Raven Cilley
Pronouns: she/her
Research Mentor(s): George King
Research Mentor School/College/Department: Astronomy / LSA
Program: UROPF
Session: Session 4 (1:40pm – 2:30pm)
Authors: Raven Cilley, George King, Lia Corrales
Abstract
As an exoplanet passes in front of its host star, the star may dim enough for a clear dip to be shown in its luminosity. However, planets are small compared to the size of their host star, and as such the difference in luminosity is a tiny percentage of the star’s original brightness. By looking for exoplanet transits in the X-ray spectrum, the atmosphere of the planet can aid in blocking the star’s radiation and cause a larger dip. Observing transiting exoplanets in X-rays can also provide more information than visible observations about the properties of the planet and how it interacts with its host star’s intense radiation. However, X-rays are notoriously harder to measure as stars are dimmer in the X-ray portion of the spectrum, so specialized telescopes must be used. AXIS is a proposed X-ray observational satellite that would, in addition to other purposes, aid in high-energy exoplanet studies by measuring higher count rates than previously available. This project seeks to discover transit targets that are luminous enough in the X-rays that they could be studied by AXIS. To start, a sample of stars with known transiting exoplanets was taken from the NASA Exoplanet Archive, and sorted to contain nearby targets. Then, the X-ray luminosity (Lx) of each star was found by utilizing either previous measurements or known relationships between Lx and the star’s rotation period or age. These luminosities were used to calculate the X-ray flux. Finally, the theoretical count rate in AXIS of each star was calculated, the corresponding transit light curve was estimated, and the best targets were selected.
