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Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass

Crepp, Justin R. and Johnson, John Asher (2011) Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass. Astrophysical Journal, 733 (2). Art. No. 126. ISSN 0004-637X.

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We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, β Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple formation mechanisms are at work. Upon relaxing our assumption that planets in ultra-wide (a > 100 AU) orbits resemble the RV sample, our simulations suggest that the companions found orbiting late-type stars (AB Pic, 1RXSJ1609, GSC 06214, etc.) are consistent with a formation channel distinct from that of RV planets. These calculations explain why planets have thus far been imaged preferentially around A-stars and K-, M-stars, but no spectral types in between, despite concerted efforts targeting F-, G-stars.

Item Type:Article
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Crepp, Justin R.0000-0003-0800-0593
Johnson, John Asher0000-0001-9808-7172
Additional Information:© 2011 The American Astronomical Society. Received 2010 June 21; accepted 2011 April 19; published 2011 May 16. We are grateful for discussions with Ruslan Belikov, whose questions during the Sagan symposium in Pasadena motivated us to perform this study. We thank Chas Beichman, Kelly Plummer, and Dennis Wittman for support using the Bluedot super-computing cluster at NExScI, and Eric Nielsen for helpful conversations about Monte Carlo simulations. Brendan Bowler, Adam Kraus, Lynne Hillenbrand, Sasha Hinkley, and Eric Nielsen read an early draft of this manuscript and provided valuable feedback that improved the presentation of our results. We thank Jessica Lu, John Carpenter, and the anonymous referee for additional helpful comments. This study made use of the NStED database.
Subject Keywords:planetary systems; methods: numerical; methods: statistical
Issue or Number:2
Classification Code:PACS: 92.82.-j; 97.20.Jg; 97.10.Yp; 98.35.Pr; 97.10.Wn
Record Number:CaltechAUTHORS:20110607-074910517
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Official Citation:Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass Justin R. Crepp and John Asher Johnson doi: 10.1088/0004-637X/733/2/126
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23918
Deposited By: Ruth Sustaita
Deposited On:07 Jun 2011 15:11
Last Modified:09 Mar 2020 13:18

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