GBT23B-203

Detangling the 3D Multi-phase Structure of the Perseus Cloud with 18cm OH

Abstract

We propose to observe the 18cm OH spectral line to trace the diffuse molecular medium of the Perseus Molecular Cloud. Given the quality of new 3D dust maps (Leike 2020), new OH data mapping the diffuse molecular gas of these clods will allow to trace the transition between atomic envelopes of these condensing clouds, and the denser cores, where stars will likely form. Existing data from HI and CO alone do not appear to trace the transition-zone of the ISM between these two extremes. The volume density profiles of these clouds can be accurately measured at the parsec resolution. We predict that the CO-bright portions of these clouds will also be bright in OH, and that our OH radial profiles will trace the "CO-dark" portion of these clouds radially until the gas becomes mostly atomic.

These data will allow to accurately measure the "CO-dark" gas content of these local clouds, ascertain the molecular fraction of the transition portion of the cloud, and better constrain the radial volume density profile of the cloud by adding in the 'missing' or 'dark gas' component of gas not traced by HI or CO.

Investigators

Name	Institution
Michael Busch *	California at San Diego, University of
Catherine Zucker	Center for Astrophysics | Harvard & Smithsonian
Joanne Dawson	Macquarie University; Commonwealth Scientific and Industrial Research Organisation
Lars Bonne	Universities Space Research Association
Enrico Di Teodoro	Firenze, Università degli Studi di
Min-Young Lee	Wisconsin at Madison, University of; Max-Planck-Institut für Radioastronomie; Korea Astronomy and Space Science Institute; Commissariat à l'Energie Atomique
Gyueun Park	Korea Astronomy and Space Science Institute

* indicates the PI