New exoplanet detection program for citizen scientists

The SETI Institute and its partner Unistellar are launching a new exoplanet detection program that will engage citizen scientists worldwide. Amateur astronomers, using either Unistellar’s eVscope or another telescope, are invited to help confirm exoplanet candidates identified by NASA’s Transiting Exoplanet Survey Satellite (TESS) by observing possible exoplanet transits from Earth .

Most known exoplanets have been discovered using the transit method, most notably by the Kepler mission and now TESS. A transit is when a planet passes between its star and the observer, who sees the star eclipse as the planet orbits. The demand for follow-up observations of passing exoplanets is greater than ever. There are currently more than 5,100 confirmed exoplanets, and thousands more discoveries have yet to be confirmed. This program will focus its efforts on exo-Jupiters discovered by these NASA missions.

Some estimates suggest that TESS will identify more than 10,000 candidate exoplanets. Follow-up observations are essential for unconfirmed exoplanets to determine if the candidates are false positives, such as those caused by eclipsing binaries or low-mass stellar transits. Regular reobservations by ground-based systems are necessary for confirmed planets to keep their orbital ephemeris updated. The potential for citizen scientists to contribute to exoplanet research is high and has exciting implications for STEM education.

The opportunities for amateur astronomers to observe their collected data and contribute to exoplanet research or education have been largely unattainable. High costs and a high level of technical expertise required to operate, build or operate observation devices are barriers. The Unistellar Exoplanet Campaign offers professional mentoring and curated goals. It can make meaningful contributions to exoplanet research (e.g. photometric data to monitor transit times and confirm traditional and long-period exoplanets) while involving lay people and students in this exciting work.

One of the new network’s most recent achievements is the discovery of the TESS planet candidate named TOI 1812.01. TOI 1812 is a strange multi-planet system first discovered by TESS. It is 563 light-years from Earth and consists of three gaseous planets: a 3-Earth-radius sub-Neptune planet in an 11-day orbit, a 5-Earth-radius sub-Saturn planet in a 43-day orbit, and an outer one 9- Earth radii Saturn-sized planet (TOI 1812.01) on a previously unrestricted orbit.

Three gaseous planets with such a large radius range make TOI 1812 an ideal system for understanding how giant planets form and migrate. Additionally, due to the cool temperature of host star K2V, TOI 1812.01 is less than twice as irradiated as Earth and could even be an exciting target for future exomond searches.

However, the missing piece of the puzzle that precludes further characterization was the unknown orbital period of TOI 1812.01. TESS observed two 8-hour transits of this planet, separated by a sizeable data gap that left a number of aliases as possible orbital periods. Sparse radial velocity data and statistical analysis highlighted the three most likely orbital periods: 71 days, 87 days, or 112 days.

These three possibilities corresponded to three possible transit windows in July and August 2022. The network observed each window, each requiring transcontinental campaigns. Across the three windows we had 27 datasets contributed by 20 astronomers from seven countries.

The network successfully excluded transits during the first two windows. It detected the transit exit (end) during the third window on August 27, 2022 and confirmed the orbital period of 112 days.

This effort demonstrates the Citizen Science Network’s unique ability to contribute to the recovery of orbital ephemeris of extremely valuable long-period, long-transit exoplanets such as TOI 1812.01. This work, including the unistellar observations, is being prepared for manuscript to formally confirm the nature of the exoplanetary system and will be presented at the IAC in Paris on Tuesday September 20th.

“Observing exoplanets like TOI 1812.01 as they transit or pass by their host stars is a critical component in confirming their nature as true planets and ensuring we are able to study these planetary systems in the future,” said Paul Dalba, SETI Institute Research Scientist and 51 Pegasi b Fellow of the Heising-Simons Foundation. “The specific characteristics of this planet, namely its long orbit and long transit time, place it in a category where a globally coordinated citizen science such as the Unistellar Network can be extremely effective.”

“This early success demonstrates the power of putting science directly in the hands of people; a core principle of this partnership between the SETI Institute, Unistellar and NASA,” added Tom Esposito, research assistant at the SETI Institute and space science director at Unistellar. “Citizen astronomers around the world coming together to educate humanity about new planets being discovered so many trillions of miles away is, quite simply, amazing.”