The frequency of low-mass exoplanets

S. J. O'Toole, H. R A Jones, C. G. Tinney, R. P. Butler, G. W. Marcy, B. Carter, J. Bailey, R. A. Wittenmyer

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

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 (HD16417b), and here we reconfirm the detection of HD4308b. 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 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 16days and minimum masses greater than 3M .

Original languageEnglish
Pages (from-to)1732-1741
Number of pages10
JournalAstrophysical Journal
Volume701
Issue number2
DOIs
Publication statusPublished - 2009

    Fingerprint

Keywords

  • Methods: numerical
  • Methods: statistical
  • Planetary systems
  • Stars: individual (HD 4308, HD 16417, HD 84117)

Cite this

O'Toole, S. J., Jones, H. R. A., Tinney, C. G., Butler, R. P., Marcy, G. W., Carter, B., ... Wittenmyer, R. A. (2009). The frequency of low-mass exoplanets. Astrophysical Journal, 701(2), 1732-1741. https://doi.org/10.1088/0004-637X/701/2/1732