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Hubble Telescope Sheds Light On Mysterious, Green Space Blob

Back in 2007, as part of a crowd-sourced study program called Galaxy Zoo, a Dutch school teacher discovered a very odd celestial object: It looked like a great, green blob floating in space and at the time it was inexplicable.

Today, thanks to the Hubble telescope, we have an unbelievable picture of Hanny's Voorwerp, or Hanny's Object, as it is now known. And we also have a better idea of what it is: Researchers saidthe blob is not a galaxy but a "twisting rope of gas, or tidal tail, about 300,000 light-years long that wraps around the galaxy [IC 2497]."

In a press release from the University of Alabama, Dr. Bill Keel, professor of astronomy and leader of Hubble's Hanny's Voorep study, presented two surprising findings:

First, that very young stars are forming inside the tidal tail. "The region may have been churning out stars for several million years," said Keel. "They are so dim that they have previously been lost in the brilliant light of the surrounding gas."

Keel told us that this is remarkable because this is not the kind of environment in which you would usually find star formation.

Second, Hanny's Voorwerp was lit up by a powerful beacon of light called a quasar, which formed as a byproduct of the harsh conditions created by a supermassive black hole at the center of the galaxy. Keel said the tail likely formed as the result of energy from two merging galaxies. That green light we see is glowing oxygen.

"We just missed catching the quasar because it turned off no more than 200,000 years ago, so what we’re seeing is the afterglow from the quasar," said Keel. "This implies that it might flicker on and off, which is typical of quasars, but we’ve never seen such a dramatic change happen so rapidly."

Update at 2:56 p.m. ET: We just spoke to Dr. Keel. He notes that one of the things this study might prove is that these kinds of objects and this kind process may be "pretty common."

"We were working under the assumption that this would've have been the closest quasar to us," he said. "But it's weird that it would doing something so unusual."

Keel said beyond the science, this is also an illustration of how important a project like Galaxy Zoo is. Essentially, Galaxy Zoo allows hundreds or thousands of volunteers to sift through images after taking a quick tutorial of what to look for.

Keel is looking for more green blobs, and he's using volunteers to find them. Galaxy Zoo users looked through images of 15,000 galaxies. They narrowed that down to 100 galaxies of interest and then scientists further winnowed it down to 18, which they will look at using high-powered telescopes.

Copyright 2020 NPR. To see more, visit https://www.npr.org.

Eyder Peralta
Eyder Peralta is NPR's East Africa correspondent based in Nairobi, Kenya.