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Magnetism common to all cosmic jets?
Posted: 26 November 2010

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Astronomers have found the first evidence of a magnetic field in a jet of material ejected by a young star, offering insight into jet formation and the role of magnetic fields in star birth.

Radio jets emitted by the young star are shown in yellow on a background infrared image from the Spitzer Space Telescope. The yellow bars show the orientation of the magnetic field in the jet as measured by the VLA. Green bars show magnetic-field orientation in the dusty envelope surrounding the young star. Two other young stars are seen at sides of the jet. Image: Carrasco-Gonzalez et al., Curran et al., Bill Saxton, NRAO/AUI/NSF, NASA.

Jets of particles are already known to be associated with black holes, neutron stars that are feeding off companion stars, and young stars that are still growing. Until now, magnetic fields had been detected in the jets associated with black holes and neutron stars, but the association with jets in young stars had not been confirmed.

The finding of a 27 light year long jet interacting with a magnetic field at young star IRAS 18162-2048 provides strong evidence that all three types of jets originate through a common process.

“We see for the first time that a jet from a young star shares this common characteristic with the other types of cosmic jets,” says Luis Rodriguez, of the National Autonomous University of Mexico, UNAM. The characteristic is polarization, which gives a preferential alignment to the electric and magnetic fields of the radio waves, as detected by the National Science Foundation’s Very Large Array (VLA) radio telescope. Studying the 5,500 light year distant target for 12 hours, the team found that polarized radio waves from the jet arise when fast-moving electrons interact with magnetic fields.

Jets from young stars emit radiation imprinted with information regarding the temperatures, speeds and densities of materials within the jets, which, when combined with the magnetic field data, can provide insight into the mechanics of how jets are generated, as well as of the role magnetic fields play in forming new stars.

“In the future, combining several types of observations could give us an overall picture of how magnetic fields affect the young star and all its surroundings,” says Rodriguez. “This would be a big advance in understanding the process of star formation.”