Colloquium on Sep. 14, 2023

Exploring the variety of red transients

Speaker: Yongzhi Cai (YNAO)

Venue: SWIFAR Building 2111

Time: 15:00 PM, Thursday, Sep. 14, 2023

Abstract:

In the era of modern all-sky surveys, the number of transients is increasing at an exponential rate. However, an emerging category shows absolute magnitudes intermediate between Core-Collapse Supernovae (CC SNe) and classical Novae (i.e., -15<Mv<-10 mag). They are usually dubbed as "Gap Transients". In this poorly-known gap, we distinguish them as giant eruptions of massive stars (including luminous blue variables; LBVs), intermediate luminosity red transients (ILRTs), and luminous red novae (LRNe). ILRTs show Type IIP/L-like light curves and Type IIn-like spectra. The progenitor analysis suggests that ILRT precursors are moderately massive (8-15Msun), embedded in dusty cocoons. Electron Capture SN mechanism in super-AGB star is a plausible explanation for ILRTs. LRNe usually display double-peaked light curves and their spectra experience a metamorphosis evolution. The observation of Galactic LRN V1309 Sco provides unequivocal proofs of the final merging event. LRNe are believed to be a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. To date, ILRTs and LRNe are often merely understood phenomenologically rather than based on physical nature. In my talk, I will present the results from our observational campaign of luminous red nova AT 2021biy in the year of 2021/2022 as well as a brief overview of the current observational results on ILRTs and LRNe.

Report PPT:  SWIFAR_Yongzhi Cai.pdf