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Astron. Astrophys. 347, L5-L8 (1999)

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Letter to the Editor

CO(4-3) and CO(3-2) studies of M 51 and NGC 6946

Ch. Nieten 1, M. Dumke 1,2, R. Beck 1 and R. Wielebinski 1

1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
2 Institut de Radioastronomie Millimétrique, 300, rue de la Piscine, F-38406 St. Martin d'Hères, France

Received 26 March 1999 / Accepted 7 June 1999


We have mapped several nearby galaxies in the CO(4-3) line transition with the Heinrich-Hertz-Telescope on Mt. Graham, Arizona, during an excellent weather period in December 1998. Here we report on our observations of M 51 and NGC 6946. The results suggest a concentration of highly excited CO gas to the nuclei of these galaxies. Moreover, in both objects CO(4-3) line emission was also detected for the first time in the spiral arms, several kiloparsecs away from the centre.

Key words: galaxies: individual: M 51 – galaxies: individual: NGC 6946 – galaxies: ISM – galaxies: spiral – radio lines: galaxies

Send offprint requests to: Ch. Nieten (chnieten@mpifr-bonn.mpg.de)

© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999