Astron. Astrophys. 353, L13-L17 (2000)

Letter to the Editor

SCUBA observations of NGC 6946 ^*

S. Bianchi ^1,2, J.I. Davies ¹, P.B. Alton ¹, M. Gerin ³ and F. Casoli <sup>4

1</sup> Cardiff University, Department of Physics and Astronomy, P.O. Box 913, Cardiff CF2 3YB, Wales, UK
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Radioastronomie millimétrique, ENS, 24 Rue Lhomond and UMR 8540 du CNRS, 75231 Paris Cedex 05, France
⁴ DEMIRM, Observatoire de Paris, 61 Av. de l'Observatoire and UMR 8540 du CNRS, 75014 Paris, France

Received 4 October 1999 / Accepted 1 December 1999

Abstract

We present sub-millimetre images of the spiral galaxy NGC 6946 at 450 and 850 µm. The observations have been carried out using the scan/map imaging mode of the Sub-millimetre Common User Bolometer Array (SCUBA) at the James Clark Maxwell Telescope (JCMT). The comparison with a ¹²CO(2-1) line emission map from IRAM and with an U-band image, clearly shows that the 850 µm emission is associated with molecular gas and bright star-forming regions, tracing the spiral arms. We place an upper limit of 0.7 for the V-band optical depth of dust associated with a diffuse atomic component.

Key words: ISM: dust, extinction galaxies: individual: NGC 6946 galaxies: spiral galaxies: star clusters galaxies: structure

* Based on observations at the James Clerk Maxwell Telescope. JCMT is operated by The Joint Astronomy Centre on behalf of the Particle Physics and Astronomy Research Council of the United Kingdom, the Netherlands Organisation for Scientific Research, and the National Research Council of Canada.

Send offprint requests to: bianchi@mpia-hd.mpg.de

© European Southern Observatory (ESO) 2000

Online publication: December 17, 1999

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