CH 3 GHz Observations of Molecular Clouds Along the Galactic Plane

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dc.creatorMagnani, L.
dc.creatorLugo, S.
dc.creatorDame, T. M.
dc.date2005-08-26
dc.date.accessioned2026-07-07T11:24:43Z
dc.date.available2026-07-07T11:24:43Z
dc.descriptionSpectra in the CH $^2Π_{1/2}$, J=1/2, F=1-1 transition at 3335 MHz were obtained in three 5-point crosses centered on the Galactic plane at $\ell =$ 50$\arcdeg$, 100$\arcdeg$, and 110$\arcdeg$. The lines of sight traverse both Giant Molecular Clouds (GMCs) and local, smaller entities. This transition is a good tracer of low-density molecular gas and the line profiles are very similar to CO(1-0) data at nearly the same resolution. In addition, the CH 3335 MHz line can be used to calibrate the CO-H$_2$ conversion factor (X$_{\rm CO}$) in low-density molecular gas. Although this technique underestimates X$_{\rm CO}$ in GMCs, our results are within a factor of two of X$_{\rm CO}$ values calibrated for GMCs by other techniques. The similarity of CH and CO line profiles, and that of X$_{\rm CO}$ values derived from CH and more traditional techniques, implies that most of the molecular gas along the observed lines of sight is at relatively low densities ($n \le$ 10$^3$ cm$^{-3}$).
dc.description26 pages, 12 figures, submitted to the AJ, revised after referee report
dc.identifierhttps://arxiv.org/abs/astro-ph/0508571
dc.identifierhttp://arxiv.org/abs/astro-ph/0508571
dc.identifierAstron.J.130:2725-2731,2005
dc.identifierdoi:10.1086/497538
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/195284
dc.subjectAstrophysics
dc.titleCH 3 GHz Observations of Molecular Clouds Along the Galactic Plane
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