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Far-infrared dust opacity and visible extinction in the Polaris Flare

Cambrésy, L. and Boulanger, F. and Lagache, G. and Stepnik, B. (2001) Far-infrared dust opacity and visible extinction in the Polaris Flare. Astronomy and Astrophysics, 375 (3). pp. 999-1007. ISSN 0004-6361. doi:10.1051/0004-6361:20010930.

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We present an extinction map of the Polaris molecular cirrus cloud derived from star counts and compare it with the Schlegel et al. ([CITE]) extinction map derived from the far-infrared dust opacity. We find that, within the Polaris cloud, the Schlegel et al. ([CITE]) AV values are a factor 2 to 3 higher than the star count values. We propose that this discrepancy results from a difference in τ_(FIR)/A_V between the diffuse atomic medium and the Polaris cloud. We use the difference in spectral energy distribution, warm for the diffuse atomic medium, cold for the Polaris cloud, to separate their respective contribution to the line of sight integrated infrared emission and find that the τ_(FIR)/A_V of cold dust in Polaris is on average 4 times higher than the Schlegel et al. ([CITE]) value for dust in atomic cirrus. This change in dust property could be interpreted by a growth of fluffy particles within low opacity molecular cirrus clouds such as Polaris. Our work suggests that variations in dust emissivity must be taken into account to estimate AV from dust emission wherever cold infrared emission is present (i.e. molecular clouds).

Item Type:Article
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URLURL TypeDescription Paper
Additional Information:© 2001 ESO. Article published by EDP Sciences. Received 16 June 2000; Accepted 12 June 2001; Published online 15 September 2001. L. Cambrésy acknowledges partial support from the Lavoisier grant of the French Ministry of Foreign Affairs.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Ministère de l'Europe et des AffairesUNSPECIFIED
Subject Keywords:ISM: clouds - ISM: dust, extinction - ISM: individual object: Polaris Flare - infrared: ISM: continuum
Issue or Number:3
Record Number:CaltechAUTHORS:20180227-161339798
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Official Citation:Far-infrared dust opacity and visible extinction in the Polaris Flare. L. Cambrésy, F. Boulanger, G. Lagache and B. Stepnik A&A, 375 3 (2001) 999-1007. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84979
Deposited By: Tony Diaz
Deposited On:28 Feb 2018 01:12
Last Modified:15 Nov 2021 20:24

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