Physics, cosmology, and exoplanetary science with the white dwarf stars

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White dwarfs stars are the remnants of stars like the sun that form after their nuclear furnace has gone out. There are billions of them in our galaxy and most are not doing anything interesting besides cooling off. However, some of them orbit in close binary (double-star) systems in which the stars eventually spiral together causing massive explosions, others pulverize comets and asteroids left over from their planetary systems, and still others have "starquakes" that let us conduct seismology of their interiors. This project will study interesting examples of white dwarfs to learn about the supernova explosions that astronomers use to measure distances, the composition and configuration of exoplanetary systems, and the physics of material that is 10 million times denser than lead and cannot be produced or studied in any terrestrial laboratory. This program will also facilitate student training in instrument development and provide a new observational capability for the astronomical community. The PI and his team of graduate students will carry out 3 separate investigations using white dwarfs as tools to study (1) whether hot DQ white dwarfs result from mergers of two sub-Chandrasekhar mass white dwarfs, (2) whether metal-rich white dwarfs with circumstellar dust are accreting planetary material, and (3) the properties of ZZ Ceti stars. The common thread is observations to be obtained using the SOAR telescope with the Goodman Spectrograph, which was built by the PI. With partial support from this award, the PI will build a red-channel for the spectrograph, which is of great interest to the observational community and which will further enable the three key observational programs.