New observations of a dual star system that might harbor a black hole show that hot emissions moving at nearly the speed of light do not cool or slow down as quickly as expected.
The X-ray observations of a region around the black hole or neutron star -- astronomers aren't sure which it is -- and its binary star companion show that jets of energy zoom into space at one-quarter the speed of light. The jets maintain this speed and a temperature of about 50 million degrees Kelvin (90 million Fahrenheit) more than 3 months after they're emitted.
The results suggest that a blob of material embedded in the jet runs into a slower-moving blob, reheating the stream, says lead researcher Simone Migliari of the University of Amsterdam. Details of the observations, of a binary system called SS 433, will be reported in the Sept. 6 issue of the journal Science.
"We are proposing that the reheating occurs when two blobs in the jet, launched in the same direction but with differing velocities, effectively run into each other," Migliari told SPACE.com.
An alternative explanation, he said, is that the jets are reheated by friction when matter in a jet interacts with surrounding interstellar gas and dust. But this scenario is now seen as less likely.
"The actual heating process is not clearly known, but the energy source is likely to be the massive kinetic energy of the flow," Migliari said.
For years, astronomers have observed jets of superheated matter emerging in opposite directions along the axes of rotation of many binary star systems. The material is thought to be spat out as the end result of a process whereby the more massive object -- a black hole or neutron star -- siphons matter from its companion, typically a more normal star. The matter spirals inward and is accelerated to "relatavistic" speed -- or a significant fraction of the speed of light. Most of it is consumed, but some escapes the system via the jets.
The structure and composition of these jets remains largely unknown, however.
Migliari and his colleagues put together one of the most highly resolved images ever made of a jet using the Chandra X-ray Observatory.
He said the results show that normal, hot matter extends further from a binary system than expected. The researchers observed the heated, fast-moving material about one-fourth of a light-year away from the stars. That's nearly 16,000 times the distance from the Sun to Earth.
"It is exciting because it tells us that the hot gas and iron atoms we are seeing are in the jet flow, and not just interstellar matter which has been heated by collision with a cold jet," Migliari said.
advertisement
