Collaborative Research: A New Kind of Exoplanet Direct Imaging Search: Extreme AO Imaging of Accelerating Stars

University Of Texas At San Antonio, San Antonio TX

Investigators

Abstract

Ground based telescopes with adaptive optics (AO) have now provided direct imaging (DI) detections of about 20 extrasolar gas giant planets. Targets are usually selected based on system properties like age and distance, and these surveys have low yields, about 1%. These detections do not directly measure a planet’s mass and often poorly measure its orbit. This program takes a different approach to exoplanet imaging discovery and characterization, to remedy these aspects. DI survey targets are selected from among young, nearby stars based on their accelerations across the sky, indicating they are being gravitationally pulled by a dimmer companion. The search is expected to discover new exoplanets via two world-class ground-based AO systems located in Hawaii and – due to the selection criterion – measure their masses and constrain their orbits. This project will start a collaborative partnership with Maunakea Visitor’s Center, providing funding for new exhibits that highlight the knowledge about extrasolar planets revealed from Maunakea and the cultural and biological significance of Maunakea. It will support an astronomy-related internship to a student in Hawaii in the Akamai Workforce Initiative. Local to one PI’s institution, the project supports and expands the San Antonio Teachers Training Astronomy Academy, providing effective science education professional development for Texas high school teachers who predominately teach economically disadvantaged and underrepresented minority groups. The dynamical evidence for a companion from precision astrometry is contained in the Hipparcos-Gaia Catalogue of Accelerations (HGCA): i.e., stars showing an astrometric acceleration. The project uses the Subaru Coronagraphic Extreme Adaptive Optics Project (SCExAO) coupled with the CHARIS integral field spectrograph in the near-infrared (near-IR) to discover the perturbing bodies. For the brightest planets and brown dwarfs, analogues to jovian planets, it will also obtain follow-up thermal IR imaging with NIRC2 camera on the Keck II Telescope. The new dynamical code orvara simultaneously constrains the planet’s masses and orbits from these data. The planetary atmospheres are analyzed via empirical libraries and new atmospheric models. These discoveries anchor models of substellar formation and evolution from the largest brown dwarfs to jovian exoplanets. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.