- ID:
- ivo://CDS.VizieR/J/AJ/151/26
- Title:
- Spectroscopy of five {gamma} Dor variables
- Short Name:
- J/AJ/151/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the spectroscopic orbits of five {gamma} Dor variables, HD776, HD6568, HD17310, HD19684, and HD62196. Their orbital periods range from 27.8 to 1163days and their eccentricities from 0.01 to 0.65. Of the five systems, only HD19684 shows lines of its binary companion, but those lines are always so weak and blended with the lines of the primary that we were unable to measure them satisfactorily. The velocity residuals of the orbital fits were searched for periodicities associated with pulsation. No clear, convincing case for velocity periodicities in the residuals was found in four of the five stars. However, for HD17310 we identified a period of 2.13434days, a value in agreement with the largest amplitude period previously found photometrically for that star. The velocity residuals of HD62196 have a long-term trend suggesting that it is a triple system.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/678/635
- Title:
- Spectroscopy of quasar binary candidates
- Short Name:
- J/ApJ/678/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy of binary quasar candidates, with component separations of 3"<={Delta}{theta}<6", selected from SDSS DR4 using kernel density estimation (KDE). Of our 27 new quasar pair observations, 10 are binary quasars, which doubles the number of known g<21 binaries with 3"<={Delta}{theta}<6" separations. Several of our observed binaries are wide-separation lens candidates that merit additional higher resolution spectroscopy, as well as deep imaging to search for lensing galaxies. Our candidates are initially selected by UV excess (u-g<1), but are otherwise selected irrespective of the relative colors of the quasar pair, and we thus use them to suggest optimal color similarity and photometric redshift approaches for targeting binary quasars or projected quasar pairs. We find that a third or more of all binary quasars have quite dissimilar components on the basis of a typical color similarity criterion ({chi}^2^_color_<~20). From a sample that is complete on proper scales of 23.7h^-1^kpc<R_prop_<29.9h^-1^kpc, we determine the projected quasar correlation function.
- ID:
- ivo://CDS.VizieR/J/AJ/152/10
- Title:
- Spectroscopy of subsystems in four multiple stars
- Short Name:
- J/AJ/152/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Seven spectroscopic orbits in nearby solar-type multiple stars are presented. The primary of the chromospherically active star HIP9642 is a 4.8day double-lined pair; the outer 420 year visual orbit is updated, but remains poorly constrained. HIP12780 is a quadruple system consisting of the resolved 6.7year pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days. HIP28790 is a young quintuple system composed of two close binaries, Aa,Ab and Ba,Bb, with periods of 221 and 13 days, respectively, and a single distant component C. Its subsystem Ba,Bb is peculiar, having a spectroscopic mass ratio of 0.89 but a magnitude difference of ~2.2mag. HIP64478 also contains five stars: the A-component is a 29year visual pair with a previously known 4 day twin subsystem, while the B-component is a contact binary with a period of 5.8hr, seen nearly pole-on.
- ID:
- ivo://CDS.VizieR/J/ApJ/710/1142
- Title:
- SpeX spectroscopy of low mass binaries. I.
- Short Name:
- J/ApJ/710/1142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the identification of 17 candidate brown dwarf binaries whose components straddle the L dwarf/T dwarf transition. These sources were culled from a large near-infrared spectral sample of L and T dwarfs observed with the Infrared Telescope Facility SpeX spectrograph. Candidates were selected on the basis of spectral ratios which segregate known (resolved) L dwarf/T dwarf pairs from presumably single sources. Composite templates, constructed by combining 13581 pairs of absolute flux-calibrated spectra, are shown to provide statistically superior fits to the spectra of our 17 candidates as compared to single templates. Ten of these candidates appear to have secondary components that are significantly brighter than their primaries over the 1.0-1.3um band, indicative of rapid condensate depletion at the L dwarf/T dwarf transition. Our results support prior indications of enhanced multiplicity amongst early-type T dwarfs; 53+/-7% of the T0-T4 dwarfs in our spectral sample are found to be either resolved or unresolved (candidate) pairs, although this is consistent with an intrinsic (volume complete) brown dwarf binary fraction of only 15%. If verified, this sample of spectral binaries more than doubles the number of known L dwarf/T dwarf transition pairs, enabling a broader exploration of this poorly understood phase of brown dwarf atmospheric evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/91
- Title:
- Sp. obs. of rapidly rotating stars in the Pleiades
- Short Name:
- J/ApJ/901/91
- Date:
- 18 Feb 2022 11:55:29
- Publisher:
- CDS
- Description:
- Radial velocities for the early-type stars in the Pleiades cluster have always been challenging to measure because of the significant rotational broadening of the spectral lines. The large scatter in published velocities has led to claims that many are spectroscopic binaries, and in several cases, preliminary orbital solutions have been proposed. To investigate these claims, we obtained and report here velocity measurements for 33 rapidly rotating B, A, and early F stars in the Pleiades region, improving significantly on the precision of the historical velocities for most objects. With one or two exceptions, we do not confirm any of the previous claims of variability, and we also rule out all four of the previously published orbital solutions, for HD 22637, HD 23302, HD 23338, and HD 23410. We do find HD 22637 to be a binary but with a different period (71.8d). HD 23338 is likely a binary as well, with a preliminary 8.7yr period also different from the one published. Additionally, we report a 3635d orbit for HD 24899, another new spectroscopic binary in the cluster. From the 32 bona fide members in our sample, we determine a mean radial velocity for the Pleiades of 5.79+/-0.24km/s, or 5.52+/-0.31km/s when objects with known visual companions are excluded. Adding these astrometric binaries to the new spectroscopic ones, we find a lower limit to the binary fraction among the B and A stars of 37%. In addition to the velocities, we measure vsini for all stars, ranging between 69 and 317km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A38
- Title:
- SPOTS II. Planets Orbiting Two Stars
- Short Name:
- J/A+A/593/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large number of direct imaging surveys for exoplanets have been performed in recent years, yielding the first directly imaged planets and providing constraints on the prevalence and distribution of wide planetary systems. However, like most of the radial velocity ones, these generally focus on single stars, hence binaries and higher-order multiples have not been studied to the same level of scrutiny. This motivated the Search for Planets Orbiting Two Stars (SPOTS) survey, which is an ongoing direct imaging study of a large sample of close binaries, started with VLT/NACO and now continuing with VLT/SPHERE. To complement this survey, we have identified the close binary targets in 24 published direct imaging surveys. Here we present our statistical analysis of this combined body of data. We analysed a sample of 117 tight binary systems, using a combined Monte Carlo and Bayesian approach to derive the expected values of the frequency of companions, for different values of the companion's semi-major axis. Our analysis suggest that the frequency of sub-stellar companions in wide orbit is moderately low (=>13% with a best value of 6% at 95% confidence level) and not significantly different between single stars and tight binaries. One implication of this result is that the very high frequency of circumbinary planets in wide orbits around post-common envelope binaries, implied by eclipse timing, cannot be uniquely due to planets formed before the common-envelope phase (first generation planets), supporting instead the second generation planet formation or a non-Keplerian origin of the timing variations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/491/215
- Title:
- Supplementary data for 146 candidate young stars
- Short Name:
- J/MNRAS/491/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The past two decades have seen dramatic progress in our knowledge of the population of young stars of age <200Myr that lie within 150pc of the Sun. These nearby, young stars, most of which are found in loose, comoving groups, provide the opportunity to explore (among many other things) the dissolution of stellar clusters and their diffusion into the field star population. Here, we exploit the combination of astrometric and photometric data from Gaia and photometric data from GALEX (UV) and 2MASS (near-IR) in an attempt to identify additional nearby, young, late-type stars. Specifically, we present a sample of 146 GALEX UV-selected late-type (predominantly K-type) field stars with Gaia-based distances <125pc (based on Gaia Data Release 1) that have isochronal ages <80Myr even if equal-components binaries. We investigate the spectroscopic and kinematic properties of this sample. Despite their young isochronal ages, only ~10 per cent of stars among this sample can be confidently associated with established nearby, young moving groups (MGs). These candidate MG members include five stars newly identified in this study. The vast majority of our sample of 146 nearby young star candidates have anomalous kinematics relative to the known MGs. These stars may hence represent a previously unrecognized population of young stars that has recently mixed into the older field star population. We discuss the implications and caveats of such a hypothesis - including the intriguing fact that, in addition to their non-young-star-like kinematics, the majority of the UV-selected, isochronally young field stars within 50pc appear surprisingly X-ray faint.
- ID:
- ivo://CDS.VizieR/V/136
- Title:
- Teff and metallicities for Tycho-2 stars
- Short Name:
- V/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have created specialized target lists for radial velocity surveys that are biased toward stars that (1) possess planets and (2) are easiest to observe with current detection techniques. We use a procedure that uniformly estimates fundamental stellar properties of Tycho 2 stars, with errors, using spline functions of broadband photometry and proper motion found in Hipparcos/Tycho 2 and 2MASS. We provide estimates of effective temperature and distance for 2.4 million Tycho 2 stars that lack trigonometric distances. For stars that appear to be FGK dwarfs, we also derive [Fe/H] and identify unresolved binary systems with mass ratios 1.25<M1/M2<3.0. For FGK dwarfs with photometric error {sigma}_V_<0.05, or V<9, our temperature model gives a 1{sigma} error of {sigma}_T_=+58.7/-65.9K and our metallicity model gives a 1{sigma} error of {sigma}_[Fe/H]_=+0.13/-0.14dex. The binarity model can be used to remove 70% of doubles with 1.25<M1/M2<3.0 from a magnitude-limited sample of dwarfs at a cost of cutting 20% of the sample. Our estimates of distance and spectral type enable us to isolate 354,822 Tycho 2 dwarfs, 321,996 absent from Hipparcos, with giant contamination of 2.6% and 7.2%, respectively. Roughly 100,000 of these stars, not in Hipparcos, have sufficiently low photometric errors to retain 0.13-0.3dex [Fe/H] accuracy and 80-100K temperature accuracy (1{sigma}). Our metallicity estimates have been used to identify targets for N2K, a large-scale radial velocity search for hot jupiters, which has verified the errors presented here. The catalogs that we publish can be used to further large-scale studies of Galactic structure and chemical evolution and to provide potential reference stars for narrow-angle astrometry programs such as the Space Interferometry Mission and large-aperture optical interferometry.
- ID:
- ivo://CDS.VizieR/J/AJ/144/62
- Title:
- Tertiary companions to close spectroscopic binaries
- Short Name:
- J/AJ/144/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200AU to 10000AU (~10"-->~10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5^+5.2^_-3.7_%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%.
- ID:
- ivo://CDS.VizieR/V/60
- Title:
- 15th Complementary Catalog of SBs
- Short Name:
- V/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the orbits and the derived masses of 436 spectroscopic binaries for which articles were published between 1982 and 1986. The magnitudes and spectral types are from the Centre de Donnees astronomiques de Strasbourg. The notes are not included in this electronic version.
