Astron. Astrophys. 358, 494-498 (2000)

Deep search for CO emission
in the Low Surface Brightness galaxy Malin 1

J. Braine ¹, F. Herpin ^1,2 and S.J.E. Radford <sup>3

1</sup> Observatoire de Bordeaux, UMR 5804, CNRS/INSU, B.P. 89, 33270 Floirac, France
² CSIC, IEM, Departemento de Fisica Molecular, Serrano 121, 28006 Madrid, Spain
³ National Radio Astronomy Observatory, 949 N. Cherry Ave., Tucson, AZ 85721, USA

Received 25 November 1999 / Accepted 21 January 2000

Abstract

A sensitive search for CO emission from the Low Surface Brightness Galaxy Malin 1 has yielded negative results. The nucleus and several positions corresponding to regions of star formation in the disk were observed in the CO(1-0) and CO(2-1) lines with no detection. Use of a "standard" conversion factor yields . However, rather than argue that there is very little molecular gas in Malin 1, where some star formation is currently taking place, we attribute the non-detection chiefly to the low temperature of the gas. Detection of CO may be rendered still more difficult by a subsolar metallicity.

Key words: galaxies: abundances galaxies: evolution galaxies: individual: Malin 1 galaxies: ISM galaxies: spiral radio lines: galaxies

Send offprint requests to: Jonathan Braine

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Contents

• 1. Introduction
• 2. CO observations
• 3. Results and analysis
  • 3.1. CO intensities and H₂ masses
  • 3.2. Star formation and the expected H₂ mass
  • 3.3. Why we do not detect CO
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 8, 2000
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