演講資訊

摘要：

Intermediate-mass stars (2-8 M_☉) display a broad distribution of rotation rates and have drawn attention following the discovery of extended main-sequence turnoffs in young and intermediate-age clusters. The rapidly and slowly rotating stars preferentially populate the redder and bluer regions of the main sequence, respectively. This makes the upper main sequence regions of clusters’ color-magnitude diagram appear broader compared to other evolutionary sequences. However, additional effects such as differential reddening can also contribute to this broadening, complicating the interpretation and calibration of stellar rotation models. While fast rotation is expected for stars with radiative envelopes, the origin and frequency of the slow-rotating population remain unclear. Proposed mechanisms include tidal synchronization in binaries, mergers, and star-disk interactions during the pre-main-sequence phase. In the first part of the talk, I will discuss our recent work on (i) the classification of clusters into different categories based on the distribution of slow and fast rotators and (ii) the fraction of slow rotators among intermediate-mass stars. In the second part of the talk, I will discuss the early spin-down pathways of intermediate-mass stars, using the massive star-forming cluster Trumpler 14 as a case study.