* Astronomy

Title: Discovery of a probable 4-5 Jupiter-mass exoplanet to HD 95086 by direct-imaging
Authors: J. Rameau , G. Chauvin , A.-M. Lagrange , A. Boccaletti , S. P. Quanz , M. Bonnefoy , J. H. Girard , P. Delorme , S. Desidera , H. Klahr , C. Mordasini , C. Dumas , M. Bonavita , T. Meshkat , V. Bailey , and M. Kenworthy

Direct imaging has just started the inventory of the population of gas giant planets on wideorbits around young stars in the solar neighborhood. Following this approach, we carried out a deep imaging survey in the near-infrared using VLT/NaCo to search for substellar companions. We report here the discovery in L ' (3.8µm) images of a probable companion orbiting at 56 AU the young (10  17 Myr), dusty, and early-type (A8) star HD 95086. This discovery is based on observations with more than a year-time-lapse. Our first epoch clearly revealed the source at ~ 10 sigma while our second epoch lacked good observing conditions hence yielding a ~ 3 sigma detection. Various tests were thus made to rule out possible artifacts. This recovery is consistent with the signal at the rst epoch but requires cleaner conrmation. Nevertheless, our astrometric precision suggests the companion to be comoving with the star, with a 3 sigma confidence level. The planetary nature of the source is reinforced by a non-detection in Ks-band (2.18µm) images according to its possible extremely red Ks - L ' colour. Conversely, background contamination is rejected with good condence level. The luminosity yields a predicted mass of about 4-5 Jupiter masses (at 10-17 Myr) using "hot-start" evolutionary models, making HD 95086 b the exoplanet with the lowest mass ever imaged around a star.

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