Citizen Scientists Find Green Blobs in Hubble Galaxy Shots

Excerpt from wired.com

In 2007, A Dutch schoolteacher named Hanny var Arkel

discovered a weird green glob of gas in space. Sifting through pictures

of galaxies online, as part of the citizen science project Galaxy Zoo,

she saw a cloud, seemingly glowing, sitting next to a galaxy.

Intrigued, astronomers set out to find more of these objects, dubbed

Hanny’s Voorwerp (“Hanny’s object” in Dutch). Now, again with the help

of citizen scientists, they’ve found 19 more of them, using the Hubble

space telescope to snap the eight haunting pictures in the gallery

above.

Since var Arkel found the first of these objects, hundreds more

volunteers have swarmed to help identify parts of the universe in the

Galaxy Zoo gallery. To find this new set, a couple hundred volunteers

went through nearly 16,000 pictures online (seven people went through all

of them), clicking yes/no/maybe as to whether they saw a weird green

blob. Astronomers followed up on the galaxies they identified using

ground-based telescopes, and confirmed 19 new galaxies surrounded by

green gas.

What causes these wispy tendrils of gas to glow? Lurking at the

center of each of these galaxies is a supermassive black hole, millions

to billions times as massive as the sun, with gravity so strong that

even light can’t escape them. As nearby gas and dust swirls into the

black hole, like water circling a drain, that material heats up,

producing lots of radiation—including powerful ultraviolet. Beaming out

from the galaxy, that ultraviolet radiation strikes nearby clouds of

gas, left over from past collisions between galaxies. And it makes the

clouds glow an eerie green. “A lot of these bizarre forms we’re seeing

in the images arise because these galaxies either interacted with a

companion or show evidence they merged with a smaller galaxy,” says William Keel, an astronomer at the University of Alabama, Tuscaloosa.

The eight in this gallery, captured with Hubble, are especially

weird. That’s because the quasar, the black-hole engine that’s supposed

to be churning out the ultraviolet radiation, is dim—too dim, in fact,

to be illuminating the green gas. Apparently, the once-bright quasar has

faded. But because that UV light takes hundreds of thousands of years

to travel, it can continue to illuminate the gas long after its light

source has died away.  

That glowing gas can tell astronomers a lot about the quasar that

brought it to light. “What I’m so excited about is the fact that we can

use them to do archaeology,” says Gabriela Canalizo,

an astronomer at the University of California, Riverside, who wasn’t

part of the new research. Because the streaks of gas are so vast,

stretching up to tens of thousands of light years, the way they glow

reveals the history of the radiation coming from the quasar. As the

quasar fades, so will the gas’s glow, with the regions of gas closer to

the quasar dimming first. By analyzing how the glow dwindles with

distance from the quasar, astronomers can determine how fast the quasar

is fading. “This was something we’ve never been able to do,” Canalizo

says.

Measuring how fast the quasar fades allows astronomers to figure out

exactly what’s causing it to turn off in the first place. “What makes

them dim is running out of material to eat,” Canalizo says. That could

happen if the quasar is generating enough radiation to blow away all the

gas and dust surrounding the black hole—the same gas and dust that

feeds it. Without a steady diet, the quasar is powerless to produce

radiation. Only if more gas happens to make its way toward the black

hole can the quasar turn on again. The glowing gas can provide details

of this process, and if other mechanisms are at play.

With more powerful telescopes, astronomers will likely find many

more. Hanny’s Verwoort, it turns out, may not be that weird after all.

Source Article from http://feedproxy.google.com/~r/AscensionEarth2012/~3/qMKJK2AJTMI/citizen-scientists-find-green-blobs-in.html

[ Add Comment ]

Citizen Scientists Find Green Blobs in Hubble Galaxy Shots