggest that the observed gas phase overabundance of Ti is likely the result of selective photo-evaporation of Ti-bearing grains. Some mechanisms for such a scenario are proposed.

  13. The Spatially-resolved Interacting Winds of Eta Carinae: Implications on the Orbit Orientation

    Science.gov (United States)

    Gull, Theodore R.; Nielsen, K.E.; Corcoran, M.; Hamaguchi, K.; Madura, T.; Russell, C.; Hillier, D.J.; Owocki. S.; Okazaki, A.T.

    2010-01-01

    Medium-dispersion long slit spectra, recorded by HST/STIS (R=8000, Theta=0.l"), resolve the extended wind-wind interaction region of the massive binary, Eta Carinae. During the high state, extending for about five years of the 5.54-year binary period, lines of [N II], [Fe III], [S III], [Ar III] and [Ne III] extend outwards to 0.4" with a velocity range of -500 to +200 km/s. By comparison, lines of [Fe II] and [Ni II] extend to 0.7" with a velocity range of -500 to +500 km/s. During the high state, driven by the lesser wind of Eta Car B and photo-ionized by the FUV of Eta Car B, the high excitation lines originate in or near the outer ballistic portions of the wind-wind interaction region. The lower excitation lines ([Fe II] and [Ni II D originate from the boundary regions of the dominating wind of Eta Car A. As the binary system has an eccentricity exceeding 0.9, the two stars approach quite close across the periastron, estimated to be within 1 to 2 AU. As a result, Eta Car B moves into the primary wind structure, cutting off the FUV supporting the ionization of the high state lines. Forbidden emission lines of the doubly-ionized species disappear, He II 4686 drops along with the collapse of the X-ray flux. This behavior is understood through the 3-D models of A. Okazaki and of E. R. Parkin and Pittard. Discussion will address the orbit orientation relative to the geometry of the Homunculus, ejected by Eta Carinae in the 1840s.

  14. Spitzer spectral line mapping of protostellar outflows: I. Basic data and outflow energetics

    CERN Document Server

    Neufeld, David A; Giannini, Teresa; Melnick, Gary J; Bergin, Edwin A; Yuan, Yuan; Maret, Sebastien; Tolls, Volker; Guesten, Rolf; Kaufman, Michael J

    2009-01-01

    We report the results of spectroscopic mapping observations carried out toward protostellar outflows in the BHR71, L1157, L1448, NGC 2071, and VLA 1623 molecular regions using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope. These observations, covering the 5.2 - 37 micron spectral region, provide detailed maps of the 8 lowest pure rotational lines of molecular hydrogen and of the [SI] 25.25 micron and [FeII] 26.0 micron fine structure lines. The molecular hydrogen lines, believed to account for a large fraction of the radiative cooling from warm molecular gas that has been heated by a non-dissociative shock, allow the energetics of the outflows to be elucidated. Within the regions mapped towards these 5 outflow sources, total H2 luminosities ranging from 0.02 to 0.75 L(solar) were inferred for the sum of the 8 lowest pure rotational transitions. By contrast, the much weaker [FeII] 26.0 micron fine structure transition traces faster, dissociative shocks; here, only a small fraction of the fast ...

  15. ANAESTHESIA FOR EVALUATION AND EXCISION OF TRACHEAL TUMOUR AT CARINA EXTENDING INTO RIGHT MAIN BRONCHUS: CASE REPORT

    Directory of Open Access Journals (Sweden)

    Deepraj Singh

    2014-04-01

    Full Text Available A tracheal tumor at carinal angle is uncommon. Presented here is an interesting case of a 22 year old, HBsAg positive female with a tracheal tumor at carina extending into the right main bronchus. The patient reported shortness of breath along with fatigue and cough. Routine and other appropriate investigations were done during which X-ray chest and CT scan revealed right lung collapse with ipsilateral shift of mediastinum. Telescopic evaluation and biopsy performed under general anesthesia using supraglottic Jet Ventilation further revealed proliferative growth arising from the anterior wall of the carina extending into the right main bronchus. Subsequently, excision of the tumor through tracheotomy under general anesthesia was carried out. The patient recovered completely with no postoperative complications.

  16. Molecular clouds in the Carina arm - large-scale properties of molecular gas and comparison with H I

    Energy Technology Data Exchange (ETDEWEB)

    Grabelsky, D.A.; Cohen, R.S.; Bronfman, L.; Thaddeus, P.; May, J.

    1987-04-01

    Results from the first large-scale survey in the CO (J = 1 - 0) line of the Vela-Carina-Centaurus region of the southern Milky Way are reported. The results demonstrate that molecular clouds in the Galaxy are largely confined to the spiral arms and that CO is therefore an extremely good tracer of the large-scale structure of the system. The Carina arm is the dominant feature in the data. Its abrupt tangent at l of roughly 280 deg and characteristic loop in the (l, v) diagram are unmistakable evidence for CO spiral structure. When the emission is integrated over velocity and latitude, the height of the step seen in the tangent direction indicate that the arm-interarm contrast is at least 13:1. 44 references.

  17. Molecular clouds in the Carina arm - Large-scale properties of molecular gas and comparison with H I

    Science.gov (United States)

    Grabelsky, D. A.; Cohen, R. S.; Bronfman, L.; Thaddeus, P.; May, J.

    1987-01-01

    Results from the first large-scale survey in the CO (J = 1 - 0) line of the Vela-Carina-Centaurus region of the southern Milky Way are reported. The results demonstrate that molecular clouds in the Galaxy are largely confined to the spiral arms and that CO is therefore an extremely good tracer of the large-scale structure of the system. The Carina arm is the dominant feature in the data. Its abrupt tangent at l of roughly 280 deg and characteristic loop in the (l, v) diagram are unmistakable evidence for CO spiral structure. When the emission is integrated over velocity and latitude, the height of the step seen in the tangent direction indicate that the arm-interarm contrast is at least 13:1.

  18. Planetary Nebulae and How to Observe Them

    CERN Document Server

    Griffiths, Martin

    2012-01-01

    Astronomers' Observing Guides provide up-to-date information for amateur astronomers who want to know all about what is it they are observing. This is the basis of the first part of the book. The second part details observing techniques for practical astronomers, working with a range of different instruments. Planetary Nebulae and How to Observe Them is intended for amateur astronomers who want to concentrate on one of the most beautiful classes of astronomical objects in the sky. This book will help the observer to see these celestial phenomena using telescopes of various apertures. As a Sun-like star reaches the end of its life, its hydrogen fuel starts to run out. It collapses until helium nuclei begin nuclear fusion, whereupon the star begins to pulsate, each pulsation throwing off a layer of the star's atmosphere. Eventually the atmosphere has all been ejected as an expanding cloud of gas, the star's core is exposed and ultraviolet photons cause the shell of gas to glow brilliantly - that's planetary ...

  19. FU Orionis Outbursts and the Solar Nebula

    Science.gov (United States)

    Bell, Robbins; Young, Rich (Technical Monitor)

    1998-01-01

    Protostellar systems are variable on many timescales. The FU Orionis outburst is one of the most drastic forms of variability known to occur in low mass stellar systems. During a typical outburst lasting several decades, system luminosities may be a hundred times what is normal of the quiescent state. FU Orionis outburst events are believed to have significant impacts on the thermal structure of the protosolar nebula. Their existence has been utilized to explain features in the meteoritic record from thermally induced homogenization to chondrule formation. Recent numerical models have shown the viability of the hypothesis that the radiation observed during outburst is emitted by a luminous circumstellar disk transporting mass at a thousand times the quiescent rate. We will begin by describing what is known about the FU Orionis outburst phenomenon from recent observations and theory. We will discuss evidence that suggests that outburst radiation is emitted by a circumstellar disk rather than by the star and will briefly describe the thermal instability as a mechanism for outburst. Additional information is contained in the original extended abstract.

  20. Radio Observations of Elongated Pulsar Wind Nebulae

    Science.gov (United States)

    Ng, Stephen C.-Y.

    2015-08-01

    The majority of pulsars' rotational energy is carried away by relativistic winds, which are energetic particles accelerated in the magnetosphere. The confinement of the winds by the ambient medium result in synchrotron bubbles with broad-band emission, which are commonly referred to as pulsar wind nebulae (PWNe). Due to long synchrotron cooling time, a radio PWN reflects the integrated history of the system, complementing information obtained from the X-ray and higher energy bands. In addition, radio polarization measurements can offer a powerful probe of the PWN magnetic field structure. Altogether these can reveal the physical conditions and evolutionary history of a system.I report on preliminary results from high-resolution radio observations of PWNe associated with G327.1-1.1, PSRs J1015-5719, B1509-58, and J1549-4848 taken with the Australia Telescope Compact Array (ATCA). Their magnetic field structure and multiwavelength comparison with other observations are discussed.This work is supported by a ECS grant of the Hong Kong Government under HKU 709713P. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

  1. Modelling of asymmetric nebulae. II. Line profiles

    CERN Document Server

    Morisset, C

    2006-01-01

    We present a tool, VELNEB_3D, which can be applied to the results of 3D photoionization codes to generate emission line profiles, position-velocity maps and 3D maps in any emission line by assuming an arbitrary velocity field. We give a few examples, based on our pseudo-3D photoionization code NEBU_3D (Morisset, Stasinska and Pena, 2005) which show the potentiality and usefulness of our tool. One example shows how complex line profiles can be obtained even with a simple expansion law if the nebula is bipolar and the slit slightly off-center. Another example shows different ways to produce line profiles that could be attributed to a turbulent velocity field while there is no turbulence in the model. A third example shows how, in certain circumstances, it is possible to discriminate between two very different geometrical structures -- here a face-on blister and its ``spherical impostor'' -- when using appropriate high resolution spectra. Finally, we show how our tool is able to generate 3D maps, similar to the ...

  2. Embedded Star Formation in the Eagle Nebula

    CERN Document Server

    Thompson, R I; Hester, J J; Thompson, Rodger I.; Smith, Bradford A.

    2002-01-01

    M16=NGC 6611, the Eagle Nebula, is a well studied region of star formation and the source of a widely recognized Hubble Space Telescope (HST) image. High spatial resolution infrared observations with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on HST reveal the detailed morphology of two embedded star formation regions that are heavily obscured at optical wavelengths. It is striking that only limited portions of the visually obscured areas are opaque at 2.2 microns. Although the optical images imply substantial columns of material, the infrared images show only isolated clumps of dense gas and dust. Rather than being an active factory of star production, only a few regions are capable of sustaining current star formation. Most of the volume in the columns may be molecular gas and dust, protected by capstones of dense dust. Two active regions of star formation are located at the tips of the optical northern and central large ``elephant trunk'' features shown in the WFPC2 images. They are em...

  3. The Distance Scale of Planetary Nebulae

    CERN Document Server

    Bensby, T

    2001-01-01

    By collecting distances from the literature, a set of 73 planetary nebulae with mean distances of high accuracy is derived. This sample is used for recalibration of the mass-radius relationship, used by many statistical distance methods. An attempt to correct for a statistical peculiarity, where errors in the distances influences the mass--radius relationship by increasing its slope, has been made for the first time. Distances to PNe in the Galactic Bulge, derived by this new method as well as other statistical methods from the last decade, are then used for the evaluation of these methods as distance indicators. In order of achieving a Bulge sample that is free from outliers we derive new criteria for Bulge membership. These criteria are much more stringent than those used hitherto, in the sense that they also discriminate against background objects. By splitting our Bulge sample in two, one with optically thick (small) PNe and one with optically thin (large) PNe, we find that our calibration is of higher ac...

  4. ELEMENT DISTRIBUTIONS IN THE CRAB NEBULA

    International Nuclear Information System (INIS)

    Images of the Crab Nebula have been obtained through custom interference filters that transmit emission from the expanding supernova remnant in He II λ4686, Hβ, He I λ5876, [O I] λλ6300, 6364, [N II] λλ6548, 6583, [S II] λλ6716, 6731, [S III] λ9069, and [C I] λλ9823, 9850. We present both raw and flux-calibrated emission-line images. Arrays of 19,440 photoionization models, with extensive input abundance ranges, were matched pixel by pixel to the calibrated data in order to derive corresponding element abundance or mass-fraction distributions for helium, carbon, nitrogen, oxygen, and sulfur. These maps show distinctive structure, and they illustrate regions of gas in which various stages of nucleosynthesis have apparently occurred, including the CNO cycle, helium burning, carbon burning, and oxygen burning. It is hoped that the calibrated observations and chemical abundance distribution maps will be useful for developing a better understanding of the precursor star evolution and the supernova explosive process.

  5. Kn 26, a New Quadrupolar Planetary Nebula

    CERN Document Server

    Guerrero, Martin A; Ramos-Larios, Gerardo; Vazquez, Roberto

    2013-01-01

    Once classified as an emission line source, the planetary nebula (PN) nature of the source Kn 26 has been only recently recognized in digital sky surveys. To investigate the spectral properties and spatio-kinematical structure of Kn 26, we have obtained high spatial-resolution optical and near-IR narrow-band images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data reveal an hourglass morphology typical of bipolar PNe. A detailed analysis of its morphology and kinematics discloses the presence of a second pair of bipolar lobes, making Kn 26 a new member of the subclass of quadrupolar PNe. The time-lap between the ejection of the two pairs of bipolar lobes is much smaller than their dynamical ages, implying a rapid change of the preferential direction of the central engine. The chemical composition of Kn 26 is particularly unusual among PNe, with a low N/O ratio (as of type II PNe) and a high helium abundance (as of type I PNe), although not atypica...

  6. Planetary Nebula Kinematics in M101

    Science.gov (United States)

    Herrmann, Kimberly A.; Ciardullo, Robin

    2011-02-01

    Look at a spiral; what do you see? Stars zooming `round in the galaxy! Their motions indicate total mass, but how much is DM, stars, and gas? Study motions in and out; first find monochromatic stars- that's my kind. Find us, get our velocities, then: determine disk mass! I'm a PN! Rotation curves indicate the total mass of spirals, but halo mass profiles cannot be decoupled from the visible disk mass using rotation curves alone. To break this disk-halo degeneracy, we have been using planetary nebulae (PNe) to measure the z-component of the stellar velocity dispersion in the disks of face-on spirals. These measurements of σ_z, coupled with straightforward assumptions, have yielded disk surface mass estimates over several scale lengths (h_R) in 6 spirals. We find that in the inner regions of galaxies (R galaxy, M101, to R > 8 h_R. Last year we imaged M101 with the wide-field Mosaic camera on the KPNO 4-m telescope. This proposal is to perform follow-up spectroscopy on ~240 PNe in M101 with WIYN/Hydra.

  7. The inner knot of the Crab nebula

    Science.gov (United States)

    Lyutikov, Maxim; Komissarov, Serguei S.; Porth, Oliver

    2016-02-01

    We model the inner knot of the Crab nebula as a synchrotron emission coming from the non-spherical MHD termination shock of relativistic pulsar wind. The post-shock flow is mildly relativistic; as a result the Doppler beaming has a strong impact on the shock appearance. The model can reproduce the knot location, size, elongation, brightness distribution, luminosity and polarization provided the effective magnetization of the section of the pulsar wind producing the knot is low, σ ≤ 1. In the striped wind model, this implies that the striped zone is rather wide, with the magnetic inclination angle of the Crab pulsar ≥45°; this agrees with the previous model-dependent estimate based on the gamma-ray emission of the pulsar. We conclude that the tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock and that this shock is a site of efficient particle acceleration. On the other hand, the deduced low magnetization of the knot plasma implies that this is an unlikely site for the Crab's gamma-ray flares, if they are related to the fast relativistic magnetic reconnection events.

  8. Planetary Nebulae in the Small Magellanic Cloud

    CERN Document Server

    Ventura, P; Di Criscienzo, M; García-Hernández, D A; Dell'Agli, F

    2016-01-01

    We analyse the planetary nebulae (PNe) population of the Small Magellanic Cloud (SMC), based on evolutionary models of stars with metallicities in the range $10^{-3} \\leq Z \\leq 4\\times 10^{-3}$ and mass $0.9 M\\odot < M < 8M\\odot$, evolved through the asymptotic giant branch (AGB) phase. The models used account for dust formation in the circumstellar envelope. To characterise the PNe sample of the SMC, we compare the observed abundances of the various species with the final chemical composition of the AGB models: this study allows us to identify the progenitors of the PNe observed, in terms of mass and chemical composition. According to our interpretation, most of the PNe descend from low-mass ($M < 2 M\\odot$) stars, which become carbon rich, after experiencing repeated third dredge-up episodes, during the AGB phase. A fraction of the PNe showing the signature of advanced CNO processing are interpreted as the progeny of massive AGB stars, with mass above $\\sim 6 M\\odot$, undergoing strong hot bottom ...

  9. Visual Binaries in the Orion Nebula Cluster

    CERN Document Server

    Reipurth, Bo; Connelley, Michael S; Bally, John

    2007-01-01

    We have carried out a major survey for visual binaries towards the Orion Nebula Cluster using HST images obtained with an H-alpha filter. Among 781 likely ONC members more than 60" from theta-1 Ori C, we find 78 multiple systems (75 binaries and 3 triples), of which 55 are new discoveries, in the range from 0.1" to 1.5". About 9 binaries are likely line-of-sight associations. We find a binary fraction of 8.8%+-1.1% within the limited separation range from 67.5 to 675 AU. The field binary fraction in the same range is a factor 1.5 higher. Within the range 150 AU to 675 AU we find that T Tauri associations have a factor 2.2 more binaries than the ONC. The binary separation distribution function of the ONC shows unusual structure, with a sudden steep decrease in the number of binaries as the separation increases beyond 0.5", corresponding to 225 AU. We have measured the ratio of binaries wider than 0.5" to binaries closer than 0.5" as a function of distance from the Trapezium, and find that this ratio is signifi...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-01

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

  11. The contribution of quasar outflows to cosmological structure formation

    Science.gov (United States)

    Arav, Nahum

    2011-10-01

    A vast new discovery space is opened up by the high sensitivity of COS in the far UV. These new capabilities are ushering a revolution in the study of AGN outflows. We now have the ability to obtain high quality data on objects up to a redshift of about 1, providing access to ten times more {and better} diagnostic absorption lines than was possible with STIS {which could only observe outflows at z<0.05 with sufficient S/N}. These diagnostics will allow us to quantify how much do quasar outflow contribute to AGN feedback. On the way to this lofty goal, we'll be able to resolve important questions in the study of these outflows: Where are they situated within the host galaxy? What is their ionization equilibrium and chemical abundances? Unlike ground-based observations, COS data can yield the answers to all these questions for the most ubiquitous outflows, and therefore connect them to our developing understanding of cosmological structure formation.Our analysis of recent archived COS observations gives a concrete example for the above claims; including the first determination of the distance from the central source for a high-ionization outflow. Here we propose an archive program to look through the 520 COS G130M and G160M orbits of AGN archive observations, identify quasar outflows and publish the analyses of the best cases.

  12. The role of cosmic ray pressure in accelerating galactic outflows

    CERN Document Server

    Simpson, Christine M; Marinacci, Federico; Pfrommer, Christoph; Springel, Volker; Glover, Simon C O; Clark, Paul C; Smith, Rowan J

    2016-01-01

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

  13. High-velocity molecular outflows hear massive young stellar objects

    Institute of Scientific and Technical Information of China (English)

    吴月芳; 李月兴; 杨传义; 雷成明; 孙金江; 吕静; 韩溥

    1999-01-01

    By mapping the 12CO J=1—0 lines in IRAS 05391-0217, 06114+1745 and 06291+0421, three new high-velocity bipolar molecular outflows are found. Parameters of these outflows are derived, which suggest that they are massive and energetic outflows with total kinetic energies of about 1038 J and mass loss rates about 10-5 M⊙/a. The driving sources are identified by analyzing the positions, intensities and color temperatures of the associated infrared sources. These outflows are most likely driven by single sources which correspond to massive young stellar objects. In these regions H2O masers have been detected located near the embedded infrared sources, which indicates that their exciting mechanism may be correlated with that of the CO outflows. The relationship between the parameters of outflows and central sources shows that high-velocity outflow and thermal radiation of a star are two basic correlated but different features in the evolution of young stars.

  14. Evolution of Protostellar Outflow around Low-mass Protostar

    CERN Document Server

    Machida, Masahiro N

    2013-01-01

    The evolution of protostellar outflow is investigated with resistive magneto-hydrodynamic nested-grid simulations that cover a wide range of spatial scales (\\sim 1AU - 1pc). We follow cloud evolution from the pre-stellar core stage until the infalling envelope dissipates long after the protostar formation. We also calculate protostellar evolution to derive protostellar luminosity with time-dependent mass accretion through a circumstellar disk. The protostellar outflow is driven by the first core prior to protostar formation and is directly driven by the circumstellar disk after protostar formation. The opening angle of the outflow is large in the Class 0 stage. A large fraction of the cloud mass is ejected in this stage, which reduces the star formation efficiency to \\sim 50%. After the outflow breaks out from the natal cloud, the outflow collimation is gradually improved in the Class I stage. The head of the outflow travels more than \\sim 10^5AU in \\sim 10^5 yr. The outflow momentum, energy and mass derived ...

  15. PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS

    International Nuclear Information System (INIS)

    A protostellar jet and outflow are calculated for ∼270 yr following the protostar formation using a three-dimensional magnetohydrodynamics simulation, in which both the protostar and its parent cloud are spatially resolved. A high-velocity (∼100 km s–1) jet with good collimation is driven near the disk's inner edge, while a low-velocity (≲ 10 km s–1) outflow with a wide opening angle appears in the outer-disk region. The high-velocity jet propagates into the low-velocity outflow, forming a nested velocity structure in which a narrow high-velocity flow is enclosed by a wide low-velocity flow. The low-velocity outflow is in a nearly steady state, while the high-velocity jet appears intermittently. The time-variability of the jet is related to the episodic accretion from the disk onto the protostar, which is caused by gravitational instability and magnetic effects such as magnetic braking and magnetorotational instability. Although the high-velocity jet has a large kinetic energy, the mass and momentum of the jet are much smaller than those of the low-velocity outflow. A large fraction of the infalling gas is ejected by the low-velocity outflow. Thus, the low-velocity outflow actually has a more significant effect than the high-velocity jet in the very early phase of the star formation

  16. Suppression of galactic outflows by cosmological infall and circumgalactic medium

    CERN Document Server

    Singh, Priyanka; Bagla, Jasjeet S; Nath, Biman B

    2016-01-01

    We investigate the relative importance of two galactic outflow suppression mechanisms : a) Cosmological infall of the intergalactic gas onto the galaxy, and b) the existence of a hot circumgalactic medium (CGM). Considering only radial motion, the infall reduces the speed of outflowing gas and even halts the outflow, depending on the mass and redshift of the galaxy. For star forming galaxies there exists an upper mass limit beyond which outflows are suppressed by the gravitational field of the galaxy. We find that infall can reduce this upper mass limit approximately by a factor of two (independent of the redshift). Massive galaxies ($\\gtrsim 10^{12} M_{\\odot}$) host large reservoir of hot, diffuse CGM around the central part of the galaxy. The CGM acts as a barrier between the infalling and outflowing gas and provides an additional source of outflow suppression. We find that at low redshifts ($z\\lesssim3.5$), the CGM is more effective than the infall in suppressing the outflows. Together, these two processes...

  17. Molecular Line Observations of the Tornado Nebula and its Eye

    CERN Document Server

    Lazendic, J S; Yusef-Zadeh, F; Wardle, M; Green, A; Whiteoak, J

    2003-01-01

    We present millimetre and NIR molecular-line observations of the Tornado nebula and its Eye. The observations were motivated by the presence of OH(1720 MHz) maser emission towards the nebula, believed to be an indicator of interaction between a supernova remnant and a molecular cloud. We found that the distribution of molecular gas around the Tornado complements its radio morphology, implying that the nebula's appearance has been influenced by the structure of the surrounding molecular gas. Our NIR H$_2$ observations revealed the presence of shocked molecular gas at the location where the nebula is expanding into the surrounding molecular cloud. It has been suggested that the Eye of the Tornado is related to the nebula on the basis of their apparent proximity. Our NIR and millimetre-line observations show that the two objects are not spatially related. Br $\\gamma$ line emission, in conjuction with IR data at longer wavelengths and high-resolution radio continuum observations, suggests that the Eye is a massiv...

  18. The discovery of a highly polarized bipolar nebula

    Science.gov (United States)

    Wolstencroft, Ramon D.; Scarrott, S. M.; Menzies, J.

    1989-01-01

    During a search for the optical counterparts of IRAS sources whose flux peaks at 25 microns, a small faint bipolar nebula was discovered in Monoceros at the position of IRAS 07131-0147. The CCD images display the object's considerable structure. The central star seems relatively free of closeby nebulosity: the two lobes have a bow-tie structure with those parts nearest to the star consisting of series of small knots. The outer parts of the lobes seem to be made up of filaments streaming away from knots. On the basis of its optical spectrum, the central star was classified as a M5-6 giant. In the IRAS color classification scheme of Van der Veen and Habing (1988), the central star is VIb which indicates that there are distinct hot and cold components of circumstellar dust and that the mass loss process may have temporarily abated. Therefore, it is proposed that the object is in the post main sequence stage of evolution and is a protoplanetary nebulae. Young protoplanetary nebulae have totally obscured central stars illuminating reflective lobes whereas older ones such as M2-9 have lobes seen in emission from gas ionized by the central hot star which is clearly visible. Since the central object of IRAS07131-0147 is a relatively unobscured late type star and the lobes are seen only by reflection, it is suggested that this nebula is a protoplanetary nebula in an evolutionary stage intermediate between that of CRL2688 and M2-9.

  19. Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region

    CERN Document Server

    Nielsen, K E; Weis, K; Gull, T R; Stahl, O; Bomans, D J

    2009-01-01

    We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae spectrum, and extends the previously presented analyses with the HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for element...

  20. Outflow and hot dust emission in broad absorption line quasars

    International Nuclear Information System (INIS)

    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 (βNIR) 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 βNIR 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 βNIR 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 βNIR 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 βNIR 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.

  1. Contribution of alluvial groundwater to the outflow of mountainous catchments

    Science.gov (United States)

    Käser, Daniel; Hunkeler, Daniel

    2016-02-01

    Alluvial aquifers in mountainous regions cover typically a limited area. Their contribution to catchment storage and outflow is rarely isolated; alluvial groundwater discharge under gauging stations is generally assumed negligible; and hydrological models tend to lump alluvial storage with other units. The role of alluvial aquifers remains therefore unclear: can they contribute significantly to outflow when they cover a few percent of catchment area? Should they be considered a dynamic storage unit or merely a transmission zone? We address these issues based on the continuous monitoring of groundwater discharge, river discharge (one year), and aquifer storage (6 months) in the 6 km2 alluvial system of a 194 km2 catchment. River and groundwater outflow were measured jointly through "coupled gauging stations." The contribution of alluvial groundwater to outflow was highest at the outlet of a subcatchment (52 km2), where subsurface discharge amounted to 15% of mean annual outflow, and 85% of outflow during the last week of a drought. In this period, alluvial-aquifer depletion supported 75% of the subcatchment outflow and 35% of catchment outflow—thus 3% of the entire catchment supported a third of the outflow. Storage fluctuations occurred predominantly in the aquifer's upstream part, where heads varied over 6 m. Not only does this section act as a significant water source, but storage recovers also rapidly at the onset of precipitation. Storage dynamics were best conceptualized along the valley axis, rather than across the more conventional riparian-channel transect. Overall the contribution of alluvial aquifers to catchment outflow deserves more attention.

  2. Herschel spectral mapping of the Helix nebula (NGC 7293): Extended CO photodissociation and OH+ emission

    OpenAIRE

    Etxaluze, M.; Cernicharo, J.; Goicoechea, J. R.; van Hoof, P. A. M.; Van de Steene, G. C.; Groenewegen, M. A. T.; Swinyard, B. M.; Barlow, M.J.; Matsuura, M.; Lim, T. L.; Pearson, C.; Polehampton, E. T.; Kerschbaum, F.; Lique, F.; Royer, P.

    2014-01-01

    Context. The Helix nebula (NGC 7293) is our closest planetary nebulae. Therefore, it is an ideal template for photochemical studies at small spatial scales in planetary nebulae. Aims. We aim to study the spatial distribution of the atomic and the molecular gas, and the structure of the photodissociation region along the western rims of the Helix nebula as seen in the submillimeter range with Herschel. Methods. We used five SPIRE FTS pointing observations to make atomic and molecular spectral ...

  3. Misalignment of Magnetic Fields and Outflows in Protostellar Cores

    CERN Document Server

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

    2012-01-01

    Theoretical models of star formation generally assume that bipolar outflows are parallel to the mean magnetic-field direction in protostellar cores. Here we present results of \\lambda1.3 mm dust polarization observations toward 16 nearby, low-mass protostars, mapped with ~2.5" resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. If one assumes that outflows emerge along the rotation axes of circumstellar disks, then our results imply that these disks are not aligned with the fields in the cores from which they formed.

  4. Gravitational Microlensing and the Structure of Quasar Outflows

    CERN Document Server

    Chelouche, D

    2005-01-01

    We show that invaluable information on the structure of quasar outflows can be obtained by considering microlensing (ML) induced variability of absorption line troughs in lensed quasars. Depending on the structure and geometry of the outflowing gas, such extrinsic line variability can be manifested as changes to the equivalent width of the line as well as line profile distortions. Here we consider several physically distinct outflow models, having very similar spectral predictions, and show how ML induced absorption line variability can be used to distinguish between them. The merits of future systematic studies of these effects are exemplified.

  5. Dissipation in Relativistic Outflows: A Multisource Overview

    CERN Document Server

    Thompson, Christopher

    2013-01-01

    Relativistically expanding sources of X-rays and gamma-rays cover an enormous range of (central) compactness and Lorentz factor. The underlying physics is discussed, with an emphasis on how the dominant dissipative mode and the emergent spectrum depend on these parameters. Photons advected outward from high optical depth are a potentially important source of Compton seeds. Their characteristic energy is bounded below by ~1 MeV in pair-loaded outflows of relatively low compactness, and remains near ~1 MeV at very high compactness and low matter loading. This is compared with the characteristic energy of O(1) MeV observed in the rest frame spectra of many sources, including gamma-ray bursts, OSSE jet sources, MeV Blazars, and the intense initial 0.1 s pulse of the March 5 event. Additional topics discussed include the feedback of pair creation on electron heating and the formation of non-thermal spectra, their effectiveness at shielding the dissipative zone from ambient photons, direct Compton damping of irregu...

  6. Radiation Transport for Explosive Outflows: Opacity Regrouping

    CERN Document Server

    Wollaeger, Ryan T

    2014-01-01

    Implicit Monte Carlo (IMC) and Discrete Diffusion Monte Carlo (DDMC) are methods used to stochastically solve the radiative transport and diffusion equations, respectively. These methods combine into a hybrid transport-diffusion method we refer to as IMC-DDMC. We explore a multigroup IMC-DDMC scheme that, in DDMC, combines frequency groups with sufficient optical thickness. We term this procedure "opacity regrouping". Opacity regrouping has previously been applied to IMC-DDMC calculations for problems in which the dependence of the opacity on frequency is monotonic. We generalize opacity regrouping to non-contiguous groups and implement this in \\supernu, a code designed to do radiation transport in high-velocity outflows with non-monotonic opacities. We find that regrouping of non-contiguous opacity groups generally improves the speed of IMC-DDMC radiation transport. We present an asymptotic analysis that informs the nature of the Doppler shift in DDMC groups and summarize the derivation of the Gentile-Fleck ...

  7. Optically thick outflows in ultraluminous supersoft sources

    CERN Document Server

    Urquhart, Ryan

    2015-01-01

    Ultraluminous supersoft sources (ULSs) are defined by a thermal spectrum with colour temperatures ~0.1 keV, bolometric luminosities ~ a few 10^39 erg/s, and almost no emission above 1 keV. It has never been clear how they fit into the general scheme of accreting compact objects. To address this problem, we studied a sample of seven ULSs with extensive Chandra and XMM-Newton coverage. We find an anticorrelation between fitted temperatures and radii of the thermal emitter, and no correlation between bolometric luminosity and radius or temperature. We compare the physical parameters of ULSs with those of classical supersoft sources, thought to be surface-nuclear-burning white dwarfs, and of ultraluminous X-ray sources (ULXs), thought to be super-Eddington stellar-mass black holes. We argue that ULSs are the sub-class of ULXs seen through the densest wind, perhaps an extension of the soft-ultraluminous regime. We suggest that in ULSs, the massive disk outflow becomes effectively optically thick and forms a large ...

  8. Recombination Lines of CII in the Spectra of Planetary Nebulae

    CERN Document Server

    Sochi, Taha

    2010-01-01

    The current report presents the work carried out by the author to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. One of these targets contains 9 atomic terms while the other contains 26 terms. For each one of these targets, theoretical data concerning bound and autoionizing states were generated in the intermediate coupling approximation by R-matrix and Autostructure codes and compared to experimental data. The comparison revealed very good agreement. These theoretical data were then used to generate emissivity data and compare it to the carbon recombination lines found in the observational line list of Zhang et al [2005] on the planetary nebula NGC 7027. The main tool used in this analysis is the `Emissivity' code which is a prog...

  9. Revised predictions of neutrino fluxes from Pulsar Wind Nebulae

    CERN Document Server

    Di Palma, Irene; Amato, Elena

    2016-01-01

    Several Pulsar Wind Nebulae (PWNe) have been detected in the TeV band in the last decade.The TeV emission is typically interpreted in a purely leptonic scenario, but this usually requires that the magnetic field in the Nebula be much lower than the equipartition value and the assumption of an enhanced target radiation at IR frequencies. In this work we consider the possibility that, in addition to the relativistic electrons, also relativistic hadrons are present in these nebulae. Assuming that part of the emitted TeV photons are of hadronic origin, we compute the associated flux of $\\sim 1-100$ TeV neutrinos. We use the IceCube non detection to put constraints on the fraction of TeV photons that might be contributed by hadrons and estimate the number of neutrino events that can be expected from these sources in ANTARES and in KM3Net.

  10. Optical identification of dust within the Crab Nebula's filaments

    International Nuclear Information System (INIS)

    Optical continuum images of the Crab Nebula are presented which reveal numerous, small dark spots across the face of the Crab's amorphous synchrotron nebula. These spots range in size from being unresolved at 0.8-arcsec resolution to about 5 arcsec, exhibit Delta(m)4470 = 0.08-0.44, and are most visible in the shorter-wavelength continuum images. Comparisons with images taken using interference filters centered on various emission lines indicate that these dark features are coincident with forbidden O I, C I, and S II bright cores of selected filaments. This positional coincidence plus a wavelength dependence similar to that exhibited by conventional interstellar dust establishes the presence of dust within at least some of the Crab Nebula's filaments. 26 refs

  11. Mass-loading of bow shock pulsar wind nebulae

    CERN Document Server

    Morlino, G; Vorster, M

    2016-01-01

    We investigate the dynamics of bow shock nebulae created by pulsars moving supersonically through a partially ionized interstellar medium. A fraction of interstellar neutral hydrogen atoms penetrating into the tail region of a pulsar wind will undergo photo-ionization due to the UV light emitted by the nebula, with the resulting mass loading dramatically changing the flow dynamics of the light leptonic pulsar wind. Using a quasi 1-D hydrodynamic model of relativistic flow we find that if a relatively small density of neutral hydrogen, as low as $10^{-4}$ cm$^{-3}$, penetrate inside the pulsar wind, this is sufficient to strongly affect the tail flow. Mass loading leads to the fast expansion of the pulsar wind tail, making the tail flow intrinsically non-stationary. The shapes predicted for the bow shock nebulae compare well with observations, both in H$\\alpha$ and X-rays.

  12. The surprising Crab pulsar and its nebula: a review

    International Nuclear Information System (INIS)

    The Crab nebula and its pulsar (referred to together as ‘the Crab’) have historically played a central role in astrophysics. True to this legacy, several unique discoveries have been made recently. The Crab was found to emit gamma-ray pulsations up to energies of 400 GeV, beyond what was previously expected from pulsars. Strong gamma-ray flares, of durations of a few days, were discovered from within the nebula, while the source was previously expected to be stable in flux on these time scales. Here we review these intriguing and suggestive developments. In this context we give an overview of the observational properties of the Crab and our current understanding of pulsars and their nebulae. (review article)

  13. Indirect measurement of Delta outflow using ultrasonic velocity meters and comparison with mass-balance calculated outflow

    Science.gov (United States)

    Oltmann, Richard N.

    1998-01-01

    A measurement of the quantity of water flowing from the Sacramento-San Joaquin Delta into Suisun Bay (Delta outflow) has been desired by those studying and managing the San Francisco Bay/Delta estuary since the 1920s.  Historically, Delta outflow has been estimated using a mass-balance calculation that uses measured Delta inflows and exports, and imprecise estimates of consumptive use for the approximately 2,000 small agricultural diversions with the Delta.  The DWR has estimated Delta outflow for 1929 to present using the computer program DAYFLOW.

  14. A MegaCam Survey of Outer Halo Satellites. VI: The Spatially Resolved Star Formation History of the Carina Dwarf Spheroidal Galaxy

    CERN Document Server

    Santana, Felipe A; de Boer, T J L; Simon, Joshua D; Geha, Marla; Côté, Patrick; Guzmán, Andrés E; Stetson, Peter; Djorgovski, S G

    2016-01-01

    We present the spatially resolved star formation history (SFH) of the Carina dwarf spheroidal galaxy, obtained from deep, wide-field g,r imaging and a metallicity distribution from the literature. Our photometry covers $\\sim2$ deg$^2$, reaching up to $\\sim10$ times the half-light radius of Carina with a completeness higher than $50\\%$ at $g\\sim24.5$, more than one magnitude fainter than the oldest turnoff. This is the first time a combination of depth and coverage of this quality has been used to derive the SFH of Carina, enabling us to trace its different populations with unprecedented accuracy. We find that Carina's SFH consists of two episodes well separated by a star formation temporal gap. These episodes occurred at old ($>10$ Gyr) and intermediate ($2$-$8$ Gyr) ages. Our measurements show that the old episode comprises the majority of the population, accounting for $54\\pm5\\%$ of the stellar mass within $1.3$ times the King tidal radius, while the total stellar mass derived for Carina is $1.60\\pm0.09\\tim...

  15. Nucleosynthesis in Outflows from the Inner Regions of Collapsars

    CERN Document Server

    Pruet, J; Hoffman, R D; Pruet, Jason; Thompson, Todd

    2004-01-01

    We consider nucleosynthesis in outflows originating from the inner regions of viscous accretion disks formed after the collapse of a rotating massive star. We show that wind-like outflows driven by viscous and neutrino heating can efficiently synthesize Fe-group elements moving at near-relativistic velocities. The mass of 56Ni synthesized and the asymptotic velocities attained in our calculations are in accord with those inferred from observations of SN1998bw and SN2003dh. These steady wind-like outflows are generally proton rich, characterized by only modest entropies, and consequently synthesize essentially nothing heavier than the Fe-group elements. We also discuss bubble-like outflows resulting from rapid energy deposition in localized regions near or in the accretion disk. These intermittent ejecta emerge with low electron fraction and are a promising site for the synthesis of the A=130 r-process peak elements.

  16. Effects of Outflow Area on Pool Boiling in Vertical Annulus

    International Nuclear Information System (INIS)

    To identify the effects of an outflow area on pool boiling heat transfer in a vertical annulus, three different flow recreates were studied experimentally. For the test, a heated tube of smooth stainless steel and water at atmospheric pressure were used. Both annuli with open and closed bottoms were considered. To validate the effects of the outflow area on the heat transfer, the results of the annulus with the reactors were compared with the data for the plain annulus without the reactors. The reduction of the outflow area ultimately results in a decrease in the heat transfer. As the outflow area is very small, a slight increase in heat transfer is also observed. The major cause of this tendency is explained as the difference in the intensity of liquid agitation cause by the movement of coalesced bubbles. It is identified that the convective flow, pulsating flow, and evaporative mechanism are considered as the important mechanisms

  17. Estimation of cold plasma outflow during geomagnetic storms

    CERN Document Server

    Haaland, S; André, M; Maes, L; Baddeley, L; Barakat, A; Chappell, R; Eccles, V; Johnsen, C; Lybekk, B; Li, K; Pedersen, A; Schunk, R; Welling, D

    2016-01-01

    Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic observations and a novel technique to estimate the flux and total outflow during the various phases of geomagnetic storms. Our results indicate large variations in both outflow rates and transport throughout the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized ...

  18. About the seasonal and fortnightly variabilities of the Mediterranean outflow

    Directory of Open Access Journals (Sweden)

    C. Millot

    2011-06-01

    Full Text Available CTD time series from the HYDRO-CHANGES programme and INGRES projects have been collected simultaneously (2004–2008 on the shelf of Morocco and at the sills of Camarinal and Espartel in the strait of Gibraltar. They provide information that supports results recently obtained from the analysis of the two former time series, as well as from a reanalysis of GIBEX CTD profiles (1985–1986. The outflow of Mediterranean Waters, which does not show a clear seasonal variability before entering the strait, strongly mixes within the strait, due mainly to the internal tide, with the seasonally variable inflow of Atlantic Water. The outflow thus gets marked seasonal and fortnightly variabilities within the strait. Furthermore, since the outflowing waters entering the strait display marked spatial heterogeneity and long-term temporal variabilities, accurately predicting the characteristics of the Mediterranean outflow into the North Atlantic Ocean appears almost impossible.

  19. A radio nebula associated with Circinus X-1

    Science.gov (United States)

    Haynes, R. F.; Komesaroff, M. M.; Jauncey, D. L.; Caswell, J. L.; Milne, D. K.; Kesteven, M. J.; Wellington, K. J.; Preston, R. A.

    1986-01-01

    An investigation of the variable source Circinus X-1 is reported that reveals that this eccentric double-star system is embedded in a nebula of steady radio emission extending over several parsecs, orders of magnitude larger than the binary stellar system responsible for the fluctuating component of emission. This is in marked constrast to most X-ray binaries, where an envelope of radio emission in conspicuously absent. There are difficulties in explaining the emission, but analogies with SS433 and the Crab nebula suggest possible models.

  20. A radio search for planetary nebulae near the galactic center

    International Nuclear Information System (INIS)

    Because of galactic center is a hostile environment, and because planetaries are weak radio emitters, it is not clear a priori that one expects to detect any planetary nebulae at all in the nuclear region of the Galaxy. Therefore the expected lifetime and flux density distribution of galactic center nebulae is considered. The principal observational results from the Westerbork data, and the results of some pilot observations with the Very Large Array, which were intended to distinguish planetaries from other radio sources on an individual basis are given. (Auth.)

  1. Planetary nebulae in 2014: A review of research

    CERN Document Server

    Zijlstra, Albert

    2015-01-01

    Planetary nebulae had a double anniversary in 2014, 250 year since their discovery and 150 year since the correct spectroscopic identification. This paper gives an overview of planetary nebula research published in 2014. Topics include surveys, central stars, abundances, morphologies, magnetic fields, stellar population and galactic dynamics. An important continuing controversy is the discrepancy between recombination-line and forbidden-line abundances. A new controversy is the relation between symbiotic stars and [WC] stars. PN of the year is undoubtedly CRL 618, with papers on its binary symbiotic/[WC] nucleus, rapid stellar evolution, expanding jets and magnetic fields.

  2. s-process Enrichment in the Planetary Nebula NGC 3918

    CERN Document Server

    García-Rojas, J; Luridiana, V; Sterling, N C; Morisset, C

    2014-01-01

    We present deep, high-resolution (R~40000) UVES at VLT spectrophotometric data of the planetary nebula NGC 3918. This is one of the deepest spectra ever taken of a planetary nebula. We have identified and measured more than 700 emission lines and, in particular, we have detected very faint lines of several neutron-capture elements (s-process elements: Kr, Xe and Rb) that enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up.

  3. Symmetric vs. asymmetric planetary nebulae: morphology and chemical abundances

    CERN Document Server

    Maciel, W J

    2010-01-01

    We analyse a large sample of galactic planetary nebulae based on their chemical composition and morphology. A recent morphological classification system is adopted, and several elements are considered, namely He, N, O, S, Ar, Ne, and C in order to investigate the correlations involving these elements and the different PN types. Special emphasis is given to the differences between symmetric (round or elliptical) nebulae and those that present some degree of asymmetry (bipolars or bipolar core objects). The results are compared with previous findings both for PN in the Galaxy and in the Magellanic Clouds.

  4. The shape of the LoTr 5 planetary nebula

    OpenAIRE

    Brosch, Noah; Hoffman, Yehuda

    1998-01-01

    We observed the large and faint planetary nebula (PN) around IN Com in H-alpha and [NII] light with a coronagraphic CCD device on the Wise Observatory reflector blocking the light from the central star. Our goal was to provide a second image of the object with which to confirm the features seen in the only published photograph from the paper reporting the discovery of this object. The nebula is extremely faint, but a combination of images totalling ~one and a half hours of exposure shows it f...

  5. Observations of the Crab Nebula with Early HAWC Data

    CERN Document Server

    Greus, Francisco Salesa

    2015-01-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a TeV gamma-ray detector, completed in early 2015. HAWC started science operations in August 2013 with a third of the detector taking data. Several known gamma-ray sources have already been detected with the first HAWC data. Among these sources, the Crab Nebula, the brightest steady gamma-ray source at very high energies in our Galaxy, has been detected with high significance. In this contribution I will present the results of the observations of the Crab Nebula with HAWC, including time variability, and the detector performance based on early data.

  6. Facilitating NASA Earth Science Data Processing Using Nebula Cloud Computing

    Science.gov (United States)

    Pham, Long; Chen, Aijun; Kempler, Steven; Lynnes, Christopher; Theobald, Michael; Asghar, Esfandiari; Campino, Jane; Vollmer, Bruce

    2011-01-01

    Cloud Computing has been implemented in several commercial arenas. The NASA Nebula Cloud Computing platform is an Infrastructure as a Service (IaaS) built in 2008 at NASA Ames Research Center and 2010 at GSFC. Nebula is an open source Cloud platform intended to: a) Make NASA realize significant cost savings through efficient resource utilization, reduced energy consumption, and reduced labor costs. b) Provide an easier way for NASA scientists and researchers to efficiently explore and share large and complex data sets. c) Allow customers to provision, manage, and decommission computing capabilities on an as-needed bases

  7. Observing by hand sketching the nebulae in the nineteenth century

    CERN Document Server

    Nasim, Omar W

    2014-01-01

    Today we are all familiar with the iconic pictures of the nebulae produced by the Hubble Space Telescope's digital cameras. But there was a time, before the successful application of photography to the heavens, in which scientists had to rely on handmade drawings of these mysterious phenomena.           Observing by Hand sheds entirely new light on the ways in which the production and reception of handdrawn images of the nebulae in the nineteenth century contributed to astronomical observation. Omar W. Nasim investigates hundreds of unpublished observing books and paper records from six ninete

  8. An Analysis of Spectra in the Red Rectangle Nebula

    Indian Academy of Sciences (India)

    Frédéric Zagury

    2005-12-01

    This paper presents an analysis of a series of spectra in the Red Rectangle nebula. Only the reddest part of the spectra can safely be attributed to light from the nebula, and indicates Rayleigh scattering by the gas, in conformity with the large angles of scattering involved and the proximity of the star. In the blue, light from HD 44179, refracted or scattered in the atmosphere, dominates the spectra. This paper questions the reliability of ground-based broad-band spectra of extended objects in the blue.

  9. Fe/Ni ratio in the Ant Nebula Mz 3

    CERN Document Server

    Zhang, Y

    2006-01-01

    We have analyzed the [Fe II] and [Ni II] emission lines in the bipolar planetary nebula Mz~3. We find that the [Fe II] and [Ni II] lines arise exclusively from the central regions. Fluorescence excitation in the formation process of these lines is negligible for this low-excitation nebula. From the [Fe II]/[Ni II] ratio, we obtain a higher Fe/Ni abundance ratio with respect to the solar value. The current result provides further supporting evidence for Mz 3 as a symbiotic Mira.

  10. Ultra Fast Outflows: Galaxy-Scale Active Galactic Nucleus Feedback

    OpenAIRE

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

    2012-01-01

    We show, using global 3D grid-based hydrodynamical simulations, that Ultra Fast Outflows (UFOs) from Active Galactic Nuclei (AGN) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous hot hydrostatic medium. The outflow floods through the inter-cloud channels, sweeps up the hot ISM, and ablates and disperses the dense cl...

  11. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    Science.gov (United States)

    Cappi, M.; Tombesi, F.; Giustini, M.

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  12. Searching for molecular outflows in Hyper-Luminous Infrared Galaxies

    OpenAIRE

    D. Calderón; Bauer, F. E.; Veilleux, S; Graciá-Carpio, J; Sturm, E; P. Lira; Schulze, S.; Kim, S.

    2016-01-01

    We present constraints on the molecular outflows in a sample of five Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet at 119 {\\mu}m. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indi...

  13. Characterization of molecular outflows in the substellar domain

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-01

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

  14. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    CERN Document Server

    Cappi, M; Giustini, M

    2013-01-01

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  15. Identifying the Main Driver of Active Region Outflows

    Science.gov (United States)

    Baker, D.; van Driel-Gesztelyi, L.; Mandrini, C. H.; Démoulin, P.; Murray, M. J.

    2012-08-01

    Hinode's EUV Imaging Spectrometer (EIS) has discovered ubiquitous outflows of a few to 50 km s-1 from active regions (ARs). The characteristics of these outflows are very curious in that they are most prominent at the AR boundary and appear over monopolar magnetic areas. They are linked to strong non-thermal line broadening and are stronger in hotter EUV lines. The outflows persist for at least several days. Whereas red-shifted down flows observed in AR closed loops are well understood, to date there is no general consensus for the mechanism(s) driving blue-shifted AR-related outflows. We use Hinode EIS and X-Ray Telescope observations of AR 10942 coupled with magnetic modeling to demonstrate for the first time that the outflows originate from specific locations of the magnetic topology where field lines display strong gradients of magnetic connectivity, namely quasi-separatrix layers (QSLs), or in the limit of infinitely thin QSLs, separatrices. The strongest AR outflows were found to be in the vicinity of QSL sections located over areas of strong magnetic field. We argue that magnetic reconnection at QSLs, separating closed field lines of the AR and either large-scale externally connected or ‘open’ field lines, is a viable mechanism for driving AR outflows which are potentially sources of the slow solar wind. In fact, magnetic reconnection along QSLs (including separatricies) is the first theory to explain the most puzzling characteristics of the outflows, namely their occurrence over monopolar areas at the periphery of ARs and their longevity.

  16. Capital Outflow Controls and Income Distribution in Malaysia

    OpenAIRE

    Jarita Duasa

    2008-01-01

    The study seeks to analyze the impact of capital outflow controls, imposed by Malaysian government on September 1998, on income distribution. Regression analysis using OLS (Ordinary Least Square), 2SLS (Two Stages Least Square) and GMM (Generalised Method of Moment) methods of estimation reveals that the capital outflow controls reduce inequality of income distribution in the country. The controls are believed to result in improvement of export-led industries, through devaluation from control...

  17. Advection-Dominated Accretion with Infall and Outflows

    OpenAIRE

    Beckert, Thomas

    2000-01-01

    We present self-similar solutions for advection-dominated accretion flows with radial viscous force in the presence of outflows from the accretion flow or infall. The axisymmetric flow is treated in variables integrated over polar sections and the effects of infall and outflows on the accretion flow are parametrised for possible configurations compatible with the self-similar solution. We investigate the resulting accretion flows for three different viscosity laws and derive upper limits on t...

  18. Fast outflows and star formation quenching in quasar host galaxies

    Science.gov (United States)

    Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

    2016-06-01

    Negative feedback from active galactic nuclei (AGN) is considered a key mechanism in shaping galaxy evolution. Fast, extended outflows are frequently detected in the AGN host galaxies at all redshifts and luminosities, both in ionised and molecular gas. However, these outflows are only potentially able to quench star formation, and we are still lacking decisive evidence of negative feedback in action. Here we present observations obtained with the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) H- and K-band integral-field of two quasars at z ~ 2.4 that are characterised by fast, extended outflows detected through the [Oiii]λ5007 line. The high signal-to-noise ratio of our observations allows us to identify faint narrow (FWHManti-correlated with the fast outflows. The ionised outflows therefore appear to be able to suppress star formation in the region where the outflow is expanding. However, the detection of narrow spatially extended Hα emission indicates star formation rates of at least ~50-90 M⊙ yr-1, suggesting either that AGN feedback does not affect the whole galaxy or that many feedback episodes are required before star formation is completely quenched. On the other hand, the narrow Hα emission extending along the edges of the outflow cone may also lead also to a positive feedback interpretation. Our results highlight the possible double role of galaxy-wide outflows in host galaxy evolution. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, P.ID: 086.B-0579(A) and 091.A-0261(A).The reduced data cubes 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/591/A28

  19. Tracing outflows in the AGN forbidden region with SINFONI

    CERN Document Server

    Kakkad, D; Padovani, P; Cresci, G; Husemann, B; Carniani, S; Brusa, M; Lamastra, A; Lanzuisi, G; Piconcelli, E; Schramm, M

    2016-01-01

    AGN driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were maximum. Radiatively driven outflows are therefore believed to be common during this epoch. We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially-resolved kinematics of the [OIII]5007 line in two targets which reveal the morphology and spatial extension of the outflows. We present J and H+K band SINFONI observations of 5 AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km/s) and kiloparsec scale extended ionized outflows in at...

  20. The Implications of Extreme Outflows from Extreme Starbursts

    Science.gov (United States)

    Heckman, Timothy M.; Borthakur, Sanchayeeta

    2016-05-01

    Interstellar ultraviolet absorption lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We exploit the wide dynamic range provided by this new sample to determine scaling relations of outflow velocity with galaxy stellar mass (M *), circular velocity, star formation rate (SFR), SFR/M *, and SFR/area. We argue that these results can be accommodated within the general interpretational framework we previously advocated, in which a population of ambient interstellar or circumgalactic clouds is accelerated by the combined forces of gravity and the momentum flux from the starburst. We show that this simple physical picture is consistent with both the strong cosmological evolution of galactic outflows in typical star-forming galaxies and the paucity of such galaxies with spectra showing inflows. We also present simple parameterizations of these results that can be implemented in theoretical models and numerical simulations of galaxy evolution.