In:
The Astrophysical Journal, American Astronomical Society, Vol. 878, No. 2 ( 2019-06-20), p. 131-
Abstract:
Gas and dust properties in the Chamaeleon molecular cloud complex have been investigated with emission lines from the atomic hydrogen (H i ) and 12 CO molecules, dust optical depth at 353 GHz ( τ 353 ), and J -band infrared extinction ( A J ). We have found a scatter correlation between the H i integrated intensity ( W H i ) and τ 353 in the Chamaeleon region. The scattering has been examined in terms of a possible large optical depth in H i emission ( τ H i ) using a total column density ( N H ) model based on τ 353 . A nonlinear relation of τ 353 with the ∼1.2 power of A J has been found in opaque regions ( A J ≳ 0.3 mag), which may indicate a dust evolution effect. If we apply this nonlinear relation to the N H model (i.e., N H ∝ τ 353 1 / 1.2 ) allowing arbitrary τ H i , the model curve reproduces well the W H i – τ 353 scatter correlation, suggesting optically thick H i ( τ H i ∼ 1.3) extended around the molecular clouds. Based on the correlations between the CO integrated intensity and the N H model, we have derived the CO-to-H 2 conversion factor ( X CO ) on ∼1.°5 scales (corresponding to ∼4 pc) and found spatial variations of X CO ∼ (0.5–3) × 10 20 cm −2 K −1 km −1 s across the cloud complex, possibly depending on the radiation field inside or surrounding the molecular clouds. These gas properties found in the Chamaeleon region are discussed through a comparison with other local molecular cloud complexes.
Type of Medium:
Online Resource
ISSN:
0004-637X
,
1538-4357
DOI:
10.3847/1538-4357/ab2051
Language:
Unknown
Publisher:
American Astronomical Society
Publication Date:
2019
detail.hit.zdb_id:
2207648-7
detail.hit.zdb_id:
1473835-1
SSG:
16,12
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