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The results of new spectroscopic analyses of 30 stars with giant planet and/or brown dwarf companions are presented. Values for T eff and [Fe/H] are used in conjunction with Hipparcos data and Padova isochrones to derive masses, ages, and theoretical surface gravities. These new data are combined with spectroscopic and photometric metallicity estimates of other stars harboring planets and published samples of F, G, and K dwarfs to compare several subsets of planet bearing stars with similarly well-constrained control groups. The distribution of [Fe/H] values continues the trend uncovered in previous studies in that stars hosting planetary companions have a higher mean value than otherwise similar nearby stars. We also investigate the relationship between stellar mass and the presence of giant planets and find statistically marginal but suggestive evidence of a decrease in the incidence of radial velocity companions orbiting relatively less massive stars. If confirmed with larger samples, this would represent a critical constraint to both planetary formation models as well as to estimates of the distribution of planetary systems in our galaxy.

The results of a new spectroscopic analysis of HD 75289, recently reported to harbor a Jovian-mass planet, are presented. From high-resolution, high-S/N ratio spectra, we derive [Fe/H] = +0.28 ± 0.05 for this star, in agreement with the spectroscopic study of Gratton et al., published 10 years ago. In addition, we present a re-analysis of the spectra of υ And and τ Boo; our new parameters for these two stars are now in better agreement with photometrically-derived values and with the recent spectroscopic analyses of Fuhrmann et al. We also report on extended abundance analyses of 14 Her, HD 187123, HD 210277, and ρ 1 Cnc.If we include the recent spectroscopic analyses of HD 217107 by Randich et al. and Sadakane et al., who both reported [Fe/H] ∼ +0.30 for this star, we can state that all the "hot-Jupiter" systems studied to date have metal-rich parent stars. We find that the mean [C/Fe] and [Na/Fe] values among the stars-with-planets sample are smaller than the corresponding quantities among field stars of the same [Fe/H].

Using very high-resolution (R∼ 125,000) and high quality (S/N ≥ 350) spectra, we have searched for 6 Li in stars hosting extra-solar planets. From detailed profile-fitting of the Li i resonance line at 6707.7Å, we find no significant amount of 6 Li relative to the 7 Li for any of 8 planet bearing stars ( 6 Li/ 7 Li ≤ 0.0 -0.03 ) with a strong Li i lines. In particular, we do not confirm the presence of 6 Li with 6 Li/ 7 Li = 0.13 reported by Israelian et al.(2001) for HD 82943, a star with two known planets. Several of the 8 stars plus HD 219542 A, the planet-less primary of a binary, have been identified in the literature as possible recipients of accreted terrestrial material. For all of the planet-hosting stars and an additional 5 planet-less stars, we find no 6 Li.

We present an analysis of the longest timescale microlensing events discovered by the MACHO Collaboration during a 7 year survey of the Galactic bulge. We find six events that exhibit very strong microlensing parallax signals due, in part, to accurate photometric data from the GMAN and MPS collaborations. The microlensing parallax fit parameters are used in a likelihood analysis, which is able to estimate the distances and masses of the lens objects based on a standard model of the Galactic velocity distribution. This analysis indicates that the most likely masses of five of the six lenses are greater than 1 M , which suggests that a substantial fraction of the Galactic lenses may be massive stellar remnants. This could explain the observed excess of long-timescale microlensing events. The lenses for events MACHO-96-BLG-5 and MACHO-98-BLG-6 are the most massive, with mass estimates of M=M ¼ 6 þ10 À3 and M=M ¼ 6 þ7 À3 , respectively. The observed upper limits on the absolute brightness of main-sequence stars for these lenses are less than 1 L , so both lenses are black hole candidates. The black hole interpretation is also favored by a likelihood analysis with a Bayesian prior using a conventional model for the lens mass function. We consider the possibility that the source stars for some of these six events may lie in the foreground Galactic disk or in the Sagittarius (Sgr) dwarf galaxy behind the bulge, but we find that bulge sources are likely to dominate our microlensing parallax event sample. Future Hubble Space Telescope observations of these events can either confirm the black hole lens hypothesis or detect the lens stars and provide a direct measurement of their masses. Future observations of similar events by the Space Interferometry Mission or the Keck or VLT interferometers, as explained by Delplancke, Gó rski, & Richichi, will allow direct measurements of the lens masses for stellar remnant lenses as well.