Slashdot Mirror

← Back to Stories (view on slashdot.org)

Hubble Confirms Nature of Mysterious Green Blob

Posted by CmdrTaco on from the send-in-kilowog dept.

An anonymous reader writes "In 2007, Dutch secondary school biology teacher Hanny van Arkel spotted something mysterious in the night sky. Combing through Galaxy Zoo, an online database set up to enlist the public's help in classifying galaxies, she came across a glowing green smudge of light approximately 650 million light-years away. The object, which became known as Hanny's Voorwerp (Dutch for 'object'), is one of the most mysterious in the universe. Now, detailed Hubble Space Telescope images and new x-ray observations presented here today at the 217th meeting of the American Astronomical Society may finally confirm what it is."

6 of 140 comments (clear)

  1. And for those not interested in reading TFA by gomiam · · Score: 5, Informative
    ... the blob is, according to observations, a gas cloud who was irradiated until recently by a now dead quasar. The irradiation excited the oxygen atoms in the cloud, making it glow green.

    I think it wouldn't have been too much to add this to the entry.

    1. Re:And for those not interested in reading TFA by Pharmboy · · Score: 5, Funny

      I think it wouldn't have been too much to add this to the entry.

      But unnecessary. Everyone on Slashdot would have read the entire article and found out anyway, right?

      --
      Tequila: It's not just for breakfast anymore!
  2. Reminds me of a Star Trek quote by Kufat · · Score: 5, Funny

    Kirk: Bones, there's a... voorwerp... out there.
    Bones: Why is any object we don't understand always called "a voorwerp"?

  3. Interesting by gman003 · · Score: 5, Informative

    The article also brings up an interesting point: since the glow is caused by radiation from a quasar a few hundred thousand light years away, but that quasar is not currently active, it means that quasars can die extremely quickly, in about 200,000 years if TFA is correct. That's a blink of an eye in astronomic terms.

    It also counts as physical evidence for black holes evaporating, which is good.

    1. Re:Interesting by InsurrctionConsltant · · Score: 5, Interesting

      Nope, even then. You need to read up a little about the timeframes here.

      The evaporation of black holes according to Hawking radiation is an unimaginably, incomprehensibly, comically slow process. So slow, that in this universe, the passive absorption of the cosmic microwave background is sufficient to render it irrelevant –the black hole still absorbs background photons at a greater rate than it generates radiation:

      A stellar black hole of one solar mass has a Hawking temperature of about 100 nanokelvins. This is far less than the 2.7 K temperature of the cosmic microwave background. Stellar mass (and larger) black holes receive more mass from the cosmic microwave background than they emit through Hawking radiation and will thus grow instead of shrink. To have a Hawking temperature larger than 2.7 K (and be able to evaporate), a black hole needs to be lighter than the Moon (and therefore a diameter of less than a tenth of a millimeter). (wikipedia.org)

      Elsewhere I have seen the figure of 10^61 times the age of the universe for the evaporation (and this is in a black-body condition: no matter absorbed whatsoever) of a BH of merely 30 solar masses. Recall we are talking about a Quasar: something hundreds of millions of solar masses and up. These things have lifetimes so vast as to render even the word "astronomical" meaninglessly trifling. Think numbers of years with more digits than you could write in your lifetime.

  4. Detailed Explanation by Waveney · · Score: 5, Informative

    For a detailed explanation see Bill Keels post http://blogs.zooniverse.org/galaxyzoo/2011/01/10/hannys-voorwerp-and-hubble-what-did-we-learn/