SH040-05
A NASA Pioneer SmallSat to study the Structure and Evolution of ExoJupiter Atmospheres (SEEJ:)
Monday, 14 December 2020: 16:12
Virtual
Scott J. Wolk1, Christopher Samuel Moore1, Jaesub Hong2, Suzanne Romaine3, Althea Moorhead4, Dennis Lee Gallagher4, Lisa Kaltenegger5, Bradford Wargelin6 and Vinay Kashyap7, (1)Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, United States, (2)Harvard University, Cambridge, MA, United States, (3)Smithsonian Astrophysical Observatory, Cambridge, MA, United States, (4)NASA Marshall Space Flight Center, Huntsville, AL, United States, (5)Cornell University, Ithaca, United States, (6)Harvard-Smithsonian Center for Astrophysics, Cambridge, United States, (7)Center for Astrophysics | Harvard & Smithsonian, Cambridge, MA, United States
Abstract:
The most important effects on an exoplanet atmosphere are driven by high-energy photons and particles from the host star, which heat and ionize the planetary atmosphere, potentially leading to its loss. The rarest, largest flares are disproportionately important. SEEJ will study the Structure and Evolution of ExoJupiter atmospheres with long observations, with cumulative exposures well beyond those conducted by any other mission. SEEJ will measure how often high energy flares of a given size occur, and establish, for the first time the statistics of these crucial events on exoplanet hosts. Observing transits SEEJ will measure the thermospheric scale height, and so the inflation or damage to the exoJupiter atmosphere. SEEJ will provide the data for theory to tie the rare flares and their effects together via improved models of exoplanet thermospheres.
The X-rays emitted by an exoplanet host star is critical to the atmosphere of the planet. Specifically, X-rays can induce both life-enabling and life-threatening photochemistry in planetary atmospheres. Similarly, observed X-ray flares may be harbingers of coronal mass ejections which can aid the development of life by removing primary, hydrogen-dominated atmospheres or threaten its existence by depleting secondary atmospheres and specific critical species such as ozone. An understanding of the behavior of stellar coronae at all phases of stellar/planetary evolution is fundamental to our ability to gauge the cumulative impact of stellar X-rays on planetary atmospheres.
- The First Objective of SEEJ is to characterize the X-ray emission for a diversity of planet hosting stars through long term monitoring, and use this as input to exo-planet atmospheric models to determine effect on planetary atmospheres, and possible feedback between the planet and star.
- The Second Objective of SEEJ is to detect and measure planetary exospheric structure through the shape and extent of the upper atmosphere for a variety of exoplanets.
SEEJ will provide detailed X-ray transit light curve profiles of suitable targets accumulating them by observing multiple exoplanet transits. SEEJ will monitor roughly 40 transits of as many as 7 X-ray bright exoplanet hosts in a single year.
