2009A&A...508L..35K


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.08CET01:58:10

2009A&A...508L..35K - Astronomy and Astrophysics, volume 508, L35-38 (2009/12-4)

Probing the evolution of molecular cloud structure. From quiescence to birth.

KAINULAINEN J., BEUTHER H., HENNING T. and PLUME R.

Abstract (from CDS):

Probability distribution of densities is a fundamental measure of molecular cloud structure, containing information on how the material arranges itself in molecular clouds. We derive the probability density functions (PDFs) of column density for a complete sample of prominent molecular cloud complexes closer than d ≲200pc. For comparison, additional complexes at d≃250-700pc are included in the study. We derive near-infrared dust extinction maps for 23 molecular cloud complexes, using the nicest colour excess mapping technique and data from the 2MASS archive. The extinction maps are then used to examine the column density PDFs in the clouds. The column density PDFs of most molecular clouds are well-fitted by log-normal functions at low column densities (0.5mag<AV≲3-5mag, or -0.5<logAV/<A>V≲1). But at higher column densities prominent power-law-like wings are common. In particular, we identify a trend among the PDFs: active star-forming clouds always have prominent non-log-normal wings. In contrast, clouds without active star formation resemble log-normals over the whole observed column density range or show only low excess of higher column densities. This trend is also reflected in the cumulative forms of the PDFs, showing that the fraction of high column density material is significantly larger in star-forming clouds. These observations agree with an evolutionary trend where turbulent motions are the main cloud-shaping mechanism for quiescent clouds, but the density enhancements induced by them quickly become dominated by gravity (and other mechanisms), which is in turn strongly reflected by the shape of the column density PDFs. The dominant role of the turbulence is restricted to the very early stages of molecular cloud evolution, comparable to the onset of active star formation in the clouds.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: structure - stars: formation - dust, extinction - evolution

Simbad objects: 25

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Number of rows : 25

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 LDN 1333 DNe 02 26 04 +75 28.5           ~ 53 0
2 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1122 0
3 NGC 1499 HII 04 03 18 +36 25.3           ~ 156 0
4 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3650 0
5 NAME Ori A MoC 05 38 -07.1           ~ 2744 0
6 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1011 1
7 NAME Musca Cld 12 23 -71.3           ~ 167 0
8 NAME Coalsack Nebula DNe 12 31 19 -63 44.6           ~ 246 0
9 IRAS 12340-7958 * 12 37 39.7466355997 -80 15 13.713429632   16.11 14.39 13.63 9.81 ~ 101 0
10 NAME Cha III MoC 12 37.8 -80 15           ~ 131 2
11 NAME Cha II MoC 12 54 -77.2           ~ 304 0
12 NAME Lupus I Cld 15 43 02.1 -34 09 06           ~ 236 0
13 LDN 134 MoC 15 53 36.3 -04 35 26           ~ 195 0
14 NAME Lupus III SFR 16 09.6 -39 03           ~ 283 0
15 LDN 1719 DNe 16 19.9 -20 07           ~ 22 0
16 NAME Lupus V MoC 16 21 -37.5           ~ 57 0
17 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3138 1
18 LDN 204 DNe 16 47 47.3 -12 05 16           ~ 51 0
19 NAME the Pipe Nebula DNe 17 30 -25.0           ~ 351 1
20 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 962 2
21 NAME CrA Dark Cloud MoC 19 01 51 -36 58.9           ~ 412 0
22 IRAS 20582+7724 Y*O 20 57 12.9187221407 +77 35 43.655738044           ~ 113 0
23 LDN 1228 DNe 20 57 13 +77 35.8           ~ 122 0
24 NAME Cepheus A SFR 22 56 17.9 +62 01 49           ~ 704 2
25 NAME Ori B GMC MoC ~ ~           ~ 14 0

    Equat.    Gal    SGal    Ecl

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2021.03.08-01:58:10

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