Astrometric planet search around M8-L2 dwarfs from the ground and with Gaia
Abstract
Ultra-cool dwarfs are very low-mass stars or brown dwarfs and because of their faintness they are difficult targets for radial velocity and transit planet searches. High-precision astrometry is one way to efficiently discover planets around these objects. We are conducting a planet search survey of 20 M8-L2 using ground-based imaging astrometry with FORS2 at VLT. The realised accuracy of 100 micro-arcseconds allows us to set stringent constraints on the presence of planets, to discover astrometric binaries, and to measure parallaxes with an unprecendented precision of 0.1 %. The obtained detection limits firmly establish that giant planets are rare around UCDs at all separations. The astrometric performance of our programme is comparable to what is expected from Gaia observations of single faint objects and we discuss potential synergies for planet searches around ultracool dwarfs. We estimate that Gaia will be able to characterise ∼100 astrometric binaries with an ultracool primary.
- Publication:
-
Memorie della Societa Astronomica Italiana
- Pub Date:
- 2014
- DOI:
- 10.48550/arXiv.1407.0590
- arXiv:
- arXiv:1407.0590
- Bibcode:
- 2014MmSAI..85..674S
- Keywords:
-
- Stars: low-mass;
- Brown dwarfs;
- Planetary systems;
- Binaries: close;
- Astrometry;
- Parallaxes;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- To appear in the Proceedings of the GREAT-ESF workshop "Gaia and the unseen - the brown dwarf question", Torino, 24-26 March 2014, published in the Memorie della Societa' Astronomica Italiana (SAIt), eds R. Smart, D. Barrado, J. Faherty