It’s becoming clearer and clearer that the spooky mystery of Hanny’s Voorwerp — the glowing green blob discovered in 2007 by Dutch schoolteacher Hanny van Arkel – is no longer. Last fall, Hayden Rampadarath of the University of Manchester, U.K. and his colleagues said they had figured out the problem, and now they have published their solution. According to a paper, posted on the Arxiv on 22 June and accepted in Astronomy & Astrophysics, the Voorwerp – which means ‘object’ in Dutch — is a cloud of gas, ionized by jets from a nearby black hole.

Using radio telescope arrays in Europe, the authors found that the galaxy adjacent to the blob indeed has a supermassive black hole at its center. These active black holes fire jets of radiation that could excite the nearby nebula of gas to glow green.

So it’s time for the Voorwerp, discovered by van Arkel while participating in the Galaxy Zoo project, to get a new name! Anyone know how to say “black hole-ionized nebula” in Dutch?

Picture: Dan Smith, Peter Herbert, Matt Jarvis & the ING