Subjects: Astronomy submitted time 2024-08-20 Cooperative journals: 《天文学报》
FENG Fa-bo
RUI Yi-cheng
DU Zhi-mao
LIN Qing
ZHANG Cong-cong
ZHOU Dan
CUI Kai-ming
OGIHARA Masahiro
YANG Ming
LIN Jie
CAI Yong-zhi
YANG Tao-zhi
PANG Xiao-ying
JIAN Ming-jie
LI Wen-xiong
GUO Heng-xiao
SHI Xian
SHI Jian-chun
LI Jian-yang
GUO Kang-rou
Abstract： 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.
Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
FANG Wen-feng
YAO Song
YU Yong
WANG Lei
SHAN Xing-mei
SHEN Lu-run
WANG Qi
CHEN Zhen-dong
LIN Qing
DU Zhi-mao
YAO Jia-wen
Abstract： The Double-focus One-meter Telescope, located at the Wangshu Observatory of the Shanghai Astronomy Museum, is currently the largest aperture telescope dedicated to popular science in China. The telescope adopts a dual-focus design scheme that allows manual switching between the prime and Nasmyth focus. The Nasmyth focus primarily serves visual observations for popular science, while the prime focus is equipped with a scientific-grade CMOS sensor, offering a field of view of 1.5 ◦ × 1.1 ◦ . The larger field of view is suitable not only for live broadcast events but also for extensive research on various topics such as surveys of novae and supernovae, investigations of small celestial bodies in the solar system, and monitoring of artificial satellites. The astrometric precison at the prime focus of the telescope was analyzed and evaluated based on actual observation data. The results indicate that for star images with a signal-to-noise ratio greater than 5, the repeatability of measured coordinates is better than 0.1 pixel. When the signal-to-noise ratio is 30, the repeatability improves to better than 0.05 pixel. Using the high-precision Gaia DR3 catalog as the reference, the analysis reveals the presence of significant non-linear characteristics in the observation images obtained at the prime focus of the telescope. Consequently, a 3-order model (20-parameter) is necessary for data reduction. For the test observation data, the observational precision for stars brighter than 15th magnitude is approximately 0.05′′ , with the precision decreasing gradually as the magnitude becomes fainter. The observational precision for 17.5th magnitude is around 0.1′′ .
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