Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-08T02:47:17.160Z Has data issue: false hasContentIssue false
  • English
  • Français

Molecular Clouds in M51 and in the Galaxy

Published online by Cambridge University Press:  30 March 2016

Per Friberg  and
Åke Hjalmarson
Per Friberg
Affiliation:
Onsala Space ObservatoryS-43900 ONSALASWEDEN
Åke Hjalmarson
Affiliation:
Onsala Space ObservatoryS-43900 ONSALASWEDEN

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Studies of molecular clouds in nearby galaxies require high angular resolution. Ten arcseconds corresponds to 0.5 kpc at the distance of M51. Typical gigant molecular clouds (GMC:s) have a size of 5-30 pc (Solomon et al. 1985). However complexes of GMC: s (Superclouds) can be several hundred parsecs (Elmegreen 1985; Rivolo et al. 1985). The higest angular resolution achived in CO(J=1-0) line observations of external galaxies is 7” (Lo et al 1984,1985). The resolution problem can be eased by observing M31 with a distance of only ⋍ 690 kpc (10” corresponds to 34 pc), which has been done by Combes et al. 1977a,b; Boulanger et al. 1984; Ryden and Stark 1985; Stark 1985; Blitz 1985; Ichikawa et al. 1985. In M31 the CO emission is strongly concetrated to the spiral arms with a arm interarm ratio of ≥ 25 (Ryden and Stark 1985; Stark 1985). The emission is caused by many small clouds unresolved with present resolution together with some larger clouds. Streaming is observed to occur across the arms. Extragalatic studies have the advantage of being more easy to interpret in terms of arm interarm contrast, noncircular motion, and galatic structure. They also make possible studies of the mass fraction of gas as a function of radius in different morphological types of galxies. Answers to questions like “Do any relation exist between galaxy type and molecular abundance?” are very important for our understanding of galatic evolution.

Type
Joint Discussions
Information
Highlights of Astronomy , Volume 7: Highlights of Astronomy. As presented at the XIXth General Assembly of the IAU, 1985 , 1986 , pp. 513 - 518
Copyright
Copyright © Reidel 1986

References

Andersson, M. 1985, in Proc. ESO-IRAM-ONSALA Workshop on (Sub)Millimeter Astronomy, eds. Shaver, P.A., and Kjär, K., ESO Conference and Workshop Proc. 22, p.353.Google Scholar
Blitz, L. 1985, Astrophys.J., 296, 481.Google Scholar
Boulanger, F., Bystedt, J., Casoli, F., and Combes, F. 1984, Astron. Astrophys.(Letters), 140, L5.Google Scholar
Burton, W.B., Gordon, M.A., Bania, T.M., and Lockman, F.G. 1975, Astrophys.J., 202, 30.Google Scholar
Cohen, R.S., and Thaddeus, P. 1977, Astrophys.J.(Letters). 217, L155.Google Scholar
Cohen, R.S., Cong, H., Dame, T.M., and Taddeus, P. 1980, Astropys.J.(Letters), 239, L53.Google Scholar
Combes, F., Encrenaz, P.J., Lucas, R., and Weliachew, L 1977a, Astron. Astrophys. 55, 311.Google Scholar
Combes, F., Encrenaz, P.J., Lucas, R., and Weliachew, L 1977b, Astron. Astrophys. (Letters), 61, L7.Google Scholar
Dame, T.M 1984, Ph.D. thesis Columbia University Google Scholar
Elmegreen, B.G. 1985, in Birth and Infancy of Stars, Lectures delivered at Les Houches summer school, eds. Omomt, A., and Lucas, R., (Amsterdam North-Holland)Google Scholar
Evans II, N.J., Plambeck, R.L., and Davis, J.H. 1979, Astrophys.J.(Letters), 227, L25.Google Scholar
Friberg, P. 1986, in preparation Goad, J.W., De Vency, J.B., and Goad, L.E. 1979, Astron. Astrophys. Suppl., 39, 439.Google Scholar
Goldsmith, P.F., Langer, W.E., and Wilson, R.W. 1985, preprintGoogle Scholar
Gordon, M.A., and Burton, W.B. 1976, Astrophys.J., 208, 346.Google Scholar
Harris, A., Townes, C.M., Matsakis, P.N., and Palmer, P. 1983, Astrophys. J.(Letters), 265, L63.Google Scholar
Ichikawa, T., Nakano, M., Tanaka, Y.D., Saito, M., Nakai, N., Sofue, Y., and Eaifu, N. 1985, Publ. Astron. Soc. Japan, 37, 439.Google Scholar
Jacq, T., Baudry, A., and Despois, D. 1985 in Proc. ESO-IRAM-ONSALA Workshop on (Sub)Millimeter Astronomy, eds. Shaver, P.A., and Kjär, K., ESO Conference and Workshop Proc. 22, p.251.Google Scholar
Johansson, L.E.B., and Booth, R.S. 1986, in preparationGoogle Scholar
Knapp, G.R., Stark, A.A., and Wilson, R.W. 1985, Astron.J., 90, 254.Google Scholar
Lo, E.Y., Berge, G., Claussen, M., Heiligman, G., Eeene, J., Masson, C., Phillips, T., Sargent, A., Scoville, N., Scott, S., Watson, D., and Woody, D. 1985, in Proc. URSI International Symposia on Millimeter and Submillimeter Wave Astronomy (Granada), p. 219.Google Scholar
Lo, K.Y., Berge, G., Claussen, M., Heiligman, G., Leighton, R.B., Masson, C., Moffet, A.T., Phillips, T., Sargent, A., Scott, S., Wannier, P.G., and Woody, D. 1984, Astrophys.J.(Letters), 282, L59.Google Scholar
May, J., Alvarez, H., Garay, G., Murphy, D., Cohen, R.S., and Thaddeus, P., 1985, in Proc. ESO-IRAM-ONSALA Workshop on (Sub)Millimeter Astronomy, eds. Shaver, P.A., and Kjär, K., ESO Conference and Workshop Proc. 22, p.245.Google Scholar
Murphy, D.C., Myers, P.C. 1985, Astrophys.J., 298, 818.Google Scholar
Rivolo, A.R., Solomon, P.M., and Sanders, D.B. 1986, in pressGoogle Scholar
Rydbeck, G., Hjalmarson, A., and Rydfaeck, O.E.H. 1985, Astron. Astrophys. 144, 282.Google Scholar
Ryden, B.S., and Stark, A.A. 1985, preprintGoogle Scholar
Sanders, D.B., Solomon, P.M., and Scoville, N.Z. 1984, Astrophys.J., 276, 182.Google Scholar
Scoville, N.Z., and Solomon, P.M. 1975, Astrophys.J. (Letters), 199, L105.Google Scholar
Scoville, N.Z., Sofier, B.T., Heugebauer, G., Young, J.S., Mathews, K., and Yerka, J. 1985, Astrophys.J., 289, 129.Google Scholar
Snell, R.L., Langer, W.D., and Frerking, A.M. 1982, Astrophys.J., 255, 149.Google Scholar
Solomon, P.M., Sanders, D.B., and Rivolo, A.R., 1985, Astrophys.J.(Letters), 219, L24.Google Scholar
Stark, A.A. 1979, Ph.D. thesis Prinston University Google Scholar
Stark, A.A. 1985, in The Milky Way Galaxy, IAU Symposia No. 106, ed. Woerden, H. van et al. (Dordrecht, Holland: D. Reidel Publishing Co.) p. 455.Google Scholar
Ungerechts, H., Walmsley, C.M., and Winnewisser, G. 1980, Astron. Astrophys., 88, 259.Google Scholar
Wilson, T.L., Walmsley, C.M., Henkel, C., Pauls, T., and Mattes, H. 1980, Astron. Astrophys., 91, 36.Google Scholar
Wilson, T.L. 1985, in Proc. ESO-IRAM-ONSALA Workshop on (Sub)Millimeter Astronomy, eds. Shaver, P.A., and Kjär, K., ESO Conference and Workshop Proc. 22, p.401. c.f. also Comments Astrophys., 11, 83.Google Scholar