Improved orbital solution and masses for the very low-mass multiple system LHS 1070

TL;DR

This study refines the orbital parameters and masses of the LHS 1070 system's components using combined astrometric and spectroscopic data, providing new insights into their dynamics and mass estimates.

Contribution

It presents the first precise orbital solution for the A-BC system and constrains the orbit of the B and C components, improving understanding of the system's dynamics.

Findings

Masses of B and C match theoretical models but not empirical tracks.

No evidence found for a fourth component in LHS 1070.

Orbits of B and C are likely co-planar.

Abstract

We present a refined orbital solution for the components A, B, and C of the nearby late-M type multiple system LHS 1070. By combining astrometric datapoints from NACO/VLT, CIAO/SUBARU, and PUEO/CFHT, as well as a radial velocity measurement from the newly commissioned near infrared high-resolution spectrograph CRIRES/VLT, we achieve a very precise orbital solution for the B and C components and a first realistic constraint on the much longer orbit of the A-BC system. Both orbits appear to be co-planar. Masses for the B and C components calculated from the new orbital solution (M_(B+C) = 0.157 +/- 0.009 M_sun) are in excellent agreement with theoretical models, but do not match empirical mass-luminosity tracks. The preliminary orbit of the A-BC system reveals no mass excess for the A component, giving no indication for a previously proposed fourth (D) component in LHS 1070.