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Published August 1, 2012 | Published
Journal Article Open

Searching for Young Jupiter Analogs around AP Col: L-band High-contrast Imaging of the Closest Pre-main-sequence Star


The nearby M-dwarf AP Col was recently identified by Riedel et al. as a pre-main-sequence star (age 12-50 Myr) situated only 8.4 pc from the Sun. The combination of its youth, distance, and intrinsically low luminosity make it an ideal target to search for extrasolar planets using direct imaging. We report deep adaptive optics observations of AP Col taken with VLT/NACO and Keck/NIRC2 in the L band. Using aggressive speckle suppression and background subtraction techniques, we are able to rule out companions with mass m ≥ 0.5-1 M_Jup for projected separations a > 4.5 AU, and m ≥ 2 M_Jup for projected separations as small as 3 AU, assuming an age of 40 Myr using the COND theoretical evolutionary models. Using a different set of models, the mass limits increase by a factor of ≳2. The observations presented here are the deepest mass-sensitivity limits yet achieved within 20 AU on a star with direct imaging. While Doppler radial velocity surveys have shown that Jovian bodies with close-in orbits are rare around M-dwarfs, gravitational microlensing studies predict that 17^(+6)_(–9)% of these stars host massive planets with orbital separations of 1-10 AU. Sensitive high-contrast imaging observations, like those presented here, will help to validate results from complementary detection techniques by determining the frequency of gas giant planets on wide orbits around M-dwarfs.

Additional Information

© 2012 American Astronomical Society. Received 2012 March 20; accepted 2012 May 30; published 2012 July 17. We thank ESO for granting us Director's Discretionary Time for our VLT/NACO observations and are indebted to Lowell Tacconi-Garman and Julien Girard for their excellent support during the observing run. S.P.Q. thanks D. Spiegel for useful discussions about theoretical models of planetary atmospheres. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and of NASA's Astrophysics Data System. Facilities: VLT:Yepun (NACO), Keck:II (NIRC2). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program number 288.C-5005(A).

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Published - Quanz2012p19346Astrophys_J.pdf


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