Browsing by Subject "planets and satellites: dynamical"

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    The Mcdonald Observatory Planet Search: New Long-Period Giant Planets And Two Interacting Jupiters In The HD 155358 System
    (2012-04) Robertson, Paul; Endl, Michael; Cochran, William D.; MacQueen, Phillip J.; Wittenmyer, Robert A.; Horner, Jonathan; Brugamyer, Erik J.; Simon, Attila E.; Barnes, Stuart I.; Caldwell, Caroline; Robertson, Paul; Endl, Michael; Cochran, William D.; MacQueen, Phillip J.; Brugamyer, Erik J.; Barnes, Stuart I.; Caldwell, Caroline
    We present high-precision radial velocity (RV) observations of four solar-type (F7-G5) stars-HD 79498, HD 155358, HD 197037, and HD 220773-taken as part of the McDonald Observatory Planet Search Program. For each of these stars, we see evidence of Keplerian motion caused by the presence of one or more gas giant planets in long-period orbits. We derive orbital parameters for each system and note the properties (composition, activity, etc.) of the host stars. While we have previously announced the two-gas-giant HD 155358 system, we now report a shorter period for planet c. This new period is consistent with the planets being trapped in mutual 2:1 mean-motion resonance. We therefore perform an in-depth stability analysis, placing additional constraints on the orbital parameters of the planets. These results demonstrate the excellent long-term RV stability of the spectrometers on both the Harlan J. Smith 2.7 m telescope and the Hobby-Eberly telescope.
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    New Observational Constraints On The Nu Andromedae System With Data From The Hubble Space Telescope And Hobby-Eberly Telescope
    (2010-06) McArthur, Barbara E.; Benedict, G. Fritz; Barnes, Rory; Martioli, Elder; Korzennik, Sylvain; Nelan, Ed; Butler, R. Paul; McArthur, Barbara E.; Benedict, G. Fritz; Martioli, Elder
    We have used high-cadence radial velocity (RV) measurements from the Hobby-Eberly Telescope with existing velocities from the Lick, Elodie, Harlan J. Smith, and Whipple 60 '' telescopes combined with astrometric data from the Hubble Space Telescope Fine Guidance Sensors to refine the orbital parameters and determine the orbital inclinations and position angles of the ascending node of components v And A c and d. With these inclinations and using M(*) = 1.31M(circle dot) as a primary mass, we determine the actual masses of two of the companions: And A c is 13.98+ 2.3 -5.3 MJUP, and. And A d is 10.25(-3.3)(+0.7) M(JUP). These measurements represent the first astrometric determination of mutual inclination between objects in an extrasolar planetary system, which we find to be 29 degrees.9 +/- 1 degrees. The combined RV measurements also reveal a long-period trend indicating a fourth planet in the system. We investigate the dynamic stability of this system and analyze regions of stability, which suggest a probable mass of v And A b. Finally, our parallaxes confirm that v And B is a stellar companion of v And A.