- ID:
- ivo://CDS.VizieR/J/MNRAS/443/3174
- Title:
- 72 faint CV candidates in CRTS
- Short Name:
- J/MNRAS/443/3174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over six years of operation, the Catalina Real-time Transient Survey (CRTS) has identified 1043 cataclysmic variable (CV) candidates - the largest sample of CVs from a single survey to date. Here, we provide spectroscopic identification of 85 systems fainter than g>=19, including three AM Canum Venaticorum binaries, one helium-enriched CV, one polar and one new eclipsing CV. We analyse the outburst properties of the full sample and show that it contains a large fraction of low-accretion-rate CVs with long outburst recurrence times. We argue that most of the high-accretion-rate dwarf novae in the survey footprint have already been found and that future CRTS discoveries will be mostly low-accretion-rate systems. We find that CVs with white-dwarf-dominated spectra have significantly fewer outbursts in their CRTS light curves compared to disc-dominated CVs, reflecting the difference in their accretion rates. Comparing the CRTS sample to other samples of CVs, we estimate the overall external completeness to be 23.6 per cent, but show that as much as 56 per cent of CVs have variability amplitudes that are too small to be selected using the transient selection criteria employed by current ground-based surveys. The full table of CRTS CVs, including their outburst and spectroscopic properties examined in this paper, is provided in the online materials.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/297/885
- Title:
- Faint galaxies KIc photometry
- Short Name:
- J/MNRAS/297/885
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The excess number of blue galaxies at faint magnitudes is a subject of much controversy. Recent Hubble Space Telescope results have revealed a plethora of galaxies with peculiar morphologies tentatively identified as the evolving population. We report the results of optical spectroscopy and near-infrared photometry of a sample of faint HST galaxies from the Medium Deep Survey to ascertain the physical properties of the faint morphological populations. We find four principal results. First, the population of objects classified as 'peculiar' are intrinsically luminous in the optical (M_B_~-19). Secondly these systems tend to be strong sources of [OII] line luminosity. Thirdly the optical-infrared colours of the faint population (a) confirm the presence of a population of compact blue galaxies and (b) show the stellar populations of irregular/peculiar galaxies encompass a wide range in age. Finally a surface-brightness comparison with the local galaxy sample of Freiz et al. (1996AJ....111..174F) shows that these objects are not of anomalously low surface brightness, rather we find that all morphological classes have evolved to a higher surface brightness at higher redshifts (z>0.3).
- ID:
- ivo://CDS.VizieR/J/AJ/124/1651
- Title:
- Faint high-latitude carbon stars SDSS photometry
- Short Name:
- J/AJ/124/1651
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 39 faint high-latitude carbon stars (FHLCs) from Sloan Digital Sky Survey (SDSS) commissioning data. The objects, each selected photometrically and verified spectroscopically, range over 16.6<r*<20.0 and show a diversity of temperatures as judged by both colors and NaD line strengths. Although a handful of these stars were previously known, these objects are, in general, too faint and too warm to be effectively identified in other modern surveys such as the Two Micron All Sky Survey, nor are their red/near-IR colors particularly distinctive. We present proper-motion measures for each object, indicating that the sample is a mixture of extremely distant (greater than 100kpc) halo giant stars, useful for constraining halo dynamics, and members of the recently recognized exotic class of very nearby dwarf carbon (dC) stars.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2838
- Title:
- Faint high-latitude carbon stars SDSS photometry
- Short Name:
- J/AJ/127/2838
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search of more than 3000deg^2^ of high-latitude sky by the Sloan Digital Sky Survey has yielded 251 faint high-latitude carbon stars (FHLCs), the large majority previously uncatalogued. We present homogeneous spectroscopy, photometry, and astrometry for the sample. The objects lie in the 15.6<r<20.8 range and exhibit a wide variety of apparent photospheric temperatures, ranging from spectral types near M to as early as F. Proper-motion measurements for 222 of the objects show that at least 50%, and quite probably more than 60%, of these objects are actually low-luminosity dwarf carbon (dC) stars, in agreement with a variety of recent, more limited investigations that show that such objects are the numerically dominant type of star with C_2_ in the spectrum. This SDSS homogeneous sample of ~110 dC stars now constitutes 90% of all known carbon dwarfs and will grow by another factor of 2-3 by the completion of the survey. As the spectra of the dC and the faint halo giant C stars are very similar (at least at spectral resolution of 10^3^), despite a difference of 10mag in luminosity, it is imperative that simple luminosity discriminants other than proper motion be developed. We use our enlarged sample of FHLCs to examine a variety of possible luminosity criteria, including many previously suggested, and find that, with certain important caveats, JHK photometry may segregate dwarfs and giants.
- ID:
- ivo://CDS.VizieR/J/MNRAS/470/1512
- Title:
- Faint LSB galaxy cand. in Perseus cluster
- Short Name:
- J/MNRAS/470/1512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of 89 low surface brightness (LSB), and thus low stellar density galaxy candidates in the Perseus cluster core, of the kind named 'ultra-diffuse galaxies', with mean effective V-band surface brightnesses 24.8-27.1mag/arcsec^2^, total V-band magnitudes -11.8 to -15.5mag, and half-light radii 0.7-4.1kpc. The candidates have been identified in a deep mosaic covering 0.3deg^2^, based on wide-field imaging data obtained with the William Herschel Telescope. We find that the LSB galaxy population is depleted in the cluster centre and only very few LSB candidates have half-light radii larger than 3kpc. This appears consistent with an estimate of their tidal radius, which does not reach beyond the stellar extent even if we assume a high dark matter content (M/L=100). In fact, three of our candidates seem to be associated with tidal streams, which points to their current disruption. Given that published data on faint LSB candidates in the Coma cluster --with its comparable central density to Perseus-- show the same dearth of large objects in the core region, we conclude that these cannot survive the strong tides in the centres of massive clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/104/1765
- Title:
- Faint Stroemgren photometry
- Short Name:
- J/AJ/104/1765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have initiated a faint photometric survey in the Stroemgren system covering ~1 square degree and including 1238 objects in order to develop samples which best probe the thick disk population. The catalog of observations are presented here. They were acquired without kinematic or metallicity biases and are complete to V=17.3-18.5, depending on the field, for 810 early to relatively late type (K0 V or G5 III) stars. Photometric metallicities were derived for 508 stars and indicate a metal-poor stellar population, consistent with a mixture of thick disk and halo stars. While the Stroemgren u-band was not part of the survey, follow-up u-band observations of 32 survey objects indicate that intermediate color survey stars (0.3<=b-y<=0.5) are main-sequence or slightly evolved stars, while redder survey stars (b-y>=0.5) are giants. The survey catalog is available in electronic form upon request.
- ID:
- ivo://CDS.VizieR/J/AJ/152/91
- Title:
- Faint UBVRI standard stars at +50{deg} declination
- Short Name:
- J/AJ/152/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise and accurate CCD-based UBVRI photometry is presented for ~2000 stars distributed around the sky in a declination zone centered approximately at +50{deg}. Their photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems through observations of the UBVRI standard stars presented in the various works of Landolt. The magnitude and color range for these stars are 12<~V<~22 and -0.3<~(B-V)<~1.8, respectively. Each star averages 13 measures in each UBVRI filter from data taken on 41 different photometric nights obtained over a 21 month period. Hence, there now exists a network of faint UBVRI photometric standard stars centered on the declination zones {delta}=-50{deg}, 0{deg}, and +50{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/1215
- Title:
- Faint UV standards from Swift, GALEX and SDSS
- Short Name:
- J/ApJ/725/1215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u~17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20000<T_eff_<50000K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures.
- ID:
- ivo://CDS.VizieR/J/MNRAS/360/1345
- Title:
- F- and G-type stars in solar neighbourhood
- Short Name:
- J/MNRAS/360/1345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new metallicity distribution and an age-metallicity relation are presented for 437 nearby F and G turn-off and sub-giant stars selected from radial velocity data of Nidever et al. (2002, Cat. J/ApJS/141/503). Photometric metallicities are derived from uvby-H{beta} photometry, and the stellar ages from the isochrones of Bergbusch & VandenBerg (2001ApJ...556..322B) as transformed to uvby photometry using the methods of Clem et al. (2004, Cat. J/AJ/127/1227).
- ID:
- ivo://CDS.VizieR/J/A+A/384/491
- Title:
- Fast-rotating nearby solar-type stars. I.
- Short Name:
- J/A+A/384/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velocities, vsini, Li abundances and X-ray luminosities and investigate the single or binary nature of the sample stars. Such a careful analysis of our sample shows a large fraction of binaries (~62%) and of young single disk stars. In particular, at least 9 stars can be considered bona-fide PMS or ZAMS objects, and 30 stars are identified as SBs for the first time. Information on the presence of Ca II K emission and on optical variability is given for some of the stars of the sample. The photometry has been obtained at the European Southern Observatory (ESO-La silla, Chile) during several observing runs (19/11-03/12 1993, 24/11-04/12 1994, 15-28/01/1995 and 1-12/10/1995), by using the 50cm ESO telescope. The figures were published in paper II.
