The Mystery of the Short-lived Firefly
A mysterious object that brightened intensely before fading away
over seven months is unlike anything astronomers have seen before.
The object, known as SCP 06F6, was first spotted in February 2006
during a routine set of observations by the Hubble Space Telescope. No
previous object had been noted at this position of the sky in Bootes,
suggesting that the object is normally too faint to be detected. This
implies that the object brightened by a factor of 120. Supernovae
are known to brighten by this factor, however they usually take around
20 days, compared with this object’s 100 days.
Additionally, its spectrum is somewhat strange – no other similar object has been recorded in the Sloan Digital Sky Survey, which to date has mapped more than a quarter of the sky. The spectrum displays a few spectral lines, but none of them appear to match up with any known elements.
Lead author, Kyle Barbary of the University of California,
Berkeley says, 'Because we can't see anything we recognise in the
spectrum, we can't tell if it's even in the galaxy or in another
galaxy.' Suggestions for this object include a white dwarf within our Galaxy and a very distant (~12 billion light years) supernova.
Barbary doubts the latter explanation, commenting,
'If the transient were more distant than this, we would see signs of
absorption from intergalactic hydrogen in the blue part of the
spectrum.'
Another confusing piece of the puzzle is the fact that the
object’s fading brightness is seen to be at the same rate as its rise,
creating a symmetrical, bell-shaped light-curve. Supernovae usually
have non-symmetric light curves i.e. they fade much more slowly than
they brighten. The researchers intend to re-observe the part of the sky in coming months, hoping that the object re-appears.
