Hidden Companions to Intermediate-mass Stars. X. Solving for the Mass Ratio in the Spectroscopic Binary Zubenelgenubi = α 2 Librae
Abstract
Zubenelgenubi = α 2 Librae is a nearby double-lined spectroscopic binary that forms a quadruple system with α 1 Librae. The radial velocity amplitude for the rapidly rotating primary is subject to a systematic uncertainty and as a result only a lower limit q = 0.81 to the mass ratio has been previously reported. Here we present a VLTI/GRAVITY interferometric observation of Zubenelgenubi in which we measured a K band flux ratio of 74.7%, resulting in isochrone masses M Aa = 1.95 M ⊙ and M Ab = 1.79 M ⊙ (q = 0.92). The fact that the projected rotational velocities differ by a factor of three despite the similar masses suggests that the stellar spin axes are significantly misaligned in spite of the small semimajor axis a = 0.52 au or alternatively that the primary is a merger product. *Based on observations collected at the European Southern Observatory, Chile, Program ID 111.24UP.001.
- Publication:
-
Research Notes of the American Astronomical Society
- Pub Date:
- August 2023
- DOI:
- 10.3847/2515-5172/acf28f
- Bibcode:
- 2023RNAAS...7..180W
- Keywords:
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- Multiple stars;
- Spectroscopic binary stars;
- A stars;
- Optical interferometry;
- 1081;
- 1557;
- 5;
- 1168