Star formation and molecular cloud structure at low metallicity

Lowell Observatory, Flagstaff AZ

Investigators

Abstract

New stars are continuously forming in galaxies like the Milky Way. Galaxies begin as mostly hydrogen atoms, but nuclear fusion inside of stars produces heavier atoms. These atoms, like carbon and oxygen, are spewed out by dying stars, changing the chemistry of the space between the stars. The process begins again with the formation of new giant clouds of gas, which become cold and dense enough that atoms bond together to form molecules. New molecular clouds begin to form the next generations of stars. These heavy atoms from the first generation of stars are caught up in a molecular cloud and absorb ultraviolet light from nearby stars. The absorption helps to protect the fragile molecules from being broken apart, again changing the chemistry of the clouds. The investigator seeks to understand these chemical processes by comparison of the Milky Way to the chemistry in nearby dwarf irregular galaxies. These small galaxies have much less of the heavy atoms compared to spiral galaxies like the Milky Way. As a result, the outer parts of molecular clouds in those dwarf galaxies are destroyed, leaving smaller molecular clouds than are found in spiral galaxies. The investigator is studying the structure of molecular clouds in tiny dwarf galaxies. The investigator seeks to understand the consequences on star formation in dwarf galaxies due to the differences in molecular abundance. Stars are forming in dwarf galaxies, and the investigator plans additional observations to understand the nature of the gas in these galaxies. The answers to these questions will help us to understand star formation in the early universe, before heavy atoms were formed. The investigator leads the Lowell Observatory Native American Astronomy Outreach Program, which pairs astronomers with 4th-8th grade teachers in the Navajo and Hopi Nations. The program holds tri-annual teacher workshops that introduce teachers to classroom activities enhancing their understanding of astronomy. The collaborators create culturally responsive curriculum that enables Native students to see themselves as scientists and addresses the tribal and educational standards. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.