Planetary and exoplanetary Astronomy Lunch Seminar for 2019-12-16

Series: Planetary and exoplanetary Astronomy Lunch Seminar
Date: Monday 16-Dec-2019
Time: 11:15-12:15
Location: ATL 1250
Speaker: Thomas Fauchez (GSFC)
Title: From Climates to Biosignatures: Comparative Planetology within the TRAPPIST-1 System

The TRAPPIST-1 system will be a prime target for atmospheric characterization with JWST due to the small size of the host star, its relative proximity to the Earth and frequent transits of the seven planets. Three planets are in the habitable zone of the system, namely TRAPPIST-1e, 1f and 1g. The planet being the one most likely to be habitable, receiving the right amount of stellar flux to allow liquid water on the surface across a large range of atmospheric configurations. However, the detectability of atmospheric molecular species may be severely impacted by the presence of clouds and/or hazes in their atmosphere.

In this work, we performed 3-D Global Climate Model (GCM) simulations with the LMD Generic model supplemented by 1-D photochemistry simulations at the terminator with the Atmos model to simulate several possible atmospheres for TRAPPIST-1e, 1f and 1g: 1) CO2 rich atmospheres, 2) Archean Earth, and 3) modern Earth with a focus on TRAPPIST-1e. JWST synthetic transit spectra were computed using the GSFC Planetary Spectrum Generator (PSG).

We show that the use of 3-D Global Climate Models, taking self-consistentcy into account for the effect of clouds and sub-saturation, is crucial to evaluatng the detectability of atmospheric molecules of interest as well as interpreting in a more global approach (and thus robust and relevant) future detections. We find that TRAPPIST-1e, 1f and 1g atmospheres, with clouds and/or hazes, could be detected with the NIRSpec prism from the CO2 absorption line at 4.3 μm in less than 15 transits at 3σ or less than 30 transits at 5σ. This number of transits is reasonably achievable during JWST's life time. However, our analysis suggests that other gas such as O2, O3, CO, CH4 would require hundreds (or thousands) of transits to be detectable. We also find that H2O, mostly confined in the lower atmosphere, is very challenging to detect for these planets or similar systems if the planets' atmosphere is not in a moist greenhouse state.

These preliminary results therefore address the weaknesses of JWST's ability to characterize habitable exoplanets. Advances required beyond JWST to detect the atmosphere of a habitable exoplanet are discussed in reference to the status of future observatories and their proposed design strategies, highlighting the importance of instrument stability, aperture size and wavelength range.

For further information contact PALS coordinator Dr. Lori Feaga at feaga@astro.umd.edu or (301)-405-1383.

SPECIAL ACCOMMODATIONS:

Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.

DIRECTIONS AND PARKING

Directions and information about parking can be found here.

This page was automatically generated on: 11-Dec-2019.