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High-precision radial velocity (RV) measurements spanning the years 1980.8-2000.0 are presented for the nearby (3.22 pc) K2 V star e Eri. These data, which represent a combination of six independent data sets taken with four different telescopes, show convincing variations with a period of ≈7 yr. A least-squares orbital solution using robust estimation yields orbital parameters of period yr, velocity amplitude m s Ϫ1 , ec-P p 6.9K p 19 centricity , projected companion mass , and semimajor axis AU. Ca ii e p 0.6 M sin i p 0.86 M a p 3.4Jupiter 2 H and K S-index measurements spanning the same time interval show significant variations with periods of 3 and 20 yr yet none at the RV period. If magnetic activity were responsible for the RV variations, then it produces a significantly different period than is seen in the Ca ii data. Given the lack of Ca ii variation with the same period as that found in the RV measurements, the long-lived and coherent nature of these variations, and the high eccentricity of the implied orbit, Keplerian motion due to a planetary companion seems to be the most likely explanation for the observed RV variations. The wide angular separation of the planet from the star (approximately 1Љ) and the long orbital period make this planet a prime candidate for both direct imaging and space-based astrometric measurements.

Vand /-band HST Planetary Camera images of the great spiral galaxy in Andromeda, M31, show that its inner nucleus consists of two components separated by 0':49. The outer isophotes of the nucleus at 1 ~ 4 < r < 3 ~0 are elongated, but are concentric with the M31 bulge. The nuclear component with the lower surface brightness, P2, is also coincident with the bulge photocenter to-0~05; we argue that it is at the kinematic center of the galaxy. The brighter nuclear component, Pl, is well resolved and corresponds to the nuclear core imaged by Stratoscope II. The central V-band luminosity density for Pl is 5 X 10 4 L)p pc-3 • P2 is highly elongated and has a shallow cusp. Its central V-band luminosity density is > 2 X 10 L 0 pc-3. The total nucleus cannot be modeled as the superposition of two systems each with elliptical and concentric isophotes. The dark zone between the two peaks is deep and is either evidence for strong dust absorption or that the nuclear components are steeply truncated in this region. No strong changes in the V-I color are observed over the nucleus, however. Thus if dust absorption generates the asymmetric nuclear morphology, the dust grain size must be unusually large or the dust optical depth must be extremely high. Alternatively the higher surface brightness, off-center nuclear component Pl may be a separate stellar system. The nuclear velocity dispersion profiles of Dressler & Richstone [ApJ, 324, 701 (1988)] and Kormendy [ApJ, 325, 128 (1988)] already show that Pl cannot be a dynamically cold system such as a globular cluster. Requiring Pl to survive destruction by a central black hole in M31 may also lead to lower limits on its mass-to-light ratio. This hypothesis requires us to be looking at M31 at a special time; however, the lifetime of Pl against orbital decay may be substantially longer than naive dynamical friction arguments would indicate. Under this picture, we argue that P 1 is more likely to be a cannibalized galactic nucleus, possibly having its own central black hole.

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We have used hydrogen fluoride for generating reference absorption lines in coudé spectra. This eliminates the systematic errors inherent in conventional radial-velocity measurements, where the comparison beam does not follow exactly the same path as starlight. In a test of this method an accuracy of 15 m s -1 was achieved using sunlight. Pressure shifts have been measured for the HF 3-0 band R branch lines.