- ID:
- ivo://CDS.VizieR/J/MNRAS/300/303
- Title:
- UV-selected galaxy redshift survey
- Short Name:
- J/MNRAS/300/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table contains the first results of a spectroscopic survey of galaxies constructed from a flux-limited sample of stars, galaxies and QSOs imaged at 2000{AA} with the FOCA balloon-borne imaging camera (see Milliard et al., 1992A&A...257...24M) The galaxies were selected in the rest frame ultraviolet (UV), in Selected Area 57. Accurate positions for the UV sources have been obtained by matching with optical counterparts using APM scans of the Palomar Sky Survey limited at B=20.5. The results presented here are derived from optical spectroscopy conducted with the WIYN telescope and the WHT for 142 faint sources. The redshift distribution for this UV- selected sample extends over 0<z<0.5, and a high fraction of the sources show intense nebular emission lines and UV-optical colours bluer than normal Hubble sequence galaxies. Updated results for these galaxies were published later (see Sullivan et al. 2000, Cat. <J/MNRAS/312/442>)
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/442
- Title:
- UV-selected galaxy redshift survey. II.
- Short Name:
- J/MNRAS/312/442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present further spectroscopic observations for a sample of galaxies selected in the vacuum ultraviolet (UV) at 2000{AA} from the FOCA balloon-borne imaging camera of Milliard et al. (1992A&A...257...24M). This work represents an extension of the initial study by Treyer et al. (Cat. <J/MNRAS/300/303>). Our enlarged catalogue contains 433 sources (~3 times as many as in our earlier study) across two FOCA fields. 273 of these are galaxies, nearly all with redshifts z~0-0.4. Nebular emission-line measurements are available for 216 galaxies, allowing us to address issues of excitation, reddening and metallicity. The UV and H{alpha} luminosity functions strengthen our earlier assertions that the local volume-averaged star formation rate is higher than indicated from earlier surveys. Moreover, internally within our sample, we do not find a steep rise in the UV luminosity density with redshift over 0<z<0.4. Our data are more consistent with a modest evolutionary trend, as suggested by recent redshift survey results. Investigating the emission-line properties, we find no evidence for a significant number of AGN in our sample; most UV-selected sources to z~0.4 are intense star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/127
- Title:
- UV spectra of classical T Tauri stars
- Short Name:
- J/ApJ/784/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The far-ultraviolet (FUV; 912-1700 {AA}) radiation field from accreting central stars in classical T Tauri systems influences the disk chemistry during the period of giant planet formation. The FUV field may also play a critical role in determining the evolution of the inner disk (r<10 AU), from a gas- and dust-rich primordial disk to a transitional system where the optically thick warm dust distribution has been depleted. Previous efforts to measure the true stellar+accretion-generated FUV luminosity (both hot gas emission lines and continua) have been complicated by a combination of low-sensitivity and/or low-spectral resolution and did not include the contribution from the bright Ly{alpha} emission line. In this work, we present a high-resolution spectroscopic study of the FUV radiation fields of 16 T Tauri stars whose dust disks display a range of evolutionary states. We include reconstructed Ly{alpha} line profiles and remove atomic and molecular disk emission (from H_2_ and CO fluorescence) to provide robust measurements of both the FUV continuum and hot gas lines (e.g., Ly{alpha}, N V, C IV, He II) for an appreciable sample of T Tauri stars for the first time. We find that the flux of the typical classical T Tauri star FUV radiation field at 1 AU from the central star is ~10^7^ times the average interstellar radiation field. The Ly{alpha} emission line contributes an average of 88% of the total FUV flux, with the FUV continuum accounting for an average of 8%. Both the FUV continuum and Ly{alpha} flux are strongly correlated with C IV flux, suggesting that accretion processes dominate the production of both of these components. On average, only ~0.5% of the total FUV flux is emitted between the Lyman limit (912 {AA}) and the H_2_(0-0) absorption band at 1110 {AA}. The total and component-level high-resolution radiation fields are made publicly available in machine-readable format.
2944. UV spectra of old novae
- ID:
- ivo://CDS.VizieR/J/A+A/560/A49
- Title:
- UV spectra of old novae
- Short Name:
- J/A+A/560/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview of the UV spectral properties of old novae as a class. The data and results of this paper, together with data from the outburst phases, will be utilized in a follow-up study to determine statistical properties and to investigate correlations among the physical parameters of the quiescent and eruptive phases.
- ID:
- ivo://CDS.VizieR/J/A+A/470/317
- Title:
- UV spectra of the central star of Sh 2-216
- Short Name:
- J/A+A/470/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a comprehensive spectral analysis of LS V +46 21 in order to compare its photospheric properties to theoretical predictions from stellar evolution theory as well as from diffusion calculations. LS V +46 21 is the DAO-type central star of the planetary nebula Sh 2-216. High-resolution, high-S/N ultraviolet observations obtained with FUSE and STIS aboard the HST as well as the optical spectrum have been analyzed in order to determine the photospheric parameters and the spectroscopic distance. We performed a detailed spectral analysis of the ultraviolet and optical spectrum by means of state-of-the-art NLTE model-atmosphere techniques. From the NIV-NV, OIV-OVI, SiIV-SiV, and FeV-FeVII ionization equilibria, we determined an effective temperature of 95+/-2kK with high precision. The surface gravity is logg=6.9+/-0.2. An unexplained discrepancy appears between the spectroscopic distance d=224^+46^_-58_pc and the parallax distance d=129^+6^_-5_pc of LS V +46 21. For the first time, we have identified Mg IV and Ar VI absorption lines in the spectrum of a hydrogen-rich central star and determined the Mg and Ar abundances as well as the individual abundances of iron-group elements (Cr, Mn, Fe, Co, and Ni). With the realistic treatment of metal opacities up to the iron group in the model-atmosphere calculations, the so-called Balmer-line problem (found in models that neglect metal-line blanketing) vanishes. Spectral analysis by means of NLTE model atmospheres has presently arrived at a high level of sophistication, which is now hampered largely by the lack of reliable atomic data and accurate line-broadening tables. Strong efforts should be made to improve upon this situation.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/69
- Title:
- UV spectroscopy of solar-mass stars
- Short Name:
- J/ApJ/754/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare high-resolution ultraviolet spectra of the Sun and thirteen solar-mass main-sequence stars with different rotational periods that serve as proxies for their different ages and magnetic field structures. In this, the second paper in the series, we study the dependence of ultraviolet emission-line centroid velocities on stellar rotation period, as rotation rates decrease from that of the Pleiades star HII314 (P_rot_=1.47days) to {alpha} Cen A (P_rot_=28days). Our stellar sample of F9 V to G5 V stars consists of six stars observed with the Cosmic Origins Spectrograph on the Hubble Space Telescope (HST) and eight stars observed with the Space Telescope Imaging Spectrograph on HST. We find a systematic trend of increasing redshift with more rapid rotation (decreasing rotation period) that is similar to the increase in line redshift between quiet and plage regions on the Sun. The fastest-rotating solar-mass star in our study, HII314, shows significantly enhanced redshifts at all temperatures above logT=4.6, including the corona, which is very different from the redshift pattern observed in the more slowly rotating stars. This difference in the redshift pattern suggests that a qualitative change in the magnetic-heating process occurs near P_rot_=2days. We propose that HII314 is an example of a solar-mass star with a magnetic heating rate too large for the physical processes responsible for the redshift pattern to operate in the same way as for the more slowly rotating stars. HII314 may therefore lie above the high activity end of the set of solar-like phenomena that is often called the "solar-stellar connection."
2947. UV spectrum of CrII
- ID:
- ivo://CDS.VizieR/J/ApJS/202/15
- Title:
- UV spectrum of CrII
- Short Name:
- J/ApJS/202/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new observations of the spectrum of singly ionized chromium (CrII) in the region 1142-3954{AA}. The spectra were recorded with the National Institute of Standards and Technology 10.7m normal-incidence vacuum spectrograph and FT700 vacuum ultraviolet Fourier transform spectrometer. More than 3600 lines are classified as transitions among 283 even and 368 odd levels. The new spectral data are used to re-optimize the energy levels, reducing their uncertainties by a typical factor of 20.
2948. UV spectrum of eta Car
- ID:
- ivo://CDS.VizieR/J/ApJS/157/138
- Title:
- UV spectrum of eta Car
- Short Name:
- J/ApJS/157/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated the far- through mid-UV (1150-2360{AA}) spectrum of {eta} Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The {eta} Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed on broad stellar wind features. This paper provides a description of the observed spectrum including the wind features, the interstellar absorption, and the emission spectrum from the surrounding nebula, but with the emphasis on the absorption spectrum formed in the foreground ejecta. The ejecta absorption spectrum has a complicated velocity structure in which two velocity structures, at -146 and -513km/s, are easily distinguished.The complete spectrum, with nebular and interstellar line identifications, is available in the electronic edition of the paper.
2949. UV spectrum of eta Car
- ID:
- ivo://CDS.VizieR/J/ApJS/71/983
- Title:
- UV spectrum of eta Car
- Short Name:
- J/ApJS/71/983
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJS/163/173
- Title:
- UV spectrum of eta Car in 2003.5
- Short Name:
- J/ApJS/163/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) high-resolution near-ultraviolet (NUV) spectra of Car's central source recorded before, during and after the 2003.5 spectroscopic minimum. Our focus is on the narrow absorption lines formed in multiple circumstellar shells, superimposed on the broad P Cygni stellar wind features, and how they respond to the flux variations of Car across the minimum. Over 30 separate narrow-line velocity components are identified: three around 146km/s, many between 323 and 587km/s, and a few exceeding 1000km/s.
