I am primarily interested in understanding and mitigating the impact of stellar radial velocity (RV) variability on the detection and characterization of Earth-mass planets orbiting Sun-like stars. To help meet this goal, I primarily use our nearest star, the Sun, as a laboratory to understand how convective motions and other magnetic phenomenon in the solar atmosphere create RV variability several times larger than the 10 cm/s RV semiamplitude of the Earth.
You can find a full list of my publications on NASA ADS.
Understanding Granulation with GRASS
Granules are convective cells in the photosphere of stars. In the Sun, they appear as irregularly shaped bright regions surrounded by darker regions known as intergranular lanes. Many granules can be seen in the image at right, which shows a patch of the solar surface observed the by Daniel K. Inouye Solar Telescope (DKIST). The turbulent convection in these cells creates a source of persistent RV noise on the order of several tens of cm/s. To understand the precise effects of these granules on RV surveys, I use high spectral resolution observations of the Sun to create synthetic spectra with realistic perturbations from granules. This tool, the GRanulation And Spectrum Simulator (GRASS) is available on GitHub.
In addition to granulation, other features in the atmospheres of stars can cause large RV anomalies. These phenomena include sunspots, magnetic network, and plage, among others. To study how these regions and the altered velocity flows therein manifest in RV measurements, I use data from the Solar Dynamics Observatory (SDO) to classify these different regions, and then calculate their contribution to the observed suppression of convective blueshift as a function of limb angle. An example classification image is show at right. You can read the paper now on on arXiv!
Solar System SETI
As part of Jason Wright's graduate course in SETI, I co-authored a paper in which we searched for radio signals transmitted by a hypothetical probe using the solar gravitational lens to aid in communciation across interstellar distances (Tusay and Huston et al. 2022). The observations conducted for this work targeted the antipode of the Alpha Centauri system. In a follow-up work, we show that over 1500 additional archival observations conducted with the Greenbank Telescope were fortuitously pointed at the antipodes of stars within 100 parsecs of the Sun. To facilitate the analysis of these observations, we have tabulated the drift rates and other relevant parameters for searching these data for artificial signals.
The HTML article can be found here; a PDF of this work and a supplemental Jupyter Notebook are available on GitHub.
