Tianyu-Search for the Second Solar System and Explore the Dynamic Univers

Giant planets like Jupiter and Saturn, play important roles in the formation and habitability of Earth-like planets. The detection of solar system analogs that have multiple cold giant planets is essential for our understanding of planet habitability and planet formation. Although transit surveys such as Kepler and Transiting Exoplanet Survey Satellite (TESS) have discovered thousands of exoplanets, these missions are not sensitive to long period planets due to their limited observation baseline. The Tianyu project, comprising two 1-meter telescopes (Tianyu-I and II), is designed to detect transiting cold giant planets in order to find solar system analogs. Featuring a large field of view and equipped with a high-speed complementary metal-oxide-semiconductor (COMS) camera, Tianyu-I will perform a high-precision photometric survey of about 100 million stars, measuring light curves at hour-long cadence. The candidates found by Tianyu-I will be confirmed by Tianyu-II and other surveys and follow-up facilities through multi-band photometry, spectroscopy, and high resolution imaging. Tianyu telescopes will be situated at an elevation about 4000 meters in Lenghu, chosen as the premier observation site in China. With a photometric precision of 0.1\% for stars with $V<14$\;mag, and 1\% for stars with $V<18$\;mag, Tianyu is expected to find more than 300 transiting exoplanets, including about 12 cold giant planets, over five years. Assuming coplanarity for solar system analogs and an occurrence rate of 10\% for Earth twins, a five-year survey of Tianyu would discover 1--2 solar system analogs, which could be confirmed by Earth-hunting missions such as Earth 2.0. Moreover, Tianyu is also designed for non-exoplanetary exploration, incorporating multiple survey modes covering timescales from sub-seconds to months, with a particular emphasis on events occurring within the sub-second to hour range. It excels in observing areas such as infant supernovae, rare variable stars and binaries, tidal disruption events, Be stars, cometary activities, and interstellar objects. These discoveries not only enhance our comprehension of the universe but also offer compelling opportunities for public engagement in scientific exploration.