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A&A 438, L29-L32 (2005)
DOI: 10.1051/0004-6361:200500111

Letter

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

G. Chauvin¹, A.-M. Lagrange², B. Zuckerman³, C. Dumas¹, D. Mouillet⁴, I. Song³, J.-L. Beuzit², P. Lowrance⁵ and M. S. Bessell<sup>6

1</sup>  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 5.5'' 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 4.7, 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?

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© ESO 2005