- ID:
- ivo://CDS.VizieR/J/ApJ/745/119
- Title:
- Close companions to young stars. I. ChaI & Tau
- Short Name:
- J/ApJ/745/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a multiplicity survey of 212 T Tauri stars in the Chamaeleon I and Taurus-Auriga star-forming regions, based on high-resolution spectra from the Magellan Clay 6.5m telescope. From these data, we achieved a typical radial velocity (RV) precision of ~80m/s with slower rotators yielding better precision, in general. For 174 of these stars, we obtained multi-epoch data with sufficient time baselines to identify binaries based on RV variations. We identified eight close binaries and four close triples, of which three and two, respectively, are new discoveries. The spectroscopic multiplicity fractions we find for Chamaeleon I (7%) and Taurus-Auriga (6%) are similar to each other, and to the results of field star surveys in the same mass and period regime. However, unlike the results from imaging surveys, the frequency of systems with close companions in our sample is not seen to depend on primary mass. Additionally, we do not find a strong correlation between accretion and close multiplicity. This implies that close companions are not likely the main source of the accretion shut down observed in weak-lined T Tauri stars. Our results also suggest that sufficient RV precision can be achieved for at least a subset of slowly rotating young stars to search for hot Jupiter planets.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/144/93
- Title:
- Close white dwarf + M dwarf binaries (WD+dM)
- Short Name:
- J/AJ/144/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of close white dwarf and M dwarf (WD+dM) binary systems and examine the effect that a close companion has on the magnetic field generation in M dwarfs. We use a base sample of 1602 white dwarf main-sequence binaries from Rebassa-Mansergas et al. to develop a set of color cuts in GALEX, SDSS, UKIDSS, and 2MASS color space. Then using the SDSS Data Release 8 spectroscopic database, we construct a sample of 1756 WD+dM high-quality pairs from our color cuts and previous catalogs. We separate the individual WD and dM from each spectrum using an iterative technique that compares the WD and dM components to best-fit templates. Using the absolute height above the Galactic plane as a proxy for age, and the H{alpha} emission line as an indicator for magnetic activity, we investigate the age-activity relation for our sample for spectral types <=M7. Our results show that early-type M dwarfs (<=M4) in close binary systems are more likely to be active and have longer activity lifetimes compared to their field counterparts. However, at a spectral type of M5 (just past the onset of full convection in M dwarfs), the activity fraction and lifetimes of WD+dM binary systems become more comparable to that of the field M dwarfs. One of the implications of having a close binary companion is presumed to be increased stellar rotation through disk disruption, tidal effects, or angular momentum exchange. Thus, we interpret the similarity in activity behavior between late-type dMs in WD+dM pairs and late-type field dMs to be due to a decrease in sensitivity in close binary companions (or stellar rotation), which has implications for the nature of magnetic activity in fully convective stars. Using the WD components of the pairs, we find WD cooling ages to use as an additional constraint on the age-activity relation for our sample. We find that, on average, active early-type dMs tend to be younger and that active late-type dMs span a much broader age regime making them indistinguishable from the inactive late-type population. We also show that magnetic strength, as measured by H{alpha}, is comparable between paired and field M dwarfs until a spectral type of M6/M7 where M dwarf activity for stars with close companions becomes much stronger. In addition, we present 37 very close candidate pairs with fast-moving orbits that display radial velocity changes over hour timescales.
- ID:
- ivo://CDS.VizieR/J/A+A/450/681
- Title:
- Companions to close spectroscopic binaries
- Short Name:
- J/A+A/450/681
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have surveyed a sample of 165 solar-type spectroscopic binaries (SB) with periods from 1 to 30 days for higher-order multiplicity. 62 targets have been observed with the NACO adaptive optics system and 13 new physical tertiary companions were detected. Another 12 new wide companions (5 still tentative) were retrieved from the 2MASS (<II/246>) sky survey. Our binaries belong to 161 stellar systems; of these 64 are triple, 11 quadruple and 7 quintuple. After correction for incomplete detection, the fraction of SBs with additional companions is 63+/-5%. We find that this fraction is a strong function of the SB period P, reaching 96% for P<3d and dropping to 36% for P>12d. Period distributions of SBs with and without tertiaries are significantly different, but their mass ratio distributions are identical. New statistical data on the multiplicity of close SBs indicate that their periods and mass ratios were established very early, but periods of SBs within triples were further shortened by angular momentum exchange with companions.
- ID:
- ivo://CDS.VizieR/J/AJ/132/663
- Title:
- Differential Velocities of very low mass SBs
- Short Name:
- J/AJ/132/663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of a survey for radial velocity variability in a heterogeneous sample of very low mass stars and brown dwarfs. One distinguishing characteristic of the survey is its time span, which allows an overlap between spectroscopic binaries and those that can be found by high angular resolution imaging. Despite our relatively low velocity precision, we are able to place a new constraint on the total binary fraction in these objects, which suggests that they are more likely the result of extending the same processes at work at higher masses into this mass range, rather than a distinct mode of formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/2709
- Title:
- Double-lined spectroscopic binaries catalog
- Short Name:
- J/MNRAS/492/2709
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of a selected set of 69 double-lined spectroscopic binaries (SB2) with well defined visual and spectroscopic orbits was carried out. The orbital parallax, the mass, the colour, and the luminosity of each component were derived from observational data for almost all of these systems. We have also obtained an independent estimation of the component masses by comparing the colour-luminosity diagram (CMD) to the stellar evolution tracks reported by Pietrinferni. Nearly all of the observational points on the CMD are located between two tracks of slightly different mass or which fall very close to the one corresponding to a unique mass value. The masses obtained from the stellar model are in good agreement with their empirical values determined by parallax techniques (orbital, dynamical, and Gaia). This means that our adopted model is rather reliable and can therefore be used to infer further information, such as the age of each component in the studied systems. Our results indicate a fair correspondence between the age of primaries and secondary stars within 3{sigma}. Nevertheless, we caution that these age indications suffer of uncertainties due to both inhomogeneities/low precision of the adopted photometric data and possible systematics. Finally, it is statistically shown that along with the orbital and trigonometric parallaxes, the dynamical parallax can serve as a reliable tool for distance estimates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/510/1515
- Title:
- Double-lined spectroscopic binaries in M11
- Short Name:
- J/MNRAS/510/1515
- Date:
- 10 Jan 2022 09:23:04
- Publisher:
- CDS
- Description:
- We have developed a new method for spectral analysis of binaries. Our method successfully identifiesSB2 candidates from high-resolution Gaia-ESO spectra. Compared to the commonly used cross-correlation function analysis, it works for binaries with rapidly rotating components. We test our method on synthetic and observational spectra of BAFG-stars with vsin(i) from 1 to 330km/s in the open cluster M11. We confirm five previously detected SB2 candidates and find 19 new ones. For three SB2 candidates we find circular orbits and obtain dynamical mass ratios.
- ID:
- ivo://CDS.VizieR/III/278
- Title:
- Double stars with wide separations in the AGK3
- Short Name:
- III/278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large list of common proper motion stars selected from the third Astronomischen Gesellschaft Katalog (AGK3) was monitored with the CORAVEL (for COrrelation RAdial VELocities) spectrovelocimeter, in order to prepare a sample of physical binaries with very wide separations. In paper I,66 stars received special attention, since their radial velocities (RV) seemed to be variable. These stars were monitored over several years in order to derive the elements of their spectroscopic orbits. In addition, 10 of them received accurate RV measurements from the SOPHIE spectrograph of the T193 telescope at the Observatory of Haute-Provence. For deriving the orbital elements of double-lined spectroscopic binaries (SB2s), a new method was applied, which assumed that the RV of blended measurements are linear combinations of the RV of the components. 13 SB2 orbits were thus calculated. The orbital elements were eventually obtained for 52 spectroscopic binaries (SBs), two of them making a triple system. 40 SBs received their first orbit and the orbital elements were improved for 10 others. In addition, 11 SBs were discovered with very long periods for which the orbital parameters were not found. It appeared that HD 153252 has a close companion, which is a candidate brown dwarf with a minimum mass of 50 Jupiter masses. In paper II, 80 wide binaries (WBs) were detected, and 39 optical pairs were identified. Adding CPM stars with separations close enough to be almost certain they are physical, a "bias-controlled" sample of 116 wide binaries was obtained, and used to derive the distribution of separations from 100 to 30,000 au. The distribution obtained doesn't match the log-constant distribution, but is in agreement with the log-normal distribution. The spectroscopic binaries detected among the WB components were used to derive statistical informations about the multiple systems. The close binaries in WBs seem to be similar to those detected in other field stars. As for the WBs, they seem to obey the log-normal distribution of periods. The number of quadruple systems is in agreement with the "no correlation" hypothesis; this indicates that an environment conducive to the formation of WBs doesn't favor the formation of subsystems with periods shorter than 10 years.
- ID:
- ivo://CDS.VizieR/V/64
- Title:
- Eighth Orbital Elements of Spectroscopic Binaries
- Short Name:
- V/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The complete description of the catalogue, as well as the notes, is to be found in the Publ. Dominion Astrophys. Obs. 17 (1989). The present machine-readable version was transformed from the file provided by A.H. Batten for easier computer readability. Compared to the printed version, please note the following: 1) The four columns No. f(m) m.sin^3(i) a.sin(i) are NOT included in the computer version. No. (running number) is the line number of the main file (from 1 to 1469) f(m) (expressed in Solar Masses) can be computed from the Fortran formula 1.0385E-7 * (1-e*e)**1.5 * K(1)**3 * P a(*)sin i (expressed in km) can be computed from the Fortran formula 13751 * sqrt(1-e*e) * K(*) * P m(*)sin3i (expressed in Solar Masses) can be computed from the Fortran formula 1.0385E-7 * (1-e*e)**1.5 * K(*) * (K(1)+K(2))**2 * P The parameters are K(*) = velocity amplitude of the components, expressed in km/s; P = Period, expressed in days, sometimes in years; e = eccentricity 2) The notes, which make the bulk of the printed catalogue (pages 129-304), are NOT included.
- ID:
- ivo://CDS.VizieR/J/A+AS/136/453
- Title:
- Equivalent widths of spectroscopic binaries
- Short Name:
- J/A+AS/136/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopic observations are presented for 19 single-lined binaries (giants and dwarfs) with orbital elements and mass functions similar to those of barium stars, two radial velocity non-variable barium stars, and two standards. All binary systems contain an unseen low-mass component, presumably, a white dwarf. The equivalent widths and oscillator strengths are given for all measured spectral lines.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A80
- Title:
- EREBOS project. I.
- Short Name:
- J/A+A/630/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing post-common-envelope binaries are highly important for resolving the poorly understood, very short-lived common-envelope phase of stellar evolution. Most hot subdwarfs (sdO/Bs) are the bare helium-burning cores of red giants that have lost almost all of their hydrogen envelope. This mass loss is often triggered by common-envelope interactions with close stellar or even substellar companions. Cool companions to hot subdwarf stars such as late-type stars and brown dwarfs are detectable from characteristic light-curve variations - reflection effects and often eclipses. In the recently published catalog of eclipsing binaries in the Galactic Bulge and in the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey, we discovered 125 new eclipsing systems showing a reflection effect seen by visual inspection of the light curves and using a machine-learning algorithm, in addition to the 36 systems previously discovered by the Optical Gravitational Lesing Experiment (OGLE) team. The Eclipsing Reflection Effect Binaries from Optical Surveys (EREBOS) project aims at analyzing all newly discovered eclipsing binaries of the HW Vir type (hot subdwarf + close, cool companion) based on a spectroscopic and photometric follow up to derive the mass distribution of the companions, constrain the fraction of substellar companions, and determine the minimum mass needed to strip off the red-giant envelope. To constrain the nature of the primary we derived the absolute magnitude and the reduced proper motion of all our targets with the help of the parallaxes and proper motions measured by the Gaia mission and compared those to the Gaia white-dwarf candidate catalog. It was possible to derive the nature of a subset of our targets, for which observed spectra are available, by measuring the atmospheric parameter of the primary, confirming that less than 10% of our systems are not sdO/Bs with cool companions but are white dwarfs or central stars of planetary nebula. This large sample of eclipsing hot subdwarfs with cool companions allowed us to derive a significant period distribution for hot subdwarfs with cool companions for the first time showing that the period distribution is much broader than previously thought and is ideally suited to finding the lowest-mass companions to hot subdwarf stars. The comparison with related binary populations shows that the period distribution of HW Vir systems is very similar to WD+dM systems and central stars of planetary nebula with cool companions. In the future, several new photometric surveys will be carried out, which will further increase the sample of this project, providing the potential to test many aspects of common-envelope theory and binary evolution.
