סמינר באסטרונומיה ובאסטרופיזיקה: The Perseus Molecular Cloud: A Laboratory for Studying the Earliest Stage of Star Formation

Abstract:

Recent observations of galaxies at both low and high redshifts have shown a strong correlation between star formation rates and molecular gas contents, suggesting that the ability to form the molecular gas out of the atomic interstellar medium controls the evolution of individual galaxies. Yet, what physical processes regulate the fraction of molecular gas in galaxies is not fully understood. 

 
In this talk, I will present results from a series of our studies on the HI and H2 properties of the Perseus molecular cloud. First of all, we have found that Perseus is embedded in a large, diffuse HI envelope, which provides the minimum surface density of ~10 solar mass/pc2 required for shielding H2 against photodissociation. Our studies based on HI emission/absorption and infrared observations have then put constraints on the physical conditions of the cold and warm neutral medium in the HI envelope for the first time and suggest that diffuse HI envelopes may hold the key to understanding the formation and evolution of molecular clouds. 

מארגת הסמינר: פרופ' שרה בק