时间：2025年2月26日 (周三)
地点：天文大厦三楼大会议室 (#腾讯会议：840-5543-5958)

1. 09:30-10:30 Small Bodies in the Solar System: Insights from Comets, Asteroids, and Interstellar Objects
Abstract: One of the great challenges in astronomy is understanding how planetary systems emerge from protoplanetary disks and how this relates to our own Solar System's formation. In the Solar System, detailed information on planet formation and migration can be obtained by studying small bodies, such as asteroids and comets. In this talk, I will focus on three hot topics in current small body research. First, I will present  multi-wavelength observations of 2I/Borisov, the first confirmed active extrasolar comet observed within our Solar System. Second, I will discuss high-resolution imaging studies of large asteroids using SPHERE/VLT, a second-generation extreme adaptive optics (AO) instrument. I will present SPHERE case studies of asteroids (130) Elektra and (31) Euphrosyne, as well as the physical and dynamical studies of the Euphrosyne family. Lastly, I will present our analysis of the JWST observations of two distant comets, C/2019 O3 and C/2019 E3, which are remarkable for developing a coma well beyond the usual distance where water ice is known to sublimate. Our preliminary results show a surprising diversity in terms of gas production rates and ice absorption features.
Speaker: 杨彬 (杨彬博士是智利迭戈波塔莱斯大学教授，同时也是美国行星科学研究所的高级研究员。毕业于美国夏威夷大学，在加入迭戈波塔莱斯大学前，她曾分别在NASA天文生物学研究所和欧洲南方天文台（ESO）工作。她的研究重点集中在行星系统的形成，尤其是太阳系的形成和演化。她的研究方向涵盖星际天体、太阳系内水的分布与特性，以及天文生物学等领域。她的研究方法是使用最先进的空间的和地面的设备，例如JWST, ALMA和VLT等等。她利用多波段观测，通过研究太阳系小天体（如小行星和彗星）的特性，验证太阳系形成模型。)

2. 10:45-11:45 Rotational and orbital evolution of asteroids under the thermal forces
Abstract: Asteroids are the leftover planetesimals that are the building blocks of planets, offering crucial insights into the history of the solar system. The rotational and orbital distributions of asteroids serve as critical diagnostics for understanding their physical properties and evolutionary pathways. Thermal forces, namely the YORP and Yarkovsky effects, play a fundamental role in shaping the long-term rotational and orbital dynamics of these small bodies. This talk will explore the mechanisms by which thermal forces drive the evolution of asteroids, focusing on how they alter rotational states—such as spin rates and axis orientations—and contribute to the orbital drift of both single and binary systems. Recent advances in observational techniques, combined with progress in theoretical and numerical modeling, have provided new insights into these processes, enabling a deeper understanding of asteroid evolution. Upcoming observation opportunities, such as those offered by Gaia and LSST, promise a golden era for detecting asteroid populations and unraveling their long-term evolution and physical properties.
Speaker: 周文翰 (Dr. Wen-Han Zhou obtained his Ph.D. at the Observatoire de la Côte d’Azur, France and is going to conduct postdoc research at the University of Tokyo as a JSPS fellow. His research interests include the dynamics of small bodies and the evolution of planetary systems. He has published 7 first-author papers in peer-reviewed journals, with an additional paper recently accepted by Nature Astronomy.)

3. 14:00-15:00 The first Saturn Trojan
Abstract: Saturn has long been the only giant planet in our solar system without any known Trojan members. With serendipitous archival observations and refined orbit determination, we identify that 2019 UO14 is a Trojan of the gas giant. However, the object is only a transient Trojan currently librating around the leading Lagrange point L₄ of the Sun-Saturn system in a period of ∼0.7 kyr. Our N-body numerical simulation shows that 2019 UO14 was likely captured as a Centaur and became trapped around L₄ ∼2 kyr ago from a horseshoe coorbital. The current Trojan state will be maintained for another millennium or thereabouts before transitioning back to a horseshoe state. Additionally, we characterize the physical properties of 2019 UO14. Assuming a linear phase slope of 0.06 ± 0.01 mag deg-1, the mean r-band absolute magnitude of the object was determined to be H_r = 13.11 ± 0.07, with its color measured to be consistent with that of Jupiter and Neptune Trojans and not statistically different from Centaurs. Although the short-lived Saturn Trojan exhibited no compelling evidence of activity in the observations, we favor the possibility that it could be an active Trojan. If confirmed, 2019 UO14 would be marked as the first active Trojan in our solar system. We conservatively determine the optical depth of dust within our photometric aperture to be ≲ 10^-7, corresponding to a dust mass-loss rate to be ≲1 kg s-1, provided that the physical properties of dust grains resemble Centaur 29P/Schwassmann–Wachmann 1.
Speaker: 许文韬 (Dr. Man-To Hui is currently an assistant professor affiliated at the State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology. In 2019 he obtained his PhD in planetary sciences from UCLA and thereafter moved to the Institute for Astronomy, the University of Hawaii, where he worked as an NEO Follow-up Fellow until the COVID19 pandemic. To honour his academic achievement, he was honoured with the asteroid naming of (51166) Huimanto by the International Astronomical Union in 2021.)