| |
 |
| Paper: |
Simultaneous Determination of the Cosmic Ray Ionization Rate and
Fractional Ionization in DR21(OH) |
| Volume: |
449, Astronomical Polarimetry 2008: Science from Small to Large Telescopes |
| Page: |
225 |
| Authors: |
Hezareh, T.; Houde, M.; Vastel, C.; Peng, R. |
| Abstract: |
We present a new method for the simultaneous calculation of the cosmic
ray ionization rate, ζH2}, and the ionization
fraction, χe, in dense molecular clouds. A simple
network of chemical reactions dominant in the creation and destruction
of HCNH+ and HCO+ is used in conjunction with observed pairs
of rotational transitions of several molecular species in order to
determine the electron and H3+ abundances.
The cosmic ray ionization rate is then calculated by taking advantage
of the fact that, in dark clouds, it governs the rate of creation
of H3+. We apply this technique to the case of the star-forming
region DR21(OH), where we successfully detected the (J=3→2)
and (J=4→3) rotational transitions of HCNH+. The significance
of our method lies in the ability to determine N(H3+)
and χe directly from observations, and estimate
ζH2 accordingly. Our results, ζH2=3.1×10–18s–1
and χ=3.2×10–8, are consistent with recent
determinations in other objects. |
|
|
|
|
|
