I find it difficult to buy someof the interpretation, but that is not too important. We have an interesting structure that obviouslyasks questions.
It also helps publicize the systemin place to allow individuals to search through the data to locateoddities. Hanny’s Voorwerp is a greatname for something like this. Data needseyeballs and it is a scientific fool who does not share data willingly.
We presently have theory for thegalactic lifecycle that appears okay, but could easily be leading us astray. Thus asking an unobserved quasar to light upa portion of a dust belt is too convenient by far.
Hubble Zooms in on a Space Oddity
ScienceDaily (Jan. 11, 2011) — One of the strangest space objectsever seen is being scrutinized by the penetrating vision of NASA's Hubble SpaceTelescope. A mysterious, glowing green blob of gas is floating in space near aspiral galaxy. Hubble uncovered delicate filaments of gas and a pocket of youngstar clusters in the giant object, which is the size of our Milky Way galaxy.
In this image by NASA's Hubble Space Telescope, an unusual, ghostlygreen blob of gas appears to float near a normal-looking spiral galaxy. Thebizarre object, dubbed Hanny's Voorwerp (Hanny's Object in Dutch), is the onlyvisible part of a 300,000-light-year-long streamer of gas stretching around thegalaxy, called IC 2497. The greenish Voorwerp is visible because a searchlightbeam of light from the galaxy's core illuminated it. This beam came from aquasar, a bright, energetic object that is powered by a black hole. The quasarmay have turned off about 200,000 years ago. (Credit: NASA, ESA, W. Keel (
), and the Galaxy Zoo Team) University of Alabama
The Hubble revelations are the latest finds in an ongoing probe ofHanny's Voorwerp (Hanny's Object in Dutch), named for Hanny van Arkel, theDutch teacher who discovered the ghostly structure in 2007 while participatingin the online Galaxy Zoo project. Galaxy Zoo enlists the public to helpclassify more than a million galaxies catalogued in the Sloan Digital SkySurvey. The project has expanded to include the Hubble Zoo, in which the publicis asked to assess tens of thousands of galaxies in deep imagery from theHubble Space Telescope.
In the sharpest view yet of Hanny's Voorwerp, Hubble's Wide FieldCamera 3 and Advanced Camera for Surveys have uncovered star birth in a regionof the green object that faces the spiral galaxy IC 2497, located about 650million light-years from Earth. Radio observations have shown an outflow of gasarising from the galaxy's core. The new Hubble images reveal that the galaxy'sgas is interacting with a small region of Hanny's Voorwerp, which is collapsingand forming stars. The youngest stars are a couple of million years old.
"The star clusters are localized, confined to an area that is overa few thousand light-years wide," explains astronomer William Keel of the
University of Alabamain ,leader of the Hubble study. "The region may have been churning out starsfor several million years. They are so dim that they have previously been lostin the brilliant light of the surrounding gas." Tuscaloosa
Recent X-ray observations have revealed why Hanny's Voorwerp caught theeye of astronomers. The galaxy's rambunctious core produced a quasar, apowerful light beacon powered by a black hole. The quasar shot a broad beam oflight in Hanny's Voorwerp's direction, illuminating the gas cloud and making ita space oddity. Its bright green color is from glowing oxygen.
"We just missed catching the quasar, because it turned off no morethan 200,000 years ago, so what we're seeing is the afterglow from thequasar," Keel says. "This implies that it might flicker on and off,which is typical of quasars, but we've never seen such a dramatic change happenso rapidly."
The quasar's outburst also may have cast a shadow on the blob. Thisfeature gives the illusion of a gaping hole about 20,000 light-years wide inHanny's Voorwerp. Hubble reveals sharp edges around the apparent opening,suggesting that an object close to the quasar may have blocked some of thelight and projected a shadow on Hanny's Voorwerp. This phenomenon is similar toa fly on a movie projector lens casting a shadow on a movie screen.
Radio studies have revealed that Hanny's Voorwerp is not just an islandgas cloud floating in space. The glowing blob is part of a long, twisting ropeof gas, or tidal tail, about 300,000 light-years long that wraps around thegalaxy. The only optically visible part of the rope is Hanny's Voorwerp. Theilluminated object is so huge that it stretches from 44,000 light-years to136,000 light-years from the galaxy's core.
The quasar, the outflow of gas that instigated the star birth, and thelong, gaseous tidal tail point to a rough life for IC 2497.
"The evidence suggests that IC 2497 may have merged with anothergalaxy about a billion years ago," Keel explains. "The Hubble imagesshow in exquisite detail that the spiral arms are twisted, so the galaxy hasn'tcompletely settled down."
In Keel's scenario, the merger expelled the long streamer of gas fromthe galaxy and funneled gas and stars into the center, which fed the blackhole. The engorged black hole then powered the quasar, which launched two conesof light. One light beam illuminated part of the tidal tail, now called Hanny'sVoorwerp.
About a million years ago, shock waves produced glowing gas near thegalaxy's core and blasted it outward. The glowing gas is seen only in Hubbleimages and spectra, Keel says. The outburst may have triggered star formationin Hanny's Voorwerp. Less than 200,000 years ago, the quasar dropped inbrightness by 100 times or more, leaving an ordinary-looking core.
New images of the galaxy's dusty core from Hubble's Space TelescopeImaging Spectrograph show an expanding bubble of gas blown out of one side ofthe core, perhaps evidence of the sputtering quasar's final gasps. Theexpanding ring of gas is still too small for ground-based telescopes to detect.
"This quasar may have been active for a few million years, whichperhaps indicates that quasars blink on and off on timescales of millions ofyears, not the 100 million years that theory had suggested," Keel says. Headded that the quasar could light up again if more material is dumped aroundthe black hole.
Keel is presenting his results on Jan. 10, 2011, at the AmericanAstronomical Society meeting in Seattle, Wash.