Hubble Confirms Nature of Mysterious Green Blob

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."

Comments

Re:Interesting

[InsurrctionConsltant]

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.

Re:And for those not interested in reading TFA

[ErroneousBee]

The Voorwerp and galaxy are both 650 million light years away from Earth, and they are about 200,000 light years away from each other.

I think this is the timeline ( I do a bit of galaxyzoo now and then):

So ( about 650 million ) + ( some millions ) of years ago the galaxy had a big ole black hole in the middle, which was gobbling up matter in the galaxy. The matter fell into the hole like water down a drain, spinning round the hole as it fell in. All this spinning matter creates enormous magnetic fields that create jets at the poles of the spinning matter. The matter in these jets blasted off at sub-light speeds and became the voorwerp cloud in space. There should be a cloud on the opposite side of the galaxy, but I havent seen any mention of this, so it entirely possible that the cloud was there anyway and was not shot out of the galaxy.

So we now have a galaxy and a cloud of gas nearby.

Then ( about 650 million ) + ( a few million ) years ago the galaxy is a Quasar, the black hole in the middle is powering a massive outpouring of light, the whole of the middle of the galaxy is glowing, and that light is running off into space and causing the voorwerp cloud to glow. Pressure from the light is also causing the cloud to collapse and start forming stars.

So we have a really bright galaxy (Quasar) and a glowing gas cloud.

Then ( about 650 million ) + ( about 200,000 ) years ago the black hole stops gobbling matter and can no longer power the Quasar. The galaxy stops glowing, but its massive light outpouring is still travelling through space and is still causing the Voorwerp cloud to glow.

Then ( about 650 million ) years ago is the picture we see today:

1. A Galaxy looking pretty normal.
2. A cloud of gas that is glowing as it is still illuminated by light that took 200,000 years to get from the galaxy to the cloud.
3. We see stars in the cloud that are no older than a few millions of years old, as the Quasar started up, light pressure caused the gas cloud to collapse into stars and has now shut down again.

In the future the cloud will stop glowing as the wave of Quasar light passes through it and is gone. There will still be stars that we can view. The Voorwerp will become a dwarf galaxy orbiting the ex-quasar galaxy.

From the above time line, we infer these facts:

• The galaxy is not glowing like a quasar, but the voorwerp 2000,000 light years away is under full illumination from the Quasar. So the Quasar has gone from full blast to completly shut down in 200,000 years.
• The stars in the voorwerp are only a couple of million years old, so the Voorwerp was only illuminated by the Quasar for a few million years.

Notes:

• The sun is about 4 billion years old.
• The green colour mentioned in the article is simply the fact that hot oxygen emits radiation at a specific wavelength that is not actually green, but has to be represented as a colour in telescope images for us to view. This wavelength just happens to be represented as green by Hubble. It was Blue in the galaxyzoo image (supplied by the Sloan automatic survey scope).
• This never gets mentioned, but Hanny had a hairstyle and guitar that made her like a bloke in her avatar image on galaxyzoo.