Collaborative Research: Identifying the Best Stars for Direct Imaging Planet Surveys and Performing an Initial Search

About This Grant

Discovering planets orbiting other stars can teach us about how they form, and capabilities now exist to find gas giants orbiting at 5-30AU from their stars (an AU is the distance between the Earth and the Sun), like Jupiter and Saturn do in the Solar System. Unlike commonly employed indirect methods to sense a planet, the technique of infrared direct imaging requires that the planet still glows from its heat of formation. Hence stars that have newly formed, which may be accompanied by newly-formed planets, need to be identified and targeted. Imaged planets can be followed up with spectroscopy to characterize their atmospheres and determine their fundamental properties, and about a dozen have been found to date. Sometimes the youth of nearby stars can be inferred from how they move in groups with other stars, however a very limited number of these stars are currently known. In this work, isolated stars that are less than 1 billion years old will be identified, and their ages determined. Some of those stars will be targeted to search for planets, and the full catalog of stars will be published for follow-on imaging by others. Mentoring programs for undergraduate students in summer research will be done with combination of a traditional in-person mentoring at NMSU and an innovative online experience for a larger number of students at ASU. To produce an all-sky catalog of nearby (<50 parsec), young (<1 gigayear) stars, a combination of multiple spectroscopic and photometric age indicators across a range of spectral types will be interpreted with a robust statistical framework. The team will employ X-ray flux, Gaia-measured space velocity, and TESS-derived rotational periods, then confirm their youth with high resolution optical spectra for lithium abundance, H-alpha emission, and calcium emission. They will also screen the targets for binarity with snapshot Adaptive-Optics observations and radial-velocity monitoring. As the youngest nearby stars are identified, the team will begin a direct imaging planet search with available high contrast AO imagers, including Gemini-North/GPI, LBT/LMIRcam+SHARK, and Subaru/SCEx-AO. Undergraduate researchers will participate in observing runs (in-person or virtually), gain experience in data analysis, and present their results at conferences or in virtual reports/posters at team meetings. Graduate students at both institutions will participate in mentoring. 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.