From the solar corona to stellar coronae

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 Time:  Thursday, November 25, 2021, 02:00pm
 Title:  From the solar corona to stellar coronae
 Speaker:  Prof. Hui Tian (PKU)

S727 & Online via Zoom


As the outermost layer of the solar atmosphere, the corona plays a key role in shaping the plasma and magnetic field environment of the solar system. The quiescent corona has a temperature of about one million Kelvin, and it remains unclear what physical mechanisms heat the coronal plasma to such a high temperature. Occasionally, a large amount of energy is explosively released in the corona, resulting in solar flares and coronal mass ejections that could significantly disturb the Earth space environment. Both coronal heating and coronal eruptions are governed by the magnetic field. However, the coronal magnetic field is extremely difficult to measure. By observing the pervasive propagating transverse MHD waves in the corona, we have recently mapped the global magnetic field of the corona for the first time. Here I will briefly introduce this result. I will also discuss how to extend the observing strategies and analysis methods for the solar corona to the research field of stellar coronae. In recent years, more and more researchers realize that the XUV and particle radiation produced by various types of magnetic activity in the stellar coronae could affect the habitability of exoplanets by changing the composition and leading to erosion of the planetary atmospheres. Thus, it is most important to effectively monitor the host stars' coronae and their activity. To achieve this goal, we need to build advanced host star-dedicated EUV and X-ray (1-350 Å) telescopes, to perform long-term and continuous observations of the nearby host stars of potentially habitable exoplanets. Such observations are crucial for a precise evaluation of the impact of stellar activity on the habitability of exoplanets.

Dr. Hui Tian obtained his Ph.D. from Peking University in 2010. From 2010 to 2012 he was an ASP Postdoc Fellow at the National Center for Atmospheric Research, USA. Then he served as an astrophysicist for more than three years at Harvard-Smithsonian Center for Astrophysics. He returned to China in 2015, and is now a professor at Peking University. He also serves as the director of the Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences. Dr. Tian is mainly working on solar physics, and his research interests include solar atmospheric dynamics and stellar magnetic activity. He is a Co-Chair of the "Atmospheric Heating" science working group of ESA’s Solar Orbiter mission, and a member on the Steering Committee of the Coronal Solar Magnetism Observatory, USA. He received the Harvey Prize from the Solar Physics Division of the American Astronomical Society in 2020.

Host: Sharon Xuesong Wang