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by The Kavli Foundation
from
Eurekalert
Website �
This is an artist's impression of the record-breakingly powerful, superluminous supernova ASASSN-15lh as it would appear from an exoplanet located about
10,000 light years
away in the host galaxy of the supernova. � � Record-shattering cosmic blast could help crack the case of
extreme supernova explosions
than a typical supernovae �
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Stunned astronomers have witnessed a
cosmic explosion about 200 times more powerful than a typical
supernova - events which already rank amongst the mightiest
outbursts in the universe - and more than twice as luminous as the
previous record-holding supernova. �
If that statistic does not impress,
consider that this luminosity level is approximately 20 times the
entire output of the 100 billion stars comprising our Milky Way
galaxy. � Given its uncanny brightness and closeness, ASASSN-15lh might offer key clues in unlocking the secrets of this baffling class of celestial detonations.
ASASSN-15lh was first glimpsed in June 2015 by twin telescopes with 14-centimeter diameter lenses in Cerro Tololo, Chile conducting the All Sky Automated Survey for SuperNovae (ASAS-SN), an international collaboration headquartered at The Ohio State University. (Hence ASASSN-15lh's somewhat menacing moniker.) � These two tiny telescopes sweep the skies to detect suddenly appearing objects like ASASSN-15lh that are intrinsically very bright, but are too far away for human observers to notice.
Subo Dong and colleagues immediately put out word about the sighting of ASASSN-15lh in order for as much data as possible to be gathered. �
Multiple, far larger ground-based
telescopes across the globe, as well as NASA's Swift satellite, have
since taken part in an intense observing campaign that continues to
this day. �
By examining this bright, slowly fading
afterglow, astronomers have gleaned a few basic clues about the
origin of ASASSN-15lh. �
This spectrum puzzled the ASAS-SN team
members, for it did not resemble any of spectra from the 200 or so
supernovae the project had discovered to date. � Dong found a close spectral match for ASASSN-15lh in a 2010 superluminous supernova, and if they were indeed of a kind, then ASASSN-15lh's distance would be confirmable with additional observations. � Nearly 10 days passed as three other telescopes, stymied by bad weather and instrument mishaps, attempted to gather these necessary spectra. � Finally, the 10-meter South African Large Telescope (SALT) secured the observations of elemental signatures verifying ASASSN-15lh's distance and extreme potency.
The ongoing observations have further 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 epic explosions so named for lacking signatures of the chemical element hydrogen in their spectra. �
ASASSN-15lh has likewise shown a rate of
temperature decrease and radius expansion similar to some previously
discovered Type I superluminous supernova. �
Type I superluminous supernova seen to
date have all burst forth in dim galaxies both smaller in size and
that churn out stars much faster than the Milky Way. � Exceptionally, however, ASASSN-15lh's galaxy appears even bigger and brighter than the Milky Way. �
On the other hand, ASASSN-15lh might in
fact reside in an as-yet-unseen, small, faint neighboring galaxy of
its presumed, large galactic home. �
With Hubble, Dong and colleagues will
obtain the most detailed views yet of the aftermath of ASASSN-15lh's
stunning explosion. Important insights into the true wellspring of
its power should then come to light. � But ASASSN-15lh is so potent that this compelling magnetar scenario just falls short of the required energies. � Instead, ASASSN-15lh-esque supernovae might be triggered by the demise of incredibly massive stars that go beyond the top tier of masses most astronomers would speculate are even attainable.
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