2017/05/10 by Per Calissendorff, M. Janson, Markus Janson +12 · 13 citations
Physics and Astronomy · #Ambiguity #Astrometry #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Milky Way #Orbital elements #Orbital period #Parallax #Photometry (optics) #Physics #Stars #Stellar, planetary, and galactic studies #Telescope #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201730725
published in Astronomy and Astrophysics 604, A82 (EDP Sciences) · 9 pages, 7 figures, accepted for publication in Astronomy & Astrophysics
arxiv created 2017/05/10 · openalex publication_date 2017/05/31 · arxiv updated 2018/06/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We combine new Lucky Imaging astrometry from New Technology Telescope/AstraLux Sur with already published astrometry from the AstraLux Large M-dwarf Multiplicity Survey to compute orbital elements and individual masses of the 2MASS J10364483+1521394 triple system belonging to the Ursa-Major moving group. The system consists of one primary low-mass M-dwarf orbited by two less massive companions, for which we determine a combined dynamical mass of MB + C = 0.48 ± 0.14 M⊙. We show from the companions’ relative motions that they are of equal mass (with a mass ratio of 1.00 ± 0.03), thus 0.24 ± 0.07 M⊙ individually, with a separation of 3.2 ± 0.3 AU, and we conclude that these masses are significantly higher (30%) than what is predicted by theoretical stellar evolutionary models. The biggest uncertainty remains the distance to the system, here adopted as 20.1 ± 2.0 pc based on trigonometric parallax, whose ambiguity has a major impact on the result. With the new observational data we are able to conclude that the orbital period of the BC pair is 8.41+0.04-0.02yr.