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851. GALEX and Gaia data for APOGEE red clump stars
ID:
ivo://CDS.VizieR/J/ApJ/872/95
Title:
GALEX and Gaia data for APOGEE red clump stars
Short Name:
J/ApJ/872/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
Although core helium-burning red clump (RC) stars are faint at ultraviolet wavelengths, their ultraviolet (UV)-optical color is a unique and accessible probe of their physical properties. Using data from the Galaxy Evolution Explorer All Sky Imaging Survey (GALEX AIS), Gaia Data Release 2, and the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE) DR14 survey, we find that spectroscopic metallicity is strongly correlated with the location of an RC star in the UV-optical color-magnitude diagram. The RC has a wide spread in (NUV-G)_0_ color of over 4mag compared to a 0.7mag range in (G_BP_-G_RP_)_0_. We propose a photometric, dust-corrected, UV-optical (NUV-G)_0_ color-metallicity [Fe/H] relation using a sample of 5175 RC stars from APOGEE. We show that this relation has a scatter of 0.16dex and is easier to obtain for large, wide-field samples than for spectroscopic metallicities. Importantly, the effect may be comparable to the spread in RC color attributed to extinction in other studies.
852. GALEX BCG galaxies sample properties
ID:
ivo://CDS.VizieR/J/A+A/611/A42
Title:
GALEX BCG galaxies sample properties
Short Name:
J/A+A/611/A42
Date:
21 Oct 2021
Publisher:
CDS
Description:
At low redshift, early-type galaxies often exhibit a rising flux with decreasing wavelength in the 1000-2500{AA} range, called "UV upturn". The origin of this phenomenon is debated, and its evolution with redshift is poorly constrained. The observed GALEX FUV-NUV color can be used to probe the UV upturn up to redshift about 0.5. We aim to provide constraints on the existence of the UV upturn up to redshift ~0.4 in Brightest Cluster Galaxies (BCG) galaxies located behind the Virgo cluster, using data from the GUViCS survey. We estimate the FUV and NUV observed magnitudes for BCGs from the maxBCG catalog in the GUViCS fields. We increase the number of non local galaxies identified as BCGs with GALEX photometry from a few tens of galaxies to 166 (64 when restricting this sample to relatively small error-bars). We also estimate a central color within a 20-arcsec aperture. By using the r band luminosity from the maxBCG catalog, we can separate blue FUV-NUV due to recent star formation and candidate upturn cases. We use Lick indices to verify their similitude to redshift 0 upturn cases. We clearly detect a population of blue FUV-NUV BCGs in the redshift range 0.10-0.35, vastly improving the existing constraints at these epochs by increasing the number of galaxies studied, and by exploring a redshift range with no previous data (beyond 0.2), spanning 1 more Gyr in the past. These galaxies bring new constrains that can help distinguish between assumptions concerning the stellar populations causing the UV upturn phenomenon. The existence of a large number of UV upturns around redshift 0.25 favors the existence of a binary channel among the sources proposed in the literature.
853. GALEX NUV observations of bright M-type stars
ID:
ivo://CDS.VizieR/J/ApJ/798/41
Title:
GALEX NUV observations of bright M-type stars
Short Name:
J/ApJ/798/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lepine & Gaidos catalog (2011, J/AJ/142/138) of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831{AA}) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5{sigma}) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these "false positives" (FPs) as ~16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.
854. GALEX spectral database correction with IUE SEDs
ID:
ivo://CDS.VizieR/J/AJ/157/107
Title:
GALEX spectral database correction with IUE SEDs
Short Name:
J/AJ/157/107
Date:
21 Oct 2021
Publisher:
CDS
Description:
The CALSPEC database of absolute spectral energy distributions (SEDs) from the Hubble Space Telescope is based on pure hydrogen model atmosphere calculations for three unreddened white dwarf stars and represents the current UV flux calibration standard with a precision approaching 1% for well observed stars. Following our previous work to correct International Ultraviolet Explorer (IUE) fluxes, this paper provides an average correction for the Galaxy Evolution Explorer (GALEX) spectral database that places GALEX fluxes on the current CALSPEC scale. Our correction is derived by comparing GALEX spectroscopic flux distributions with CALSPEC and corrected IUE SEDs. This recalibration is relevant for any project based on GALEX archival spectroscopic data, e.g., UV or multi-wavelength analyses, correlating GALEX spectra with other existing or future databases, and planning of new observations. The recalibration will be applied to our planned catalog of corrected GALEX SEDs.
855. Gal. redshift survey near HST/COS AGN sight lines
ID:
ivo://CDS.VizieR/J/ApJS/237/11
Title:
Gal. redshift survey near HST/COS AGN sight lines
Short Name:
J/ApJS/237/11
Date:
21 Oct 2021
Publisher:
CDS
Description:
To establish the connection between galaxies and UV-detected absorption systems in the local universe, a deep (g<=20) and wide (~20' radius) galaxy redshift survey is presented around 47 sight lines to UV-bright AGNs observed by the Cosmic Origins Spectrograph (COS). Specific COS science team papers have used this survey to connect absorbers to galaxies, groups of galaxies, and large-scale structures, including voids. Here we present the technical details of the survey and the basic measurements required for its use, including redshifts for individual galaxies and uncertainties determined collectively by spectral class (emission-line, absorption-line, and composite spectra) and completeness for each sight line as a function of impact parameter and magnitude. For most of these sight lines, the design criteria of >90% completeness over a >1Mpc region down to <~0.1L* luminosities at z<=0.1 allows a plausible association between low-z absorbers and individual galaxies. Ly{alpha} covering fractions are computed to approximate the star-forming and passive galaxy populations using the spectral classes above. In agreement with previous results, the covering fraction of star-forming galaxies with L>=0.3L* is consistent with unity inside one virial radius and declines slowly to >50% at four virial radii. On the other hand, passive galaxies have lower covering fractions (~60%) and a shallower decline with impact parameter, suggesting that their gaseous halos are patchy but have a larger scale-length than star-forming galaxies.
856. GAMA blended spectra catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/449/4277
Title:
GAMA blended spectra catalogue
Short Name:
J/MNRAS/449/4277
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the catalogue of blended galaxy spectra from the Galaxy And Mass Assembly (GAMA) survey. These are cases where light from two galaxies are significantly detected in a single GAMA fibre. Galaxy pairs identified from their blended spectrum fall into two principal classes: they are either strong lenses, a passive galaxy lensing an emission-line galaxy; or occulting galaxies, serendipitous overlaps of two galaxies, of any type. Blended spectra can thus be used to reliably identify strong lenses for follow-up observations (high-resolution imaging) and occulting pairs, especially those that are a late-type partly obscuring an early-type galaxy which are of interest for the study of dust content of spiral and irregular galaxies. The GAMA survey setup and its AUTOZ automated redshift determination were used to identify candidate blended galaxy spectra from the cross-correlation peaks. We identify 280 blended spectra with a minimum velocity separation of 600km/s, of which 104 are lens pair candidates, 71 emission-line-passive pairs, 78 are pairs of emission-line galaxies and 27 are pairs of galaxies with passive spectra. We have visually inspected the candidates in the Sloan Digital Sky Survey (SDSS) and Kilo Degree Survey (KiDS) images. Many blended objects are ellipticals with blue fuzz (Ef in our classification). These latter 'Ef' classifications are candidates for possible strong lenses, massive ellipticals with an emission-line galaxy in one or more lensed images. The GAMA lens and occulting galaxy candidate samples are similar in size to those identified in the entire SDSS. This blended spectrum sample stands as a testament of the power of this highly complete, second-largest spectroscopic survey in existence and offers the possibility to expand e.g. strong gravitational lens surveys.
857. GAMA DR3 - Simple Spectrum Access
ID:
ivo://lam.cesam.aspic/gama_dr3/q/ssa
Title:
GAMA DR3 - Simple Spectrum Access
Short Name:
GAMA3 SSAP
Date:
20 May 2021 06:32:29
Publisher:
The CeSAM VO team
Description:
Spectra from the third data release (DR3) of GAMA.
858. Gamma Vel cluster membership and IMF
ID:
ivo://CDS.VizieR/J/A+A/589/A70
Title:
Gamma Vel cluster membership and IMF
Short Name:
J/A+A/589/A70
Date:
21 Oct 2021
Publisher:
CDS
Description:
Understanding the properties of young open clusters, such as the Initial Mass Function (IMF), star formation history and dynamic evolution, is crucial to obtain reliable theoretical predictions of the mechanisms involved in the star formation process. We want to obtain a list, as complete as possible, of confirmed members of the young open cluster Gamma Velorum, with the aim of deriving general cluster properties such as the IMF. We used all available spectroscopic membership indicators within the Gaia-ESO public archive together with literature photometry and X-ray data and, for each method, we derived the most complete list of candidate cluster members. Then, we considered photometry, gravity and radial velocities as necessary conditions to select a subsample of candidates whose membership was confirmed by using the lithium and H{alpha} lines and X-rays as youth indicators. We found 242 confirmed and 4 possible cluster members for which we derived masses using very recent stellar evolutionary models. The cluster IMF in the mass range investigated in this study shows a slope of {alpha}=2.6+/-0.5 for 0.5<M/M_{sun}<1.3 and {alpha}=1.1+/-0.4 for 0.16<M/M_{sun}_<0.5 and is consistent with a standard IMF. The similarity of the IMF of the young population around gamma^2^ Vel to that in other star forming regions and the field suggests it may have formed through very similar processes.
859. G64-12 and G64-37 linelist and EWs
ID:
ivo://CDS.VizieR/J/A+A/586/A67
Title:
G64-12 and G64-37 linelist and EWs
Short Name:
J/A+A/586/A67
Date:
21 Oct 2021
Publisher:
CDS
Description:
Studies of extremely metal-poor stars indicate that chemical abundance ratios [X/Fe] have a root mean square scatter as low as 0.05dex (12%). It remains unclear whether this reflects observational uncertainties or intrinsic astrophysical scatter arising from physical conditions in the ISM at early times. We measure differential chemical abundance ratios in extremely metal-poor stars to investigate the limits of precision and to understand whether cosmic scatter or observational errors are dominant. We used high-resolution (R~95000) and high signal-to-noise (S/N=700 at 5000{AA}) HIRES/Keck spectra to determine high-precision differential abundances between two extremely metal-poor stars through a line-by-line differential approach. We determined stellar parameters for the star G64-37 with respect to the standard star G64-12. We performed EW measurements for the two stars for the lines recognized in both stars and performed spectral synthesis to study the carbon abundances. Results. The differential approach allowed us to obtain errors of {sigma}(Teff)=27K, {sigma}(logg)=0.06dex, {sigma}([Fe/H])=0.02dex and {sigma}(vt)=0.06km/s. We estimated relative chemical abundances with a precision as low as {sigma}([X/Fe])~0.01dex. The small uncertainties demonstrate that there are genuine abundance differences larger than the measurement errors. The observed Li difference cannot be explained by the difference in mass because the less massive star has more Li. It is possible to achieve an abundance precision around ~0.01-0.05dex for extremely metal-poor stars, which opens new windows on the study of the early chemical evolution of the Galaxy.
860. Gas and dust in star-forming region rho OphA
ID:
ivo://CDS.VizieR/J/A+A/608/A133
Title:
Gas and dust in star-forming region rho OphA
Short Name:
J/A+A/608/A133
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate to what degree local physical and chemical conditions are related to the evolutionary status of various objects in star-forming media. rho Oph A displays the entire sequence of low-mass star formation in a small volume of space. Using spectrophotometric line maps of H_2_, H_2_O, NH_3_, N_2_H^+^, O_2_, OI, CO, and CS, we examine the distribution of the atomic and molecular gas in this dense molecular core. The physical parameters of these species are derived, as are their relative abundances in rho Oph A. Using radiative transfer models, we examine the infall status of the cold dense cores from their resolved line profiles of the ground state lines of H_2_O and NH_3_, where for the latter no contamination from the VLA 1623 outflow is observed and line overlap of the hyperfine components is explicitly taken into account. The stratified structure of this photon dominated region (PDR), seen edge-on, is clearly displayed. Polycyclic aromatic hydrocarbons (PAHs) and OI are seen throughout the region around the exciting star S1. At the interface to the molecular core 0.05pc away, atomic hydrogen is rapidly converted into H_2_, whereas OI protrudes further into the molecular core. This provides oxygen atoms for the gas-phase formation of O_2_ in the core SM1, where X(O_2_)~5x10^-8^. There, the ratio of the O_2_ to H_2_O abundance [X(H_2_O)~5x10^-9^] is significantly higher than unity. Away from the core, O_2_ experiences a dramatic decrease due to increasing H_2_O formation. Outside the molecular core, on the far side as seen from S1, the intense radiation from the 0.5pc distant early B-type star HD147889 destroys the molecules. Towards the dark core SM1, the observed abundance ratio X(O_2_)/X(H_2_O)>1, which suggests that this object is extremely young, which would explain why O_2_ is such an elusive molecule outside the solar system.

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