Articles in Gamma Rays
I’ve just been reading Parallel Worlds by Michio Kaku. He is very skilled at making complex topics easy to follow. And that helps me to generate ideas rather than just trying to keep up. This is from page 126:
Gamma Ray Bursters… releasing within seconds the entire energy output of our Sun over its entire life history (about 10 billion years).
That amount of energy is hard to imagine. The current thinking is that a GRB is the result of a hypernova – a super supernova. And all the energy would be released in two narrow directions which are known as a jets. The closest potential hypernova that we know of is Eta Carinae.
This from Wikipedia:
It is possible that the Eta Carinae hypernova or supernova, when it occurs, could affect Earth, about 7,500 light years away. It is unlikely, however, to affect terrestrial lifeforms directly, as they will be protected from gamma …
Gamma Rays have been detected from a nova (not to be confused with a supernova) for the first time, something that has surprised scientists. I’m guessing that unlike supernovae, we are unable to tell if a nova event is likely to occur any time soon from a nearby star. This is the latest in a string of news reports where space is acting differently to what scientists previously believed – so keep that in mind when scientists insist we are safe from space nasties…
Radioactive elements decay at a constant rate, is something that is taught in high school. Wrong. When you are observing the decay year by year, it is pretty much constant. However it has just been discovered that the intra-year decay rate fluctuates due to how close we are to the Sun, and when there are solar flares.
In June 2000, shortly after being knighted, Arthur C Clarke said:
“Some of the greatest threats to mankind’s future, are global warming, pollution, gamma ray bursts and the threat of an asteroid hitting the earth.
…Gamma ray bursts are sudden outbursts of energy – several times more powerful than the sun – which may suddenly occur,” he elucidated.
“If it happens during any of our lifetimes, we have all had it. I think that such a phenomenon may have affected evolution and if it happens again, there is nothing we can do about it.”
7.5 billion years ago, 7.5 billion light years from us, a star exploded.
The light from this gamma ray burst took until last month to be reach Earth. For a couple of hours this explosion was visible to the naked eye, making it the most distant thing a human has ever seen unaided.
Consider the power behind such a burst, to be visible from the other end of the universe. And wonder how much it could harm you if it occured much closer to home.
The spinning wheel is generated by two massive stars, 8000 light years away, circling each other every eight months. Gigantic clouds of gas streaming off the stars are being stretched by the stellar dance into a spiral, much as water spirals from a rotating garden sprinkler.
Eight years ago Dr Tuthill’s team, using Hawaii’s huge Keck telescope, discovered that one of the objects is a highly unstable beast called a Wolf-Rayet star. They inevitably die in huge explosions that may sometimes produce deadly gamma ray bursts.
Now Dr Tuthill’s team has made another discovery. Overlapping 11 time-lapse images of the 30 billion-kilometre-long gas spiral, they have concluded that Earth is almost directly above one pole of the doomed star, dubbed WR 104. When Wolf-Rayet stars explode, much of their energy is blasted from the poles.
“From our vantage point,” said Dr Tuthill, “we are looking right down the gun barrel. That’s what’s got …
The current theory holds that that gamma ray bursts like GRB 070125 are given off by super-jumbo-sized stars that run out of fuel and violently collapse to form black holes, explains Neil Gehrels, principal investigator of NASA’s Swift telescope.
Such huge stars can only be created in very gas and dust-rich parts of galaxies where lots of other stars are also being born. So it makes no sense to find such a star living and dying in the empty space between galaxies.
Yet another space nasty to worry about. If it doesn’t come from a star we can see, then the possibility exists that we can be zapped from one that is either a star we cannot see, or not a star at all. More at Discovery.com
In the new research, Douglas Galante and Jorge Ernesto Horvath of the University of São Paolo, Brazil, argued that gamma-ray bursts could shine their lethal effects across a whole galaxy, and damage life over greater distances still. The study is to appear in a forthcoming issue of the International Journal of Astrobiology.
The bursts could cause “global environmental changes and biospheric damage” even at distances five times the Milky Way’s width, they wrote.
Gamma-ray bursts are thought to emerge mainly from the poles of a collapsing star. This creates two, oppositely-shining beams of radiation shaped like narrow cones. Planets not lying in these cones would be comparatively safe; the chief worry is for those that do.
Galante and Horvath identified three aspects of gamma-ray bursts as particularly deadly.
The first is a flash of gamma rays, the highest-energy form of light. The flash can imperil even the most radiation-resistant organisms known, the bacterium …