Open AccessThe near‐infrared extinction law in regions of high A V
Author(s) -
Moore T. J. T.,
Lumsden S. L.,
Ridge N. A.,
Puxley P. J.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08923.x
Subject(s) - extinction (optical mineralogy) , physics , astrophysics , flattening , interstellar medium , limit (mathematics) , law , astronomy , galaxy , optics , mathematical analysis , mathematics , political science
We present a spectroscopic study of the shape of the dust‐extinction law between 1.0 and 2.2 μm towards a set of nine ultracompact H ii regions with A V ≳ 15 mag . We find some evidence that the reddening curve may tend to flatten at higher extinctions, but just over half of the sample has extinction consistent with or close to the average for the interstellar medium (ISM). There is no evidence of extinction curves significantly steeper than the standard law, even where water ice is present. Comparing the results to the predictions of a simple extinction model, we suggest that a standard extinction law implies a robust upper limit to the grain‐size distribution at around 0.1–0.3 μm. Flatter curves are most likely the result of changes in this upper limit, although the effects of flattening as a result of unresolved clumpy extinction cannot be ruled out.