What exactly is the object recently discovered by the Hubble Space Telescope’s Advanced Camera for Surveys in the constellation Boötes? If it’s a supernova, it’s an odd one, since it took five times longer (100 days) to reach peak brightness than a normal supernova. In fact, indications are it brightened by a factor of more than 200 since late January. As discussed in a June 19 New Scientist story, its spectrum is unusual, its color has not changed since the first observations came in, and it does not seem to be situated in a host galaxy.
If distance measurements of 5.5 billion light years are accurate, it is also brighter than a Type 1A supernova should be at that distance. Then again, redshift uncertainties make the distance readings problematic. An unusual supernova at a far greater distance, perhaps as much as 12 billion light years? Nobody knows at this point.
The object was flagged by the Supernova Cosmology Project headquartered at Lawrence Berkeley National Laboratory, an online library of whose papers and presentations can be found here. An image and finding chart are also available online (look under ‘Unidentified Transient F-006,’ and thanks to Larry Klaes for the pointer). In the context of our recent discussions of macro-engineering and SETI — and in hopes of discovering a new class of stellar object — it goes without saying that this find will receive scrutiny from many different quarters.