In a particularly stunning example of the Einstein Cross, astronomers have discovered a supernova that can be observed again and again. Gravitational lensing effects result in the light from the stellar explosion taking 4 different routes, each route taking a different amount of time to reach Earth. The star SN Refsdal is/was 9.3 billion light years from Earth, while the lensing galaxy cluster MACS J1149.6+2223 sits a little closer at 5 billion light years distant.
While this isn't the first example of the Einstein Cross effect proposed in 1969, it is the first example of a supernova being viewed through one.
The full paper is available on Sciencemag.org for a fee, but Physics World has an adequate summary of the discovery.
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Einstein Cross Shows Us the Same Supernova Explosion Four Times
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(Score: 5, Informative) by Justin Case on Saturday March 07 2015, @01:35PM
A common question is if the light rays are being distorted by an intermediate mass why isn't the image a ring?
The best answer I've seen is here:
https://physics.stackexchange.com/questions/14056/how-does-gravitational-lensing-account-for-einsteins-cross [stackexchange.com]
tl;dr: the lens is a galaxy, not a point, so the distortion is not symmetrical. Plus math and dark matter, woo-hoo!
(Score: 5, Interesting) by dx3bydt3 on Saturday March 07 2015, @01:58PM
When the initial discovery of this back in November was posted here [soylentnews.org] I commented on the possibility of the known luminosity being useful.
What could be even more cool is that this might not only be the first gravitationally lensed supernova discovered, but it also might be a different type of supernova than any we've seen before. According to a National Geographic article [nationalgeographic.com]:
"the spectrum of light from the explosion doesn't match any of the known types of supernovae. Scientists' best guess right now is that it's a peculiar type of core-collapse supernova, similar to one that went off in 1987 in the Large Magellanic Cloud. It's also possible that nine billion years ago, stars were following a slightly different set of rules. The younger universe contained fewer metals, scientists say, and the stars grew bigger and died faster. So it's not inconceivable that supernovae behaved differently, too."
(Score: 4, Funny) by pkrasimirov on Saturday March 07 2015, @02:19PM
It seems the news also go via Einstein Cross. That's okay because I didn't get it the first time. Much like some memes.
P.S. Did you hear about the ice bucket challenge yet?
(Score: -1, Offtopic) by Anonymous Coward on Saturday March 07 2015, @02:26PM
I took the ice bucket challenge. I soaked my scrotum in a bucket of ice water until it turned blue, like my friends challenge me to. It hurt a lot. I still don't understand how I helped fight cancer, but whatever. I did my part in this battle against a deadly killer.
(Score: 3, Interesting) by Anonymous Coward on Saturday March 07 2015, @02:20PM
Partial core collapses are known to give of different wave lengths of light, and dispersal patterns that are different from total core collapses.
A common misconception among amateurs is that supernova occurrence involves an "explosion" or "expansion" at first. The evidence today suggests it's the opposite. There is a partial or total core collapse of the star. The immense pressure and forces result in a supercriticality forming within the star. Basically a smaller, newer, denser, gravitationally-stronger star begins to form somewhere within the core of the existing star.
This new star formation, depending on where it occurs, can have different effects upon its host star. If it happens within the host star's core, we see a traditional full-body collapse take place. The entire host star collapses in onto the new star. This additional influx of matter is what leads to the eventual expansion of a supernova. It's quite a complex process, but it basically involves the matter separating at the quark level. This releases tremendous energy, which overcomes that of the gravitational forces present in the collapsed star. It's at this point that it expands, shooting out quarks. Very shortly after, these quarks will being to recombine into the elements we're familiar with.
A partial core collapse involves the supercriticality of this new star not forming fully within the core of the existing star, but somewhere along the edge of the core. Now in a star that's millions of miles in diameter, this region is quite massive. Only part of the host star collapses into the supercriticality of the new star. The loss of matter causes the remainder of the host star to lose integrity. This loss of integrity allows additional smaller supercriticalities to form, each attracting some of the matter from the host star. The final result is several smaller, weaker supercriticalities surrounding the larger, stronger initial supercriticality. Eventually the largest supercriticality will collapse and release its matter in the form of quarks, which will proceed to destroy the weaker supercriticalities.
My personal belief is that the patterns we're seeing in this case are the stronger supecriticality, surrounded by the smaller weaker supercriticalities that formed due to a partial core collapse of the host star.
(Score: 3, Funny) by lentilla on Saturday March 07 2015, @05:33PM
That's right folks, it's Cosmic Groundhog Day.
(Score: 0) by Anonymous Coward on Sunday March 08 2015, @12:39PM
there's probably more gavitational lensing then not. considering that most light sources ARE massive globes of fuseing hydrogen.
furthermore we lack the sensitivity to detect so most lensing goes unnoticed.
i would wager that a regular flashlight pointed straight up into the night sky will lense back (see above) abit like the badly hit golf ball on the moon that will hit the back of your head : )