Map of radio emissions from a microquasar, believed to be powered by a black hole swallowing a companion star.
Black holes usually are identified by their intense X-rays. But the newly discovered microquasar has only modest X-ray emissions. It was discovered when the researchers also found other wavelengths of electromagnetic radiation coming from the same part of the sky.
As a result, the newly discovered microquasar "may be just one of a large population of such objects that have previously been overlooked," R.P. Fender of the University of Amsterdam wrote in a commentary accompanying the study, which is presented in the June 30 issue of the journal Science.
If so, microquasars "may well be a substantial, if not dominant, source of high-energy particles and photons [light particles] produced in our galaxy," wrote Fender.
The discovery was made by Josep Maria Paredes and Marc Ribo of the University of Barcelona, Spain; Josep Marti at the University of Jaen, Spain and Maria Massi of the Max Planck Institute for Radioastronomy in Bonn, Germany.
A
, or quasi-stellar radio source, is a super-bright object that spews various forms of electromagnetic radiation -- X-rays, light, radio waves and so on -- and is powered by billions of stars falling into a supermassive black hole.As matter and light are sucked in by the giant black holes incredible gravity, other matter and radiation are hurled away from the black hole. So quasars emit the energy of trillions of Earths suns. But they are so far away -- sometimes at the edge of the observable universe -- that they look like stars.
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A microquasar also emits a variety of wavelengths, but is much smaller and "is powered by matter of a single star pulled into a very compact object -- a black hole of a few solar masses or a neutron star," Paredes said. A neutron star is a collapsed star less dense than a black hole.
Before the latest discovery, only about 10 microquasars had been found, he added.
The new microquasar, known as star LS 5039, is located in our general neighborhood of the Milky Way galaxy about 9,100 light-years from Earth, or 53 million billion miles (85 million billion kilometers). Only two other microquasars are closer to Earth and a third is about the same distance, Paredes said.
The Spanish team first identified LS 5039 as an X-ray- and light-emitting binary star with a persistent radio emission. In the new study, Paredes and colleagues studied the microquasars radio emissions using dish-shaped antennas, including the Very Large Array of 27 dishes in New Mexico and the Very Long Baseline Array of 10 antenna dishes scattered in different states.
Jets of matter
They learned that two radio-emitting jets of high-energy electrons and other matter spew from the objects central core at perhaps one-fifth the speed of light.
Each jet extends about 147 light-minutes into space (1.6 billion miles or 2.6 billion kilometers) -- roughly 18 times the distance between the Earth and sun.
The astronomers noted the same area of the sky produced persistent gamma-ray emissions that were detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory, a satellite that recently was
on a controlled reentry into Earths atmosphere.Paredes said EGRET found more than 100 gamma ray-emitting objects that have not yet been identified. By looking for objects that emit X-rays, light, radio waves, gamma rays and other wavelengths, scientists may "confirm that the microquasar phenomenon is not as rare as it seems," Paredes and colleagues wrote.
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