- ID:
- ivo://CDS.VizieR/J/A+A/544/A65
- Title:
- GALEX Arecibo SDSS survey. VI.
- Short Name:
- J/A+A/544/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10^M_{sun}_ and redshifts 0.025<z<0.05. GASS targets are selected from the Sloan Digital Sky Survey (SDSS) spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys, and are observed until detected or until a gas mass fraction limit of a few per cent is reached. This second data installment includes new Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earlier work.
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- ID:
- ivo://CDS.VizieR/II/312
- Title:
- GALEX-DR5 (GR5) sources from AIS and MIS
- Short Name:
- II/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy Evolution Explorer (GALEX) is an ultraviolet space telescope launched in 2003. It observes in 2 ultraviolet bands, FUV (far-UV) and NEV (near-UV), which characteristics are: -------------------------------------------------------------------- FUV NUV -------------------------------------------------------------------- Bandwidth 1344-1786 1771-2831 ({AA}) Effective wavelength 1538.6 2315.7 ({AA}) Astrometry (R<0.6deg) 0.59 0.49 (arcsec) Photometry 0.05 0.03 (ABmag) Zero point 18.82 20.08 (ABmag) Image resolution 4.2 5.3 (arcsec/pix) Spectral resolution 200 118 ({delta}{lambda}/{lambda}) -------------------------------------------------------------------- Two catalogs of UV sources from GALEX surveys are provided: * the All-sky Imaging Survey (AIS), containing 65.3million sources over 21435 square degrees, has a 5{sigma} depth in FUV/NUV of 19.9/20.8 (AB magnitudes); * the Medium-depth Imaging Survey (MIS), with 12.6million sources, covers 1579 square degrees and has a 5{sigma} depth in FUV/NUV of 22.6/22.7 (AB magnitudes). See also the description by Bianchi et al. (2011MNRAS.411.2770B)
- ID:
- ivo://CDS.VizieR/J/AJ/133/1780
- Title:
- GALEX/SDSS quasar catalog
- Short Name:
- J/AJ/133/1780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the broadband UV and optical properties of z~<3.4 quasars matched in the Galaxy Evolution Explorer (GALEX) General Data Release 1 (GR1) and the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3). Of the 6371 SDSS DR3 quasars covered by 204 GALEX GR1 tiles, 5380 (84%) have near-UV detections, while 3034 (48%) have both near-UV and far-UV detections using a matching radius of 7". Most of the DR3 sample quasars are detected in the near-UV until z~1.7, with the near-UV detection fraction dropping to ~50% by z~2.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/572
- Title:
- GALEX/Spitzer photometry in NGC 7331
- Short Name:
- J/ApJS/173/572
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850um is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b_8_) that is highest in the outer part of the disk, even though the local star formation intensity peaks in the ring. Bolometric luminosity and UV attenuation are correlated in substructures on 0.4kpc scales, with a relationship similar to that established for starburst galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/60
- Title:
- GALEX Time Domain Survey I. UV variable sources
- Short Name:
- J/ApJ/766/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~40deg^2^ of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. We characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5{sigma} level in at least one epoch. We measure the statistical properties of the UV variability, including the structure function on timescales of days and years. We report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). We detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to |{Delta}m|=4.6mag and 2.9mag, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by dormant supermassive black hole. We calculate a surface density for variable sources in the UV with NUV<23mag and |{Delta}m|>0.2mag of ~8.0, 7.7, and 1.8deg^-2^ for quasars, active galactic nuclei, and RR Lyrae stars, respectively. We also calculate a surface density rate in the UV for transient sources, using the effective survey time at the cadence appropriate to each class, of ~15 and 52deg^-2^/yr for M dwarfs and extragalactic transients, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/185
- Title:
- GALEX ultraviolet atlas of nearby galaxies
- Short Name:
- J/ApJS/173/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present images, integrated photometry, and surface-brightness and color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; lambda_eff_=1516{AA}) and near-ultraviolet (NUV; lambda_eff_=2267{AA}) bands. Our catalog of objects is derived primarily from the GALEX Nearby Galaxies Survey (NGS) supplemented by galaxies larger than 1' in diameter serendipitously found in these fields and in other GALEX exposures of similar of greater depth. The sample analyzed here adequately describes the distribution and full range of properties (luminosity, color, star formation rate [SFR]) of galaxies in the local universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/13
- Title:
- GALEX ultraviolet halos around bright stars
- Short Name:
- J/ApJ/734/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have discovered ultraviolet (UV) halos extending as far as 5{deg} around four (of six) bright UV stars using data from the Galaxy Evolution Explorer satellite. These halos are due to scattering of the starlight from nearby thin, foreground dust clouds. We have placed limits of 0.58+/-0.12 and 0.72+/-0.06 on the phase function asymmetry factor (g) in the FUV (1521{AA}) and NUV (2320{AA}) bands, respectively. We suggest that these halos are a common feature around bright stars and may be used to explore the scattering function of interstellar grains at small angles.
- ID:
- ivo://CDS.VizieR/J/AJ/130/825
- Title:
- GALEX ultraviolet variability catalog
- Short Name:
- J/AJ/130/825
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present version 1.0 of the NASA Galaxy Evolution Explorer (GALEX) ultraviolet variability (GUVV) catalog, which contains information on 84 time-variable and transient sources gained with simultaneous near-ultraviolet (NUV) and far-ultraviolet (FUV) photometric observations. These time-variable sources were serendipitously revealed in the various 1.2{deg} diameter star fields currently being surveyed by the GALEX satellite in two ultraviolet bands (NUV 1750-2750{AA}, FUV 1350-1750{AA}) with limiting AB magnitudes of 23-25. The largest amplitude variable objects currently detected by GALEX are M dwarf flare stars, which can brighten by 5-10mag in both the NUV and FUV bands during short-duration (<500s) outbursts. Other types of large-amplitude ultraviolet variable objects include ab-type RR Lyrae stars, which can vary periodically by 2-5mag in the GALEX FUV band. This first GUVV catalog lists galactic positions and possible source identifications in order to provide the astronomical community with a list of time-variable objects that can now be repeatedly observed at other wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/528/A107
- Title:
- GALEX Ultraviolet Virgo Cluster Survey (GUViCS)
- Short Name:
- J/A+A/528/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering ~40 sq. deg in the far UV (FUV, {lambda}_eff_=1539{AA}, {Delta}{lambda}=442{AA}) and ~120 sq. deg in the near UV (NUV, {lambda}_eff_=2316{AA}, {Delta}{lambda}=1060{AA}). The goal of the survey is to study the ultraviolet (UV) properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and regardless of prior knowledge of their star formation activity. The UV data will be combined with those in other bands (optical: NGVS; far-infrared - submm: HeViCS; HI: ALFALFA) and with our multizone chemo-spectrophotometric models of galaxy evolution to make a complete and exhaustive study of the effects of the environment on the evolution of galaxies in high density regions. We present here the scientific objectives of the survey, describing the observing strategy and briefly discussing different data reduction techniques. Using UV data already in-hand for the central 12 sq. deg we determine the FUV and NUV luminosity functions of the Virgo cluster core for all cluster members and separately for early- and late-type galaxies and compare it to the one obtained in the field and other nearby clusters (Coma, A1367). This analysis shows that the FUV and NUV luminosity functions of the core of the Virgo clusters are flatter (alpha~-1.1) than those determined in Coma and A1367. We discuss the possible origin of this difference.
