The mid-infrared extinction law in the darkest cores of the Pipe Nebula
- Author(s)
- J. Ascenso, C. J. Lada, J. Alves, C. G. Román-Zúñiga, M. Lombardi
- Abstract
Context. The properties of dust grains, in particular their size
distribution, are expected to differ from the interstellar medium to the
high-density regions within molecular clouds. Aims: We measure
the mid-infrared extinction law produced by dense material in molecular
cloud cores. Since the extinction at these wavelengths is caused by
dust, the extinction law in cores should depart from what is found in
low-density environments if the dust grains have different properties.
Methods: We used the unbiased LINES method to measure the slope
of the reddening vectors in color-color diagrams. We derived the
mid-infrared extinction law toward the dense cores B59 and FeSt 1-457 in
the Pipe Nebula over a range of visual extinction between 10 and 50 mag,
using a combination of Spitzer/IRAC and ESO NTT/VLT data.
Results: The mid-infrared extinction law in both cores departs
significantly from a power law between 3.6 and 8 μm, suggesting that
these cores contain dust with a considerable fraction of large dust
grains. We find no evidence of any dependence in the extinction law with
column density up to 50 mag of visual extinction in these cores, and no
evidence of any variation between our result and those for other clouds
at lower column densities reported elsewhere in the literature. This
suggests either that large grains are present even in low column density
regions or that the existing dust models need to be revised at
mid-infrared wavelengths. We find a small but significant difference in
the extinction law of the two cores, which we tentatively associate with
the onset of star formation in B59.
Based on observations made with ESO Telescopes at the La Silla Paranal
Observatory under program IDs 62.I-0866, 65.I-0083, 67.C-0514, and
069.C-0426.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Harvard-Smithsonian Center for Astrophysics, Universidad Nacional Autonoma de Mexico, European Southern Observatory (Germany), Università degli Studi di Milano-Bicocca
- Journal
- Astronomy & Astrophysics
- Volume
- 549
- No. of pages
- 8
- ISSN
- 0004-6361
- DOI
- https://doi.org/10.1051/0004-6361/201220658
- Publication date
- 01-2013
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103004 Astrophysics, 103003 Astronomy
- Keywords
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/8262fc01-0257-4158-a80f-3d30147657ef