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- Title
Astrometric planet search around southern ultracool dwarfs.
- Authors
Sahlmann, J.; Lazorenko, P. F.; Ségransan, D.; Martín, E. L.; Mayor, M.; Queloz, D.; Udry, S.
- Abstract
Using astrometric measurements obtained with the FORS2/VLT camera, we are searching for low-mass companions around 20 nearby ultracool dwarfs. With a single-measurement precision of ~0.1 milli-arcsec, our survey is sensitive to a wide range of companion masses from planetary companions to binary systems. Here, we report the discovery and orbit characterisation of a new ultracool binary at a distance of 19.5 pc from Earth that is composed of the M8.5-dwarf primary DE0630-18 and a substellar companion. The nearly edge-on orbit is moderately eccentric (e = 0:23) with an orbital period of 1120 d, which corresponds to a relative separation in semimajor axis of approximately 1.1 AU. We obtained a high-resolution optical spectrum with UVES/VLT and measured the system's heliocentric radial velocity. The spectrum does not exhibit lithium absorption at 670.8 nm, indicating that the system is not extremely young. A preliminary estimate of the binary's physical parameters tells us that it is composed of a primary at the stellar-substellar limit and a massive brown-dwarf companion. DE0630-18 is a new very low-mass binary system with a well-characterised orbit.
- Subjects
DWARF stars; ASTROMETRY; BINARY systems (Astronomy); STELLAR orbits; BROWN dwarf stars; STELLAR mass
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2015, Vol 577, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201525757