Christian I. Johnson

Dr. Christian I. Johnson is a Senior Staff Scientist working on the Cosmic Origins Spectrograph for the Hubble Space Telescope. Dr. Johnson's primary COS related duties include high cadence monitoring of instrument performance, archive and database management, detector modeling, and CalCOS pipeline debugging and testing. He serves as the lead for the COS Monitoring group. Dr. Johnson uses high resolution spectroscopy, broad-band photometry, and theoretical models to investigate the chemical composition, kinematics, and formation history of resolved stellar populations. He primarily focuses on understanding the origin and evolution of old Milky Way globular clusters and the Galactic bulge via the detailed chemistry of individual stars.

He has extensive experience managing and processing large data sets on high performance computing clusters, developing stand-alone pipelines for data reduction and analysis, planning and executing observations using various ground and space-based observatories, and developing new machine learning codes.

Dr. Johnson is co-PI of the Blanco DECam Bulge Survey (BDBS), which imaged over 200 square degrees of the Southern Galactic bulge with the Dark Energy Camera to obtain ugrizY photometry for nearly 250 million bulge stars. He maintains several collaborations with researchers all over the world, and has published over 60 papers in peer-reviewed journals.

He is affiliated with Johns Hopkins University as an Associate Research Scientist, and previously held an NSF Postdoctoral Fellowship position at UCLA and a Clay Postdoctoral Fellowship position at the Smithsonian Astrophysical Observatory.

Education:

PhD in Astronomy, Indiana University
MA in Astronomy, Indiana University
BS in Astronomy, University of Texas

Science Interests:

• Multiple Populations in globular clusters
• Galactic bulge
• Nucleosynthesis
• High performance computing
• Point Spread Function photometry in crowded fields
• Wide field imaging and multi-fiber spectroscopy
• Dwarf galaxies and stellar streams
• Metal-poor stars

Research Topics: Local Group Galaxies; Galaxy Formation and Evolution; Stellar Populations; Star Clusters; Resolved Stellar Populations; Astrochemistry; Chemical Abundances

ORCID ID: 0000-0002-8878-3315