Star Light, Star Bright, Its Explanation is Out of Sight
January 6th, 2009
This pair of NASA Hubble Space Telescope pictures shows the appearance of a mysterious burst of light that was detected on February 21, 2006, brightened over 100 days, and then faded into oblivion after another 100 days. The source of the outburst remains unidentified. The event was detected serendipitously in a Hubble search for supernovae in a distant cluster of galaxies. The light-signature of this event does not match the behavior of a supernova or any previously observed astronomical transient phenomenon in the universe. Astronomers do not know the object's distance, so it can either be in our Milky Way galaxy or at a great astronomical distance. The optical spectrum of the object contains absorption features that have not yet been identified. This may represent a previously undetected class of transient phenomenon in the universe. Credit: NASA, ESA, and K. Barbary (University of California, Berkeley/Lawrence Berkeley National Lab, Supernova Cosmology Project)
(PhysOrg.com) -- A mysterious flash of light from somewhere near or far in the universe is still keeping astronomers in the dark long after it was first detected by NASA's Hubble Space Telescope in 2006. It might represent an entirely new class of stellar phenomena that has previously gone undetected in the universe, say researchers.
Astronomers commonly observe intense flashes of light from a variety of stellar explosions and outbursts, such as novae and supernovae. Hubble discovered the cosmic flash on February 21, 2006. It steadily rose in brightness for 100 days, and then dimmed back to oblivion after another 100 days.
The rise and fall in brightness has a signature that simply has never been recorded for any other type of celestial event. Supernovae peak after no more than 70 days, and gravitational lensing events are much shorter. Therefore, this observation defies a simple explanation, reports Kyle Barbary of the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, Calif. He is describing the bizarre Hubble observation at the 213th meeting of the American Astronomical Society in Long Beach, Calif. "We have never seen anything like it," he concludes.
The spectral fingerprints of light coming from the object, cataloged as SCP 06F6, also have eluded identification as being due to any specific element. One guess is that the features are redshifted molecular carbon absorption lines in a star roughly one billion light-years away.
But searches through various astronomical survey catalogs for the source of the light have not uncovered any evidence for a star or galaxy at the location of the flash. The Supernova Cosmology Project at LBNL discovered it serendipitously in a search for supernovae.
Hubble was aimed at a cluster of galaxies 8 billion light-years away in the spring constellation Bootes. But the mystery object could be anywhere in between, even in the halo of our own Milky Way galaxy.
Papers published by other researchers since the event was reported in June 2006, have suggested a bizarre zoo of possibilities: the core collapse and explosion of a carbon rich star, a collision between a white dwarf and an asteroid, or the collision of a white dwarf with a black hole.
But Barbary does not believe that any model offered so far fully explains the observations. "I don't think we really know what the discovery means until we can observe similar objects in the future."
All-sky surveys for variable phenomena, such as those to be conducted with the planned Large Synoptic Survey Telescope, may ultimately find similar transient events in the universe.
Provided by Hubble Centre
Mar 23, 2009 |
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While the majority of lensing events can be short rare longer ones are certainly possible, after all the duration only depends on the relative velocities of objects. The steady rise and fall of brightness seems to support lensing, first the object moves into focus then out of it, finally the irregular shape at the photo also can be seen as supporting this.
I don't seriously believe this, and agree that lensing is the most likely (known) coause, but aliens can't be ruled out.
Possibly LGM.
Lensing could be. Superhuman said that lensing could be longer because of the velocities of the galaxies. I don't really agree. The angle needed to focus the star in our telescopes is very sensitive. Any deviation due to speed (our own and that of the lensing galaxy and the one we see behind that one) will have a huge effect on the way wee see it. So I tend to agree with the article that Lensing couldn't be it (but to be honest, I can't rule it out completely either).
We also have to keep in mind that collissions could be an answer. After all, the universe is so immensly fast, what we have seen is smaller than what we haven't seen. I think this is indeed a not yet recorded event that we will see more often in the future (yes, also when this is alien life that enjoys blowing up suns for example. Once you have done the first I can imagine you want to do another).
My point is that longer lensing is certainly possible and shouldn't be outright dismissed based on the fact that we only registered short lensing events so far. Nothing prevents longer events from taking place, they are only less probable.
The better synchronized the velocities of 2 objects on the opposite sides of the lensing mass the longer the event. Yes, the focus is very sensitive but there are also countless stars and galaxies to choose from so there does not seem to be an easy way to estimate how common it might be.
We would need to have such an estimate - probability of lensing events as a function of their duration to say something more definitive but I suspect we haven't observed the Universe long enough to determine it though I might be wrong on this. (It might also be possible to model this function based on mass distribution in the Universe but it would still have to be confirmed experimentally)
Also I can't see how there is such an increase in the amount of light between the before and after photos if it's down to gravitational lensing, which can, after all, only enlarge the image, not increase the quantity of light.
I suppose that if there were a dust cloud that masked the light completely and then the lens moved into position so that it refracted all the light around the cloud, you could get an increase in light. Seems an extremely unlikely arrangement though.
I think you are right to say that lensing could not (in that extend) increase the light. It would have to be some other phenomenon (but it could be made visible by lensing and all the moving objects etc...)
But even as something is extremely unlikely, but will happen very often in such a large galaxy. The fact that it is probably the first time we have seen it, contributes to the fact that is unlikely.