Mike Wall, Space.com (November 9, 2010)
"Scientists have detected two gigantic bubbles of high-energy radiation spilling out from the Milky Way's center that may have erupted from a supermassive black hole.
"The mysterious structures each span 25,000 light-years across, meaning that together they cover more than half the area of the visible sky, and are emitting gamma rays, the highest-energy wavelength of light.
"The bulbous features may be evidence of a burst of star formation a few million years ago, researchers said. Or they may have been produced when a supermassive black hole in the center of our galaxy gobbled up a bunch of gas and dust.
"The newly discovered structures remain an enigma for now, scientists said. [New photo of gamma-ray bubbles]
" 'We don't fully understand their nature or origin,' said study leader Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics...."
The article gives a brief overview of how astronomers looked for these oversize bubbles - and why.
We're not completely in the dark about what these things are - or what caused them. In general terms, at least. Specifics? That's going to take a lot more work. What we do know is that there was an enormous amount of energy involved in making the bubbles. And their appearance should narrow down possibilities for what started them:
"...Researchers aren't yet sure what created the bubbles. But the structures appear to have sharp, well-defined edges, suggesting they were formed by a large, rapid and relatively recent release of energy.
"Two leading candidate causes, according to Finkbeiner, are a surge of star formation several million years ago and a burst of activity by the Milky Way's central black hole, which is as massive as four million suns...."
(from Space.com, used w/o permission)
"These newly discovered gamma-ray bubbles extend 50,000 light-years, roughly half of the Milky Way's width, as shown in this illustration. Hints of the bubbles' edges were first observed in X-rays (blue) by ROSAT, a Germany-led mission operating in the 1990s. The gamma rays mapped by Fermi (magenta) extend much farther from the galaxy's plane. Credit: NASA's Goddard Space Flight Center...."
The Lemming's very interested in this sort of thing. Your experience may vary. That picture is a half-scale thumbnail of the one on the Space.com website. They've got two more: one showing a full-sky projection that gives an idea of what these twin bubbles 'look' like in the extremely high-frequency wavelengths the astronomers were studying.
One thing this almost certainly doesn't mean is that the Milky Way galaxy is exploding, and we're all doomed. Quite a few galaxies of the sort we live in have activity something like this happening in their core. We've known about the Milky Way's central black hole for some time, by the way. That was quite a discovery.
It's just as well that our star is in a more-or-less circular orbit around the Milky Way's core, and stays pretty much in the plane of the galaxy. As it is, we've got great seats for this show.
Or, rather, our robot observatories in space do. Very high-frequency 'light' like what these bubbles are emitting doesn't travel well through Earth's atmosphere. Which is just as well for us.
Related posts:
- "A Galactic 'Supervolcano' - No Kidding"
(September 7, 2010) - "Gamma Ray Flare in Pegasus"
(December 13, 2009) - "Re-Thinking This Galaxy's Habitable Zone"
(September 23, 2008) - "A Cool Map of the Milky Way Galaxy"
(July 27, 2008) - "Our Galaxy is Twice the Size Previously Thought"
(February 23, 2008)
No comments:
Post a Comment