Aims: We present a study of the orbits of the triple system LHS 1070, with the aim to determine individual masses of its components.
Methods: Sixteen new relative astrometric positions of the three components in the K band were obtained with NACO at the VLT, Omega CASS at the 3.5 m telescope on Calar Alto, and other high-spatial-resolution instruments. We combined them with data from the literature and fit orbit models to the dataset. We derived an improved fit for the orbit of LHS 1070 B and C around each other, and an estimate for the orbit of B and C around A.
Results: The orbits are nearly coplanar, with a misalignment angle of less than 10°. The masses of the three components are MA = 0.13...0.16 M⊙, MB = 0.077 ± 0.005 M⊙, and MC = 0.071 ± 0.004 M⊙. Therefore, LHS 1070 C is certainly, and LHS 1070 B probably a brown dwarf. Comparison with theoretical isochrones shows that LHS 1070 A is either fainter or more massive than expected. One possible explanation would be that it is a binary. However, the close companion reported previously could not be confirmed.
Astronomy and Astrophysics
- Pub Date:
- May 2012
- stars: low-mass;
- brown dwarfs;
- stars: fundamental parameters;
- stars: individual: LHS 1070;
- binaries: close;
- celestial mechanics;
- Astrophysics - Solar and Stellar Astrophysics
- 9 pages, 8 figures, accepted by Astronomy and Astrophysics