Astronomy & Astrophysics Seminar: H I-to-H2 Transitions in the Perseus Molecular Cloud

Abstract:

Conversion of hydrogen gas from atomic (H I) to molecular (H2) form is of critical importance for the evolution of the interstellar medium (ISM) and for star-formation in galaxies.

We apply the Sternberg et al. (2014) theoretical model for H I-to-H2 conversions in photodissociation regions (PDRs), to analyze observations of HI and H2 column densities (Lee et al. 2015) in the Perseus molecular cloud.

We constrain the radiation intensity to gas density ratio in the HI shielding envelopes and the nature of the HI-to-H2 transitions.

Our analysis (Bialy et al. 2015) implies that in addition to cold neutral gas (CNM), less dense thermally-unstable gas (UNM) significantly contributes to the shielding of the H2 cores in Perseus.

Seminar Organizer: Prof. Amiel Sternberg