This week’s in person astrophysics seminar will be by Sam Gill (Warwick).
Sam will be around in Leicester from about 11am to 6pm. Please let me know if you’d like to meet up.
Bridging the Gap between Hot Jupiters and Ice Giants
Abstract: While thousands of transiting exoplanets are now known, the observed population is very strongly biased to hot, close-in planets with short orbital periods. This bias is a particular problem because transits also provide our best opportunities to characterise exoplanets, including atmospheric composition by transmission spectroscopy and orbital obliquity by the Rossiter-McLaughlin effect. The NASA TESS mission is a wide-field photometric survey that is sensitive to exoplanet transits on bright stars across most of the sky. However, it observes most stars for only 27 d at a time, so for orbital-periods longer than 13.5 d TESS is most likely to see only one transit event. Where a second transit is detected in the the extended mission, a photometric period search is more efficient, since a finite number of period aliases are allowed. However, with two years separating the TESS epochs, our simulations show that photometric follow up remains essential for efficient identification of the correct period. I will present recent results from a search for long-period transiting planets with TESS and NGTS. Single-transit events from TESS are followed up with high-precision ground-based photometry from the twelve NGTS telescopes at the ESO Paranal observatory in Chile. I will show results for several new planets, including a long-period multi-planet system. Long-period transiting planets orbiting bright stars are needed for characterization observations that will test models of exoplanet formation, migration and evolution.