Astronomy Seminar: Detection and Characterization of M-dwarf Planets with Next Generation Instruments

Guðmundur Kári Stefánsson (Princeton)

Abstract: Planets orbiting nearby M-dwarfs—the most numerous stars in the galaxy and our nearest stellar neighbors—are advantageous for detailed characterization. The low mass of M-dwarfs increases the Radial Velocity (RV) semi-amplitude of planets orbiting in their Habitable-zones (HZ), making such planets detectable with current RV facilities. Further, the large planet-to-star radius ratios of M-dwarf planets make them favorable targets for atmospheric characterization. Despite these advantages, M-dwarf planets have been poorly studied until recently due to the intrinsic faintness of their host stars in optical band-passes. However, with new facilities operating at redder wavelengths, we are gaining further insights into their properties and occurrence rates. In this talk, I will discuss two new technologies and how we are using them to detect and characterize nearby M-dwarf planets. First, I will discuss Engineered Diffusers—nano-fabricated pieces of optics capable of molding the image of a star into a broad and stabilized top-hat shape—which we have used to obtain some of the highest precision transit observations from the ground (60ppm in 30min bins). Second, I will discuss two new Doppler spectrographs I am involved with, the near-infrared Habitable-zone Planet Finder (HPF) on the 10m Hobby-Eberly Telescope, and the NEID spectrograph on the 3.5m WIYN Telescope. I will describe the ongoing HPF survey to detect planets in the HZ around nearby (<25pc) mid-to-late M-dwarfs, and how we are using HPF to gain insights into the properties and orbital architectures of transiting M-dwarf planet systems recently discovered by the K2 and TESS missions.

Short Bio: Guomundur Stefansson is a Henry Norris Russell Fellow at Princeton University focusing on developing and using next-generation instruments to better detect and characterize exoplanets from the ground. Guomundur received his PhD at Penn State University in 2019 working with Suvrath Mahadevan focusing on the development of Engineered Diffuser Technology for precision ground-based exoplanet transit observations, and on the design and commissioning of two next-generation Doppler spectrographs—the Habitable-zone Planet Finder on the 10m Hobby Eberly Telescope and the NEID spectrograph on the 3.5m WIYN Telescope—to detect and characterize planets around nearby stars.



Meeting ID: 922 9117 7635

Passcode: 215882