Anthony A. Misch

A Planetary Companion to HD 40979 and Additional Planets Orbiting HD 12661 and HD 38529

We report the detection of three extrasolar planets from the Lick and Keck observatories. The F8 V star HD 40979 has a companion with orbital period P = 263.1 ± 3 days, eccentricity e = 0.25 ± 0.05, and velocity semiamplitude K = 101.2 ± 5.6 m s-1. The inferred semimajor axis is 0.83 AU and M sin i = 3.28MJup. Observations of planetary companions orbiting the G6 V star HD 12661 and the G4 IV star HD 38529 have already been published, and here we report additional, longer period companions for both of these stars. The outer companion to HD 12661 has Pc = 1444.5 ± 12.5 days, ec = 0.20 ± 0.04, and Kc = 27.6 ± 2.5 m s-1. Adopting a stellar mass of 1.07 M☉, we find Mc sin i = 1.57MJup and a semimajor axis of 2.56 AU. The second companion to HD 38529 has Pc = 2174 ± 30 days, ec = 0.36 ± 0.05, and Kc = 170.5 ± 9 m s-1. The assumed mass of 1.39 M☉ for HD 38529 yields Mc sin i = 12.7MJup and a semimajor axis of 3.68 AU. Photometric observations at Fairborn Observatory reveal low-amplitude brightness variations in HD 40979 and HD 38529 due to rotational modulation in the visibility of photospheric starspots, and they yield rotation periods of 7.0 and 35.7 days, respectively, very different from the planetary orbital periods. The orbital parameters of these two systems are compared with updated parameters for all of the known multiple-planet systems. Updated velocities are provided for the Andromedae system.

THE BETA PROBLEM: A STUDY OF ABELL 262

We present an investigation of the dynamical state of the cluster A262. Existing optical line-of-sight velocities for select cluster galaxies have been augmented by new data obtained with the Automated Multi-Object Spectrograph at Lick Observatory. We —nd evidence for a virialized early-type population distinct from a late-type population infalling from the Pisces-Perseus supercluster ridge. We also report on a tertiary population of low-luminosity galaxies the velocity dispersion of which distinguishes them from both the early- and late-type galaxies. We supplement our investigation with an analysis of archival X-ray data. A temperature is determined using ASCA GIS data, and a gas pro—le is derived from ROSAT HRI data. The increased statistics of our sample results in a picture of A262 with signi—cant diUerences from earlier work. A previously proposed solution to the ii b-problem ˇˇ in A262 in which the gas temperature is signi—cantly higher than the galaxy temperature is shown to result from using too low a velocity dispersion for the early-type galaxies. Our data present a consistent picture of A262 in which there is no ii b-problem,ˇˇ and the gas and galaxy temperature are roughly comparable. There is no longer any requirement for extensive galaxy-gas feedback to drastically overheat the gas with respect to the galaxies. We also demonstrate that entropy —oor models can explain the recent discovery that the b values determined by cluster gas and the cluster core radii are correlated. . .. . . . . .. . . . . . . . .. . . . . .. . . . . .. . . .