Abstract Details

Name: Nand Kumar Chakradhari
Affiliation: Pt. Ravishankar Shukla University, Raipur
Conference ID: ASI2020_84
Title : A glimpse of Thermonuclear Supernovae
Authors and Co-Authors : N. K. Chakradhari, D. K. Sahu and G. C. Anupama
Abstract Type : Invited
Abstract Category : Extragalactic Astronomy
Abstract : Thermonuclear Supernovae also known as Type-Ia Supernovae (SNe Ia) are identified by the presence of Si II 6355 angstrom absorption feature in their optical spectra taken around peak brightness. They are believed to be thermonuclear explosions of a white dwarf (WD) either accreting matter from its companion or merging with another WD in a binary system. Majority of them, known as ‘normal’ SNe Ia form a remarkably homogeneous class. Their light curve properties such as post-peak decline in the light curve, the shape of the light curve and the stretch parameter etc. are found to be correlated with their luminosity. This correlation has made SNe Ia very important astronomical objects to use them as standard candles for distance estimation. Furthermore, the high luminosities of SNe Ia enable us to see them at great distances in the Universe. SNe Ia have been used to measure the cosmic expansion history, leading to the discovery of accelerating Universe. However, with so much of advancement, the detailed explosion mechanism and the nature of progenitors are still under investigation. Though, it appears fairly clear that SNe Ia arise from explosion of WD, it is still unclear whether they all come from the same or different channels. One way to understand this is to look for the observational signatures. The recent development in the observational facilities has improved SNe Ia statics. With growing statics, deviation from the observed homogeneity and the occurrence of peculiar and exceptional events are also seen. Extremely luminous ‘super-Chandra’ SNe Ia are among them. Luminosity determination requires an accurate estimate of reddening suffered by SNe Ia. Several studies have suggested lower values of total-to-selective extinction than its canonical value of 3.1 towards SNe Ia in their host galaxies. Hence one should be careful when these objects are being used as distance indicators.