A large-scale extinction map of the Galactic Anticentre from 2MASS

D. Froebrich, G. C. Murphy, M. D. Smith, J. Walsh, C Del Burgo

Research output: Contribution to journalJournal articleResearchpeer-review


We present a 127 × 63-deg2 extinction map of the Anticentre of the Galaxy, based on 〈J−H〉 and 〈H−K〉 colour excess maps from the Two-Micron All-Sky Survey. This 8001-deg2 map with a resolution of 4 arcmin is provided as online material. The colour excess ratio 〈J−H〉/〈H−K〉 is used to determine the power-law index of the reddening law (β) for individual regions contained in the area (e.g. Orion, Perseus, Taurus, Auriga, Monoceros, Camelopardalis, Cassiopeia). On average we find a dominant value of β= 1.8 ± 0.2 for the individual clouds, in agreement with the canonical value for the interstellar medium. We also show that there is an internal scatter of β values in these regions, and that in some areas more than one dominant β values are present. This indicates large-scale variations in the dust properties. The analysis of the AV values within individual regions shows a change in the slope of the column density distribution with distance. This can be attributed either to a change in the governing physical processes in molecular clouds on spatial scales of about 1 pc or to an AV dilution with distance in our map.
Original languageEnglish
JournalRoyal Astronomical Society. Monthly Notices
Issue number4
Pages (from-to)1447-1460
Publication statusPublished - 2007
Externally publishedYes


  • ISM: clouds
  • Dust, extinction
  • Galaxy: structure
  • Infrared: ISM

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