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Table 1

Observed values of the power-law exponent β (Col. 4) in different phases of the ISM (from diffuse HI gas to GMCs).

Region Distance Tracer β Peak 1 Peak 2 Reference
[pc] [pc] [pc]

Diffuse HI HI 2.6–2.8 Green et al. (1993)
North Polar Spur HI 3.6 Miville-Deschenes (2003)

Diffuse Clouds
Polaris Flare 150 13CO 1 → 0 2.77 Stutzki et al. (1998)
Polaris Flare 13CO 2 → 1 2.76 Falgarone et al. (1998), Stutzki et al. (1998)

low-mass SF cloud

Perseus 300 13CO 1 → 0 3.07 2.7 (>10) Bensch et al. (2001)
Perseus 13CO 1 → 0 3.09 Sun et al. (2006)
Perseus 13CO 2 → 1 3.03 Sun et al. (2006)
Perseus 12CO 1 → 0 3.08 Sun et al. (2006)
Perseus 12CO 3 → 2 3.15 Sun et al. (2006)
Perseus extinction 2.55 Sun et al. (2006)
Perseus extinction 2.16 2.5 (>10)
Taurus 140 extinction 2.20 0.5 3.5
Chameleon 160 extinction 2.25 0.4 4.6
Pipe Nebula 140 extinction 2.36 1.5 3.8
IC 5146 400 extinction 2.37 (1.4) (>4.5)
Lupus 100 extinction 2.49 (1.5) (>10)
Coalsack 150 extinction 2.57
Corona Australis 170 extinction 2.65 2.9

GMC

W3 2200 extinction 2.07 11
Cygnus 1700 13CO 1 → 0 2.47 4 40 this study
Cygnus extinction 2.42
Orion A 450 13CO 1 → 0 2.54 6 Bensch et al. (2001)
Orion A extinction 2.49
Orion B 450 13CO 1 → 0 2.68 6 Bensch et al. (2001)
Orion B extinction 2.40  >13
Orion A+B extinction 2.49 17
Mon R2 800 13CO 1 → 0 2.76 2.75  >11 Bensch et al. (2001)
Mon R2 extinction 2.26 3.9  >20
Mon OB1 800 extinction 2.55 (4)  >10
Rosette 1600 13CO 1 → 0 2.66  >7.5 Heyer et al. (2006)
Rosette extinction 2.55
NGC 2264 800 13CO 1 → 0 2.54 6.7 Bensch et al. (2001)
NGC 2264 extinction 2.45
Vela 700 extinction 3.12  >7

Notes. Values for β obtained from our extinction maps are indicated in bold. Columns 5 and 6 indicate the size scale in parsec where spectra show peak values. Values in parenthesis are less reliable, the spectrum shows no prominent peak there. Values given only for peak 2 indicate that there is only one prominent peak. Note that for Orion we determined β individually for the subregions Orion A and B (for direct comparison with the 13CO data) and for the whole complex, which is also shown in Fig. 4.

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