期刊
ASTROPHYSICAL JOURNAL
卷 746, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/746/1/37
关键词
astrometry; planetary systems; stars: individual (GJ 317); techniques: radial velocities
资金
- Carnegie Postdoctoral Fellowship
- NASA Astrobiology Institute [NNA09DA81A]
- Carnegie Observatories TAC
- NASA OSS [NNX07AR40G]
- Carnegie Institution of Washington
- NSF [AST-0307493]
- UC-Keck and NASA-Keck Time Assignment Committees
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0908870] Funding Source: National Science Foundation
We have obtained precision astrometry of the planet host M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. The resulting absolute magnitudes suggest that it is metal-rich and more massive than previously assumed. This result strengthens the correlation between high metallicity and the presence of gas giants around low-mass stars. At 15.3 pc, the minimal astrometric amplitude for planet candidate GJ 317b is 0.3 mas (edge-on orbit), just below our astrometric sensitivity. However, given the relatively large number of observations and good astrometric precision, a Bayesian Monte Carlo Markov Chain analysis indicates that the mass of planet b has to be smaller than twice the minimum mass with a 99% confidence level, with a most likely value of 2.5 M-Jup. Additional radial velocity (RV) measurements obtained with Keck by the Lick-Carnegie Planet search program confirm the presence of an additional very long period planet candidate, with a period of 20 years or more. Even though such an object will imprint a large astrometric wobble on the star, its curvature is yet not evident in the astrometry. Given high metallicity, and the trend indicating that multiple systems are rich in low-mass companions, this system is likely to host additional low-mass planets in its habitable zone that can be readily detected with state-of-the-art optical and near-infrared RV measurements.
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