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Register a new userMasses of the components of SB2 binaries observed with Gaia. III. Accurate SB2 orbits for 10 binaries and masses of HIP 87895
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In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the SOPHIE spectrograph at the Haute--Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 % when the astrometric measurements of Gaia are taken into account. In this paper we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881 days. Using the TODMOR algorithm we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 % for the ten binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 % and 1.2 % respectively.
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Double-lined spectroscopic binaries (SB2s) are one of the main sources of stellar masses, as additional observations are only needed to give the inclinations of the orbital planes in order to obtain the individual masses of the components. For this reason, we are observing a selection of SB2s using the SOPHIE spectrograph at the Haute-Provence observatory in order to precisely determine their orbital elements. Our objective is to finally obtain masses with an accuracy of the order of one percent by combining our radial velocity (RV) measurements and the astrometric measurements that will come from the Gaia satellite. We present here the RVs and the re-determined orbits of 10 SB2s. In order to verify the masses we will derive from Gaia, we obtained interferometric measurements of the ESO VLTI for one of these SB2s. Adding the interferometric or speckle measurements already published by us or by others for 4 other stars, we finally obtain the masses of the components of 5 binary stars, with masses ranging from 0.51 to 2.2 solar masses, including main-sequence dwarfs and some more evolved stars whose location in the HR diagram has been estimated.
The orbital motion of non-contact double-lined spectroscopic binaries (SB2), with periods of a few tens of days to several years, holds unique accurate informations on individual stellar masses, that only long-term monitoring can unlock. The combination of radial velocity measurements from high-resolution spectrographs and astrometric measurements from high-precision interferometers allows the derivation of SB2 components masses down to the percent precision. Since 2010, we observed a large sample of SB2 with the SOPHIE spectrograph at the Observatoire de Haute-Provence, aiming at the derivation of orbital elements with sufficient accuracy to obtain masses of components with relative errors as low as 1$%$ when the astrometric measurements of the Gaia satellite will be taken into account. In this paper we present the results from six years of observations of 14 SB2 systems with periods ranging from 33 to 4185 days. Using the TODMOR algorithm we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the 28 stellar components are then obtained with a sample average accuracy of 1.0$pm$0.2$,%$. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 61100, HIP 95995 and HIP 101382 with relative errors for components (A,B) of respectively (2.0, 1.7)$,%$, (3.7, 3.7)$,%$, and (0.2, 0.1)$,%$. Using the Cesam2k stellar evolution code, we could constrain the initial He-abundance, age and metallicity for HIP 61100 and HIP 95995.
The expected performance of GAIA satellite on eclipsing binaries is reviewed on the basis of (a) combined Hipparcos and ground-based observations mimicking GAIA data harvest, and (b) accurate simulations using the latest instrument model. It is found that for a large majority of the 16000 SB2 eclipsing binaries that GAIA will discover at magnitudes V<13, the orbital solutions and physical parameters will be derived with formal accuracies better than 2%. For the same stars the GAIA parallax errors will be about 5 micro-arcsec, i.e. an error of 0.5% at 1 kpc, which will allow to iteratively refine of the parameters and physics used in orbital modeling. The detectability of SB2 binaries by the already up and running spectral survey RAVE is discussed. It is found that all F-to-M SB2 binaries showing a velocity separation >=35 km/sec and a luminosity ratio >=0.5 will be recognized as such.
We report the results of abundance determination for the components of the SB2 star 66 Eri (M_A/M_B=0.97) from high resolution CCD echelle spectra with S/N>=100 taken with the 1-m telescope of Special Astrophysical Observatory (Zelenchuck, Russia). The atmospheric parameters of the components were determined using all available photometric, spectrophotometric and spectral data. The abundances of 27 elements were found. The abundances of components are different. The B component, previously classified as an Hg-Mn star, does not show anomalies typical of this group such as deficit of He, Al and excess of P, Ga, but shows overabundances of heavy elements which amount up to 4-5 dex. The A component also shows moderate Mn and Ba excess. Lines of other heavy elements were not detected. Estimates of upper limits to their abundances do not permit to exclude completely the presence of fainter anomalies in the A component either.
We present results from Speckle inteferometric observations of fifteen visual binaries and one double-line spectroscopic binary, carried out with the HRCam Speckle camera of the SOAR 4.1 m telescope. These systems were observed as a part of an on-going survey to characterize the binary population in the solar vicinity, out to a distance of 250 parsec. We obtained orbital elements and mass sums for our sample of visual binaries. The orbits were computed using a Markov Chain Monte Carlo algorithm that delivers maximum likelihood estimates of the parameters, as well as posterior probability density functions that allow us to evaluate their uncertainty. Their periods cover a range from 5 yr to more than 500 yr; and their spectral types go from early A to mid M - implying total system masses from slightly more than 4 MSun down to 0.2 MSun. They are located at distances between approximately 12 and 200 pc, mostly at low Galactic latitude. For the double-line spectroscopic binary YSC8 we present the first combined astrometric/radial velocity orbit resulting from a self-consistent fit, leading to individual component masses of 0.897 +/- 0.027 MSun and 0.857 +/- 0.026 MSun; and an orbital parallax of 26.61 +/- 0.29 mas, which compares very well with the Gaia DR2 trigonometric parallax (26.55 +/- 0.27 mas). In combination with published photometry and trigonometric parallaxes, we place our objects on an H-R diagram and discuss their evolutionary status. We also present a thorough analysis of the precision and consistency of the photometry available for them.
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