In January of 2014, an incredibly bright supernova illuminated the night sky. The star responsible for this light show was located in the Cigar Galaxy (also known as M82), and is located about 12-million light-years from Earth.
The supernova, named SN 2014J, grew to a peak brightness that actually challenged it's host galaxy, that is to say, the supernova from a single star was nearly as bright as all of the light from the galaxy combined. It was easily visible to amateur astronomers (and actually discovered by an astronomy workshop at the University College London Observatory).
The supernova was classified as a Type Ia. Long story short, Type Ia supernovae happen when a white dwarf, which has been slowly siphoning material off of its companion star, finally reaches a certain mass and eventually explodes. When SN 2014J lit up the sky, telescopes and observatories from all over the world (and in orbit around it) trained their gaze on that point of light. One of the most interesting observations comes from the Chandra X-ray observatory, which saw nothing at all.
Our current models governing the behavior of Type Ia supernovae predict a torrent of X-rays. Since Chandra didn't see any X-rays, astronomers are left with a puzzle to solve. In addition to the lack of X-rays, astronomers found the area around SN 2014J was very clean, basically devoid of other gases. If the white dwarf was siphoning material from a companion star, we'd expect to see a lot more debris around the supernova. At the moment, it's hypothesized that the white dwarf might have had a series of smaller eruptions that cleared the area before it detonated. Another hypothesis suggests this event was really the merging of two white dwarfs. Observations of the area over the next few years will help up to solve the mystery as we seek to understand our universe a little better.