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We have compared Monte Carlo photoionization models of H II regions with a uniform density distribution with models with the same central stars and chemical compositions but with 3-D hierarchical clumps. We compare the abundances of He, N,…

Astrophysics · Physics 2009-11-10 John S. Mathis , Kenneth Wood

We report results from a FUSE survey of interstellar molecular hydrogen (H2) along 45 sight lines to AGN at high Galactic latitudes (|b| > 20 degrees). Most (39 of 45) of the sight lines show detectable Galactic H2 absorption from Lyman and…

Astrophysics · Physics 2009-11-13 Kristen Gillmon , J. Michael Shull , Jason Tumlinson , Charles Danforth

Context. Departures from local thermodynamic equilibrium (LTE) distort the calcium abundance derived from stellar spectra in various ways, depending on the lines used and the stellar atmospheric parameters. The collection of atomic data…

Solar and Stellar Astrophysics · Physics 2019-03-13 Y. Osorio , K. Lind , P. S. Barklem , C. Allende Prieto , Oleg Zatsarinny

We list and analyze H I absorption lines at redshifts 2 < z < 4 with column density (12 < log(N_HI) < 19) in 40 high-resolutional (FWHM = 8.0 km/s) quasar spectra obtained with the Keck+HIRES. We de-blend and fit all H I lines within 1,000…

Astrophysics · Physics 2008-11-26 T. Misawa , D. Tytler , M. Iye , D. Kirkman , N. Suzuki , D. Lubin , N. Kashikawa

Using UV spectra obtained with FUSE, HST, and/or IUE, we determine interstellar column densities of 12CO, 13CO, and/or C_2 for ten Galactic sight lines with 0.37<E(B-V)<0.72. The N(CO)/N(H_2) ratio varies over a factor of 100 in this…

Astrophysics · Physics 2009-05-29 P. Sonnentrucker , D. E. Welty , J. A. Thorburn , D. G. York

We present an extensive analysis of the gas-phase abundances and depletion behaviors of neutron-capture elements in the interstellar medium (ISM). Column densities (or upper limits to the column densities) of Ga II, Ge II, As II, Kr I, Cd…

Astrophysics of Galaxies · Physics 2018-06-07 Adam M. Ritchey , Steven R. Federman , David L. Lambert

We study metal depletion due to dust in the interstellar medium (ISM) to infer the properties of dust grains and characterize the metal and dust content of galaxies, down to low metallicity and intermediate redshift z. We provide metal…

We analyse absorption characteristics and physical conditions of extraplanar intermediate- and high-velocity gas to study the distribution of the neutral and weakly ionised Milky Way halo gas and its relevance for the evolution of the Milky…

Astrophysics · Physics 2015-05-13 N. Ben Bekhti , P. Richter , T. Westmeier , M. T. Murphy

We present a reanalysis of the HeII Lyman alpha absorption towards the quasars HS1700+6416 and HE2347-4342 using new high S/N, optical observations. An alternative analysis method is applied, which fits the high quality, optical HI data…

Astrophysics · Physics 2009-11-11 C. Fechner , D. Reimers

For the first time we have combined dispersion measures and emission measures towards 38 pulsars at KNOWN distances from which we derived the mean electron density in clouds, N_c, and their volume filling factor, F_v, averaged along the…

Astrophysics · Physics 2009-11-13 Elly M. Berkhuijsen , Peter Mueller

We present spectrophotometry of 12 Galactic and 3 Magellanic Cloud planetary nebulae (PNe). Nine of the Galactic PNe were observed by scanning the slit across the PN. We use the fluxes of collisionally excited lines (CELs) to derive…

Astrophysics · Physics 2009-11-07 Y. G. Tsamis , M. J. Barlow , X. -W. Liu , I. J. Danziger , P. J. Storey

We measured $^{35}$Cl abundances in 52 M giants with metallicities between -0.5 $<$ [Fe/H] $<$ 0.12. Abundances and atmospheric parameters were derived using infrared spectra from CSHELL on the IRTF and from optical echelle spectra. We…

Solar and Stellar Astrophysics · Physics 2021-03-16 Z. G. Maas , C. A. Pilachowski

We show that the study of the Calcium depletion is a valid an highly sensitive method for investigating the chemical and physical history of the very extended ionized nebulae seen around radio galaxies (EELR), massive ellipticals and…

Astrophysics · Physics 2007-05-23 M. Villar-Martin , L. Binette

In this paper we use a number of observations to construct an integrated picture of the ionisation in the interiors of quiescent warm opaque interstellar clouds and in the intercloud medium (ICM) outside dense HII regions and hot dilute…

Astrophysics · Physics 2009-10-30 D. W. Sciama

We analyze high-resolution UV spectra of the Mg II h and k lines for 18 members of the Hyades Cluster to study inhomogeneity along these proximate lines of sight. The observations were taken by the Space Telescope Imaging Spectrograph…

Astrophysics · Physics 2009-11-06 Seth Redfield , Jeffrey L. Linsky

We have used archival far-ultraviolet spectra from observations made by HST/STIS and FUSE to determine the column densities and rotational excitation temperatures for CO and H2, respectively, along the lines of sight to 23 Galactic O and B…

Astrophysics · Physics 2009-01-19 Eric B. Burgh , Kevin France , Stephan R. McCandliss

Using archival Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) data, we have assembled a survey of eight sightlines through high-velocity cloud Complex C. Abundances of the observed ion species vary…

Astrophysics · Physics 2009-11-07 J. A. Collins , J. M. Shull , M. L. Giroux

The composition and physical properties of several local clouds, including the Local Interstellar Cloud (LIC) in which the Sun is embedded, are derived from absorption features in the UV spectrum of the star epsilon CMa. We derive…

Astrophysics · Physics 2009-10-31 Cecile Gry , Edward B. Jenkins

Absorption features Ca II NIR and Ca II H&K of type Ia supernovae (SNe Ia) are characterized by their strong high-velocity features (HVFs). We find that, for these two features of calcium there is a puzzling anti-correlation between the…

High Energy Astrophysical Phenomena · Physics 2024-11-26 Xulin Zhao

We report on new FUSE far-UV spectroscopy of the most metal-poor blue compact dwarf galaxy I Zw 18. The new data represent an improvement over previous FUSE spectra by a factor of 1.7 in the signal-to-noise. Together with a larger spectral…

Astrophysics · Physics 2009-11-07 A. Aloisi , S. Savaglio , T. M. Heckman , C. G. Hoopes , C. Leitherer , K. R. Sembach
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