A Search For Planets in the Metal-Rich Open Cluster Praesepe
Abstract
The most promising way to distinguish between competing theories of planet formation and subsequent migration is to find and determine the basic properties of short period (< 1 yr) planets with well-determined ages younger than 1 billion years. Open clusters are the most promising locations to do this, but disappointingly no main sequence open cluster stars are known to harbor planets. This is primarily a consequence of most clusters being too distant for precise radial velocity measurements at visual wavelength. A better determined frequency of planets within open clusters would also clarify if this environment inhibits their formation, as has recently been suggested. If confirmed, that would imply that most stars will not have planets since most stars are believed to form in dense clusters. Here we request funding to support a 2-year program to search for radial velocity planets in the 600 Myr Praesepe open cluster. Praesepe is the most metal rich open cluster within 1000 pc of the sun. Based on known planet frequency - metallicity correlations, its high metallicity suggests a planet frequency enhanced by nearly a factor of 4 relative to sun- like stars; approximately 1 in 20 of its members should harbor a short period (3-10 day) hot Jupiter-like planet, and 1 in 400 of its members should have a transiting planet. The observations will be carried out using the Mayall 4-m/Echelle and Keck/HIRES facilities; nearly 100 Praesepe FGK stars will be surveyed over a 1+ year baseline. Precise radial velocities will be obtained using telluric features as a wavelength reference. We have demonstrated this technique achieves a precision of at least 50 m/s, and anticipate a final precision of 10 m/s, similar to what has been previously achieved. This precision and proposed temporal sampling will enable us to confidently identify nearly all Jupiter-sized planets with periods less than ~1 yr. The discovery of the first planets orbiting dwarf stars within an open cluster with a well determined age will establish much needed constraints on proposed models of planet formation and dynamical evolution. The proposed research directly addresses the objectives of this solicitation, to improve our understanding of the origins of solar systems. In addition, the pioneering technique of precise radial velocity measurements at red wavelengths will be further developed in this study, and will likely play an important complementary role to on-going and upcoming NASA missions (e.g. Kepler, SIM, JWST). These, in combination with young astronomers to be trained as part of this project, make this proposal a compelling investment for the future of NASA.
- Publication:
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NASA OSS Proposal
- Pub Date:
- 2010
- Bibcode:
- 2010oss..prop...93W