Measurements of the CO-to-H 2 Conversion Factor and Dust-to-Gas ...
Measurements of the CO-to-H 2 Conversion Factor and Dust-to-Gas ...
Measurements of the CO-to-H 2 Conversion Factor and Dust-to-Gas ...
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Measuring <strong>the</strong> <strong>CO</strong>-<strong>to</strong>-H2 <strong>Conversion</strong> Fac<strong>to</strong>r.<br />
ΣH2 = α<strong>CO</strong> I<strong>CO</strong><br />
α<strong>CO</strong> = 4.35 M⊙ pc -2 (K km s -1 ) -1<br />
X<strong>CO</strong> = 2×10 20 cm -2 (K km s -1 ) -1<br />
note: α<strong>CO</strong> defined here for<br />
unresolved clouds, includes He<br />
To measure α<strong>CO</strong>:<br />
1. observe <strong>CO</strong><br />
2. use ano<strong>the</strong>r tracer <strong>to</strong> get<br />
<strong>to</strong>tal amount <strong>of</strong> molecular gas<br />
3. compare with observed <strong>CO</strong><br />
O<strong>the</strong>r ways <strong>to</strong> trace <strong>the</strong> <strong>to</strong>tal amount <strong>of</strong> molecular gas:<br />
Dynamics<br />
(i.e. virial masses)<br />
γ-rays<br />
Modeling Line<br />
Emission<br />
<strong>Dust</strong>
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