M 82's stellar bar

¹ Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, 38406 St. Martin d'Hères, France
² Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK
³ Astronomisches Institut der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁴ University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK
⁵ Onsala Space Observatory, 43992 Onsala, Sweden

Corresponding author: A. Greve, greve@iram.fr

Received: 28 September 2001
Accepted: 26 November 2001

Abstract

The fueling of the starburst in M 82 may be related to a stellar bar which pushes gas towards the center where it forms stars. The observation by McKeith et al. (1993) of the near-IR Ca II photospheric absorption line allows a direct velocity measurement of the stars in M 82, and provides by this a confirmation of the predicted x₁ and x₂-orbits of the bar in M 82. From this and other observations we find that the mass of the x₂-orbit stars is ~15% of the mass of the bar, and that the mass of the bar of is 20–40% of M 82's mass. This mass concentration of ~1 kpc extent at the center of M 82 underlines the dynamic importance of the bar.