A supernova obviously. But what made the supernova? Thermonuclear supernovae are very well studied. They have even been used to measure the expansion of the universe. But we still don’t know what these supernovae come from. We have found that the youngest supernova in the galaxy, SNR G1.9+0.3, was made by the merger of two white dwarfs. Read more at the NASA press release:
Or our article:
A diverse range of engines power supernovae.
National Radio Astronomy Observatory (NRAO) and Harvard-Smithsonian Center for Astrophysics (CfA) have released a joint press release about our resent work on SN 2012ap. It is the first supernova with relativistic decelerating ejecta but with no GRB associated with it.
Astronomers using the National Science Foundation’s Very Large Array (VLA) have found a long-sought “missing link” between supernova explosions that generate gamma-ray bursts (GRBs) and those that don’t.
Read more about it at:
https://public.nrao.edu/news/pressreleases/supernova-missing-link
and
https://www.cfa.harvard.edu/news/2015-13
Or read our paper at:
Sayan Chakraborti 