August 6, 2008 | 6:24 am

Geekgirl teacher finds ‘Cosmic Ghost’

Hanny's Voorwerp and spiral galaxy IC 2497. Photo by Dan Smith, Peter Herbert, Matt Jarvis & the ING

Hanny van Arkel, a 25-year-old Dutch schoolteacher who volunteers for Galaxy Zoo – an Oxford volunteer project that allows the public to join astronomy research online—has found a strange, unique gaseous green blob that’s being dubbed a “cosmic ghost.”

The object became more officially known as Hanny’s Voorwerp (Dutch for “object”) after van Arkel posted an image to Galaxy Zoo’s forum. Astronomers soon realized it was a new astronomical find.

“At first, we had no idea what it was. It could have been in our solar system, or at the edge of the universe,“ said [Yale astrophysicist Kevin] Schawinski, a member and co-founder of the Galaxy Zoo team.

Scientists working at telescopes around the world and with satellites in space were asked to take a look at the mysterious Voorwerp. “What we saw was really a mystery,“ said Schawinski. “The Voorwerp didn’t contain any stars.“ Rather, it was made entirely of gas so hot — about 10,000 Celsius — that the astronomers felt it had to be illuminated by something powerful. They will soon use the Hubble Space Telescope to get a closer look.

Since there was no obvious source at hand in the Voorwerp itself, the team looked to find the source of illumination around the Voorwerp, and soon turned to the nearby galaxy IC 2497.

“We think that in the recent past the galaxy IC 2497 hosted an enormously bright quasar,“ Schawinski explains. “Because of the vast scale of the galaxy and the Voorwerp, light from that past still lights up the nearby Voorwerp even though the quasar shut down sometime in the past 100,000 years, and the galaxy’s black hole itself has gone quiet.“ (Science Daily)

If the quasar was still active, astronomers believe it would be visible from Earth with binoculars. Light given off by the quasar took thousands of years to reach the Voorwerp’s gas, which exists now as a kind of light echo. While similar echoes have been encountered, this is the first finding of this scale. To get a feel for its size, the Voorwerp’s hole is more than 16,000 light years across.

Van Arkel has no background in astronomy. She told the BBC that her interest in music had led her to the book “Bang! The Complete History of the Universe,” co-written by Queen guitarist Brian May.

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