Astronomers have detected a collar of gas shaped like an Elizabethan ruff that surrounds the fountainhead of particle jets emanating from SS433, a well-studied binary star system with a suspected black hole. The observation capitalizes on the unprecedented resolution of 43 combined radio telescopes and provides the closest look yet at the root of the jet phenomenon, a long-standing black hole mystery.

SS433. Photo: AMS

Dr. Katherine Blundell of Oxford University (U.K.) presented these findings this week at the meeting of the High Energy Astrophysics Division of the American Astronomical Society in Honolulu, Hawaii.

"The ruff appears to emerge perpendicular to the jets, which shoot away at near light speeds from their source in opposite directions," said Blundell. "The collar of emission surrounds the origin of the jets, which is still an unknown. The collar then smoothly joins into the jets."

Scientists do not know how black holes, notorious for pulling matter in, can produce jets of particles shooting away. Blundell said the ruff-shaped emission from SS433, 400 times the span of the Earth to the Sun, is a surprising and extraordinary new feature of particle jets.

In systems like SS433, a compact object (either a black hole or neutron star) orbits a normal star. Over time, the normal star loses mass to the compact object. This mass accelerates to high speeds towards the compact object and, in some systems through an unknown mechanism, shoots away from the compact object in opposite directions in the form of jets.

"It appears that the emission from the collar is different in origin from the emission seen in the jets, and this may be telling us about the gas reservoir which feeds this jet producing system," said Blundell.

SS433, 11,000 light years from Earth, is the first and best known example of a compact object with jets in our Galaxy. Its jets are particularly visible in the radio waveband. Blundell and her colleagues observed SS433 for three successive nights simultaneously with three different radio telescope arrays: the Very Long Baseline Array and the Very Long Array (National Radio Astronomy Observatory) and MERLIN (Jodrell Bank Observatory) -- a total of 43 telescopes using a technique called radio interferometry.

Working with Blundell on this observation are Drs. Amy Mioduszewski (Sydney University), Tom Muxlow (Jodrell) and Michael Rupen (NRAO).