Astronomy Colloquium: Whitford Lecturer Prof. Bruce Draine

Speaker: Prof. Bruce Draine

Institution: Princeton University

Title: Dust and Molecular Hydrogen in a galaxy with 3% Solar abundances

Abstract: The first galaxies form stars out of initially pristine gas.  After a

few million years the gas is enriched with heavy elements formed by

the first generation of stars.  Dust starts to appear in small

amounts, and H2 formation by catalysis on dust grains begins.

JWST Spectroscopy of I Zw 18, a very metal-poor star-forming galaxy in

the nearby universe, provides an opportunity to study these

beginnings.  The composition of the first dust is found to be very

different from dust in a mature galaxy such as the Milky Way.  The

molecular hydrogen emission spectrum allows the ortho/para ratio to be

determined, with the ortho/para ratio found to exceed 3 in some regions.

Implications will be discussed.

Zoom link here.