2007/07/25 by V. Joergens, A. Müller, A. Mueller · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Scientific Research and Discoveries #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/521825
published as Astrophys.J.666:L113-L116,2007 · 8 pages, 1 figure, ApJ Letter in press
arxiv created 2007/07/25 · openalex publication_date 2007/08/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report the discovery of a 16-20 M Jup radial velocity companion around the very young (~3 Myr) brown dwarf candidate Cha Hα 8 (M5.75-M6.5). Based on high-resolution echelle spectra of Cha Hα 8 taken between 2000 and 2007 with UVES at the VLT, a companion was detected through RV variability with a semiamplitude of 1.6 km s -1 . A Kepler fit to the data yields an orbital period of the companion of 1590 days and an eccentricity of e = 0.49. A companion minimum mass M 2 sin i between 16 and 20 M Jup is derived when using model-dependent mass estimates for the primary. The mass ratio q ≡ M 2 / M 1 might be as small as 0.2 and, with a probability of 87%, it is less than 0.4. Cha Hα 8 harbors most certainly the lowest mass companion detected so far in a close (~1 AU) orbit around a brown dwarf or very low mass star. From the uncertainty in the orbit solution, it cannot completely be ruled out that the companion has a mass in the planetary regime. Its discovery is in any case an important step toward RV planet detections around brown dwarfs. Further, Cha Hα 8 is the fourth known spectroscopic brown dwarf or very low mass binary system with an RV orbital solution and the second known very young one.