AAS Meeting #193 - Austin, Texas, January 1999
Session 97. Extra-Solar Planets and the Search for Life
Display, Saturday, January 9, 1999, 9:20am-4:00pm, Exhibit Hall 1

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[97.03] Extrasolar Planets: Masses and Orbits

G.W. Marcy (SFSU/UCB), R.P. Butler (AAO), S.S. Vogt (UCOLICK/UCSC), D.A. Fischer (SFSU/UCB)

Doppler surveys of main sequence stars have revealed 14 companions that are strong extrasolar planet candidates, as characterized by Msini < 5 Mjup. A plausible distinction between planets and more massive substellar companions appears in their mass distribution. Companions having Msini in the range 0.5--5 Mjup outnumber those between 5--50 Mjup by a factor of ~3, within 2 AU. The planets that orbit farther than 0.15 AU from their star all reside in non--circular orbits having e>0.05, i.e., more eccentric than Jupiter's orbit. Indeed, all but two of these planets have e>0.2 . This high occurrence of orbital eccentricity has lead to models in which Jupiter--like planets suffer gravitational interactions with a) other planets (Weidenschilling & Marzari 1996, Rasio & Ford 1996, Lin & Ida 1996, Levison et al. 1998), b) the disk (Artymowicz 1993) c) a companion star (Holman et al. 1996, Mazeh et al. 1996). In addition, almost all of the planets discovered to date orbit metal-rich stars, with [Fe/H]>0.0.

We report two new planet candidates around two G--type main--seqeunce stars, HD210277 and HD168443. The values of Msini are 1.17 and 4.96 Mjup, respecitively, and the orbital periods are 437 d and 58 d. Both orbits have large eccentricities, e=0.45 and e=0.54, respectively, and both stars are single. Thus, the orbital eccentricities stem from internal dynamics that involve other planets or the protoplanetary disk. The velocities for HD168443 are not adequately fit with a model that includes only one planetary companion.

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