Volume 520, September-October 2010
|Number of page(s)||4|
|Published online||23 September 2010|
Letter to the Editor
Deep near-infrared interferometric search for low-mass companions around β Pictoris*
Institut d'Astrophysique et de Géophysique, Université de Liège, 17 Allée du Six Août, 4000 Liège, Belgium e-mail: firstname.lastname@example.org
2 LAOG–UMR 5571, CNRS and Université Joseph Fourier, BP 53, 38041 Grenoble, France
3 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
4 European Southern Observatory, Casilla 19001, Santiago 19, Chile
Accepted: 3 September 2010
Aims. We search for low-mass companions in the innermost region (<300 mas, i.e., 6 AU) of the β Pic planetary system.
Methods. We obtained interferometric closure phase measurements in the K-band with the VLTI/AMBER instrument used in its medium spectral resolution mode. Fringe stabilization was provided by the FINITO fringe tracker.
Results. In a search region of between 2 and 60 mas in radius, our observations exclude at 3σ significance the presence of companions with K-band contrasts greater than 5×10-3 for 90% of the possible positions in the search zone (i.e., 90% completeness). The median 1σ error bar in the contrast of potential companions within our search region is 1.2×10-3. The best fit to our data set using a binary model is found for a faint companion located at about 14.4 mas from β Pic, which has a contrast of 1.8×10-3 ± 1.1×10-3 (a result consistent with the absence of companions). For angular separations larger than 60 mas, both time smearing and field-of-view limitations reduce the sensitivity.
Conclusions. We can exclude the presence of brown dwarfs with masses higher than 29 MJup (resp. 47 MJup) at a 50% (resp. 90%) completeness level within the first few AUs around β Pic. Interferometric closure phases offer a promising way to directly image low-mass companions in the close environment of nearby young stars.
Key words: stars: individual: β Pic / planets and satellites: detection / techniques: interferometric / planetary systems
© ESO, 2010
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