FAST Team: University of California, San Diego

Spectroscopic Analysis of Ultracool Dwarfs

FAST faculty: Adam Burgasser
Students: Christian Aganze, Christopher Theissen
SDSS Collaborators: Sarah Schmidt and Jennifer Johnson


Prof. Adam Burgasser is leading a group of graduate and undergraduate researchers in developing an APOGEE+BOSS+SpeX spectroscopic analysis program for late-type M and L dwarfs (spectral types M7 and later), called ultra-cool dwarfs. These spectral classes encompass dramatic transitions in magnetic activity trends (100% Halpha and X-ray emission to <10% emission), angular momentum evolution (slow/fast rotator mix to all fast rotators) and atmospheric chemistry (formation of condensates), and sample the mass transition between hydrogen burning stars and brown dwarfs. Their compact sizes and cool photospheres make them ideal targets for transiting habitable Earths (e.g., TRAPPIST1), and their longevity make them excellent (local) probes of the Milky Way’s star formation and chemical enrichment history. The complex atmospheres of ultracool dwarfs have long challenged atmospheric models, making it critical to develop empirical relations that allow us to determine effective temperatures, surface gravities, abundances, and multiplicity from spectral diagnostics.

Team Bios:

Christian Aganze

Christian AganzeI am originally from Rwanda and a graduate of Morehouse College (class of 2016) where I majored in Physics. My career goal is to to become a Physics professor helping young people from economically disadvantaged backgrounds to pursue careers physics and astronomy. I am a member of the Cool Star Lab at UCSD supervised by Prof. Adam Burgasser. My research interests are in observational astronomy revolving around low-mass stars and exoplanets and I am interested in characterizing population statistics to investigate the Milky Way’s galactic structure and chemical history using high-resolution spectra from APOGEE survey combined with low-resolution spectra obtained from SpeX spectrometer on Keck telescope (SpeX Prism Library). I am also interested in studying brown dwarfs atmospheres to further constrain formation and evolution models of brown dwarfs and exoplanets around the coldest stars. Before pursuing research in astronomy I worked at Morehouse College where I examined fundamental properties of dye-sensitized solar cells on a project supervised by Prof. Willie Rockward and Prof. Thomas A. Searles in collaboration with the Los Alamos National Laboratory. In my spare time, I like playing my guitar and being at the beach.

Adam Burgasser

Adam BurgasserAdam Burgasser’s research focuses on the properties of the lowest mass stars and coldest brown dwarfs, particularly L dwarfs and T dwarfs and ultracool halo subdwarfs. He uses observational techniques to infer the physical properties of cool stars, examine magnetic activity trends, search for multiples, and measure population statistics. His work incorporates many observational tools, including optical and infrared spectroscopy, high resolution imaging (including traditional and laser guide star adaptive optics), radio astronomy, space-based (HST & Spitzer) imaging, and photometric monitoring.