It took 16 years but astronomers have finally solved the mystery of the Blur Ring Nebula. Back in 2004, astronomers discovered a star surrounded by a ring of material shining in ultraviolet. After many observations with a lot of different instruments researchers now understand what’s going on.
As reported in the journal Nature, the team believes that star TYC 2597-735-1's glowing halo is not a ring at all. What we are looking at is a cone-shaped cloud of fluorescing material. The cause of this peculiar structure appears to be a stellar collision.
The astronomers believe the collision between a Sun-sized star and a smaller companion released material in two conical-shaped clouds. One cone is pointing directly at Earth with the other one diametrically opposite, making it appear like a circular halo around the star.
"The merging of two stars is fairly common, but they quickly become obscured by lots of dust as the ejecta from them expands and cools in space, which means we can't see what has actually happened," lead author Dr Keri Hoadley of Caltech said in a statement. "We think this object represents a late stage of these transient events, when the dust finally clears and we have a good view. But we also caught the process before it was too far along; after time, the nebula will dissolve into the interstellar medium, and we would not be able to tell anything happened at all."
The scenario envisioned by the team is this: A few thousand years ago, a star like the Sun swelled to a star interacting with its smaller companion. The companion siphoned gas from its larger sibling and formed a disk of material around itself. Eventually, the smaller star fell into the bigger one and the merger released a large cloud of debris into space.
The cone-shaped cloud is where the disk of material surrounding the smaller star comes in. As this cloud is released, the disk acts as a cleaver, cutting through the cloud and pushing the material into a two-cone shape that is believed to have created the ring illusion. The material moved so fast that it created shockwaves as it moved through the interstellar medium, creating the emissions seen in UV.
The discovery was possible thanks to the Galaxy Evolution Explorer mission (GALEX), an ultraviolet telescope that operated between 2003 and 2012. "Whenever you survey the sky at new wavelengths, you inevitably get new discoveries years later and beyond," said co-author Christopher Martin, professor of physics at Caltech and the former principal investigator of GALEX.
TYC 2597-735-1 is located 6,300 light-years from Earth.