Dust extinction in a small molecular cloud

被引:13
|
作者
Strafella, F [1 ]
Campeggio, L
Aiello, S
Cecchi-Pestellini, C
Pezzuto, S
机构
[1] Univ Lecce, Dipartimento Fis, I-73100 Lecce, Italy
[2] Univ Florence, Dipartimento Astron & Sci Spazio, I-50121 Florence, Italy
[3] CNR, IFSI, I-00133 Rome, Italy
来源
ASTROPHYSICAL JOURNAL | 2001年 / 558卷 / 02期
关键词
dust; extinction; ISM : clouds; ISM : globules; ISM : structure;
D O I
10.1086/322303
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The distribution of matter in a small dark cloud has been investigated observationally by using the extinction of the stellar light that is due to the dust component as a tracer. Here we present the results of a photometric study that has been carried out in the optical spectral region by means of imaging in the B, V, and I bands. The relevant information on the spatial distribution of the dust has been obtained both by counting stars and by measuring their color excesses. While star counts on a reseau grid are easily interpreted as a measurement of the average extinction A(lambda) under the assumption of a locally uniform stellar luminosity function, the color excesses averaged on the same grid are obtained by a comparison of the stellar color distributions among the reddened regions and a reference position. Color excesses have also been derived by comparing the observed stellar colors with the locus of the unreddened stars in the two-color (V-I) versus (B-V) diagram. The extinction map obtained for the globule CB 107 shows that the dust distribution at the boundary of this dark cloud can be measured and compared with models of matter distribution in these objects. By considering a density law such as n proportional to (1+(r/a)(alpha))(-beta), we find that our observations favor models with alpha =2 and beta =1. Indications are also obtained about the spatial variation in this object of the total to selective extinction R-V. In this respect we find that R-V tends to increase toward the innermost regions of CB 107, and this suggests that the mean size of the dust particles also increases. The implications of these observations on the modeling of molecular cloud boundaries are discussed, and some indications on the timescale of the physical processes responsible for their structure are derived. The penetration depth of the interstellar radiation field in these objects is also briefly discussed in the light of its possible consequences on the cloud chemistry. Lastly, the differences that we found in the color excess maps, which were obtained by means of the stellar counts and the cumulative distribution in color, respectively, suggest a clumpy distribution of matter in CB 107.
引用
收藏
页码:717 / 729
页数:13
相关论文
共 50 条
  • [1] Probing the dust responsible for Small Magellanic Cloud extinction
    Sofia, UJ
    Gordon, KD
    Clayton, GC
    Misselt, K
    Wolff, MJ
    Cox, NLJ
    Ehrenfreund, P
    ASTROPHYSICAL JOURNAL, 2006, 636 (02): : 753 - 764
  • [2] Dust in the small magellanic cloud: Interstellar polarization and extinction
    Rodrigues, CV
    Magalhaes, AM
    Coyne, GV
    Piirola, V
    ASTROPHYSICAL JOURNAL, 1997, 485 (02): : 618 - 637
  • [3] Starburst-like dust extinction in the Small Magellanic Cloud
    Gordon, KD
    Clayton, GC
    ASTROPHYSICAL JOURNAL, 1998, 500 (02): : 816 - 824
  • [4] Dust extinction and molecular cloud structure: L977
    Alves, J
    Lada, CJ
    Lada, EA
    Kenyon, SJ
    Phelps, R
    ASTROPHYSICAL JOURNAL, 1998, 506 (01): : 292 - 305
  • [5] DUST EXTINCTION AND MOLECULAR GAS IN THE DARK CLOUD IC 5146
    LADA, CJ
    LADA, EA
    CLEMENS, DP
    BALLY, J
    ASTROPHYSICAL JOURNAL, 1994, 429 (02): : 694 - 709
  • [6] Ultraviolet extinction toward a quiescent molecular cloud in the Small Magellanic Cloud
    Maiz Apellaniz, J.
    Rubio, M.
    ASTRONOMY & ASTROPHYSICS, 2012, 541
  • [7] Three-dimensional Structure and Dust Extinction in the Small Magellanic Cloud
    Yanchulova Merica-Jones, Petia
    Sandstrom, Karin M.
    Johnson, L. Clifton
    Dolphin, Andrew E.
    Dalcanton, Julianne J.
    Gordon, Karl
    Roman-Duval, Julia
    Weisz, Daniel R.
    Williams, Benjamin F.
    ASTROPHYSICAL JOURNAL, 2021, 907 (01):
  • [8] Dust grain-size distributions and extinction in the Milky Way, large magellanic cloud, and small magellanic cloud
    Weingartner, JC
    Draine, BT
    ASTROPHYSICAL JOURNAL, 2001, 548 (01): : 296 - 309
  • [10] The Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE): The Dust Extinction Curve from Red Clump Stars
    Merica-Jones, Petia Yanchulova
    Sandstrom, Karin M.
    Johnson, L. Clifton
    Dalcanton, Julianne
    Dolphin, Andrew E.
    Gordon, Karl
    Roman-Duval, Julia
    Weisz, Daniel R.
    Williams, Benjamin F.
    ASTROPHYSICAL JOURNAL, 2017, 847 (02):