- ID:
- ivo://CDS.VizieR/J/ApJ/499/112
- Title:
- HST CFRS and LDSS redshift surveys. I.
- Short Name:
- J/ApJ/499/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Hubble Space Telescope images of a complete sample of 341 galaxies drawn from the Canada-France Redhsift Survey (CFRS) and Low-Dispersion Survey Spectrograph (LDSS) ground-based redshift surveys. In this, the first paper in the series, each galaxy has been morphologically classified according to a scheme similar to that developed for the Medium Deep Survey. We discuss the reproducibility of these classifications and quantify possible biases that may arise from various redshift-dependent effects. We then discuss automated classifications of the sample and conclude, from several tests, that we can expect an apparent migration with redshift to later Hubble types that corresponds to a misclassification in our adopted machine classification system of ~24%+/-11 of the true "spirals" as "peculiars" at a redshift z~=0.9. After allowing for such biases, the redshift distribution for normal spirals, together with their luminosity function derived as a function of redshift, indicates approximately 1mag of luminosity evolution in B_AB_ by z~=1. The elliptical sample is too small for precise evolutionary constraints. However, we find a substantial increase in the proportion of galaxies with irregular morphology at large redshift from 9%+/-3% for 0.3<=z<=0.5 to 32%+/-12% for 0.7<=z<=0.9. These galaxies also appear to be the dominant cause of the rapid rise with redshift in the blue luminosity density identified in the redshift surveys. Although galaxies with irregular morphology may well comprise a mixture of different physical systems and might not correspond to present-day irregulars, it is clear that the apparently declining abundance and luminosities of our distant "irregulars" holds an important key to understanding recent evolution in the star formation history of normal galaxies.
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- 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 .
- 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/ApJ/540/1016
- Title:
- K-band & NICMOS photometry of Trapezium Cluster
- Short Name:
- J/ApJ/540/1016
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained images of the Trapezium Cluster (140"x140"; 0.3pc x 0.3pc) with the Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data with new ground-based K-band spectra (R=800) and existing spectral types and photometry, we have constructed an H-R diagram and used it and other arguments to infer masses and ages.
- ID:
- ivo://CDS.VizieR/J/ApJ/524/536
- Title:
- Nearby Ly{alpha} quasar absorbers
- Short Name:
- J/ApJ/524/536
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopy of 10 quasars obtained with the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) is presented. In the 10 sight lines, we detect 357 absorption lines above a significance level of 3{sigma} and 272 lines above a significance level of 4.5{sigma}. Automated software is used to detect and identify the lines, almost all of which are unresolved at the GHRS G140L resolution of 200km/s. After identifying Galactic lines, intervening metal lines, and higher order Lyman lines, we are left with 139 Ly{alpha} absorbers in the redshift range 0<z<0.22 (lines within 900km/s of geocoronal Ly{alpha} are not selected). These diffuse hydrogen absorbers have column densities that are mostly in the range 10^13^-10^15^cm^-2^ for an assumed Doppler parameter of 30km/s. The number density of lines above a rest equivalent width of 0.24{AA}, dN/dz=38.3{+/-}5.3, agrees well with the measurement from the Quasar Absorption-Line Key Project. There is marginal evidence for cosmic variance in the number of absorbers detected among the 10 sight lines.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/146/209
- Title:
- STIS emission-line galaxies observations
- Short Name:
- J/ApJS/146/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the first 3 years of operation the Space Telescope Imaging Spectrograph (STIS) obtained slitless spectra of ~2500 fields in parallel to prime Hubble Space Telescope (HST) observations as part of the STIS parallel survey (SPS). The archive contains ~300 fields at high Galactic latitude (|b|>30{deg}) with spectroscopic exposure times greater than 3000s. This sample contains 219 fields (excluding special regions and requiring a consistent grating angle) observed between 1997 June 6 and 2000 September 21, with a total survey area of ~160-arcmin^2^. At this depth, the SPS detects an average of one emission-line galaxy per three fields. We present the analysis of these data and the identification of 131 low- to intermediate-redshift galaxies detected by optical emission lines. The sample contains 78 objects with emission lines that we infer to be redshifted [O II] {lambda}3727 emission at 0.43<z<1.7. The comoving number density of these objects is comparable to that of H{alpha}-emitting galaxies in the NICMOS parallel observations. One quasar and three probable Seyfert galaxies are detected. Many of the emission-line objects show morphologies suggestive of mergers or interactions. The reduced data are available upon request from the authors.
