- ID:
- ivo://CDS.VizieR/J/MNRAS/472/4173
- Title:
- Bright white dwarfs for high-speed photometry
- Short Name:
- J/MNRAS/472/4173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing a very rich resource for asteroseismological studies and the search for transits from planetary debris. We have compiled an all-sky catalogue of ultraviolet, optical and infrared photometry as well as proper motions, which we propose as an essential tool for the preliminary identification and characterization of potential targets. We present data for 1864 known white dwarfs and 305 high-probability white dwarf candidates brighter than 17mag. We describe the spectroscopic follow-up of 135 stars, of which 82 are white dwarfs and 25 are hot subdwarfs. The new confirmed stars include six pulsating white dwarf candidates (ZZ Cetis), and nine white dwarf binaries with a cool main- sequence companion. We identify one star with a spectroscopic distance of only 25pc from the Sun. Around the time TESS is launched, we foresee that all white dwarfs in this sample will have trigonometric parallaxes measured by the ESA Gaia mission next year.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/601/A133
- Title:
- BVRI light curves of 3 massive binaries
- Short Name:
- J/A+A/601/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of mass and momentum exchanges in close massive binaries is very important in the subsequent evolution of the components. Such exchanges produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again. We investigated these effects for the close O-star binary LSS 3074 (O4f+O6-7:(f):), which is a good candidate for a past Roche lobe overflow (RLOF) episode because of its very short orbital period, P=2.185-days, and the luminosity classes of both components. We determined a new orbital solution for the system. We studied the photometric light curves to determine the inclination of the orbit and Roche lobe filling factors of both stars. Using phase-resolved spectroscopy, we performed the disentangling of the optical spectra of the two stars. We then analysed the reconstructed primary and secondary spectra with the CMFGEN model atmosphere code to determine stellar parameters, such as the effective temperatures and surface gravities, and to constrain the chemical composition of the components. We confirm the apparent low stellar masses and radii reported in previous studies. We also find a strong overabundance in nitrogen and a strong carbon and oxygen depletion in both primary and secondary atmospheres, together with a strong enrichment in helium of the primary star. We propose several possible evolutionary pathways through a RLOF process to explain the current parameters of the system. We confirm that the system is apparently in overcontact configuration and has lost a significant portion of its mass to its surroundings. We suggest that some of the discrepancies between the spectroscopic and photometric properties of LSS 3074 could stem from the impact of a strong radiation pressure of the primary.
- ID:
- ivo://CDS.VizieR/J/other/Obs/116.382
- Title:
- BVRI Photometry of Spectroscopic Binaries
- Short Name:
- J/other/Obs/116.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI photometry has been obtained for 82 of the spectroscopic binaries with orbits published in The Observatory by Griffin and his collaborators. The observations were obtained on nineteen nights during 1994-95. Given here are the star name, Griffin's paper number for the spectroscopic orbit, the abbreviated calendar date and heliocentric Julian Date (HJD) of the observation, the derived V, (B-V), (V-R)c, and (R-I)c values, and the phase in the spectroscopic orbit. The mean photometric values are listed in the final entry for each star. One night of poor quality, 950128, was given half weight in forming the means. The rms error of a single observation is about 0.025 mag. for all indices.
- ID:
- ivo://CDS.VizieR/J/A+AS/146/103
- Title:
- CaII H&K to CaII IRT echelle spectra
- Short Name:
- J/A+AS/146/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the CaII H&K to CaII IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H{alpha} profile of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the H{alpha} line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the E_H{alpha}_/E_H{beta}_ ratio as a diagnostic we have detected prominence-like extended material viewed off the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn. The He I D_3_ line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He I D_3_, probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the CaII H&K lines of the giants 12 Cam, FG UMa and BM CVn. All the stars analysed show clear filled-in CaII IRT lines or even notable emission reversal. The small values of the E_8542_/E_8498_ ratio we have found indicate CaII IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found.
- ID:
- ivo://CDS.VizieR/J/A+A/444/643
- Title:
- Candidate spectroscopic binaries in SDSS
- Short Name:
- J/A+A/444/643
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have examined the radial velocity data for stars spectroscopically observed by the Sloan Digital Sky Survey (SDSS) more than once to investigate the incidence of spectroscopic binaries, and to evaluate the accuracy of the SDSS stellar radial velocities.
- ID:
- ivo://CDS.VizieR/J/AJ/155/190
- Title:
- Carina Nebula hot stars: stellar parameters and RVs
- Short Name:
- J/AJ/155/190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carina Nebula is an active star-forming region in the southern sky that is of particular interest due to the presence of a large number of massive stars in a wide array of evolutionary stages. Here, we present the results of the spectroscopic analysis of 82 B-type stars and 33 O-type stars that were observed in 2013 and 2014. For 82 B-type stars without line blending, we fit model spectra from the Tlusty BSTAR2006 grid to the observed profiles of H{gamma} and He {lambda}{lambda}4026, 4388, and 4471 to measure the effective temperatures, surface gravities, and projected rotational velocities. We also measure the masses, ages, radii, bolometric luminosities, and distances of these stars. From the radial velocities measured in our sample, we find 31 single lined spectroscopic binary candidates. We find a high dispersion of radial velocities among our sample stars, and we argue that the Carina Nebula stellar population has not yet relaxed and become virialized.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A32
- Title:
- CARMENES SB2 orbital parameters
- Short Name:
- J/A+A/619/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CARMENES spectrograph is surveying ~300 M dwarf stars in search for exoplanets. Among the target stars, spectroscopic binary systems have been discovered, which can be used to measure fundamental properties of stars. Using spectroscopic observations we determine the orbital and physical properties of nine new double-line spectroscopic binary systems by analysing their radial velocity curves. We use two-dimensional cross-correlation techniques to derive the radial velocities of the targets, which are then employed to determine the orbital properties. Photometric data from the literature are also analysed to search for possible eclipses and to measure stellar variability, which can yield rotation periods. Out of the 342 stars in the CARMENES sample, only 9 have been found to be SB2s. We provide empirical orbital properties and minimum masses for the sample of spectroscopic binaries, with periods ranging from 1.13 to 8000 days and eccentricities up to ~0.54. Absolute masses are also estimated from mass-luminosity calibrations, ranging between ~0.1M_{sun}_ and ~0.6M_{sun}_. These new binary systems increase the number of double-line M dwarf binary systems with known orbital parameters by 14%, and suggest that low-mass binaries seem to have lower mass ratios than more massive systems.
- ID:
- ivo://CDS.VizieR/J/AN/340/386
- Title:
- Catalogue of spectroscopic binary candidate stars
- Short Name:
- J/AN/340/386
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the recently published Gaia second data release that includes measurements of the mean radial velocity of about 7.2 million stars, we performed a systematic comparison with other existing radial velocity catalogs to search for variations in the radial velocity measurements, with the goal that detected differences may indicate that these stars are possibly spectroscopic binary stars with only one visible component (SB1). We present a catalog of spectroscopic binary candidate stars containing 35246 stars, compiled to encourage follow-up observations obtaining spectra at different epochs of orbits of these stars to verify their binarity and to study these systems using radial velocity curves. Comparing the Gaia DR2 database with the K-M dwarf catalog, we found 16 stars that show radial velocity variations. In a comparison with the Pulkovo radial velocity catalog of Hipparcos stars, we identified a total of 539 SB1 candidate stars. In the largest radial velocity catalog available, the radial velocity experiment (RAVE) catalog, we found a total of 34691 stars that show radial velocity variations when compared to the Gaia DR2 data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/349/1069
- Title:
- Chromospherically active binaries
- Short Name:
- J/MNRAS/349/1069
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The kinematics of 237 chromospherically active binaries (CABs) were studied. The sample is heterogeneous with different orbits and physically different components from F to M spectral-type main-sequence stars to G and K giants and supergiants. The computed U, V, W space velocities indicate that the sample is also heterogeneous in velocity space.
- ID:
- ivo://CDS.VizieR/J/AJ/157/196
- Title:
- Close companions around young stars
- Short Name:
- J/AJ/157/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiplicity is a fundamental property that is set early during stellar lifetimes, and it is a stringent probe of the physics of star formation. The distribution of close companions around young stars is still poorly constrained by observations. We present an analysis of stellar multiplicity derived from Apache Point Observatory Galactic Evolution Experiment-2 spectra obtained in targeted observations of nearby star-forming regions. This is the largest homogeneously observed sample of high-resolution spectra of young stars. We developed an autonomous method to identify double-lined spectroscopic binaries (SB2s). Out of 5007 sources spanning the mass range of ~0.05-1.5 M_{sun}_, we find 399 binaries, including both radial velocity (RV) variables and SB2s. The mass ratio distribution of SB2s is consistent with being uniform for q<0.95 with an excess of twins for q>0.95. The period distribution is consistent with what has been observed in close binaries (<10 au) in the evolved populations. Three systems are found to have q~0.1, with a companion located within the brown dwarf desert. There are no strong trends in the multiplicity fraction as a function of cluster age from 1 to 100 Myr. There is a weak dependence on stellar density, with companions being most numerous at {Sigma}_*_~30 stars/pc^-2^ and decreasing in more diffuse regions. Finally, disk-bearing sources are deficient in SB2s (but not RV variables) by a factor of ~2; this deficit is recovered by the systems without disks. This may indicate a quick dispersal of disk material in short-period equal-mass systems that is less effective in binaries with lower q.
