Mon. Not. R. Astron. Soc., 502, 328-350 (2021/March-3)
A celestial matryoshka: dynamical and spectroscopic analysis of the Albireo system.
DRIMMEL R., SOZZETTI A., SCHRODER K.-P., BASTIAN U., PINAMONTI M., JACK D. and HERNANDEZ HUERTA M.A.
Abstract (from CDS):
We present a spectroscopic characterization and a new orbital solution for the binary system β Cyg Aa/Ac (MCA 55), the primary component ( β Cyg A) of the well-known wide double star Albireo. By matching evolutionary tracks to the physical parameters of all three Albireo stars ( β Cyg Aa, Ac, and B) as obtained from a spectroscopic analysis of TIGRE and IUE spectra, we confirm that they are likely coeval. Our final orbit solution is based on radial-velocity measurements taken over a baseline exceeding 120 yr, combined with relative astrometry from speckle interferometric observations and the absolute astrometry from the Hipparcos and Gaia missions. Our final orbit solution has a period of 121.65+3.34–2.90 yr with an eccentricity of 0.20+0.01–0.02. Thanks to the inclusion of the absolute astrometry, we find a mass ratio of q = 1.25+0.19–0.17, and a total mass of 9.47–3.24+5.88 M☉, indicating that the secondary (Ac) is the more massive of the pair. These results strongly suggest the presence of a fourth, unseen, member of the Albireo system. Given the current photometric data, it is likely that β Cyg A is itself a hierarchical triple. We also derive the systemic proper motion, line-of-sight velocity, and an orbital parallax of the β Cyg A system, allowing us to quantitatively assess the hypothesis that Albireo A and B form a physically bound and genealogically connected system. Finally, we find four potential members of a common proper motion group with Albireo, though none anywhere as close by as the Albireo components A to B.
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
methods: numerical - techniques: high angular resolution - techniques: radial velocities - astrometry - binaries: general - stars: individual: Albireo (or b Cyg)
Status at CDS
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