Title:Using observations of the Sun as a star to probe how stellar surface inhomogeneities affect exoplanet transits
Type of Project: Data Analysis
Skills/Interest Required The student should have interest in solar and stellar physics, data analysis, and learning about
exoplanet research. Introductory knowledge of Python (preferred) or other programming language is recommended.
Mentor: Dr. Antonija Oklopčić, Dr. Raphaëlle Haywood
The Sun is the only star whose surface we can resolve directly and at high resolution, and hence it provides a unique insight into observations of other Sun-like stars, including those that host exoplanets.
Observations of exoplanet transits -- events in which planets cross the disk of their host star and cause dimming in the observed stellar brightness -- can provide insights into the properties of exoplanet atmospheres. High-resolution transit observations at wavelengths associated with strong atomic transitions, such as
the helium line at 1083 nm, can be used to probe the uppermost layers of planetary atmospheres.
However, stellar chromospheres also produce absorption in the helium 1083 nm line. In the Sun, strong 1083 nm absorption is spatially associated with active regions and is known to be variable. Spatial and temporal variability in the stellar 1083 nm line can affect exoplanet transit observations, and inferences we make
about their atmospheres, at a level that is currently not well constrained.
This project is based on analyzing publicly available narrow-band images of the Sun taken at and around the helium 1083 nm line. The student will evaluate the effect of stellar inhomogeneity and variability in the helium 1083 nm line on exoplanet transit light curves. To do this, the student will use codes developed by
the mentors to simulate planetary transits across the Sun and produce transit light curves for a variety of planet-star configurations, and for various levels of stellar activity.
Figure 1: As the planet transits the stellar disk, the observed stellar brightness is diminished. The observed stellar light curve (i.e. brightness as a function of time) contains information about planetary atmospheres. Analyzing solar data can help us improve our understanding of how stellar properties affect exoplanet
transit light curves. Animation credit: NASA.