The discrepancy between dynamical and theoretical mass in the triplet-system 2MASS J10364483+1521394

Author(s)

Per Calissendorff, Markus Janson, Rainer Köhler, Stephen Durkan, Stefan Hippler, Xiaolin Dai, Wolfgang Brandner, Joshua Schlieder, Thomas Henning

Abstract

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 M

_{B + C} = 0.48 ± 0.14 M

_âŠ™. 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

_âŠ™ 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.

Organisation(s)

Department of Astrophysics

External organisation(s)

Stockholm University, Leopold-Franzens-Universität Innsbruck, Queen's University Belfast, Max-Planck-Institut für Astronomie, National Aeronautics & Space Administration (NASA)

Journal

Astronomy & Astrophysics

Volume

604

No. of pages

9

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201730725

Publication date

08-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

103003 Astronomy, 103004 Astrophysics

Keywords

ASJC Scopus subject areas

Astronomy and Astrophysics, Space and Planetary Science

Portal url

https://ucrisportal.univie.ac.at/en/publications/03168eaf-3fd6-4181-9ba4-b178f5ceca01

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