Letter to the Editor

A companion to AB Pic at the planet/brown dwarf boundary

¹ European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: gchauvin@eso.org
² Laboratoire d'Astrophysique, Observatoire de Grenoble, 414 rue de la piscine, Saint-Martin-d'Hères, France
³ Department of Physics & Astronomy and Center for Astrobiology, University of California, Los Angeles, Box 951562, CA 90095, USA
⁴ Laboratoire d'Astrophysique, Observatoire Midi-Pyrénées, Tarbes, France
⁵ Spitzer Science Center, Infrared Processing and Analysis Center, MS 220-6, Pasadena, CA 91125, USA
⁶ Research School of astronomy and Astrophysics Institue of Advance Studies, Australian National University, Cotter Road, Weston Creek, Canberra, ACT 2611, Australia

Received: 24 March 2005
Accepted: 19 April 2005

Abstract

We report deep imaging observations of the young, nearby star AB Pic, a member of the large Tucana-Horologium association. We have detected a faint, red source  South of the star with JHK colors compatible with that of a young substellar L dwarf. Follow-up observations at two additional epochs confirm, with a confidence level of 4.7σ, that the faint red object is a companion to AB Pic rather than it being a stationary background object. A low resolution K-band spectrum indicates an early-L spectral type for the companion. Finally, evolutionary model predictions based on the JHK photometry of AB Pic b indicate a mass of 13 to 14  if its age is ~30 Myr. Is AB Pic b a massive planet or a minimum mass brown dwarf?