Weekly Colloquium

Most weeks during the semester, we host a scholar for a one-day visit. The visit culminates with a public talk on a topic of contemporary physics or astronomy. Students are welcome to these talks, and seniors are required to attend at least nine over the course of a year. Near the end of each semester, honors thesis students give public lectures on their work.   

Our Astronomy program is part of the Five College Astronomy Department, which hosts its own colloquium series Thursdays at 3:45 pm at UMass. 

  • Contact colloquium organizer Alice Simmoneau with any questions about colloquia, or being added to our mailing list.

Tuesday, April 16, 2019

Tue, Apr 16, 2019

Professor Bruce Macintosh, Stanford University: "Direct Imaging of Extrasolar Planets"

Almost 4,000 extrasolar planets are now known, but almost all have been detected through so-called indirect methods-- measuring the parent star’s Doppler shift or brightness variations. Direct detection refers to spatially separating the planet’s light from that of the star. It is extremely challenging-- Jupiter in our solar system is 10^-9 the luminosity of the sun --but allows observations of planets inaccessible to other methods, particularly the outer parts of target systems, and allows spectral acharacterization of a planet’s atmospheric properties.

I will discuss the optical physics that makes direct detection challenging, and the techniques-- adaptive optics, coronagraphy, and image processing --that can overcome these challenges. To date, direct detection has been successful for young Jupiter-like planets, and I will show highlights of those discoveries. Finally, I will review future prospects for instruments on ground-based extremely large telescopes, or dedicated space missions with coronagraphs or formation-flying star shades which may reach the level of sensitivity needed to detect Earth-like planets around nearby stars.