Tellurics In High Fidelity Spectra

Measuring the radial velocity (RV) of a star can be complicated by atmospheric absorption features that change in depth and move with respect to the stellar features over time. Even the weakest features can the skew ultra-precise measurements of stellar lines needed for detecting an exoplanet. Recently I worked on developing a method for simultaneously fitting both telluric lines and stellar features in a semi-empirical way that utilizes our knowledge of the positions and shapes of telluric features from HITRAN to guide a physically-motivated, but analytical model of the telluric lines.  So far, I demonstrated the method by applying it to R~10^6 spectra of the Sun. From the fits, I was able to generate a new telluric-corrected solar atlas that, in addition to the set of extracted telluric spectra, can be accessed here. Check out the paper for more information. In follow-up work the method will be tested as an RV fitting tool since it has the merits of being fast, working even in the case where the barycentric velocity shift of a target is small or poorly sampled, and accurately including even the smallest telluric features in the model even if they’re not detected in the data.

Exoplanet Atmospheres

In the summer of 2016 I completed a project with Jasmina Blecic on implementing a cloud model in the soon-to-be open source atmospheric retrieval code Pyrat-Bay. This work was done as part of the Kavli Summer Program in Astrophysics and the final paper for the program that describes the work can be found here.

My current research interests are in developing novel instrument designs for the characterization of exoplanetary atmospheres. My work on building an ultra-narrowband photometer capable of simultaneous imaging of a star in two adjacent bands is described in this paper. This instrument concept could provide an efficient measurement of a single species in an exoplanet atmosphere and perform uniform surveys. Its simple design allows it to be mounted onto the back of a telescope (see left image), which can allow it to be mounted simultaneously with a spectrograph. Future plans include upgrading this instrument for potassium detection in hot Jupiters.

Telluric Water Vapor Monitoring

waterfiltersWhile the close-in habitable zones of M-dwarfs make them ideal targets for searching for Earth-sized exoplanets, observations must be done in the near-IR, where these stars are the brightest. Unfortunately, ground-based NIR observations suffer from absorption lines that dominate this part of Earth’s atmospheric transmission spectrum (shown to the right). These temporally variable features complicate both photometry and spectroscopy. To aid ground-based NIR photometric exoplanet surveys, I developed the Camera for the Automatic Monitoring of Atmospheric Lines (CAMAL) that is an inexpensive, automated system for the real-time monitoring of atmospheric water vapor content. Measuring the precipitable water vapor concurrently with science observations can improve photometric precision for exoplanet detection, where atmospheric variability can easily obscure a potential detection. Check out the paper here.

Past Work with the RESOLVE Team

At the University of Chapel Hill I worked with Professor Sheila Kannappan and the RESOLVE team performing a dark matter census of a local volume of galaxies. In addition to aiding in remote observing on SOAR and contributing to the reduction pipeline for the spectra, I used the RESOLVE dataset to study galaxy properties as a function of their environment. I completed an honors thesis under Prof. Kannappan and Prof. Berlind that can be viewed here. I also worked with David Stark to publish a study of the possibility of star formation in the Smith Cloud, which is a high velocity cloud outside the plane of the Milky Way with high HI column densities.