- ID:
- ivo://CDS.VizieR/J/AJ/129/2420
- Title:
- Proper motion derivatives of binaries
- Short Name:
- J/AJ/129/2420
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Useful constraints on the orbits and mass ratios of astrometric binaries in the Hipparcos catalog are derived from the measured proper motion differences of Hipparcos and Tycho-2 ({Delta}{mu}), accelerations of proper motions (d{mu}/dt) and second derivatives of proper motions (d^2^{mu}/dt^2^). It is shown how, in some cases, statistical bounds can be estimated for the masses of the secondary components. Two catalogs of astrometric binaries are generated, one of binaries with significant proper motion differences and the other of binaries with significant accelerations of their proper motions.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/667/520
- Title:
- Proper motions in multiple systems
- Short Name:
- J/ApJ/667/520
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the Koenigstuhl survey in the Southern Hemisphere are presented. I have searched for common proper motion companions to 173 field very low mass stars and brown dwarfs with spectral types >M5.0 V and magnitudes J<~14.5mag. I have measured for the first time the common proper motion of two new wide systems containing very low mass components, Koenigstuhl 2 AB and 3 A-BC. Together with Koenigstuhl 1 AB and 2M 0126-50 AB, they are among the widest systems in their respective classes (r=450-11900AU). I have determined the minimum frequency of field wide multiples (r>100AU) with late-type components at 5.0%+/-1.8% and the frequency of field wide late-type binaries with mass ratios q>0.5 at 1.2%+/-0.9%. These values represent a key diagnostic of evolution history and low-mass star and brown dwarf formation scenarios. In addition, the proper motions of 62 field very low mass dwarfs are measured here for the first time.
- ID:
- ivo://CDS.VizieR/J/AJ/155/149
- Title:
- Properties of co-moving stars observed by Gaia
- Short Name:
- J/AJ/155/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have estimated fundamental parameters for a sample of co-moving stars observed by Gaia and identified by Oh et al (2017, J/AJ/153/257). We matched the Gaia observations to the 2MASS and Wide-Field Infrared Survey Explorer catalogs and fit MIST isochrones to the data, deriving estimates of the mass, radius, [Fe/H], age, distance, and extinction to 9754 stars in the original sample of 10606 stars. We verify these estimates by comparing our new results to previous analyses of nearby stars, examining fiducial cluster properties, and estimating the power-law slope of the local present-day mass function. A comparison to previous studies suggests that our mass estimates are robust, while metallicity and age estimates are increasingly uncertain. We use our calculated masses to examine the properties of binaries in the sample and show that separation of the pairs dominates the observed binding energies and expected lifetimes.
- ID:
- ivo://CDS.VizieR/J/other/Nat/586.528
- Title:
- Properties of exoplanet host stars
- Short Name:
- J/other/Nat/586.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planet formation is generally described in terms of a system containing the host star and a protoplanetary disk, of which the internal properties (for example, mass and metallicity) determine the properties of the resulting planetary system. However, (proto)planetary systems are predicted and observed to be affected by the spatially clustered stellar formation environment, through either dynamical star-star interactions or external photoevaporation by nearby massive stars. It is challenging to quantify how the architecture of planetary sysems is affected by these environmental processes, because stellar groups spatially disperse within less than a billion years, well below the ages of most known exoplanets. Here we identify old, co-moving stellar groups around exoplanet host stars in the astrometric data from the Gaia satellite and demonstrate that the architecture of planetary systems exhibits a strong dependence on local stellar clustering in position-velocity phase space. After controlling for host stellar age, mass, metallicity and distance from the star, we obtain highly significant differences (with p values of 10^-5^ to 10^-2^) in planetary system properties between phase space overdensities (composed of a greater number of co-moving stars than unstructured space) and the field. The median semi-major axis and orbital period of planets in phase space overdensities are 0.087 astronomical units and 9.6 days, respectively, compared to 0.81 astronomical units and 154 days, respectively, for planets around field stars. 'Hot Jupiters' (massive, short-period exoplanets) predominantly exist in stellar phase space overdensities, strongly suggesting that their extreme orbits originate from environmental perturbations rather than internal migration or planet-planet scattering. Our findings reveal that stellar clustering is a key factor setting the architectures of planetary systems.
- ID:
- ivo://CDS.VizieR/J/AJ/143/31
- Title:
- Properties of fragile binary candidates in SDSS DR8
- Short Name:
- J/AJ/143/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 80 very wide fragile binary candidates (projected separations >10000AU) from the Sloan Digital Sky Survey Data Release Eight spectral archive. The pairs were selected based on proper motion, radial velocity, metallicity, and photometric parallax criteria. The angular separations of these pairs range from 3" to 250". The peak in the metallicity distribution of these pairs is about -0.5dex of solar metallicity. Space motions and reduced proper motion diagrams indicate that all these pairs are members of the disk. The chromospheric activity index S_HK_ of each component in 38 binary candidates having spectra of high signal-to-noise ratio and member stars of three open clusters (NGC 2420, M67, and NGC 6791) were measured. The S_HK_ versus color relation for these binary candidates is consistent with the trend seen in these open clusters. The ages implied by this relation suggest that fragile wide pairs can survive longer than 8Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJ/783/4
- Title:
- Properties of Kepler multi-planet candidate systems
- Short Name:
- J/ApJ/783/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The planet occurrence rate for multiple stars is important in two aspects. First, almost half of stellar systems in the solar neighborhood are multiple systems. Second, the comparison of the planet occurrence rate for multiple stars to that for single stars sheds light on the influence of stellar multiplicity on planet formation and evolution. We developed a method of distinguishing planet occurrence rates for single and multiple stars. From a sample of 138 bright (K_P_<13.5) Kepler multi-planet candidate systems, we compared the stellar multiplicity rate of these planet host stars to that of field stars. Using dynamical stability analyses and archival Doppler measurements, we find that the stellar multiplicity rate of planet host stars is significantly lower than field stars for semimajor axes less than 20AU, suggesting that planet formation and evolution are suppressed by the presence of a close-in companion star at these separations. The influence of stellar multiplicity at larger separations is uncertain because of search incompleteness due to a limited Doppler observation time baseline and a lack of high-resolution imaging observation. We calculated the planet confidence for the sample of multi-planet candidates and find that the planet confidences for KOI 82.01, KOI 115.01, KOI 282.01, and KOI 1781.02 are higher than 99.7% and thus validate the planetary nature of these four planet candidates. This sample of bright Kepler multi-planet candidates with refined stellar and orbital parameters, planet confidence estimation, and nearby stellar companion identification offers a well-characterized sample for future theoretical and observational study.
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/1883
- Title:
- Properties of KOI host stars
- Short Name:
- J/MNRAS/436/1883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. We use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line of sight, and find a number of systems with possible spin-orbit misalignment. We additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/789/102
- Title:
- Properties of late M-dwarfs
- Short Name:
- J/ApJ/789/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of multiplicity among low-mass stars is a key issue to understanding the formation of stars and brown dwarfs, and recent surveys have yielded large enough samples of nearby low-mass stars to study this issue statistically to good accuracy. Previously, we have presented a multiplicity study of ~700 early/mid M-type stars observed with the AstraLux high-resolution Lucky Imaging cameras. Here, we extend the study of multiplicity in M-type stars through studying 286 nearby mid/late M-type stars, bridging the gap between our previous study and multiplicity studies of brown dwarfs. Most of the targets have been observed more than once, allowing us to assess common proper motion to confirm companionship. We detect 68 confirmed or probable companions in 66 systems, of which 41 were previously undiscovered. Detections are made down to the resolution limit of ~100 mas of the instrument. The raw multiplicity in the AstraLux sensitivity range is 17.9%, leading to a total multiplicity fraction of 21%-27% depending on the mass ratio distribution, which is consistent with being flat down to mass ratios of ~0.4, but cannot be stringently constrained below this value. The semi-major axis distribution is well represented by a log-normal function with {mu}_a_= 0.78 and {sigma}_a_= 0.47, which is narrower and peaked at smaller separations than for a Sun-like sample. This is consistent with a steady decrease in average semi-major axis from the highest-mass binary stars to the brown dwarf binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/2077
- Title:
- Properties of Sirius-like binary systems
- Short Name:
- J/MNRAS/435/2077
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Approximately 70% of the nearby white dwarfs appear to be single stars, with the remainder being members of binary or multiple star systems. The most numerous and most easily identifiable systems are those in which the main-sequence companion is an M star, since even if the systems are unresolved the white dwarf either dominates or is at least competitive with the luminosity of the companion at optical wavelengths. Harder to identify are systems where the non-degenerate component has a spectral type earlier than M0 and the white dwarf becomes the less luminous component. Taking Sirius as the prototype, these latter systems are referred to here as 'Sirius like'. There are currently 98 known Sirius-like systems. Studies of the local white dwarf population within 20pc indicate that approximately 8 percent of all white dwarfs are members of Sirius-like systems, yet beyond 20pc the frequency of known Sirius-like systems declines to between 1 and 2 percent, indicating that many more of these systems remain to be found. Estimates are provided for the local space density of Sirius-like systems and their relative frequency among both the local white dwarf population and the local population of A to K main-sequence stars. The great majority of currently unidentified Sirius-like systems will likely turn out to be closely separated and unresolved binaries. Ways to observationally detect and study these systems are discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/157/144
- Title:
- Protoplanetary disk masses in Taurus
- Short Name:
- J/AJ/157/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measuring the masses of protoplanetary disks is crucial for understanding their planet-forming potential. Typically, dust masses are derived from (sub-)millimeter flux density measurements plus assumptions for the opacity, temperature, and optical depth of the dust. Here we use radiative transfer models to quantify the validity of these assumptions with the aim of improving the accuracy of disk dust mass measurements. We first carry out a controlled exploration of disk parameter space. We find that the disk temperature is a strong function of disk size, while the optical depth depends on both disk size and dust mass. The millimeter-wavelength spectral index can be significantly shallower than the naive expectation due to a combination of optical depth and deviations from the Rayleigh-Jeans regime. We fit radiative transfer models to the spectral energy distributions (SEDs) of 132 disks in the Taurus-Auriga region using a Markov chain Monte Carlo approach. We used all available data to produce the most complete SEDs used in any extant modeling study. We perform the fitting twice: first with unconstrained disk sizes and again imposing the disk size-brightness relation inferred for sources in Taurus. This constraint generally forces the disks to be smaller, warmer, and more optically thick. From both sets of fits, we find disks to be ~1-5 times more massive than when derived using (sub-)millimeter measurements and common assumptions. With the uncertainties derived from our model fitting, the previously measured dust mass-stellar mass correlation is present in our study but only significant at the 2{sigma} level.