APERTURE SYNTHESIS OBSERVATIONS OF MOLECULAR AND ATOMIC GAS IN THE WOLF-RAYET STARBURST GALAXY HENIZE-2-10

We present aperture synthesis observations of the atomic (H I) and molecular (CO) gas in the Wolf-Rayet starburst galaxy Henize 2-10 (He 2-10). Our 12CO (1→0) observations from the Owens Valley Radio Observatory represent the first aperture synthesis data on molecular gas in a blue compact galaxy. The 12CO (1→0) data reveal a rotating disk or bar of molecular material with a 30″×5″ elongation to the Southeast which we interpret as a tidal tail. We also see a kinematically distinct CO feature with a molecular gas mass of at least 4.0×106 script M sign⊙, perhaps indicative of a collision or interaction. The peak of the molecular gas distribution is offset by ∼100 pc from the optical peak containing a population of some 400 Wolf-Rayet stars. The rotation curve derived from our CO velocity field indicates that, unless the inclination of He 2-10 is extremely low, young starburst knots in the nucleus, which have been termed "proto globular clusters," comprise up to half of the dynamical mass in the inner 70 pc. A search for H I companions detected none to a limit of <3.5 × 106 script M sign⊙. The global H I velocity field is predominantly solid body, and shows a small elongation to the Southeast which might be regarded as a tidal tail. This H I feature points in the same direction as the elongation seen in CO, suggesting a past merger or galactic interaction. High spatial resolution maps reveal a low H I surface brightness in the vicinity of the two starburst regions which we interpret as a real dearth of H I, perhaps the result of a replacement effect by molecular gas which fills this region. We address the bearing of these data on several scenarios proposed to explain the history of the star formation in He 2-10. Our preferred interpretation involves a moderately advanced merger between two dwarf galaxies. Another more speculative interpretation involving the accretion of small gas clouds in the mass range of a few × 106 script M signcaret;⊙ is discussed. © 1995 American Astronomical Society.