Planet Search Around Seven White Dwarfs in the Hyades Cluster Using Kernel Phase Interferometry

The discovery and confirmation of over 5500 exoplanets has revealed the existence of a diverse collection of planetary systems and provided a fuller understanding of planetary formation. The majority of these exoplanets orbit stars that will eventually become white dwarfs (WDs). Very few planets have been discovered around WDs, and none have been directly imaged. This leaves gaps in our knowledge of how planetary systems evolve as stars evolve. Directly imaging planets orbiting WDs poses challenges, as WDs are very faint and the limitations of adaptive optics cause poor ground-based image quality, making it difficult to detect planets orbiting at tight angular separations. While space observatories can offer better image quality, there is a limit to detecting planets at Solar System scales due to the lower angular resolution of these smaller telescopes. We are able to surpass these limitations by utilizing a data processing technique called kernel phase interferometry (KPI). It involves processing images taken using a conventional telescope while modeling the setup as an interferometric array. KPI is able to improve the achievable resolution of a telescope by a factor of several, enabling us to extract information lost in standard detection techniques. We are currently using KPI on archival Hubble Space Telescope data of seven WDs in the Hyades cluster to search for planets that have survived the death of their host star. Applying KPI to this dataset will result in the highest resolution planet search around WDs to date, and it will provide new constraints on post main sequence planetary evolution.