A common column density threshold for scattering at 3.6 μ m and water-ice in molecular clouds

M. Andersen, W.-F. Thi, J. Steinacker, N. Tothill

    Research output: Contribution to journalArticlepeer-review

    10 Citations (Scopus)

    Abstract

    Context. Observations of scattered light in the 1-5 μm 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. Aims. We investigate whether the large grains necessary for efficient scattering at 1-5 μm are associated with the abundance of water-ice within molecular clouds and cores. 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 μm for the same sight lines. Results. We find that there is a similar threshold for the cores in emission in scattered light at 3.6 μm (τ9.7 = 0.15 ± 0.05, AK = 0.4 ± 0.2) as water-ice (τ9.7 = 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. 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.
    Original languageEnglish
    Number of pages5
    JournalAstronomy and Astrophysics
    Volume568
    Issue numberL3
    DOIs
    Publication statusPublished - 2014

    Fingerprint

    Dive into the research topics of 'A common column density threshold for scattering at 3.6 μ m and water-ice in molecular clouds'. Together they form a unique fingerprint.

    Cite this