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23331. UVCet-typeFlareStars&RelatedObjectsCatalog
ID:
ivo://nasa.heasarc/flarestars
Title:
UVCet-typeFlareStars&RelatedObjectsCatalog
Short Name:
FlareStars
Date:
21 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the catalog of the UV Cet-type flare stars and related objects in the solar vicinity. This new catalog of flare stars includes 463 objects. It contains astrometric, spectral and photometric data as well as information on the infrared, radio and X-ray properties and general stellar parameters. This table was created by the HEASARC in October 2005 based on the merger of 3 CDS tables (table1.dat, table2.dat and atble3.dat) from the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+AS/139/555/">CDS Catalog J/A+AS/139/555/</a> . This is a service provided by NASA HEASARC .
23332. UV continuum for z~4-7 star-forming galaxies
ID:
ivo://CDS.VizieR/J/ApJ/754/83
Title:
UV continuum for z~4-7 star-forming galaxies
Short Name:
J/ApJ/754/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ultra-deep Advanced Camera for Surveys (ACS) and WFC3/IR HUDF+HUDF09 data, along with the wide-area GOODS+ERS+CANDELS data over the CDF-S GOODS field, are used to measure UV colors, expressed as the UV-continuum slope {beta}, of star-forming galaxies over a wide range of luminosity (0.1L*_z=3_ to 2L*_z=3_) at high redshift (z~7 to z~4). {beta} is measured using all ACS and WFC3/IR passbands uncontaminated by Ly{alpha} and spectral breaks. Extensive tests show that our {beta} measurements are only subject to minimal biases. Using a different selection procedure, Dunlop et al. (2012MNRAS.420..901D) recently found large biases in their {beta} measurements. To reconcile these different results, we simulated both approaches and found that {beta} measurements for faint sources are subject to large biases if the same passbands are used both to select the sources and to measure {beta}. High-redshift galaxies show a well-defined rest-frame UV color-magnitude (CM) relationship that becomes systematically bluer toward fainter UV luminosities. No evolution is seen in the slope of the UV CM relationship in the first 1.5 Gyr, though there is a small evolution in the zero point to redder colors from z~7 to z~4. This suggests that galaxies are evolving along a well-defined sequence in the L_UV_-color ({beta}) plane (a "star-forming sequence"?). Dust appears to be the principal factor driving changes in the UV color {beta} with luminosity. These new larger {beta} samples lead to improved dust extinction estimates at z~4-7 and confirm that the extinction is essentially zero at low luminosities and high redshifts. Inclusion of the new dust extinction results leads to (1) excellent agreement between the star formation rate (SFR) density at z~4-8 and that inferred from the stellar mass density; and (2) to higher specific star formation rates (SSFRs) at z>~4, suggesting that the SSFR may evolve modestly (by factors of ~2) from z~4-7 to z~2.
23333. UV-continuum slopes beta for z~4-8 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/793/115
Title:
UV-continuum slopes beta for z~4-8 galaxies
Short Name:
J/ApJ/793/115
Date:
21 Oct 2021
Publisher:
CDS
Description:
We measure the UV-continuum slope {beta} for over 4000 high-redshift galaxies over a wide range of redshifts z~4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new {beta} results reach very faint levels at z~4 (-15.5 mag: 0.006 L_z=3_^*^), z~5 (-16.5 mag: 0.014 L_z=3_^*^), and z~6 and z~7 (-17 mag: 0.025 L_z=3_^*^). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring {beta} that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in {beta}. We find that after correcting for the systematic errors (typically {Delta}{beta}~0.1-0.2) all {beta} results at z~7 from different groups are in excellent agreement. The mean {beta} we measure for faint (-18 mag: 0.1L_z=3_^*^) z~4, z~5, z~6, and z~7 galaxies is -2.03+/-0.03+/-0.06 (random and systematic errors), -2.14+/-0.06+/-0.06, -2.24+/-0.11+/-0.08, and -2.30+/-0.18+/-0.13, respectively. Our new {beta} values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer {beta}'s at lower luminosities is confirmed, as is the evolution to bluer {beta}'s at high redshifts. {beta} appears to show only a mild luminosity dependence faintward of M_UV, AB_~-19 mag, suggesting that the mean {beta} asymptotes to ~-2.2 to -2.4 for faint z>=4 galaxies. At z~7, the observed {beta}'s suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations.
23334. UV counterparts in HI clouds using ALFA surveys
ID:
ivo://CDS.VizieR/J/ApJ/808/136
Title:
UV counterparts in HI clouds using ALFA surveys
Short Name:
J/ApJ/808/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present ultraviolet (UV) follow-up of a sample of potential dwarf galaxy candidates selected for their neutral hydrogen (HI) properties, taking advantage of the low UV background seen by the GALEX satellite and its large and publicly available imaging footprint. The HI clouds, which are drawn from published Galactic Arecibo L-band Feed Array and Arecibo Legacy Fast Arecibo L-band Feed Array HI survey compact cloud catalogs, are selected to be galaxy candidates based on their spatial compactness and non-association with known high-velocity cloud complexes or Galactic HI emission. Based on a comparison of their UV characteristics to those of known dwarf galaxies, half (48%) of the compact HI clouds have at least one potential stellar counterpart with UV properties similar to those of nearby dwarf galaxies. If they are galaxies, then the star formation rates, HI masses, and star formation efficiencies of these systems follow the trends seen for much larger galaxies. The presence of UV emission is an efficient method to identify the best targets for spectroscopic follow-up, which is necessary to prove that the stars are associated with compact HI. Furthermore, searches of this nature help to refine the salient HI properties of likely dwarfs (even beyond the Local Group). In particular, HI compact clouds considered to be velocity outliers relative to their neighbor HI clouds have the most significant detection rate of single, appropriate UV counterparts. Correcting for the sky coverage of the two all-Arecibo sky surveys yielding the compact HI clouds, these results may imply the presence of potentially hundreds of new tiny galaxies across the entire sky.
23335. UV emission of stars in LAMOST. I. Catalogs
ID:
ivo://CDS.VizieR/J/ApJS/235/16
Title:
UV emission of stars in LAMOST. I. Catalogs
Short Name:
J/ApJS/235/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the ultraviolet magnitudes for over three million stars in the LAMOST survey, in which 2,202,116 stars are detected by GALEX. For 889,235 undetected stars, we develop a method to estimate their upper limit magnitudes. The distribution of (FUV-NUV) shows that the color declines with increasing effective temperature for stars hotter than 7000K in our sample, while the trend disappears for the cooler stars due to upper atmosphere emission from the regions higher than their photospheres. For stars with valid stellar parameters, we calculate the UV excesses with synthetic model spectra, and find that the (FUV - NUV) versus R'_FUV_ can be fitted with a linear relation and late-type dwarfs tend to have high UV excesses. There are 87,178 and 1,498,103 stars detected more than once in the visit exposures of GALEX in the FUV and NUV, respectively. We make use of the quantified photometric errors to determine statistical properties of the UV variation, including intrinsic variability and the structure function on the timescale of days. The overall occurrence of possible false positives is below 1.3% in our sample. UV absolute magnitudes are calculated for stars with valid parallaxes, which could serve as a possible reference frame in the NUV. We conclude that the colors related to UV provide good criteria to distinguish between M giants and M dwarfs, and the variability of RR Lyrae stars in our sample is stronger than that of other A and F stars.
23336. UVES Advanced Data Products Quasar Sample. VI.
ID:
ivo://CDS.VizieR/J/MNRAS/458/4074
Title:
UVES Advanced Data Products Quasar Sample. VI.
Short Name:
J/MNRAS/458/4074
Date:
21 Oct 2021
Publisher:
CDS
Description:
The circumgalactic medium (CGM) can be probed through the analysis of absorbing systems in the line of sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman {alpha} absorbers (sub-DLAs, defined as absorbers with 19.0 z_abs_<=3.104 from the ESO Ultra-Violet Echelle Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine these results with other measurements from the literature to produce a compilation of metallicity measurements for 92 sub-DLAs as well as a sample of 362 DLAs. We apply a multi-element analysis to quantify the amount of dust in these two classes of systems. We find that either the element depletion patterns in these systems differ from the Galactic depletion patterns or they have a different nucleosynthetic history than our own Galaxy. We propose a new method to derive the velocity width of absorption profiles, using the modelled Voigt profile features. The correlation between the velocity width {Delta}V_90_ of the absorption profile and the metallicity is found to be tighter for DLAs than for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H] metallicity of low redshift (z<1.25) sub-DLAs, which is unseen at higher redshifts. This feature can be interpreted as a signature from the metal-poor, accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs at low redshifts.
23337. UVES sky atlas
ID:
ivo://CDS.VizieR/J/A+A/407/1157
Title:
UVES sky atlas
Short Name:
J/A+A/407/1157
Date:
21 Oct 2021
Publisher:
CDS
Description:
These tables list positions, widths and peak fluxes for the sky emission lines. The listings follow the subdivision in settings which is followed throughout the text and listed in Table 3.
23338. UVES spectra of Feige 46 and LSIV -14 116
ID:
ivo://CDS.VizieR/J/A+A/643/A22
Title:
UVES spectra of Feige 46 and LSIV -14 116
Short Name:
J/A+A/643/A22
Date:
21 Oct 2021
Publisher:
CDS
Description:
Hot subdwarf stars of spectral types O and B represent a poorly understood phase in the evolution of low-mass stars, in particular of close compact binaries. A variety of phenomena are observed, which make them important tools for several astronomical disciplines. For instance, the richness of oscillations of many subdwarfs are important for asteroseismology. Furthermore, hot subdwarfs are among the most chemically peculiar stars known. Two intermediate He-rich hot subdwarf stars, LSIV -14 116 and Feige 46, are particularly interesting, because they show extreme enrichments of heavy elements such as Ge, Sr, Y, and Zr, strikingly similar in both stars. In addition, both stars show light oscillations at periods incompatible with standard pulsation theory and form the class of V366 Aqr variables. We investigate whether the similar chemical compositions extend to more complete abundance patterns in both stars and validate the pulsations in Feige 46 using its recent TESS light curve. High-resolution optical and near-ultraviolet spectroscopy are combined with non-local-thermodynamical-equilibrium model atmospheres and synthetic spectra calculated with Tlusty and Synspec to determine detailed metal abundance patterns in both stars consistently. Many previously unidentified lines are identified for the first time with transitions originating from GaIII, GeIII-IV, SeIII, KrIII, SrII-III, YIII, ZrIII-IV, and SnIV, most of which have not been observed so far in any star. The abundance patterns of 19 metals in both stars are almost identical, light metals being only slightly more abundant in Feige 46 while Zr, Sn, and Pb are slightly less enhanced compared to LSIV -14 116. Both abundance patterns are distinctively different from those of normal He-poor hot subdwarfs of similar temperature. The extreme enrichment in heavy metals of more than 4 dex compared to the Sun is likely the result of strong atmospheric diffusion processes that operate similarly in both stars while their similar patterns of C, N, O, and Ne abundances might provide clues to their as yet unclear evolutionary history. Finally, we find that the periods of the pulsation modes in Feige 46 are stable to better than dP/dt~=10^-8^s/s. This is is not compatible with dP/dt predicted for pulsations driven by the epsilon-mechanism and excited by helium-shell flashes in a star which is evolving, for example, onto the extended horizontal branch.
23339. UVES Spectrum of APM BR J0307-4945
ID:
ivo://CDS.VizieR/J/A+A/370/426
Title:
UVES Spectrum of APM BR J0307-4945
Short Name:
J/A+A/370/426
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first high-resolution (6.2 to 7.7km/s FWHM) spectra of the APM BR J0307-4945 quasar at z_em_=4.73 obtained with UVES on the 8.2m VLT Kueyen telescope. We focus our analysis on a damped Lyman-{alpha} system at z_abs_=4.466, the most distant DLA system known to the present date, observed when the age of the universe was only 1.3Gyr. The following table lists the wavelengths and equivalent widths for all absorption-line features (except the telluric lines) redwards of the quasar Ly-{alpha} emission detected at 4{sigma} in equivalent width. The transition names and approximate redshifts are specified for the features we successfully identified. About 80% of the absorption lines redwards of the quasar Ly-{alpha} emission have been identified, corresponding to 13 metal-line systems.
23340. UVES/VLT M subdwarfs
ID:
ivo://svo.cab/cat/uves
Title:
UVES/VLT M subdwarfs
Short Name:
UVES
Date:
03 Jun 2020 15:31:52
Publisher:
SVO/CAB
Description:
UVES/VLT M subdwarfs

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