GBT22A-334

Molecule formation in the Heeschen-Riegel-Crutcher Cloud

Abstract

We propose to observe Carbon Recombination Lines (CRRLs) at 750 MHz with the GBT toward the well known HI self-absorption (HISA) cloud, the Heeschen-Riegel-Crutcher (HRC) cloud. Our primary objective is to determine the spatially resolved molecule formation rate in the HRC cloud. The details of the formation of a molecular cloud are still not known. A fraction of the HISA regions is considered to be sites of molecular cloud formation. The densities of these regions are a few hundred cm^-3 and so CO is not a good tracer to estimate the molecule formation rates. Roshi & Kantharia (2011) used CRRL observations along with HI data to estimate an average molecule formation and dissociation rates in the HRC cloud. The estimated formation rate is an order of magnitude larger than the dissociation rate indicating that the HRC cloud is being converted into molecular form. These estimated were made with CRRL data set averaged over several degrees. OH and CO observations toward HRC cloud show variation at sub-degree scale indicating spatial variation of the molecule formation rate. The proposed GBT observation will measure CRRL emission with 0.3 deg angular resolution allowing us to extend the earlier analysis to sub-degree scale.

Investigators

Name	Institution
Kimberly Emig	National Radio Astronomy Observatory
Anish Roshi *	National Radio Astronomy Observatory; National Astronomy and Ionosphere Center
John Dickey	Tasmania, University of
Wendy Lane	Naval Research Laboratory
Andy Harris	Maryland, University of
mayra Lebron	Puerto Rico, University of
Pedro Salas	Green Bank Observatory

* indicates the PI