"Three Environments for Interstellar Chemistry: Gas, Dust and Ice" Seminar with Guest Speaker Professor Eric Herbst

April 21, 2017 - 3:15 pm to 4:30 pm (already occurred)
Merrill Science Center, Lecture Room 4
Professor Eric Herbst, seated and smiling in a room, surrounded by electronic laboratory equipment

Eric Herbst is the Commonwealth Professor in the Departments of Chemistry, Astronomy and Physics at the University of Virginia.

Abstract: Stars and planets form from the collapse of portions of dense interstellar clouds, which are large assemblies of cold gas and dust (10 K) in interstellar space. The gas phase is mainly molecular and contains many exotic species, including radicals, unusual isomers and anions, most of which are organic in nature. Although hydrogen is the dominant element and H2 the dominant gas-phase molecule, most organic molecules are very unsaturated and are labeled “carbon chains” by astronomers. The dust particles are covered with ices, mainly in the form of water, CO and CO2. During the collapse, the material evolves through a number of stages, starting with an isothermal era, followed by a warm-up during which the gas-phase molecular inventory changes from a mainly exotic one to one in which most organic molecules resemble standard laboratory solvents, albeit in the gas phase. Eventually a so-called protoplanetary disk is formed around the young star, and the disk can lead to the formation of planets via coagulation of the dust particles, with an initial molecular inventory at least partially determined by the chemistry that has already occurred.

Much of what we know about the physical conditions and lifetimes of the various stages of star formation derives from molecules, which, through spectroscopy and kinetic modeling, are excellent probes of sources where they exist. [1] In this talk, I will discuss the types of gas-phase and solid-state processes that synthesize molecules in assorted regions of star formation, with an emphasis on exotic gas-phase reactions and the chemistry that occurs in ice mantles.

1 E. Herbst, PCCP, 16, 3344-3359 (2014)

Contact Info

Cathy Stillerman
(413) 542-2342
image of e-mail address@amherst.edu