Presently every telescope at McDonald Observatory is utilized for the search for extrasolar planets. Here we give an overview of the precision Doppler surveys currently in progress at the 9.2 m Hobby-Eberly Telscope (HET) and the Harlan J. Smith 2.7 m telescope. Other planet search programs at McDonald Observatory include a transit search at the 0

We present the metallicity distribution function (MDF) for 24,270 G and 16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based on spectroscopy from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey. This stellar sample is significantly larger in both number and volume than previous spectroscopic

SDSS DR6 includes about 300,000 stellar spectra, and a significant fraction of them belong to members of the halo. We make use of these data to examine closely the shape of the halo metallicity distribution. Does it have a single peak? Is it bimodal? Does it offer any clues on its formation and evolution?

The spectral lines observed in penumbrae are asymmetrical, revealing the existence of spatially unresolved structures. We infer their physical properties by fitting Stokes spectra of Fe I 6301.5 Å and Fe I 6302.5 Å with model atmospheres having two magnetic components interleaved along the line-of-sight (LOS). Combining ten thousand fits, we set up

The thermal spectrum of the zodiacal light cannot be observed from the ground. We collected 27 mid-infrared (6-12mu m) spectra obtained by the spectrophotometer ISOPHOT-S on-board the Infrared Space Observatory (ISO). The observed positions are distributed over the sky region accessible by ISO. The spectrum of the zodiacal light is remarkably well

We report the largest mass-loss rate of ~5 % of the solar mass per year, directly observed in any stellar object so far during the recent outburst of the Yellow Hypergiant ρ Cas. In the fall of 2000, the enigmatic cool luminous supergiant dimmed by more than a full visual magnitude, thereby changing its spectral type form early F- to early M-type