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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 710217.0, MPI für Astronomie / Publikationen_mpia
A common column density threshold for scattering at 3.6 mm and water-ice in molecular clouds
Authors:Andersen, M.; Thi, W. -. F.; Steinacker, J.; Tothill, N.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:Astronomy and Astrophysics
Start Page:id. L3 (5 pp)
Audience:Not Specified
Abstract / Description:Context. Observations of scattered light in the 1-5 mum range have revealed dust grains in molecular cores with sizes larger than commonly inferred for the diffuse interstellar medium. It is currently unclear whether these grains are grown within the molecular cores or are an ubiquitous component of the interstellar medium. <BR /> Aims: We investigate whether the large grains necessary for efficient scattering at 1-5 mum are associated with the abundance of water-ice within molecular clouds and cores. <BR /> Methods: We combined water-ice abundance measurements for sight lines through the Lupus IV molecular cloud complex with measurements of the scattered light at 3.6 mum for the same sight lines. <BR /> Results: We find that there is a similar threshold for the cores in emission in scattered light at 3.6 mum (tau9.7 = 0.15 ± 0.05, AK = 0.4 ± 0.2) as water-ice (tau9.7 = 0.11 ± 0.01, AK = 0.19 ± 0.04) and that the scattering efficiency increases as the relative water-ice abundance increases. The ice layer increases the average grain size, which again strongly increases the albedo. <BR /> Conclusions: The higher scattering efficiency is partly due to layering of ice on the dust grains. Although the layer can be relatively thin, it can enhance the scattering substantially. Table 1 is available in electronic form at <A href=""></A>
Free Keywords:dust; extinction; ISM: clouds; stars: formation; scattering; ISM: lines and bands
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 %R 10.1051/0004-6361/201424011
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