Detalles de publicación

PP 010080

The JCMT Nearby Galaxies Legacy Survey VI: The distribution of gas and star formation in M81

J. R. Sánchez-Gallego, J. H. Knapen, J. S. Heiner, C. D. Wilson, B. E. Warren, R. J. Allen, M. Azimlu, P. Barmby, G. J. Bendo, S. Comerón, F. P. Israel, S. Serjeant, R. P. J. Tilanus, C. Vlahakis, P. van der Werf
IAC, ULL, others
We present a first complete 12 CO J=3-2 map of M81, observed as part of the Nearby Galaxies Legacy Survey being carried out at the James Clerk Maxwell Telescope. We detect 9 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 H-alpha map obtained using the Isaac Newton Telescope and archival HI, 24 microns and FUV images to uncover a correlation between the molecular gas and star forming regions in M81. 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 (10^3-10^4) cm^{-3}. We also estimated the amount of hydrogen produced in photo-dissociation regions near the locations where CO J=3-2 was detected.

 
Aceptado para publicación en A&A | Enviado el 2010-11-24 | Proyecto 3I2407