Voorwerp means “object” in Dutch. This is the generic definition received by a peculiar phenomenon spotted a while ago by a Dutch school teacher, Hanny van Arkel, while she was combing through hundreds of photos as a volunteer for the Galaxy Zoo project. For more than a year now, scientists have been trying to elude the mysterious nature of the object and it seems that some progress has been finally made.

The object is shaped as a galaxy-sized, green gas cloud situated approximately 60,000 light years away from the nearest galaxy named IC2497. Although the irregular cloud is very hot (more than 15,000 degrees Celsius), it has formed no stars. Further radio telescope observations, performed with the Westerbork Synthesis Radio Telescope (WSRT) and an e-VLBI array, also including WSRT, indicated a potential source for Voorwerp.

 

"It looks as though the jet emanating from the black hole clears a path through the dense interstellar medium of IC 2497 towards Hanny's Voorwerp", explained Prof. Mike Garrett, leader of the international team of researchers, cited by Astron. "This cleared channel permits the beam of intense optical and ultraviolet emission associated with the black hole, to illuminate a small part of a large gas cloud that partially surrounds the galaxy. The optical and ultraviolet emission heats and ionizes the gas cloud, thus creating the phenomena known as Hanny's Voorwerp."

 

The remaining question involves the source of massive amounts of hydrogen in the cloud, "There is a lot of gas out there – the WSRT observations detect a huge stream of gas that is extended across hundreds of thousands of light years," and is 5 billion times the Sun's mass, according to Dr. Gyula Jozsa, another team member.

 

Dr. Tom Oosterloo tries to offer a possible clue, "It has all the hallmarks of an interacting system – the gas probably arises from a tidal interaction between IC 2497 and another galaxy, several hundred million years ago". As to the guilty objects, he points to the west, "The stream of gas ends three hundred thousand light years westwards of IC2497 – all the evidence points towards a group of galaxies at the tip of the stream being responsible for this freak cosmic accident".