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Journal Articles Astronomy and Astrophysics - A&A Year : 2016

MASSIVE: A Bayesian analysis of giant planet populations around low-mass stars

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Abstract

Context. Direct imaging has led to the discovery of several giant planet and brown dwarf companions. These imaged companions populate a mass, separation and age domain (mass >1 MJup, orbits > 5 AU, age < 1 Gyr) quite distinct from the one occupied by exoplanets discovered by the radial velocity or transit methods. This distinction could indicate that different formation mechanisms are at play.
Aims: We aim at investigating correlations between the host star's mass and the presence of wide-orbit giant planets, and at providing new observational constraints on planetary formation models.
Methods: We observed 58 young and nearby M-type dwarfs in L'-band with the VLT/NaCo instrument and used angular differential imaging algorithms to optimize the sensitivity to planetary-mass companions and to derive the best detection limits. We estimate the probability of detecting a planet as a function of its mass and physical separation around each target. We conduct a Bayesian analysis to determine the frequency of substellar companions orbiting low-mass stars, using a homogenous sub-sample of 54 stars.
Results: We derive a frequency of for companions with masses in the range of 2-80 MJup, and % for planetary mass companions (2-14 MJup), at physical separations of 8 to 400 AU for both cases. Comparing our results with a previous survey targeting more massive stars, we find evidence that substellar companions more massive than 1 MJup with a low mass ratio Q with respect to their host star (Q < 1%), are less frequent around low-mass stars. This may represent observational evidence that the frequency of imaged wide-orbit substellar companions is correlated with stellar mass, corroborating theoretical expectations. Contrarily, we show statistical evidence that intermediate-mass ratio (1% < Q < 5%) companion with masses >2 MJup might be independent from the mass of the host star.
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Dates and versions

insu-03691476 , version 1 (09-06-2022)

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J. Lannier, P. Delorme, A. M. Lagrange, S. Borgniet, J. Rameau, et al.. MASSIVE: A Bayesian analysis of giant planet populations around low-mass stars. Astronomy and Astrophysics - A&A, 2016, 596, ⟨10.1051/0004-6361/201628237⟩. ⟨insu-03691476⟩
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