| 1. |
- Fischer, Debra A., et al.
(author)
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M2K. II. A Triple-Planet System Orbiting Hip 57274
- 2012
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 745:1, s. 21-
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Journal article (peer-reviewed)abstract
- Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with M sin i = 11.6 M-circle plus (0.036 M-Jup), an orbital period of 8.135 +/- 0.004 days, and slightly eccentric orbit e = 0.19 +/- 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has M sin i = 0.4 M-Jup with an orbital period of 32.0 +/- 0.02 days in a nearly circular orbit (e = 0.05 +/- 0.03). The third planet has M sin i = 0.53 M-Jup with an orbital period of 432 +/- 8 days (1.18 years) and an eccentricity e = 0.23 +/- 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M-circle plus that have been detected with Doppler surveys. We find that 56% +/- 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% +/- 8%, that are members of Doppler-detected, multi-planet systems.
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| 2. |
- Howard, Andrew W., et al.
(author)
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THE NASA-UC ETA-EARTH PROGRAM : I. A SUPER-EARTH ORBITING HD 7924
- 2009
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 696:1, s. 75-83
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Journal article (peer-reviewed)abstract
- We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass M-P sin i = 9.26M(circle plus) in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence of the planetary companion. No transits were detected down to a photometric limit of similar to 0.5 mmag, eliminating transiting planets with a variety of compositions. HD 7924b is one of only eight planets detected by the radial velocity technique with M-P sini < 10 M-circle plus and as such is a member of an emerging family of low-mass planets that together constrain theories of planet formation.
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