Universe’s most intense supernova was 50 times brighter than the Milky Way

Jin Ma/Beijing Planetarium

Universe’s most luminous supernova was 50 times brighter than the Milky Way

Kaboom! Astronomers have found the most violently explosive supernova so far detected in the history of the universe. Supernovae are already some of the brightest events out there but in recent decades astronomers have seen a rare new class of blasts, superluminous supernovae (SLSNe)—sometimes dubbed hypernovae. The new discovery was spotted last June by the All Sky Automated Survey for SuperNovae (ASAS-SN), a system of eight small 14-centimeter telescopes at two sites in Chile and Hawaii that can scan the entire sky every 2 to 3 days. At its peak, ASAS-SN-15lh, as the new supernova is known, was twice as luminous as any previously seen, thousands of times brighter than a normal supernova, and outshone our entire Milky Way galaxy by 50 times. (The artist’s impression above shows what it would look like from an exoplanet 10,000 light-years away in its home galaxy.) But, as the ASAS-SN team describe online today in Science, more detailed study of the object and its surroundings with larger telescopes is confounding theorists. ASAS-SN-15lh appears to fall into a class called a hydrogen-poor SLSN which theorists believe occurs when an old star, run out of fuel, creates a supernova blast while collapsing into a highly-magnetized neutron star, known as a magnetar. The magnetic energy from the magnetar—so the theory goes—then powers up the still-expanding supernova making it unusually bright. However, this sort of SLSN is expected to form in small, dim dwarf galaxies full of young stars but ASAS-SN-15lh is in a large, bright galaxy with little star formation. So, back to the drawing board. 

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