- ID:
- ivo://CDS.VizieR/J/ApJS/140/143
- Title:
- HST FOS spectral atlas
- Short Name:
- J/ApJS/140/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed the absorption line spectra of all quasars observed with the high-resolution gratings of the Faint Object Spectrograph on board the Hubble Space Telescope. We examined 788 spectra for 334 quasars and present line lists and identifications of absorption lines in the spectra of 271 of them. Analysis of the statistics of the Ly{alpha} and metal absorption systems are presented in companion papers. The data and several analysis products are available on the authors' Web site, http://lithops.as.arizona.edu/~jill/QuasarSpectra .
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- ID:
- ivo://CDS.VizieR/J/ApJ/513/168
- Title:
- HST observations of carbon in spiral galaxies
- Short Name:
- J/ApJ/513/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the gas-phase abundance ratio C/O in six H II regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet spectroscopy using the Faint Object Spectrograph on the Hubble Space Telescope. The ratios of C to O increase systematically with O/H in both galaxies, from log(C/O){~=}-0.8 at log(O/H){~=}-4.0 to log(C/O){~=}-0.1 at log(O/H){~=}-3.4. C/N shows no correlation with O/H. The rate of increase of C/O is somewhat uncertain because of uncertainty as to the appropriate UV reddening law and uncertainty in the metallicity dependence on grain depletions. However, the trend of increasing C/O with O/H is clear, confirming and extending the trend in C/O indicated previously from observations of irregular galaxies. Our data indicate that the radial gradients in C/H across spiral galaxies are steeper than the gradients in O/H. Comparing the data to chemical-evolution models for spiral galaxies shows that models in which the massive star yields do not vary with metallicity predict radial C/O gradients that are much flatter than the observed gradients.
- ID:
- ivo://CDS.VizieR/J/ApJS/122/355
- Title:
- Properties of low z QSO absorption systems
- Short Name:
- J/ApJS/122/355
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (Partial): We examine the clustering properties of low-redshift Ly{alpha} and heavy-element QSO absorption line systems seen in the spectra of 13 QSOs at the Galactic poles. This is the densest sample of ~1 degree separated QSOs observed spectroscopically with the Hubble Space Telescope to date. At the median redshift of the Ly{alpha} sample (z{=~}0.7), the QSO lines of sight are separated on transverse scales from about 15 to 200h^-1^Mpc (q_0_=0.5, H=100h.km/s/Mpc), allowing the three-dimensional clustering of the absorbers to be examined on those scales. The Galactic poles are also regions where relatively deep and wide-field galaxy redshift surveys have taken place, so the distributions of galaxies and Ly{alpha} systems can be compared within the same volume of space. There are 545 total absorption lines detected in the complete sample from 13 QSOs. We identify 307 Ly{alpha} systems, of which 18 contain heavy-element lines. We confirm the relatively slow redshift number density evolution for Ly systems at z{<=}1. There are also five likely C IV doublets in our sample, for which the Ly{alpha} line is not accessible.
