NEUTRAL HYDROGEN ASSOCIATED WITH SHELLS AND OTHER FINE-STRUCTURE IN NGC-2865 - A DYNAMICALLY YOUNG ELLIPTIC

We report the discovery of neutral hydrogen in a second elliptical gal axy with shells, NGC 2865. Very Large Array images reveal an associati on between the neutral hydrogen (H I) and the fine structure (shells, tails, and loops) in the galaxy. Similar to what we previously observe d in NGC 5128 (Centaurus A), most of the 6 x 10(8) h(-2) M. of cold ga s is found in a broken ring in the outer regions of NGC 2865 (beyond 1 /2D(25))I and is displaced to the outside of the shells and loops. The measured velocities cover a range of 500 km s(-1) around the systemic velocity. The velocity field of the outer H I has the same sense and magnitude (and line of nodes) as that of the stars in the elliptical b ody. Although NGC 2865 appears to be a relaxed elliptical galaxy, deep images, photometry, and spectroscopy suggest that the galaxy might be the recent (less than 7 Gyr) product of a major disk-disk merger-a '' dynamically young elliptical.'' Our H I data support this hypothesis. Nevertheless, the association between gas and stellar fine structure, with gas displaced outward from the stars in projected position, impli es gas motions not predicted by any of the current merger scenarios. U sing the H I ring and assuming nearly circular motion, we measure M/L( B) at large radii (4 x 1/2D(25)). We find M/L(B) = 33 +/- 4 h, a facto r of 5 greater than the value of M/L(B) found for the central regions, indicating the presence of a dark halo.