EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 404/1 Article
Free access article

Issue A&A
Volume 404, Number 1, June II 2003
Page(s) L11 - L15
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20030575



A&A 404, L11-L15 (2003)
DOI: 10.1051/0004-6361:20030575

Letter

Inverse temperature dependence of the dust submillimeter spectral index

X. Dupac1, 2, J.-P. Bernard1, N. Boudet1, M. Giard1, J.-M. Lamarre3, C. Mény1, F. Pajot4, I. Ristorcelli1, G. Serra1, B. Stepnik4, 1 and J.-P. Torre5

1  Centre d'Étude Spatiale des Rayonnements, 9 Av. du Colonel Roche, BP 4346, 31028 Toulouse Cedex 4, France
2  European Space Agency - ESTEC, Astrophysics Division, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
3  LERMA, Observatoire de Paris, 61 Av. de l'Observatoire, 75014 Paris, France
4  Institut d'Astrophysique Spatiale, Campus d'Orsay, Bât. 121, 15 rue Clémenceau, 91405 Orsay Cedex, France
5  Service d'Aéronomie du CNRS, BP 3, 91371 Verrières-le-Buisson Cedex, France

(Received 18 March 2003 / Accepted 16 April 2003)

Abstract
We present a compilation of PRONAOS-based results concerning the temperature dependence of the dust submillimeter spectral index, including data from Galactic cirrus, star-forming regions, dust associated to a young stellar object, and a spiral galaxy. We observe large variations of the spectral index (from 0.8 to 2.4) in a wide range of temperatures (11 to 80 K). These spectral index variations follow a hyperbolic-shaped function of the temperature, high spectral indices (1.6-2.4) being observed in cold regions (11-20 K) while low indices (0.8-1.6) are observed in warm regions (35-80 K). Three distinct effects may play a role in this temperature dependence: one is that the grain sizes change in dense environments, another is that the chemical composition of the grains is not the same in different environments, a third one is that there is an intrinsic dependence of the dust spectral index on the temperature due to quantum processes. This last effect is backed up by laboratory measurements and could be the dominant one.


Key words: dust, extinction -- infrared: ISM: continuum -- ISM: clouds

Offprint request: X. Dupac, xdupac@rssd.esa.int

SIMBAD Objects



© ESO 2003


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.