- ID:
- ivo://CDS.VizieR/J/ApJ/709/535
- Title:
- Masses and radii of eclipsing binaries
- Short Name:
- J/ApJ/709/535
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The currently favored method for estimating radii and other parameters of transiting-planet host stars is to match theoretical models to observations of the stellar mean density {rho}_*_, the effective temperature T_eff_, and the composition parameter [Z]. This explicitly model-dependent approach is based on readily available observations, and results in small formal errors. Its performance will be central to the reliability of results from ground-based transit surveys such as TrES, HAT, and SuperWASP, as well as to the space-borne missions MOST, CoRoT, and Kepler. Here, I use two calibration samples of stars (eclipsing binaries (EBs) and stars for which asteroseismic analyses are available) having well-determined masses and radii to estimate the accuracy and systematic errors inherent in the {rho}_*_ method. When matching to the Yonsei-Yale stellar evolution models, I find the most important systematic error results from selection bias favoring rapidly rotating (hence probably magnetically active) stars among the EB sample. If unaccounted for, this bias leads to a mass-dependent underestimate of stellar radii by as much as 4% for stars of 0.4M_{sun}_, decreasing to zero for masses above about 1.4M_{sun}_. Relative errors in estimated stellar masses are three times larger than those in radii.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/538/A74
- Title:
- Massive binaries in Cepheus OB2/3 region
- Short Name:
- J/A+A/538/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two different formation scenarios for stars of masses larger than 10M_{sun}_ exist. Although simulations within both scenarios are capable of producing stars up to the highest observed masses, the relevance of the two formation scenarios for massive star-formation is not yet clear. We aim to detect companions to massive stars to constrain the binary parameters of the multiple systems. These findings will help to constrain the formation of massive stars.
- ID:
- ivo://CDS.VizieR/J/AJ/149/26
- Title:
- Massive binary stars from an HST/FGS survey
- Short Name:
- J/AJ/149/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an all-sky survey made with the Fine Guidance Sensor on the Hubble Space Telescope to search for angularly resolved binary systems among massive stars. The sample of 224 stars is comprised mainly of Galactic O- and B-type stars and luminous blue variables, plus a few luminous stars in the Large Magellanic Cloud. The FGS TRANS mode observations are sensitive to the detection of companions with an angular separation between 0.01'' and 1.0'' and brighter than {delta}m=5. The FGS observations resolved 52 binary and 6 triple star systems and detected partially resolved binaries in 7 additional targets (43 of these are new detections). These numbers yield a companion detection frequency of 29% for the FGS survey. We also gathered literature results on the numbers of close spectroscopic binaries and wider astrometric binaries among the sample, and we present estimates of the frequency of multiple systems and the companion frequency for subsets of stars residing in clusters and associations, field stars, and runaway stars. These results confirm the high multiplicity fraction, especially among massive stars in clusters and associations. We show that the period distribution is approximately flat in increments of logP. We identify a number of systems of potential interest for long-term orbital determinations, and we note the importance of some of these companions for the interpretation of the radial velocities and light curves of close binaries that have third companions.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A125
- Title:
- 54 massive companions detected with SOPHIE
- Short Name:
- J/A+A/631/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Brown-dwarfs (BD) are substellar objects with masses intermediate between planets and stars within about 13-80M_J_. While isolated brown-dwarfs are most likely produced by gravitational collapse in molecular clouds down to masses of a few M_J_, a nonnegligible fraction of low-mass companions might be formed through the planet formation channel in protoplanetary disks. The upper mass limit of objects formed within disks is still observationnally unknown, the main reason being the strong dearth of BD companions at orbital periods shorter than 10 years, a.k.a. the brown-dwarf desert. We aim at determining the best statistics of secondary companions within the 10-100M_Jup_ range within 10au from the primary star, while minimising observational bias. This can help determining the mass limit separating planet-formed from star-formed browndwarfs. Moreover, the exact shape of the BD desert in a mass-period space is still underdetermined, and can strongly constrain the companion-star interactions mechanisms at work in close binary systems at small mass ratio. We made an extensive use of the radial velocity (RV) surveys of FGK stars below 60 pc distance to the Sun and in the northern hemisphere performed with the SOPHIE spectrograph at Observatoire de Haute-Provence. We derived the Keplerian solutions of the RV variations of 54 sources. Public astrometric data of the Hipparcos and Gaia missions allowed deriving direct astrometric solution of orbital motion and constraining the mass of the companion for most sources. We introduce GASTON, a new method to derive inclination combining RVs Keplerian and astrometric excess noise from Gaia DR1. We report the discovery of 12 new BD candidates. For 5 of them, additional astrometric data led to revise their mass in the M-dwarf regime. Among the 7 remaining objects, 4 are confirmed BD companions, and 3 others are likely also in this mass regime. Moreover, we report the detection of 42 objects in the M-dwarf mass regime 90M_J_-0.52M_{sun}_. The resulting Msin i-P distribution of BD candidates shows a clear drop in the detection rate below 80-day orbital period. Above that limit, the BD desert reveals rather wet, with a uniform distribution of the Msin i. We derive a minimum BD-detection frequency around Solar-like stars of 2.0+/-0.5%.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A140
- Title:
- Mass limits on substellar companions
- Short Name:
- J/A+A/527/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The recently completed re-reduction of the Hipparcos data by van Leeuwen (2007, Astrophys. Space Library 350) makes it possible to search for the astrometric signatures of planets and brown dwarfs known from radial velocity surveys in the improved Hipparcos intermediate astrometric data. Our aim is to put more significant constraints on the orbital parameters which cannot be derived from radial velocities alone, i.e. the inclination and the longitude of the ascending node, than was possible before. The determination of the inclination in particular allows to calculate an unambiguous companion mass, rather than the lower mass limit which can be obtained from radial velocity measurements.
- ID:
- ivo://CDS.VizieR/J/AJ/106/773
- Title:
- Mass-luminosity relation
- Short Name:
- J/AJ/106/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass-luminosity relations determined at infrared wavelengths are presented for stars with masses 1.0 to 0.08 solar masses. Using infrared speckle imaging techniques on a sample of nearby binaries, we have been able to concentrate on the lower main sequence (Mass<=0.5M_sun_), for which an accurate mass-luminosity calibration has remained problematic. In addition, the mass-visual luminosity relation for stars with 2.0>=Mass>=0.08M_sun_ is produced by implementing new photometric relations linking V to JHK wavelengths for the nearby stars, supplemented with eclipsing binary information. These relations predict that objects with masses ~0.08 solar masses have M(K)~=10 and M(V)~=18.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/17
- Title:
- Mass & radius of planets, moons, low mass stars
- Short Name:
- J/ApJ/834/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass and radius are two of the most fundamental properties of an astronomical object. Increasingly, new planet discoveries are being announced with a measurement of one of these quantities, but not both. This has led to a growing need to forecast the missing quantity using the other, especially when predicting the detectability of certain follow-up observations. We present an unbiased forecasting model built upon a probabilistic mass-radius relation conditioned on a sample of 316 well-constrained objects. Our publicly available code, Forecaster, accounts for observational errors, hyper-parameter uncertainties, and the intrinsic dispersions observed in the calibration sample. By conditioning our model on a sample spanning dwarf planets to late-type stars, Forecaster can predict the mass (or radius) from the radius (or mass) for objects covering nine orders of magnitude in mass. Classification is naturally performed by our model, which uses four classes we label as Terran worlds, Neptunian worlds, Jovian worlds, and stars. Our classification identifies dwarf planets as merely low-mass Terrans (like the Earth) and brown dwarfs as merely high-mass Jovians (like Jupiter). We detect a transition in the mass-radius relation at 2.0_-0.6_^+0.7^M_{Earth}_, which we associate with the divide between solid, Terran worlds and Neptunian worlds. This independent analysis adds further weight to the emerging consensus that rocky super-Earths represent a narrower region of parameter space than originally thought. Effectively, then, the Earth is the super-Earth we have been looking for.
- ID:
- ivo://CDS.VizieR/J/ApJ/662/413
- Title:
- 2MASS survey of wide multiplicity in 3 associations
- Short Name:
- J/ApJ/662/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for wide binary systems among 783 members of three nearby young associations: Taurus-Auriga, Chamaeleon I, and two subgroups of Upper Scorpius. Near-infrared (JHK) imagery from 2MASS was analyzed to search for wide (1"-30"; ~150-4500AU) companions to known association members, using color-magnitude cuts to reject likely background stars. We identify a total of 131 candidate binary companions with colors consistent with physical association, of which 39 have not been identified previously in the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/2618
- Title:
- M-dwarfs in Multiples (MinMs) survey. I.
- Short Name:
- J/MNRAS/449/2618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large-scale, volume-limited companion survey of 245 late-K to mid-M (K7-M6) dwarfs within 15pc. Infrared adaptive optics (AO) data were analysed from the Very Large Telescope, Subaru Telescope, Canada-France-Hawaii Telescope, and MMT Observatory to detect close companions to the sample from ~1 to 100AU, while digitized wide-field archival plates were searched for wide companions from ~100 to 10000AU. With sensitivity to the bottom of the main sequence over a separation range of 3 to 10000AU, multiple AO and wide-field epochs allow us to confirm candidates with common proper motions, minimize background contamination, and enable a measurement of comprehensive binary statistics. We detected 65 comoving stellar companions and find a companion star fraction of 23.5+/-3.2 percent over the 3 au to 10000AU separation range. The companion separation distribution is observed to rise to a higher frequency at smaller separations, peaking at closer separations than measured for more massive primaries. The mass ratio distribution across the q=0.2-1.0 range is flat, similar to that of multiple systems with solar-type primaries. The characterization of binary and multiple star frequency for low-mass field stars can provide crucial comparisons with star-forming environments and hold implications for the frequency and evolutionary histories of their associated discs and planets.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A88
- Title:
- 5 M dwarfs radial velocity curves
- Short Name:
- J/A+A/602/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a dozen super-Earths and Earth-mass planets (msini<=10M_{sun}_) around M dwarfs, with a well understood selection function. This well defined sample informs on their frequency of occurrence and on the distribution of their orbital parameters, and therefore already constrains our understanding of planetary formation. The subset of these low-mass planets that were found within the habitable zone of their host star also provide prized targets for future atmospheric biomarkers searches. We are working to extend this planetary sample to lower masses and longer periods through dense and long-term monitoring of the radial velocity of a small M dwarf sample. We obtained large numbers of HARPS spectra for the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628 and GJ 3293, from which we derived radial velocities (RVs) and spectroscopic activity indicators. We searched them for variabilities, periodicities, Keplerian modulations and correlations, and attribute the radial-velocity variations to combinations of planetary companions and stellar activity. We detect 12 planets, of which 9 are new with masses ranging from 1.17 to 10.5M_{sun}_. Those planets have relatively short orbital periods (P<40d), except two of them with periods of 217.6 and 257.8 days. Among these systems, GJ 273 harbor two planets with masses close to the one of the Earth. With a distance of 3.8 parsec only, GJ 273 is the second nearest known planetary system - after Proxima Centauri - with a planet orbiting the circumstellar habitable zone.