The Effect of Stellar Contamination on Space-based Transmission Spectroscopy is the topic of Study Analysis Group (SAG) 21 of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG).
Co-Chairs: Drs. Néstor Espinoza (STScI) and Benjamin Rackham (MIT)
Overview: Transmission spectroscopy probes the chemical composition and physical structure of the upper atmosphere of transiting exoplanets, but these measurements can also be impacted by inhomogeneities on the stellar disk, including spots, faculae, and plages. The aim of SAG 21 is to bring together an interdisciplinary team of scientists from the heliophysics, stellar astrophysics, and exoplanet communities to study the impact of stellar contamination on transmission spectra from future space-based facilities and the constraints on stellar photospheric heterogeneity enabled by transiting exoplanets.
Anyone can join SAG21 at any time; membership is open to the entire community. Simply fill out the form below.
The work of SAG21 primarily happens through its subgroups. These teams focus on specific aspects of the overarching study and are each responsible for the content in one chapter of the final report SAG 21 will provide to NASA.
Leads:
Svetlana Berdyugina, Heidi Korhonen & Alexander Shapiro
Brief Description:
This subgroup is tasked with the study of our overall knowledge of stellar photospheric heterogeneities: what are the known properties of spots and faculae from the Sun and other stars? How do they depend on stellar properties? What are the limitations on this understanding (e.g., non-solar spot configurations)? What is the impact of those properties on transmission spectroscopy of exoplanets?
Leads:
Joanna Barstow & Benjamin Rackham
Brief Description:
This subgroup is tasked with studying the state-of-the-art and limitations of the technique of stellar spectral decomposition to study photospheric heterogeneities. What has been done with this technique? How promising it is to understand stellar heterogeneities on exoplanet host stars? What are the instrumental and model limitations of the technique? How much information does it provide for transmission spectroscopy studies?
Leads:
Mahmoud Oshagh & Brett Morris
Brief Description:
This subgroup is tasked with studying the state-of-the-art and limitations of the technique of occulted active regions, where active region properties can be studied when another object (e.g., an exoplanet) occults it. What has been done with this technique? How promising it is to understand stellar heterogeneities on exoplanet host stars? What are the instrumental and model limitations of the technique? How much information does it provide for transmission spectroscopy studies?
Leads:
Yvonne Unruh & Ben Montet
Brief Description:
This subgroup is tasked with studying the state-of-the-art and limitations of the technique of unocculted active regions, where changes in observed properties (e.g., stellar flux, transit depths both as a function of time and wavelength) inform us about the properties of active regions in the star. What has been done with this technique? How promising it is to understand stellar heterogeneities on exoplanet host stars? What are the instrumental and model limitations of the technique? How much information does it provide for transmission spectroscopy studies?
Leads:
Elisa Quintana & Rob Zellem
Brief Description:
This subgroup is tasked with studying possible future complementary observations that could be performed in order to constrain stellar heterogeneities in aid of exoplanet transmission spectroscopy studies. What instruments will be available for the community in the future? What kind of observations would be the most valuable? Is there a need for new missions/instruments?
SAG 21 will host a two-day virtual meeting in Mar. 2021 with talks and discussions exploring the impact of stellar contamination on space-based transmission spectroscopy.
Learn more about the SAG 21 Community Symposium at the event website.
For any questions, please contact the SAG 21 Co-Leads, Néstor Espinoza (nespinoza [at] stsci [dot] edu) and Benjamin Rackham (brackham [at] mit [dot] edu).