Browsing by Subject "techniques : radial"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Detection Of A Third Planet In The HD 74156 System Using The Hobby-Eberly Telescope(2008-01) Bean, Jacob L.; McArthur, Barbara E.; Benedict, G. Fritz; Armstrong, Amber; Bean, Jacob L.; McArthur, Barbara E.; Benedict, G. Fritz; Armstrong, AmberWe report the discovery of a third planetary-mass companion to the G0 star HD 74156. High-precision radial velocity measurements made with the Hobby-Eberly Telescope aided the detection of this object. The best-fit triple-Keplerian model to all the available velocity data yields an orbital period of 347 days and a minimum mass of 0.4 M-Jup for the new planet. We determine revised orbital periods of 51.7 and 2477 days and minimum masses of 1.9 and 8.0 M-Jup, respectively, for the previously known planets. Preliminary calculations indicate that the derived orbits are stable, although all three planets have significant orbital eccentricities (e = 0.64, 0.43, and 0.25). With our detection, HD 74156 becomes the eighth normal star known to host three or more planets. Further study of this system's dynamical characteristics will likely give important insight into planet formation and evolutionary processes.Item An M Sin I=24 M-Circle Plus Planetary Companion To The Nearby M Dwarf Gj 176(2008-02) Endl, Michael; Cochran, William D.; Wittenmyer, Robert A.; Boss, Alan P.; Endl, Michael; Cochran, William D.; Wittenmyer, Robert A.; Boss, Alan P.We report the detection of a planetary companion with a minimum mass of m sin i 0.0771 M-Jup 24.5 M-circle plus to the nearby (d 9.4 pc) M2.5 V star GJ 176. The star was observed as part of our M dwarf planet search at the Hobby-Eberly Telescope (HET). The detection is based on 5 years of high-precision differential radial velocity (RV) measurements using the High-Resolution Spectrograph (HRS). The orbital period of the planet is 10.24 days. GJ 176 thus joins the small (but increasing) sample of M dwarfs hosting short-period planets with minimum masses in the Neptune-mass range. Low-mass planets could be relatively common around M dwarfs, and the current detections might represent the tip of a rocky planet population.