The Life Cycles of Massive Stars: A New Approach to Measure Mass Loss

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White dwarfs are very dense, planet-sized, stellar remnants produced at the end of a low-mass star's life. About 98% of all stars - including our Sun - will end their lives as white dwarfs. This research team will find and analyze dozens of white dwarfs that are located in very young star clusters in the Milky Way galaxy. Their study will provide critical insights about stellar astrophysics. They will measure and compare the masses of white dwarfs with those of other stars still undergoing fusion, in order to determine how much mass is lost over their lifetimes. This will be used to define the critical mass that separates white dwarf formation from core collapse supernova. They will use data from existing surveys and obtain new data using optical telescopes. A secondary goal is to determine the precise ages of the young star clusters in the study. Broader impacts include further training of a postdoctoral researcher in science and public outreach. The PI will continue his public lecture series on stars and stellar death. He will also collaborate with African American and Indian students at nearby schools and help with the NAACP Scientific Olympics in Maryland.Once white dwarf candidates are identified in a star cluster, the researchers will perform a detailed analysis of each cluster's color-magnitude diagram to derive the properties of the parent system. Next, they will obtain data of the newly discovered white dwarfs with multi-object spectrographs on 4 to 10-m telescopes and determine fundamental stellar properties (such as effective temperature, log g, mass, luminosity and cooling age) by fitting the Balmer line spectra to the team's white dwarf atmosphere and cooling models. They will measure the critical mass separating white dwarf from supernova formation by establishing a truncation in the white dwarf mass distribution.