Before telling you about the latest supernova that had been discovered recently, Let me explain what exactly a Supernova is:

A supernova (plural: supernovae) is a stellar explosion. They are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy
before fading from view over several weeks or months. Each explosion
ejects from one to several tens of solar masses at speeds ranging from
thousands to tens of thousands of kilometers per second. The total kinetic energy, 10⁴⁴ joules (2.5 × 10²⁸
megatons of high explosive), is about 100 times the total light output,
making supernovae some of the highest-energy explosions in the
universe. The most recent supernova in our galaxy
has been discovered by tracking the rapid expansion of its remains.
This result, using NASA’s Chandra X-ray Observatory and the National
Radio Astronomy Observatory’s Very Large Array, will help improve our
understanding of how often supernovae explode in the Milky Way galaxy.

The
supernova explosion occurred about 140 years ago, making it the most
recent in the Milky Way. Previously, the last known supernova in our
galaxy occurred around 1680, an estimate based on the expansion of its
remnant, Cassiopeia A.
Finding such a recent, obscured supernova is a first step in making a
better estimate of how often the stellar explosions occur. This is
important because supernovae heat and redistribute large amounts of
gas, and pump heavy elements out into their surroundings. They can
trigger the formation of new stars as part of a cycle of stellar death and rebirth. The explosion also can leave behind, in addition to the expanding remnant, a central neutron star or black hole.

The recent supernova explosion was not seen with optical telescopes
because it occurred close to the center of the galaxy and is embedded
in a dense field of gas and dust. This made the object about a trillion times fainter, in optical light, than an un-obscured supernova. However, the remnant it caused can be seen by X-ray and radio telescopes.

Astronomers
regularly observe supernovae in other galaxies like ours. Based on
those observations, researchers estimated about three explosions every
century in the Milky Way. The tracking of this object began in 1985, when astronomers, used the Very Large Array
to identify the remnant of a supernova explosion near the center of our
galaxy. Based on its small size, it was thought to have resulted from a
supernova that exploded about 400 to 1000 years ago. Twenty-two years
later, Chandra observations revealed the remnant had
expanded by a surprisingly large amount, about 16 percent, since 1985.
This indicates the supernova remnant is much younger than previously
thought.

That
young age was confirmed in recent weeks when the Very Large Array made
new radio observations. This comparison of data pinpoints the age of
the remnant at 140 years - possibly less if it has been slowing down -
making it the youngest on record in the Milky Way. Besides being the record holder for youngest supernova,
the object is of considerable interest for other reasons. The high
expansion velocities and extreme particle energies that have been
generated are unprecedented and should stimulate deeper studies of the
object with Chandra and the Very Large Array. These results are scheduled to appear in The Astrophysical Journal Letters.

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from the Chandra X-ray Center in Cambridge, Mass.