The Tierras Observatory: An Ultra-precise Time-series Photometer to Characterize Nearby Low-mass Stars and Their Terrestrial Exoplanets

A team led by Harvard University will perform a three-year survey of nearby small stars in pursuit of additional planets that are too small or too cool to be found by previous space- or ground-based programs. The team will also monitor known planets with long orbital periods to search for moons or systems of rings. The team will undertake a long term campaign to determine the rotation periods of low-mass stars (with 10-30% the mass of the Sun) in a volume complete sample. The project will provide training opportunities for students and fellows and will also enable research by scientists who do not have access to large research telescopes. The team will provide engagement materials and grow viewership of their YouTube channel. Middle and high school students from the US-Mexico border towns of Rio Rico and Nogales, AZ, will visit the telescope and engage in activities to learn about the search for planets and the design of telescopes. Although the study of exoplanets has seen dramatic advances in the past decade, the analogs of many of the denizens of our own Solar system remain beyond the grasp of our current observatories. Most of the known terrestrial exoplanets are significantly larger than the Earth, and, with a few notable exceptions, it remains an open question whether Mars and Mercury-sized worlds are a commonplace. No analogs of the Galilean satellites, or our Moon, or circumplanetary rings has yet been discovered to orbit an exoplanet. Time-series photometry is a path to significant progress on these questions. The Tierras Observatory is a refurbished 1.3-m ultra-precise fully-automated photometer located at the F.L. Whipple Observatory atop Mount Hopkins, Arizona. Tierras is designed to regularly achieve a photometric precision of 250 parts-per-million on a time scale of both 10 minutes and across an observing season. The observatory is now operating in science mode and regularly achieving its design photometric precision. Tierras is ready to undertake a three-year survey to detect temperate terrestrial planets as small as Mercury and search for exo-satellites. Additionally, by measuring the undetected rotation periods of low-mass stars, Tierras will also elucidate the irradiation environment of their attendant 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.