- ID:
- ivo://CDS.VizieR/J/A+A/378/556
- Title:
- UVES/VLT spectra of white dwarfs
- Short Name:
- J/A+A/378/556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have started a large survey for radial velocity variations in white dwarfs (PI R. Napiwotzki) with the aim of finding close double degenerates, which could be precursor systems for SNe Ia. The UVES spectrograph at the ESO VLT is used to obtain high resolution spectra with good S/N. During this project 1500 white dwarfs will be observed. This unique data set will also allow to derive atmospheric parameters and masses for the largest sample of white dwarfs ever analyzed in a homogeneous way. In this paper we present a catalog of objects and report results for the first sample of about 200 white dwarfs, many of which are spectroscopic confirmations of candidates from the Hamburg ESO Quasar Survey (HE, Cat. <J/A+AS/115/235>), Montreal-Cambridge-Tololo Survey (MCT), and Edinburgh-Cape Survey (EC, Cat. <J/MNRAS/287/867>) surveys. Among the peculiar spectra we identify two new magnetic DA, one previously known magnetic DA, several DA with emission cores, in some cases due to a late-type companion, and two new DBA.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/156/78
- Title:
- 44 validated planets from K2 Campaign 10
- Short Name:
- J/AJ/156/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 44 validated planets from the 10th observing campaign of the NASA K2 mission, as well as high-resolution spectroscopy and speckle imaging follow-up observations. These 44 planets come from an initial set of 72 vetted candidates, which we subjected to a validation process incorporating pixel-level analyses, light curve analyses, observational constraints, and statistical false positive probabilities. Our validated planet sample has median values of R_p_=2.2 R_{Earth}_, P_orb_=6.9 days, T_eq_=890 K, and J=11.2 mag. Of particular interest are four ultra-short period planets (P_orb_~<1 day), 16 planets smaller than 2 R_{Earth}_, and two planets with large predicted amplitude atmospheric transmission features orbiting infrared-bright stars. We also present 27 planet candidates, most of which are likely to be real and worthy of further observations. Our validated planet sample includes 24 new discoveries and has enhanced the number of currently known super-Earths (R_p_~1-2 R_{Earth}_), sub-Neptunes (R_p_~2-4 R_{Earth}_), and sub-Saturns (R_p_~4-8 R_{Earth}_) orbiting bright stars (J=8-10 mag) by ~4%, ~17%, and ~11%, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/176
- Title:
- Very low-mass binaries with Gaia DR2 data
- Short Name:
- J/ApJ/889/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of WISE 2150-7520AB (W2150AB): a widely separated (~341au) very low-mass L1+T8 co-moving system. The system consists of the previously known L1 primary 2MASS J21501592-7520367 and a newly discovered T8 secondary found at position 21:50:18.99-75:20:54.6 (MJD=57947) using Wide-field Infrared Survey Explorer data via the Backyard Worlds: Planet 9 citizen science project. We present Spitzer ch1 and ch2 photometry (ch1-ch2=1.41+/-0.04mag) of the secondary and Folded-port InfraRed Echellette prism spectra of both components. The sources show no peculiar spectral or photometric signatures, indicating that each component is likely field age. Using all observed data and the Gaia DR2 parallax of 41.3593+/-0.2799mas for W2150A we deduce fundamental parameters of log(L_bol_/L_{sun}_)=-3.69+/-0.01, Teff=2118+/-62K, and an estimated mass=72+/-12M_Jup_ for the L1 and log(L_bol_/L_{sun}_)=-5.64+/-0.02, Teff=719+/-61K, and an estimated mass=34+/-22M_Jup_ for the T8. At a physical separation of ~341au this system has E_bin_=10^41^erg, making it the lowest binding energy system of any pair with M_tot_<0.1M_{sun}_ not associated with a young cluster. It is equivalent in estimated mass ratio, E_bin_, and physical separation to the ~2Myr M7.25+M8.25 binary brown dwarf 2MASS J11011926-7732383AB (2M1101AB) found in the Chameleon star-forming region. W2150AB is the widest companion system yet observed in the field where the primary is an L dwarf or later.
- ID:
- ivo://CDS.VizieR/J/AJ/157/171
- Title:
- Visual analysis and demographics of Kepler TTVs
- Short Name:
- J/AJ/157/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We visually analyzed the transit timing variation (TTV) data of 5930 Kepler Objects of Interest (KOIs) homogeneously. Using data from Rowe et al. (2014, J/ApJ/784/45) and Holczer et al. (2015, J/ApJ/807/170; 2016, J/ApJS/225/9), we investigated TTVs for nearly all KOIs in Kepler's Data Release 24 catalog. Using TTV plots, periodograms, and phase-folded quadratic plus sinusoid fits, we visually rated each KOI's TTV data in five categories. Our ratings emphasize the hundreds of planets with TTVs that are weaker than the ~200 that have been studied in detail. Our findings are consistent with statistical methods for identifying strong TTVs, though we found some additional systems worth investigation. Between about 3-50 days and 1.3-6 Earth radii, the frequency of strong TTVs increases with period and radius. As expected, strong TTVs are very common when period ratios are near a resonance, but there is not a one-to-one correspondence. The observed planet-by-planet frequency of strong TTVs is only somewhat lower in systems with one or two known planets (7%+/-1%) than in systems with three or more known planets (11%+/-2%). We attribute TTVs to known planets in multitransiting systems but find ~30 cases where the perturbing planet is unknown. Our conclusions are valuable as an ensemble for learning about planetary system architectures and individually as stepping stones toward more-detailed mass-radius constraints. We also discuss Data Release 25 TTVs, investigate ~100 KOIs with transit duration and/or depth variations, and estimate that the Transiting Exoplanet Survey Satellite will likely find only ~10 planets with strong TTVs.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A98
- Title:
- VIsual Binary Exoplanet survey with SPHERE
- Short Name:
- J/A+A/643/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent surveys indicate that planets in binary systems are more abunda- nt than previously thought, which is in agreement with theoretical work on disc dynamics and planet formation in binaries. So far, most observational surveys, however, have focused on short-period planets in binaries, thus little is known about the occurrence rates of planets on longer periods (>10au). In order to measure the abundance and physical characteristics of wide-orbit giant exoplanets in binary systems, we have designed the 'VIsual Binary Exoplanet survey with Sphere' (VIBES) to search for planets in visual binaries. It uses the SPHERE instrument at VLT to search for planets in 23 visual binary and four visual triple systems with ages of <145Myr and distances of <150pc. We used the IRDIS dual-band imager on SPHERE to acquire high-contrast images of the sample targets. For each binary, the two components were observed at the same time with a coronagraph masking only the primary star. For the triple star, the tight components were treated as a single star for data reduction. This enabled us to effectively search for companions around 50 individual stars in binaries and four binaries in triples. We derived upper limits of <13.7% for the frequency of sub-stellar companions around primaries in visual binaries, <26.5% for the fraction of sub-stellar companions around secondaries in visual binaries, and an occurrence rate of <9.0% for giant planets and brown dwarfs around either component of visual binaries. We have combined our observations with literature measurements to astrometrically confirm, for the first time, that 20 binaries and two triple systems, which were previously known, are indeed physically bound. Finally, we discovered a third component of the binary HD 121336. The upper limits we derived are compatible with planet formation through the core accretion and the gravitational instability processes in binaries. These limits are also in line with limits found for single star and circumbinary planet search surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/341/121
- Title:
- Visual binary orbits and masses
- Short Name:
- J/A+A/341/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper gives orbits and masses for some 200 nearby visual binaries, as derived from combining ground-based and Hipparcos data. Table 6 gives identifications and notes, and points to the detailed data in Table 1 (short-P systems with mass-ratio from the Hipparcos observations), Table 3 (mass-uncertainty below 10%) or Table 4 (mass-uncertainty above 10%).
- ID:
- ivo://CDS.VizieR/J/ApJS/222/15
- Title:
- WATCHDOG: an all-sky database of Galactic BHXBs
- Short Name:
- J/ApJS/222/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the advent of more sensitive all-sky instruments, the transient universe is being probed in greater depth than ever before. Taking advantage of available resources, we have established a comprehensive database of black hole (and black hole candidate) X-ray binary (BHXB) activity between 1996 and 2015 as revealed by all-sky instruments, scanning surveys, and select narrow-field X-ray instruments on board the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), Monitor of All-Sky X-ray Image (MAXI), Rossi X-ray Timing Explorer (RXTE), and Swift telescopes; the Whole-sky Alberta Time-resolved Comprehensive black-Hole Database Of the Galaxy or WATCHDOG. Over the past two decades, we have detected 132 transient outbursts, tracked and classified behavior occurring in 47 transient and 10 persistently accreting BHs, and performed a statistical study on a number of outburst properties across the Galactic population. We find that outbursts undergone by BHXBs that do not reach the thermally dominant accretion state make up a substantial fraction (~40%) of the Galactic transient BHXB outburst sample over the past ~20 years. Our findings suggest that this "hard-only" behavior, observed in transient and persistently accreting BHXBs, is neither a rare nor recent phenomenon and may be indicative of an underlying physical process, relatively common among binary BHs, involving the mass-transfer rate onto the BH remaining at a low level rather than increasing as the outburst evolves. We discuss how the larger number of these "hard-only" outbursts and detected outbursts in general have significant implications for both the luminosity function and mass-transfer history of the Galactic BHXB population.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/765
- Title:
- White dwarf candidates using LAMOST DR3
- Short Name:
- J/MNRAS/452/765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In previous work by Gentile Fusillo et al., we developed a selection method for white dwarf candidates which makes use of photometry, colours and proper motions to calculate a probability of being a white dwarf (P_WD_). The application of our method to the Sloan Digital Sky Survey (SDSS) data release 10 resulted in =~ 66000 photometrically selected objects with a derived P_WD_, approximately =~21000 of which are high-confidence white dwarf candidates. Here, we present an independent test of our selection method based on a sample of spectroscopically confirmed white dwarfs from the Large Sky Area Multi-Fiber Spectroscopic Telescope (LAMOST) survey. We do this by cross-matching all our =~66000 SDSS photometric white dwarf candidates with the over 4 million spectra available in the third data release of LAMOST. This results in 1673 white dwarf candidates with no previous SDSS spectroscopy, but with available LAMOST spectra. Among these objects, we identify 309 genuine white dwarfs. We find that our P_WD_ can efficiently discriminate between confirmed LAMOST white dwarfs and contaminants. Our white dwarf candidate selection method can be applied to any multiband photometric survey and in this work we conclusively confirm its reliability in selecting white dwarfs without recourse to spectroscopy. We also discuss the spectroscopic completeness of white dwarfs in LAMOST, as well as deriving effective temperatures, surface gravities and masses for the hydrogen-rich atmosphere white dwarfs in the newly identified LAMOST sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/2102
- Title:
- White dwarf population from the SDSS DR12
- Short Name:
- J/MNRAS/469/2102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalogue to date, to study the evolution of the kinematical properties of the population of white dwarfs in the Galactic disc. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalogue are available, the true three-dimensional components of the stellar space velocity are obtained. This subset of the original sample comprises 20 247 objects, making it the largest sample of white dwarfs with measured three-dimensional velocities. Furthermore, the volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance R_G_=7.8 to 9.3kpc, and vertical distances from the Galactic plane ranging from Z=-0.5 to 0.5kpc. We examine the mean components of the stellar three-dimensional velocities, as well as their dispersions with respect to the Galactocentric and vertical distances. We confirm the existence of a mean Galactocentric radial velocity gradient, {partial}<V_R_>/{partial}R_G_=-3+/-5km/s/. We also confirm north-south differences in <V_z_> . Specifically, we find that white dwarfs with Z>0 (in the North Galactic hemisphere) have <V_z_><0, while the reverse is true for white dwarfs with Z<0. The age-velocity dispersion relation derived from the present sample indicates that the Galactic population of white dwarfs may have experienced an additional source of heating, which adds to the secular evolution of the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/ApJ/867/62
- Title:
- White dwarf population of Messier 67
- Short Name:
- J/ApJ/867/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- White dwarfs (WDs) are excellent forensic tools for studying end-of-life issues surrounding low- and intermediate-mass stars, and the old, solar metallicity open star cluster Messier 67 is a proven laboratory for the study of stellar evolution for solar-type stars. In this paper, we present a detailed spectroscopic study of brighter (M_g_<=12.4) WDs in Messier 67, and in combination with previously published proper motion membership determinations, we identify a clean, representative sample of cluster WDs, including 13 members with hydrogen-dominated atmospheres, at least one of which is a candidate double degenerate, and 5 members with helium-dominated atmospheres. Using this sample we test multiple predictions surrounding the final stages of stellar evolution in solar-type stars. In particular, the stochasticity of the integrated mass lost by ~1.5 solar mass stars is less than 7% of the WD remnant mass. We identify WDs likely resulting from binary evolution, including at least one blue straggler remnant and two helium-core WDs. We observe no evidence of a significant population of helium-core WDs formed by enhanced mass loss on the red giant branch of the cluster. The distribution of WD atmospheric compositions is fully consistent with that in the field, limiting proposed mechanisms for the suppression of helium atmosphere WD formation in star clusters. In short, the WD population of Messier 67 is fully consistent with basic predictions of single- and multiple-star stellar evolution theories for solar metallicity stars.
