Most powerful supernova ever seen ‘challenges all known theories’

ASASSN-15lh. It is the name of the brightest exploding star, a super-luminous supernova. It was first spotted in June 2015 (Cerro Tololo, Chile), and has been now described in an article on Science magazine.

The supernova is:

- About 200 times more powerful than a typical supernova.

- More than twice as luminous as the previous record-holding supernova.

- As bright as 570 billion of our suns.

- Some 20 times as luminous as the entire output of the 100 billion stars of our Milky Way galaxy.

The lead author of the newly released study, astronomer Subo Dong at the Kavli Institute for Astronomy and Astrophysics at Peking University. 

In a statement, he said: “ASASSN-15lh is the most powerful supernova discovered in human history.”

“The explosion’s mechanism and power source remain shrouded in mystery because all known theories meet serious challenges in explaining the immense amount of energy ASASSN-15lh has radiated.”

“The honest answer is at this point that we do not know what could be the power source for ASASSN-15lh. [It] may lead to new thinking and new observations of the whole class of super-luminous supernova,” added Dong.

Before and during supernova ASASSN-15lh. / B. Shappee and the ASAS-SN team.

The Kavli Institute statement followed: “The record-breaking blast is thought to be an outstanding example of a ‘superluminous supernova,’ a recently discovered, supremely rare variety of explosion unleashed by certain stars when they die.”

“Scientists are frankly at a loss, though, regarding what sorts of stars and stellar scenarios might be responsible for these extreme supernovae.”

MANY OPEN QUESTIONS STILL

Ongoing observations have revealed that ASASSN-15lh bears certain features consistent with hydrogen-poor (Type I) superluminous supernovae, which are one of the two main types of these explosions, EarthSky.org explained.

ASASSN-15lh has also shown a rate of temperature decrease and radius expansion similar to some previously discovered Type I superluminous supernova.

In other ways, ASASSN-15lh stands apart. It’s not just brighter, but also hotter, than most Type I supernovae.

And astronomers have questions about the supernova’s home galaxy. Most Type I supernovae have been seen in small, dim galaxies, and astronomers had contemplated the idea that the smallness and dimness of a galaxy might somehow be connected this these sorts of events.

But ASASSN-15lh’s galaxy appears bigger and brighter than our Milky Way. On the other hand, it’s also possible that ASASSN-15lh might not reside in the galaxy astronomers identify with it. It might reside instead in small, faint, as-yet-unseen galaxy.

OTHER IMAGES FROM THE UNIVERSE, TAKEN BY THE NASA: