The frequency of low-mass exoplanets

O'Toole, S. J. and Jones, H. R. A. and Tinney, C. G. and Butler, R. P. and Marcy, G. W. and Carter, B. D. ORCID: and Bailey, J. and Wittenmyer, R. A. (2009) The frequency of low-mass exoplanets. The Astrophysical Journal, 701 (2). pp. 1732-1741. ISSN 0004-637X

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We report first results from the Anglo-Australian Telescope Rocky Planet Search—an intensive, high-precision Doppler planet search targeting low-mass exoplanets in contiguous 48 night observing blocks. On this run, we targeted 24 bright, nearby and intrinsically stable Sun-like stars selected from the Anglo-Australian Planet Search's main sample. These observations have already detected one low-mass planet reported elsewhere (HD 16417b), and here we reconfirm the detection of HD 4308b. Further, we have Monte Carlo simulated data from this run on a star-by-star basis to produce robust detection constraints. These simulations demonstrate clear differences in the exoplanet detectability functions from star to star due to differences in sampling, data quality and intrinsic stellar stability. They reinforce the importance of star-by-star simulation when interpreting the data from Doppler planet searches. These simulations indicate that for some of our target stars we are sensitive to close-orbiting planets as small as a few Earth masses. The two low-mass planets present in our 24-star sample indicate that the exoplanet minimum mass function at low masses is likely to be a flat α ~ –1 (for dN/dM vprop M α) and that between 15% ± 10% (at α = –0.3) and 48% ± 34% (at α = –1.3) of stars host planets with orbital periods of less than 16 days and minimum masses greater than 3 M ⊕.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: Historic - Faculty of Sciences - Department of Biological and Physical Sciences (Up to 30 Jun 2013)
Faculty/School / Institute/Centre: Historic - Faculty of Sciences - Department of Biological and Physical Sciences (Up to 30 Jun 2013)
Date Deposited: 17 Feb 2010 01:06
Last Modified: 24 Mar 2017 03:08
Uncontrolled Keywords: methods: numerical, methods: statistical, planetary systems, stars; HD 4308; HD 16417; HD 84117
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0299 Other Physical Sciences > 029902 Complex Physical Systems
01 Mathematical Sciences > 0102 Applied Mathematics > 010299 Applied Mathematics not elsewhere classified
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
51 PHYSICAL SCIENCES > 5199 Other physical sciences > 519901 Complex physical systems
49 MATHEMATICAL SCIENCES > 4901 Applied mathematics > 490199 Applied mathematics not elsewhere classified
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
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