Hidden Companions to Intermediate-mass Stars. XIV. Discovery of a 1.8 M ☉, 0.3 au Companion to Ascella = Zeta Sagittarii A
Abstract
Zeta Sagittarii is a nearby intermediate mass 13.2 au visual binary. Here we report on a VLTI/GRAVITY interferometric observation that revealed that ζ Sgr is actually a rather compact triple system: the visual primary Ascella (A) is a close equal mass ρ = 10.9 mas ↔ 0.3 au binary. Through isochrone fitting we find masses M Aa = 1.83M ☉, M Ab = 1.81M ☉ and M B = 2.03M ☉. The hierarchy of the triple is low enough to allow for possibly interesting dynamical effects and its ultimate outcome will be a double or triple white dwarf system. We estimate that about 1 Myr ago ζ Sgr passed within a minimum distance of the Sun of 11 pc, rather than 3 pc as previously reported. *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:
- November 2023
- DOI:
- Bibcode:
- 2023RNAAS...7..245W
- Keywords:
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- Multiple stars;
- A stars;
- Optical interferometry;
- 1081;
- 5;
- 1168
