Orbital elements and individual component masses from joint spectroscopic and astrometric data of double-line spectroscopic binaries

TL;DR

This paper derives precise orbital elements and component masses for fourteen double-line spectroscopic binaries using combined spectroscopic and astrometric data, improving previous measurements and validating results against Gaia and Hipparcos parallaxes.

Contribution

The study introduces a simultaneous fitting method using MCMC for combined orbital analysis, providing improved mass and orbit estimates for binaries, including new solutions for eight previously uncharacterized systems.

Findings

Mass ratios with less than 1% uncertainty

Mass sums with about 1% uncertainty

Good agreement between orbital and Gaia/Hipparcos parallaxes

Abstract

We present orbital elements, orbital parallaxes and individual component masses, for fourteen spatially resolved double-line spectroscopic binaries derived doing a simultaneous fit of their visual orbit and radial velocity curve. This was done by means of a Markov Chain Monte Carlo code developed by our group, which produces posterior distribution functions and error estimates for all the parameters. Of this sample, six systems had high quality previous studies and were included as benchmarks to test our procedures, but even in these cases we could improve the previous orbits by adding recent data from our survey of southern binaries being carried out with the HRCam and ZORRO speckle cameras at the SOAR 4.1m and Gemini South 8.1m telescopes, respectively. We also give results for eight objects that did not have a published combined orbital solution, one of which did not have a visual orbit either. We could determine mass ratios with a typical uncertainty of less than 1%, mass sums with uncertainties of about 1% and individual component masses with a formal uncertainty of $0.01 M_\odot$ in the best cases. A comparison of our orbital parallaxes with available trigonometric parallaxes from Hipparcos and Gaia eDR3, shows a good correspondence; the mean value of the differences being consistent with zero within the errors of both catalogs. We also present observational HR diagrams for our sample of binaries, which in combination with isochrones from different sources allowed us to asses their evolutionary status and also the quality of their photometry.