ISOCAM observations of NGC 6946: Mid-IR structure

S. Malhotra, G. Helou, D. Van Buren, M. Kong, C. A. Beichman, H. Dinerstein, D. J. Hollenbach, D. A. Hunter, K. Y. Lo, S. D. Lord, N. Y. Lu, R. H. Rubin, G. J. Stacey, H. A. Thronson, M. W. Werner

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The nearby spiral galaxy NGC 6946 was observed with ISO-CAM in the mid-infrared, achieving 7z″resolution and sub-MJy sr-1 sensitivity. Images taken with CAM filters LW2 (7/μm) and LW3 (15μm) are analysed to determine the morphology of this galaxy and understand better the emission mechanisms. The mid-infrared emission follows an exponential disk with a scale length 15″. This is 60 % of the scale length in the optical R-band and radio continuum. The nuclear starburst region is too bright for reliable measurement in these images. Its surface brightness exceeds the inner disk by at least a factor of 12. The arms and interarm regions are clearly detected, with each of these components contributing about equally to the disk emission. The arm-interarm contrast is 2-4 in the mid-IR, close to that measured in the visible R band light and lower than the contrast in H α, suggesting that non-ionizing radiation contributes significantly to dust heating.

Original languageEnglish (US)
Pages (from-to)L161-L164
JournalAstronomy and Astrophysics
Issue number2
StatePublished - Nov 10 1996


  • Galaxies: ISM
  • Galaxies: spiral
  • Galaxies: structure
  • Infrared: ISM: continuum
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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