2008/04/28 by Rory Barnes, Krzysztof Goździewski, Krzysztof Gozdziewski +1 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/589712
published as Astrophys.J.680:L57-L60,2008 · 11 pages, 2 figures, 1 table. Accepted for publication in ApJ Letters. A version with full resolution figures is available at http://www.lpl.arizona.edu/~rory/publications/bgr08.pdf
arxiv created 2008/04/28 · openalex publication_date 2008/05/14 · arxiv updated 2010/04/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Most of the first-discovered extrasolar multiplanet systems were found to lie close to dynamically unstable configurations. However, a few observed multiplanet systems (e.g., HD 74156) did not show this trait. Those systems could share this property if they contain an additional planet in between those that are known. Previous investigations identified the properties of hypothetical planets that would place these systems near instability. The hypothetical planet in HD 74156 was expected to have a mass about equal to that of Saturn, a semimajor axis between 0.9 and 1.4 AU, and an eccentricity less than 0.2. HD 74156d, a planet with a mass of 1.3 Saturn masses at 1.04 AU with an eccentricity of 0.25, was recently announced. We have reanalyzed all published data on this system in order to place tighter constraints on the properties of the new planet. We find two possible orbits for this planet, one close to that already identified and another (with a slightly better fit to the data) at ~0.89 AU. We also review the current status of other planet predictions, discuss the observed single-planet systems, and suggest other systems which may contain planets in between those that are already known. The confirmation of the existence of HD 74156d suggests that planet formation is an efficient process, and planetary systems should typically contain many planets.