CAG/NTNU seminar 10/Jul/2025 12:20 S801

Dear all,

There will be a seminar at CAG/NTNU next Thursday noon given by Dr. Franticek Dinnbier, a new postdoctoral fellow at the NCTS. He works on N-body simulations of stellar clusters. I would like to invite you to take this chance to make his acquaintance if you are interested in related studies.

Best regards, Yueh-Ning Lee, on behalf of CAG/NTNU #

Venue: NTNU Gongguan campus S801

*Speaker: *Frantisek Dinnbier (NCTS)

*Title: *Open star clusters as live dynamical systems

Abstract:

Most if not all stars form in open star clusters or associations. Although open star clusters have been studied for more than a century, the high accuracy of Gaia mission opens a new window on these objects, discovering a large number of new open clusters as well as facilitating much better comparison with numerical models than previously possible. Shortly after their formation, massive stars terminate the star formation event by expelling the star forming gas. The rapid movement of the gaseous mass often has a strong impact on the dynamics of stars in the cluster. After gas expulsion, the cluster evolves mainly due to energy equipartition, mass segregation, stellar evaporation and ejection as well as the tidal field imposed by the Galaxy. From these dynamical processes, we will pay particular attention on two topics: gas expulsion, and dynamical evolution of orbital parameters of binary stars as they encounter other cluster members with emphasis on stars of spectral type B and Cepheids. We will discuss the properties of tidal tails forming around open star clusters as the consequence of early gas expulsion as well as of dynamical evaporation. We also suggest that the typical configuration for B star formation is likely in hierarchical triples, not binary stars as usually assumed.

– Yueh-Ning Lee Associate Professor, Department of Earth Sciences, National Taiwan Normal University https://www.es.ntnu.edu.tw/index.php/en/index_en/ Deputy Director, Center of Astronomy and Gravitation https://www.cag.ntnu.edu.tw/index.php/en/main/ Tel: +886-2-7749-6417 李悅寧 國立台灣師範大學 地球科學系 副教授 天文與重力中心 副主任