Dust Properties of the Dark Cloud IC 5146
- Author(s)
- C. Kramer, B. Mookerjea, J. S. Richer, C. J. Lada, J. F. Alves
- Abstract
We present the results of a submillimeter dust continuum study of a
molecular ridge in IC 5146 carried out at 850 μm and 450 μm with
SCUBA on the James Clerk Maxell Telescope (JCMT). The mapped region is
˜14'×2.' 5 in size (˜2 pc×0.3 pc) and consists
of at least four dense cores which are likely to be prestellar in
nature. To study the physical properties of the ridge and its embedded
cores, we combined the dust emission data with dust extinction data
obtained by Lada et al. (1999) from the NIR colors of background giant
stars. The ridge shows dust extinctions above ˜10 mag, rising to
up to 40 mag in the cores.
A map of dust temperatures, constructed from the continuum flux ratios,
shows strong temperature gradients: we find temperatures of up to
˜25 K in the outskirts and between the cores, down to less than 10
K in the cores themselves. Several cores appear isothermal, while two
have inwardly decreasing temperatures profiles, which is expected if the
cores are externally heated. Taking into account the derived map of dust
temperature, the resulting map of H2 column densities shows a
strong contrast between the dilute interclump medium and the dense
cores. We used the extinction data to derive in addition a map of the
dust emissivity parametrized by
κ'=κ850/κV. Its average value
corresponds well with the canonical value of Mathis (1990). The
individual cores show significant differences, i.e. κ' varies
between 1×10-5 and ˜7×10-5. We
find an inverse correlation between κ' and Tdust which
we interpret as signature of grain coagulation and the formation of ice
mantles, in accordance with models of dust evolution in dense prestellar
cores (Ossenkopf & Henning 1994, OH94) and the previous detection of
gas-phase depletion of CO (Kramer et al. 1999).
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Harvard-Smithsonian Center for Astrophysics, Universität zu Köln, University of Cambridge
- Volume
- 287
- Pages
- 25-30
- Publication date
- 2003
- Austrian Fields of Science 2012
- 103004 Astrophysics
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/dust-properties-of-the-dark-cloud-ic-5146(e8b21dec-bd56-448e-b22f-fcdf6b9b7e12).html