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The JCMT nearby galaxies legacy survey VI. The distribution of gas and star formation in M81

Sánchez-Gallego, J. R.; Knapen, J. H.; Heiner, J. S.; Wilson, C. D.; Warren, B. E.; Allen, R. J.; Azimlu, M.; Barmby, P.; Bendo, G. J.; Comerón, S.; Israel, F. P.; Serjeant, S.; Tilanus, R. P. J.; Vlahakis, C. and van der Werf, P. (2011). The JCMT nearby galaxies legacy survey VI. The distribution of gas and star formation in M81. Astronomy & Astrophysics, 527, article no. A16.

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We present the first complete 12CO J = 3−2 map of M 81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect nine regions of significant CO emission located at different positions within the spiral arms, and confirm that the global CO emission in the galaxy is low. We combine these data with a new Hα map obtained using the Isaac Newton Telescope and archival H I, 24μm, and FUV images to uncover a correlation between the molecular gas and star forming regions in M 81. For the nine regions detected in CO J = 3−2, we combine our CO J = 3−2 data with existing CO J = 1−0 data to calculate line ratios. We find that the ratio J = (3−2)/(1−0) is in agreement with the range of typical values found in the literature (0.2−0.8). Making reasonable assumptions, this allows us to constrain the hydrogen density to the range (103 −104) cm-3. We also estimated the amount of hydrogen produced in photo-dissociation regions near the locations where CO J = 3−2 was detected.

Item Type: Journal Item
Copyright Holders: 2011 ESO
ISSN: 1432-0746
Extra Information: 10 pp.
Keywords: galaxies; star formation; Hii regions
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Space
Item ID: 28697
Depositing User: Astrid Peterkin
Date Deposited: 04 May 2011 15:27
Last Modified: 25 Feb 2018 17:08
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