Interferometry Instrumentation | Advisor: John Monnier

PhD Research: Xiao Che worked with his advisor to upgrade the CHARA telescope array to better image hot stars and their environments. Che upgraded the hardware on the Michigan Infrared Combiner (MIRC), installing a photometric channel system and expanding the combiner from four to six beams to improve the instrument’s efficiency and data quality. He also led wavefront sensor development for CHARA’s adaptive optics upgrade. This will allow a nearly six-fold increase in the number of young stars that can be successfully imaged with CHARA. Che has used the array to image stellar surface structures and their environments with very high angular resolution. His imaging of the rapid rotators in the star system Regulus was the first to call into question the gravity darkening coefficient predicted by von Zeipel in 1924. And during the 2011 periastron of the Be binary delta Scorpii, Che found no evidence for the transfer of material from the secondary star to the disk of the primary as had been proposed during the previous periastron. He’s now using infrared interferometric data from other collaborators to constrain models of disk size around young stellar objects.

Why Michigan Astronomy?

Depth & Breadth: “I chose Michigan because I wanted to work in instrumentation under a very established advisor. But what surprised me was how easy it is to work with other professors on other projects. In fact, our department encourages students to switch advisors during the first three years of the PhD to provide exposure to different areas of astronomy. If you’re motivated, there are so many opportunities.”