- ID:
- ivo://CDS.VizieR/J/ApJS/232/23
- Title:
- 27 pulsating DA WDs follow-up observations
- Short Name:
- J/ApJS/232/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs; a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) and duty cycle (>90%). The space-based photometry reveals pulsation properties previously inaccessible to ground- based observations. We observe a sharp dichotomy in oscillation mode line widths at roughly 800s, such that white dwarf pulsations with periods exceeding 800s have substantially broader mode line widths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: we identify the spherical degree of 87 out of 201 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra, we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low- and intermediate-mass stars. We find that 0.51-0.73M{sun} white dwarfs, which evolved from 1.7-3.0M{sun} ZAMS progenitors, have a mean rotation period of 35hr with a standard deviation of 28hr, with notable exceptions for higher-mass white dwarfs.
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- ID:
- ivo://CDS.VizieR/J/A+A/638/A131
- Title:
- Radial velocities of 643 DA white dwarfs
- Short Name:
- J/A+A/638/A131
- Date:
- 14 Jan 2022 08:18:09
- Publisher:
- CDS
- Description:
- Close double degenerate binaries are one of the favoured progenitor channels for type Ia supernovae, but it is unclear how many suitable systems there are in the Galaxy. We report results of a large radial velocity survey for double degenerate (DD) binaries using the UVES spectrograph at the ESO VLT (ESO SNIa Progenitor surveY - SPY). Exposures taken at different epochs are checked for radial velocity shifts indicating close binary systems.We observed 689 targets classified as DA (displaying hydrogen-rich atmospheres), of which 46 turned out to possess a cool companion. We measured radial velocities (RV) of the remaining 643 DA white dwarfs.We managed to secure observations at two or more epochs for 625 targets, supplemented by eleven objects meeting our selection criteria from literature. The data reduction and analysis methods applied to the survey data are described in detail. The sample contains 39 double degenerate binaries, only four of which were previously known. 20 are double-lined systems, in which features from both components are visible, the other 19 are single-lined binaries. We provide absolute RVs transformed to the heliocentric system suitable for kinematic studies. Our sample is large enough to sub-divide by mass: 16 out of 44 low mass targets (<=0.45M_{sun}_) are detected as DDs, while just 23 of the remaining 567 with multiple spectra and mass >0.45M_{sun}_ are double. Although the detected fraction amongst the low mass objects (36.4+/-7.3%) is significantly higher than for the higher-mass, carbon/oxygen-core dominated part of the sample (3.9+/-0.8%), it is lower than the detection efficiency based upon companion star masses of 0.05M_{sun}_ or higher and a 100% binary fraction. This suggests either companion stars of mass below 0.05M_{sun}_ or some of the low mass white dwarfs are single.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/4193
- Title:
- Radial velocities of 1453 FGK
- Short Name:
- J/MNRAS/472/4193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second paper of a series of publications aiming at obtaining a better understanding regarding the nature of type Ia supernovae (SN Ia) progenitors by studying a large sample of detached F, G and K main-sequence stars in close orbits with white dwarf companions (i.e. WD+FGK binaries). We employ the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data release 4 spectroscopic data base together with Galaxy Evolution Explorer (GALEX) ultraviolet fluxes to identify 1549 WD+FGK binary candidates (1057 of which are new), thus doubling the number of known sources. We measure the radial velocities of 1453 of these binaries from the available LAMOST spectra and/or from spectra obtained by us at a wide variety of different telescopes around the globe. The analysis of the radial velocity data allows us to identify 24 systems displaying more than 3{sigma} radial velocity variation that we classify as close binaries. We also discuss the fraction of close binaries among WD+FGK systems, which we find to be ~10 per cent, and demonstrate that high-resolution spectroscopy is required to efficiently identify double-degenerate SN Ia progenitor candidates.
- ID:
- ivo://CDS.VizieR/J/AJ/124/1118
- Title:
- Radial velocities of high-velocity white dwarfs
- Short Name:
- J/AJ/124/1118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocities and complete space motions were measured for 116 white dwarf stars with M dwarf companions (WD+M), including thirteen pairs having "halo-like" velocities. These 116 WD+dM binaries were observed on the 3.5 m telescope at the Apache Point Observatory (APO) on nearly 30 half-nights between 2000 September 4 and 2001 October 20. The APO Double Imaging Spectrograph was used with a 15" slit, yielding a resolution of approximately 2arcsrc/pixel. From the near-solar abundance levels of the M dwarf companions, only one potential stellar halo white dwarf (LP 164-52) was found in the sample, 12 of the 13 high-velocity white dwarfs being actually part of the high-velocity tail of the thick disk rather than the dark matter halo of the Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/67
- Title:
- Radial velocities of low-mass white dwarfs
- Short Name:
- J/ApJ/730/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe spectroscopic observations of 21 low-mass (<=0.45M_{sun}_) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is <=30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.
- ID:
- ivo://CDS.VizieR/J/MNRAS/467/1414
- Title:
- Radial velocity changes for 439 white dwarfs
- Short Name:
- J/MNRAS/467/1414
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a sample of spectra of 439 white dwarfs (WDs) from the ESO-VLT Supernova-Ia Progenitor Survey (SPY), we measure the maximal changes in radial velocity ({Delta}RVmax) between epochs (generally two epochs, separated by up to 470d), and model the observed {Delta}RVmax statistics via Monte Carlo simulations, to constrain the population characteristics of double WDs (DWDs). The DWD fraction among WDs is f_bin_=0.10+/-0.02 (1{sigma}, random) +0.02 (systematic), in the separation range <~4au within which the data are sensitive to binarity. Assuming the distribution of binary separation, a, is a power law, dN/da{prop.to}a^alpha^, at the end of the last common-envelope phase and the start of solely gravitational-wave-driven binary evolution, the constraint by the data is alpha=-1.3+/-0.2(1{sigma}) +/-0.2 (systematic). If these parameters extend to small separations, the implied Galactic WD merger rate per unit stellar mass is R_merge_=(1-80)x10^-13^yr^-1^M_[sun}_^-1^ (2{sigma}), with a likelihood-weighted mean of R_merge_=(7+/-2)x10^-13^yr^-1^M_{sun}_^-1^ (1{sigma}). The Milky Way's specific Type Ia supernova (SN Ia) rate is likely R_Ia_~=1.1x10^-13^yr^-1^M_{sun}_^-1^ and therefore, in terms of rates, a possibly small fraction of all merging DWDs (e.g. those with massive-enough primary WDs) could suffice to produce most or all SNe Ia.
- ID:
- ivo://CDS.VizieR/III/258
- Title:
- Revised and updated First Byurakan Survey (FBS)
- Short Name:
- III/258
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eleven lists of blue stellar objects (BSOs) were published in Astrophysics in 1990-1996, found in the First Byurakan Survey (FBS) low-dispersion spectroscopic plates. The selection was carried out in the region with +33<Dec<+45 and Dec>+61 with a surface of 4000deg^2^. As a result, the catalogue of the FBS blue stellar objects (BSOs) was compiled. Its preliminary version has been available at CDS since 1999. We revised and updated the FBS BSOs catalogue with the new data from recently published optical and multiwavelength catalogues to give access to all available data and make further comparative studies of the properties of these objects possible. We made cross-correlations of the FBS BSOs catalogue with the MAPS , USNO-B1.0, SDSS, and 2MASS, as well as ROSAT, IRAS, NVSS, and FIRST catalogs , added updated SIMBAD and NED data for the objects, and provided accurate DSS1 and DSS2 positions and revised photometry. We also checked the objects for proper motion and variability. A refined classification for the low-dispersion spectra in the Digitized First Byurakan Survey (DFBS) was carried out. The revised and updated catalogue of 1103 FBS blue stellar objects is presented. The FBS blue stellar objects catalogue can be used to study a complete sample of white dwarfs, hot subdwarfs, HBB stars, cataclysmic variables, bright AGN, and to investigate individual interesting objects. This catalog supersedes the previous edition by Abrahamian et al. (Cat. II/223)
- ID:
- ivo://CDS.VizieR/J/A+A/448/579
- Title:
- Sample of confirmed WDs in GSC-II survey
- Short Name:
- J/A+A/448/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The GSC-II white dwarf survey was designed to identify faint and high proper motion objects, which we used to define a new and independent sample of cool white dwarfs. With this survey we aim to derive new constraints on the halo white dwarf space density. Also, these data can provide information on the age of thick disk and halo through the analysis of the luminosity function. On the basis of astrometric and photometric parameters, we selected candidates with mu>0.28mas/yr and RF>16 in an area of 1150 square degrees. Then, we separated white dwarfs from late type dwarfs and subdwarfs by means of the reduced proper motion diagram. Finally, spectroscopic follow-up observations were carried out to confirm the white dwarf nature of the selected candidates. We found 41 white dwarfs of which 24 are new discoveries. Here we present the full sample and for each object provide positions, absolute proper motions, photometry, and spectroscopy.
- ID:
- ivo://CDS.VizieR/J/ApJS/167/40
- Title:
- SDSS4 confirmed white dwarfs catalog
- Short Name:
- J/ApJS/167/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 9316 spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey Data Release 4. We have selected the stars through photometric cuts and spectroscopic modeling, backed up by a set of visual inspections. About 6000 of the stars are new discoveries, roughly doubling the number of spectroscopically confirmed white dwarfs. We analyze the stars by performing temperature and surface gravity fits to grids of pure hydrogen and helium atmospheres. Among the rare outliers are a set of presumed helium-core DA white dwarfs with estimated masses below 0.3M_{sun}_, including two candidates that may be the lowest-mass yet found. We also present a list of 928 hot subdwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJS/204/5
- Title:
- SDSS DR7 white dwarf catalog
- Short Name:
- J/ApJS/204/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20407 white dwarf spectra, representing 19712 stars, and provide atmospheric model fits to 14120 DA and 1011 DB white dwarf spectra from 12843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated logg if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs.
