EAPSI: Multiband Photometry Simulations to Distinguish Transiting Exoplanets from False Positives

Louie Dana R, Hyattsville MD

Investigators

Abstract

This research will be conducted in collaboration with two Japanese experts in the field of exoplanetary science, Professor Motohide Tamura and Assistant Professor Norio Narita. Both are scientists at the University of Tokyo, Department of Astronomy. Professor Narita and this project's principal investigator (PI) are members of the Transiting Exoplanet Survey Satellite (TESS) Science Team. TESS is a NASA mission that will launch in March 2018 to search most of the sky for relatively nearby transiting exoplanets. With near-term technology, mankind's best chance of finding exoplanets that could host life lies in examining the atmospheres of super-Earth planets transiting relatively cool, low-mass M-dwarf host stars within their habitable zones (Charbonneau & Deming, 2007). Simulations predict that TESS will detect about 1,700 exoplanets over its two-year primary mission, and that one-third of those planets will have radii less than twice that of Earth, with three-quarters of these super-Earths orbiting M-dwarfs (Sullivan et al., 2015). However, simulations also show that TESS will detect over 1,000 astrophysical false positives. Thus, TESS discoveries must be validated as originating from real exoplanets using additional instruments and/or techniques. The Japanese have proposed that their recently-developed Multicolor Simultaneous Camera for Studying Atmospheres of Transiting Exoplanets (MuSCAT) at Okayama Observatory be used as a tool to distinguish TESS-discovered exoplanets from false positives. The purpose of this research project is to simulate follow-up observations of TESS detections using MuSCAT, thereby revealing which planet candidates can be efficiently validated using MUSCAT, and which must be validated using other techniques. This understanding will allow astronomers to better prioritize and optimize follow-up validations of TESS detections, which in turn will lead to optimal use of valuable space assets, such as the James Webb Space Telescope (JWST). Transiting exoplanets can be distinguished from astrophysical false positives by determining the wavelength/color-dependence of the amount of stellar light received transiting exoplanets are largely achromatic when observed in different bandpasses. Thus, TESS discoveries can be validated as true transiting exoplanets by determining the wavelength/color-dependence of the amount of stellar light detected on Earth. The PI will simulate MuSCAT observations of TESS detections by developing a software code that models the performance of the MuSCAT instrument (Narita et al., 2015) and accounts for all significant noise sources, such as photon noise, sky background noise, and scintillation noise. TESS planet candidates will vary tremendously in terms of parameters such as the temperature and brightness of the host star, or size and orbital distance of the planet. To provide a realistic estimate of likely candidate planets, the PI will use the database of simulated TESS-detected exoplanets published by Sullivan et al. (2015), as well as simulated false positives detected by TESS (available to the TESS Science team). This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science (JSPS).