MEXICO: In 2009, a very bright flash of light was caught by the ROTSE IIIb telescope, sparking confusion as to its origin. Now, a paper in The Astrophysical Journal proposes that the event was the death throes of a star being swallowed by a black hole. However, the consumption is proving unusually difficult for the black hole.
On January 21, 2009, the ROTSE IIIb telescope at McDonald caught the flash of an extremely bright event. The telescope’s wide field of view takes pictures of large swathes of sky every night, looking for newly exploding stars as part of the ROTSE Supernova Verification Project (RSVP). Software then compares successive photos to find bright “new” objects in the sky – transient events like the explosion of a star or a gamma-ray burst.
With a magnitude of -22.5, this 2009 event was as bright as the “superluminous supernovae” (a new category of the brightest stellar explosions known) that the ROTSE team discovered at McDonald in recent years. The team nicknamed the 2009 event “Dougie,” after a character in the cartoon South Park. (Its technical name is ROTSE3J120847.9+430121.)
The team thought Dougie might be a supernova, and set about looking for its host galaxy (which would be much too faint for ROTSE to see). They found that the Sloan Digital Sky Survey had mapped a faint red galaxy at Dougie’s location. The team followed that up with new observations of the galaxy with one of the giant Keck telescopes in Hawaii, pinpointing the galaxy’s distance at three billion light-years.
These deductions meant Dougie had a home – but just what was he? Team members had four possibilities: a superluminous supernova; a merger of two neutron stars; a gamma-ray burst; or a “tidal disruption event” – a star being pulled apart as it neared its host galaxy’s central black hole.
