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AR 16153 (Archival Research)

Thu Jul 18 14:49:17 GMT 2024

Principal Investigator: William Sparks
PI Institution: SETI Institute
Investigators (xml)

Title: M-dwarf Exoplanet Direct Detection using Light Echoes (MEDDLE)
Cycle: 28

Abstract
We seek to directly detect exoplanets orbiting M dwarf stars using light echoes from stellar flares, leveraging Doppler shifted line emission and echo time delays to greatly enhance the exoplanet detectability. With a massive investment of HST time into M dwarf UV observations in recent years, we propose to extract all archival UV time-resolved COS and STIS spectroscopy of M dwarfs. We will seek echoes of flares from their planetary Doppler shifted spectra and time delay, and quantitatively assess the feasibility of this approach. If validated, light echoes present a detection and characterization opportunity complementary to and decades ahead of that offered by flagship-scale space telescopes such as LUVOIR, sensitive to a region of discovery space which is extremely difficult to access even for LUVOIR. The sheer numbers of M dwarfs and their proximity means they are by far the most likely to host the nearest habitable extrasolar planets. While JWST may be able to characterize the atmospheres of a small number of transiting M dwarf planets, only a tiny fraction of planets actually transit. All exoplanets orbiting active stars, however, are potentially observable using light echoes, and most M dwarfs are active at some level. The observable quantities can completely define the orbit, yield estimates of size and albedo, and identify exoplanet atmospheric lines. Hence this offers an opportunity for the detection and characterization of one of the most important classes of exoplanet: habitable, nearby, numerous. A by-product of the study will be a comprehensive overview of flare properties on M dwarf stars, enhancing our understanding of the UV environment and habitability.