Discovery of a probable 4-5 Jupiter-mass exoplanet to HD 95086 by direct-imaging

TL;DR

This paper reports the direct imaging discovery of a probable 4-5 Jupiter-mass exoplanet orbiting HD 95086, marking one of the lowest-mass exoplanets imaged around a star, using near-infrared observations with VLT/NaCo.

Contribution

First direct imaging detection of a low-mass (4-5 MJup) exoplanet around HD 95086 using deep near-infrared imaging, demonstrating the potential of this method for discovering similar planets.

Findings

Probable companion at 56 AU from HD 95086

Companion has a very red Ks - L' color suggesting a planetary nature

Estimated mass of the companion is 4-5 Jupiter masses

Abstract

Direct imaging has just started the inventory of the population of gas giant planets on wide-orbits 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' (3.8 microns) 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 first epoch but requires cleaner confirmation. 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 (2.18 microns) images according to its possible extremely red Ks - L' color. Conversely, background contamination is rejected with good confidence level. The luminosity yields a predicted mass of about 4-5MJup (at 10-17 Myr) using "hot-start" evolutionary models, making HD 95086 b the exoplanet with the lowest mass ever imaged around a star.