In a stroke of cosmic luck, astronomers for the first time witnessed the start of one of the universe's most fiery events, the end of a star's life as it exploded into a supernova.
On Jan. 9th, astronomers used a NASA X-ray satelite to spy on a star already well into its death throes, when another star in the same galaxy started to explode. The outburst was 100 billion times brighter than Earth's Sun. The scientists were able to get several ground based telescopes to join in the early viewing and the first results were published in an issue of the journal " Nature."
" A star exploded right before my eyes," lead author Alicia Sodenberg, an astrophysics researcher at Princeton University said. She likened it to winning the astronomy lottery. We caught the whole thing on tape. Another scientist, University of California astronomy professor Alex Filippenko, called it a " very special moment because this is the birth, in a sense, of the death of a star."
And what a death blast it is. As much energy is released in one second by the death of a star as by all the other stars you can see in the visible universe. Less than 1 percent of the stars will die this way, in a supernova. Most stars, including our sun, will get stronger and then slowly fade into white dwarfs, or " retired stars, " which produce little energy.
The first explosion of this supernova can only be seen in the X-ray wave length. It was spotted by NASA's Swift satelite, which looks at x-rays, and happened to be focused on the right region. The blast was so bright it flooded the satelites instrument, giving it a picture akin to " pointing your digital camera at the Sun." Soderberg said that by seeing it live in X-rays, astronomers on Earth learned of the supernova bout a month before they normally would.
The chances of two simultaneous supernovae explosions so close to each other is maybe 1 in 10,000. The odds of looking at them at the right time with the right telescope are astronomical. Add to that the serendipity of the Berkley team viewing the same region with an optical light telescope. It took pictures of the star about 3 hours before it exploded.
This new glimpse of a supernova seems to confirm decades old theories on how stars explode and die, not providing many surprises. That makes the findings a cool thing, but not one that fundamentally changes astrophysics. The galaxy Where the dual explosions occured, is a run of the mill cluster of stars, not too close and not too far away from the Milky Way in cosmic terms, The galaxy, NGC2770, is about 100 million light years away. One light year is 5.9 trillion miles.. ( do the math ;-)
The star that exploded was only about 10 million years old. It was the same size in diameter as our Sun, but about 10 to 20 times more dense. " The big stars live fast and die young," said Harvard astronomy professor Robert Kirshner. " We don't know if they leave a beautiful corpse."
The death of this star went through stages, with the core getting heavier in successive nuclear reactions and atomic particles being shed out toward the cosmos. It started out in its normal life with hydrogen being converted to helium, which is what is happening in our Sun. The helium then converts to oxygen and carbon, and into heavier and heavier elements until it turns into iron.
Thats when the star core becomes so heavy it collapses in on itself, and the supernova starts with a shock wave of particles piercing through the shell of the star, which is what the Soderberg team captured on x-rays.
People at home can simulate how this shockwave works.....
Take a basketball and a tennis ball, Get about five feet above the ground and rest the tennis ball on top of the basketball. Drop them together and when they bounce the tennis ball will soar.. The basketball is the collapsing core and the tennis ball is the shockwave that was seen by astronomers.
|
The English language is so interesting and funny.
