The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey (GPIES). This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions wi...
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Published in | arXiv.org |
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format | Paper Journal Article |
Language | English |
Published |
Ithaca
Cornell University Library, arXiv.org
10.04.2019
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Subjects | |
Online Access | Get full text |
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Summary: | We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey (GPIES). This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semi-major axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M \(>\) 1.5 \(M_\odot\) more likely to host planets with masses between 2-13 M\(_{\rm Jup}\) and semi-major axes of 3-100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semi-major axis (a) for planet populations around high-mass stars (M \(>\) 1.5M\(_\odot\)) of the form \(\frac{d^2 N}{dm da} \propto m^\alpha a^\beta\), finding \(\alpha\) = -2.4 \(\pm\) 0.8 and \(\beta\) = -2.0 \(\pm\) 0.5, and an integrated occurrence rate of \(9^{+5}_{-4}\)% between 5-13 M\(_{\rm Jup}\) and 10-100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with 0.8\(^{+0.8}_{-0.5}\)% of stars hosting a brown dwarf companion between 13-80 M\(_{\rm Jup}\) and 10-100 au. Brown dwarfs also appear to be distributed differently in mass and semi-major axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semi-major axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the RV method, our results are consistent with a peak in occurrence of giant planets between ~1-10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability. |
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ISSN: | 2331-8422 |
DOI: | 10.48550/arxiv.1904.05358 |