0 Assigned ID: 248 ----- Attempting Submission 1 (Thu Mar 05 17:00:32 GMT 2020) ----- 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. Dr. William B. Sparks has extensive experience of HST instrumentation, as principal investigator of over 30 HST science programs, and was deputy head of the Instrument Division at STScI for several years. He has substantial experience of time-tag data acquisition and processing and has developed a software infrastructure for processing and analysis of such data. He was first author on a major paper investigating the use of light echoes to directly detect exoplanets, Sparks, White, Lupu, Ford, 2018, ApJ, and pioneered, with co-I Ford, other now standard exoplanet detection methods (Sparks & Ford 2002). He is currently a senior research scientist at the SETI Institute (STScI emeritus). Dr. Richard L. White, coauthor on Sparks et al. (2018), is an expert in HST data analysis and signal processing and has developed numerous algorithms for image and data processing, deconvolution & signal extraction. He has developed a maximum likelihood algorithm (based on the Lucy method) for separating the light echo signal from the star's background contribution using the time-tagged spectroscopic data. These methods will form the basis of the echo analysis. Dr. Cynthia Froning is an expert in stellar physics, multiwavelength observations of variable stars, and FUV spectroscopic observations and instrument development. As the Project Scientist for the Cosmic Origins Spectrograph and leader of the 555 orbit GTO program, she has extensive experience in the analysis of COS data and FUV spectroscopy in general. Dr. Froning is the PI of the Mega-MUSCLES Treasury Survey (GO #15071), a large HST program to characterize the energetic radiation environments of M stars hosting exoplanets. Dr. Roxana Lupu is an expert in modeling molecular spectra in far-UV to infrared and submillimeter spectra. She and her colleagues manage large opacity databases used to model the atmospheric structure, emission, and reflected light spectra of extrasolar planets In addition, their experience in modeling the far-UV molecular fluorescence is particularly relevant for this proposal. Dr. Kevin France is PI of the HST MUSCLES Treasury Survey (GO #13650) to study the spectral and temporal properties of red dwarf stars (France et al. 2016; Loyd et al. 2016; Youngblood et al. 2016). He was also a member of the COS instrument and science teams, developing numerous community tools for spectral and temporal analysis of COS data. Dr. R. O. Parke Loyd has extensive experience in time-series analysis of FUV observations by HST COS and STIS. He has carried out surveys of stellar fluctuations (Loyd and France, 2014), assembled a catalog of exoplanet host star SEDs (Loyd et al., 2016), analyzed FUV planet transits (Kulow et al., 2014; Loyd et al., 2017), and has published an in-depth study of M Dwarf flares in the FUV (Loyd et al., 2018). Prof. Holland Ford, has in depth experience of HST throughout its history and was PI of the ACS instrument, one of Hubble's most successful. Ford's diverse interests have included using extragalactic planetary nebulae as distance indicators and tools to measure the masses of early type galaxies, instrumentation for HST, the nature of AGNs and their central massive black holes, galaxies in the early universe, the prospects for extra-terrestrial life in the oceans of solar system moons, and now extrasolar planets. Exoplanets and Exoplanet Formation 0 Regular false false true false false SUPPORTED