- ID:
- ivo://CDS.VizieR/J/MNRAS/433/3398
- Title:
- White dwarf main-sequence binaries
- Short Name:
- J/MNRAS/433/3398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectroscopic catalogue of white dwarf main-sequence (WDMS) binaries from the Sloan Digital Sky Survey (SDSS) is the largest and most homogeneous sample of compact binary stars currently known. However, because of selection effects, the current sample is strongly biased against systems containing cool white dwarfs and/or early-type companions, which are predicted to dominate the intrinsic population. In this study, we present colour selection criteria that combines optical (ugriz DR8 SDSS) plus infrared (yjhk DR9 UKIRT Infrared Sky Survey, JHK Two Micron All Sky Survey and/or W1W2 Wide-Field Infrared Survey Explorer) magnitudes to select 3419 photometric candidates of harbouring cool white dwarfs and/or dominant (M dwarf) companions. We demonstrate that 84 percent of our selected candidates are very likely genuine WDMS binaries, and that the white dwarf effective temperatures and secondary star spectral types of 71 percent of our selected sources are expected to be below <~10000-15000K, and concentrated at ~M2-3, respectively. We also present an updated version of the spectroscopic SDSS WDMS binary catalogue, which incorporates 47 new systems from SDSS DR8. The bulk of the DR8 spectroscopy is made up of main-sequence stars and red giants that were targeted as part of the Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey, therefore the number of new spectroscopic WDMS binaries in DR 8 is very small compared to previous SDSS data releases. Despite their low number, DR8 WDMS binaries are found to be dominated by systems containing cool white dwarfs and therefore represent an important addition to the spectroscopic sample. The updated SDSS DR8 spectroscopic catalogue of WDMS binaries consists of 2316 systems. We compare our updated catalogue with recently published lists of WDMS binaries and conclude that it currently represents the largest, most homogeneous and cleanest sample of spectroscopic WDMS binaries from SDSS.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/486/843
- Title:
- White dwarf-red dwarf binaries in the SDSS
- Short Name:
- J/A+A/486/843
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To reduce contamination by more distant sources, such as quasars, we have selected candidate white dwarf-red dwarf binaries from the catalogue of proper motion stars drawn from the intersection of the Sloan Digital Sky Survey (SDSS) and the USNO-B1.0 catalogue.
- ID:
- ivo://CDS.VizieR/J/AJ/148/38
- Title:
- WIYN open cluster study. LX. RV survey of NGC 6819
- Short Name:
- J/AJ/148/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8000days. These results are the product of our ongoing RV survey of NGC 6819 using the Hydra Multi-Object Spectrograph on the WIYN 3.5m telescope. We also include a detailed analysis of multiple prior sets of optical photometry for NGC 6819. Within a 1{deg} field of view, our stellar sample includes the giant branch, the red clump, and blue straggler candidates, and extends to almost 2 mag below the main sequence (MS) turnoff. For each star observed in our survey we present all RV measurements, the average RV, and velocity variability information. Additionally, we discuss notable binaries from our sample, including eclipsing binaries (WOCS 23009, WOCS 24009, and WOCS 40007), stars noted in Kepler asteroseismology studies (WOCS 4008, WOCS 7009, and WOCS 8007), and potential descendants of past blue stragglers (WOCS 1006 and WOCS 6002). We find the incompleteness-corrected binary fraction for all MS binaries with periods less than 10^4^days to be 22%+/-3% and a tidal circularization period of 6.2^+1.1^_-1.1_days for NGC 6819.
- ID:
- ivo://CDS.VizieR/J/AJ/150/10
- Title:
- WOCS. LXVI. Radial velocity survey in M35
- Short Name:
- J/AJ/150/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The young (150Myr) open cluster M35 (NGC 2168) has been one of the core clusters of the WIYN Open Cluster Study since 1997. Over these 17years we have obtained approximately 8000 radial-velocity (RV) measurements of stars in the M35 field, which we provide here. Our target sample consists of 1355 photometrically selected stars in the field of M35 within the main sequence and binary sequence of the cluster and within 13<=V<=16.5 and (B-V)>=0.6. Using our RV measurements we cleanly separate likely cluster members from field stars. We calculate RV membership probabilities for over 1200 stars in our sample. 418 are probable cluster members, of which 64 are velocity-variable (binary) systems. Here we present 52 orbital solutions for binary members of M35. This sample defines the hard binary population of M35 that dynamically powers the cluster. We also present XMM-Newton X-ray detections within the cluster. We use our large binary sample to search for interacting binaries among the X-ray sources, investigate M35's period-eccentricity distribution, and determine binary frequency. We find a circularization period of 9.9+/-1.2days and a binary frequency of 24%+/-3% for main-sequence binaries with P<10^4^days. Determining these properties in a young cluster like M35 is key to defining the initial conditions used in models of cluster dynamical evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/151/152
- Title:
- WOCS. LXXI. Spectroscopy of 5 stars in NGC 6791
- Short Name:
- J/AJ/151/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an optical color-magnitude diagram, sub-subgiants (SSGs) lie redward of the main sequence and fainter than the base of the red giant branch in a region not easily populated by standard stellar-evolution pathways. In this paper, we present multi-epoch radial velocities for five SSG candidates in the old and metal-rich open cluster NGC 6791 (8Gyr, [Fe/H]=+0.30). From these data, we are able to make three-dimensional kinematic membership determinations and confirm four SSG candidates as likely cluster members. We also identify three member SSGs as short-period binary systems and present their orbital solutions. These are the first SSGs with known three-dimensional kinematic membership, binary status, and orbital parameters since the two SSGs in M67 studied by Mathieu et al. We also remark on the other properties of these stars including photometric variability, H{alpha} emission, and X-ray luminosity. The membership confirmation of these SSGs in NGC 6791 strengthens the case that SSGs are a new class of nonstandard stellar evolution products, and that a physical mechanism must be found that explains the evolutionary paths of these stars.
- ID:
- ivo://CDS.VizieR/J/AJ/160/169
- Title:
- WOCS. LXXXII. Orbital parameters & RVs in NGC 7789
- Short Name:
- J/AJ/160/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extensive time-series radial-velocity (RV) survey of stars in the rich open cluster NGC7789 (1.6Gyr, [Fe/H]=+0.02). The stellar sample lies within an 18' circular radius from the cluster center (10pc in projection, or about 2core radii), and includes giants, red clump stars, blue stragglers, red stragglers, sub-subgiants, and main-sequence stars down to 1mag below the turnoff. Our survey began in 2005 and comprises more than 9000 RV measurements from the Hydra Multi-Object Spectrograph on the WIYN 3.5m telescope. We identify 624 likely cluster members and present the orbital solutions for 81 cluster binary stars with periods between 1.45 and 4200days. From the main-sequence binary solutions we fit a circularization period of 7.2_-1.1_^+0.6^days. We calculate an incompleteness-corrected main- sequence binary frequency of 31%{+/-}4% for binaries with periods less than 104days, similar to other WIYN Open Cluster Survey (WOCS) open clusters of all ages. We detect a blue straggler binary frequency of 33%{+/-}17%, consistent with the similarly aged open cluster NGC6819. We also find one secure, rapidly rotating sub-subgiant and one red straggler candidate in our sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/373/1483
- Title:
- W UMa type and CAB stars dynamical evolution
- Short Name:
- J/MNRAS/373/1483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital angular momentum (OAM, Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of and logJo-logP, logM-logP and logJo-logM were formed from 119 CAB and 102 W UMa stars. The log Jo-logM diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the logJo-logM diagram. Since the orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio, q, the rates of OAM loss (dlogJo/dt) and mass loss (dlogM/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the logJo-logM diagram. The evolution of q for a mass-losing detached system is unknown unless the mass-loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of Jo and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 per cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6Gyr, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A120
- Title:
- Y Cyg light curves and time of minima
- Short Name:
- J/A+A/563/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rapid advancements in light-curve and radial-velocity curve modelling, as well as improvements in the accuracy of observations, allow more stringent tests of the theory of stellar evolution. Binaries with rapid apsidal advance are particularly useful in this respect since the internal structure of the stars can also be tested. Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornerstones of critical tests of stellar evolutionary theory for massive stars. Nevertheless, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyse all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/145
- Title:
- 20yr obs. of the spectroscopic binary EC 20117-4014
- Short Name:
- J/ApJ/859/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among the competing evolution theories for subdwarf-B (sdB) stars is the binary evolution scenario. EC 20117-4014 (=V4640 Sgr) is a spectroscopic binary system consisting of a pulsating sdB star and a late F main-sequence companion; however, the period and the orbit semimajor axes have not been precisely determined. This paper presents orbital characteristics of the EC 20117-4014 binary system using 20 years of photometric data. Periodic observed minus calculated (O-C) variations were detected in the two highest-amplitude pulsations identified in the EC 20117-4014 power spectrum, indicating the binary system's precise orbital period (P=792.3d) and the light-travel-time amplitude (A=468.9s). This binary shows no significant orbital eccentricity, and the upper limit of the eccentricity is 0.025 (using 3{sigma} as an upper limit). This upper limit of the eccentricity is the lowest among all wide sdB binaries with known orbital parameters. This analysis indicated that the sdB is likely to have lost its hydrogen envelope through stable Roche lobe overflow, thus supporting hypotheses for the origin of sdB stars. In addition to those results, the underlying pulsation period change obtained from the photometric data was dP/dt=5.4(+/-0.7)x10^-14^d.d^-1^, which shows that the sdB is just before the end of the core helium-burning phase.
- ID:
- ivo://CDS.VizieR/J/ApJS/226/18
- Title:
- 5yr radial velocity measurements of 19 Cepheids
- Short Name:
- J/ApJS/226/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the radial velocity (RV) variability and spectroscopic binarity of 19 Galactic long-period (P_puls_>~10d) classical Cepheid variable stars whose trigonometric parallaxes are being measured using the Hubble Space Telescope and Gaia. Our primary objective is to constrain possible parallax error due to undetected orbital motion. Using over 1600 high-precision RVs measured between 2011 and 2016, we find no indication of orbital motion on <~5yr timescales for 18 Cepheids and determine upper limits on allowed configurations for a range of input orbital periods. The results constrain the unsigned parallax error due to orbital motion to <2% for 16 stars, and <4% for 18. We improve the orbital solution of the known binary YZ Carinae and show that the astrometric model must take into account orbital motion to avoid significant error (~+/-100{mu}arcsec). We further investigate long-timescale (P_orb_>10yr) variations in pulsation-averaged velocity v_{gamma}_ via a template fitting approach using both new and literature RVs. We discover the spectroscopic binarity of XZ Car and CD Cyg, find first tentative evidence for AQ Car, and reveal KN Cen's orbital signature. Further (mostly tentative) evidence of time-variable v_{gamma}_ is found for SS CMa, VY Car, SZ Cyg, and X Pup. We briefly discuss considerations regarding a vetting process of Galactic Leavitt law calibrators and show that light contributions by companions are insignificant for most distance scale applications.
