This year, we celebrate the 100th anniversary of the first publication of Einstein's greatest masterpiece, the General Theory of Relativity. Now astronomers using the Hubble Space Telescope have found a remarkable quadruple image of a distant exploding star which helps confirm another of that theory's most "far out" predictions.
The General Theory connects space, time, and gravity in mind-boggling ways. Strong gravity can actually warp (or bend) space and distort the flow of time. One example of gravity strong enough to do this is a dense cluster of galaxies, like the one shown on our image. Everything on this Hubble picture that is not a point of light (everything with a shape) is a galaxy of billions of stars. The cluster contains many such galaxies orbiting a common center.
Light from more distant objects behind the cluster has to go through the strong gravity of the cluster on its way to us. Einstein's theory predicts that as gravity warps space, the light from behind the cluster will have to travel through that warped space and will get twisted and bent in eerie ways. From the right angle, a single beam of light can be split into four similar images, something called an "Einstein Cross." That's just what you see in the inset on the picture.
Most amazingly, the four images of the exploding star took slightly different amounts of time to get to us through that warped space, and so we are seeing the same explosion at four different time periods. By studying the details of such complex "gravitational lenses" (as the distortion by the galaxy cluster is called), astronomers hope to learn more about how all the "stuff" in those galaxies is distributed and how much of it is regular matter and how much is dark matter.
The galaxy cluster only has a catalog number, not a name, but we know it is about 5 billion lightyears away (meaning light, traveling at the fastest permitted speed in the universe, took five billion years to reach us.) The exploding star appears to be four billion lightyears further than that -- meaning we are seeing its light from 9 billion years ago. The only reason we can see it at all is that the gravity of the galaxy cluster actually intensifies the light as well as splitting it -- just as Einstein's theory predicts.
What a wonderful image with which to celebrate the 100th anniversary of a theory that Einstein's called "the happiest thought of my life!"
(Click on the image to see it bigger -- believe me, it's worth it!)
For those of you who don't get to see fireworks today (July 4), here is an image of cosmic fireworks for your enjoyment. The glowing ring on our picture (taken with the Hubble Space Telescope) shows material ejected long ago from a star whose total explosion we saw in 1987. Recently, earlier debris from the star has been hit by the fastest moving material from the star's final explosion. The shock of collision has set knots of thicker material in the ring to glow like a necklace of sparklers.
The dramatic explosion at the end of the life of a star is called a "supernova," and this particular supernova is located in one of our closest neighbor galaxies, the Large Magellanic Cloud, about 168,000 light years away. We wish it were closer, but a visible supernova is a rare event. This was actually the first supernova explosion we have been treated to since the invention of the telescope in 1609-1610. It's been given the extremely clever name Supernova 1987A (the first such explosion seen in 1987.)
The huge star whose explosion we saw in 1987 had been losing some of its mass in earlier periods of its life and was surrounded by a cloud of its own debris. Later a wind of hot particles had blown from the star as it went through a different stage of its development. That wind had made a cavity in the gas around the star.
Now the material from the star's actual explosion, which has been moving for 27 years at great speed, has reached the inner walls of this cavity and is colliding with thicker blobs of the older material. That's the glowing ring we see so clearly in the Hubble image.
If you want to see a time lapse movie made of Hubble images taken each year as the ring started lighting up, you can see it at:
http://en.wikipedia.org/wiki/SN_1987A#mediaviewer/File:SN1987a_debris_evolution_animation.gif
Happy fireworks day!
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The big news from the world of astronomy is that a star has blown itself to pieces in a galaxy not so far, far away. The galaxy has the catalog number M82, and is only between 11 and 12 million light years away. (The nearest independent galaxy is a bit more than 2 million light years away, so, as galaxies go, M82 is one of our neighbors.)
M82 is located in the constellation of Ursa Major (the Big Bear), the same constellation that contains the well-known star pattern called the "Big Dipper." That means it is an easy target for telescopes in the Northern Hemisphere of our planet right now. Both amateur and professional astronomers are glued to their instruments, viewing and analyzing this doomed star.
Our color image, which shows the explosion -- called a supernova -- with an arrow, is from the Katzman Automatic Imagining Telescope at the Lick Observatory near San Jose (It was sent to me by Berkeley astronomer Alex Filippenko, who leads the project to discover exploding stars with this telescope.)
Astronomers are looking at the spectrum (the many different colors of light) from the exploding star. They have already discovered that this is that special kind of supernova which helped astronomers discover that the expansion of the entire universe is speeding up -- and earned them the 2011 Nobel Prize in physics.
Called a Type Ia supernova, this kind of explosion comes when a star corpse called a white dwarf is briefly re-ignited by sucking material from a close neighbor star (don't make any zombie jokes, please.) The energies involved when the white dwarf is overloaded with hot new material and blows up are so great that there is no earthly counterpart to compare them to. We are already seeing material blasting away from the explosion at speeds of 45 million miles per hour!!!
Since these supernovae are so important for understanding the universe (not just its expansion, but also its extent and how the death of old stars leads to the birth of the next generation), we are always grateful to have a nearby example to study.
If you have a telescope and want more information on how to find the galaxy and what equipment you will need to observe the supernova, see the Supernova 2014J pages at the website of Sky & Telescope magazine:http://www.skyandtelescope.com/observing/highlights/Bright-Supernova-in-M82-241477661.html
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