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Giant Magnetic Loop Stretches Between Two Stars

Superposed image of a partial radio loop on Algol's inner binary. The optical-radio registration is within 0.3 mas. Credit: University of Iowa

Using a collection of radio telescopes, astronomers have found a giant magnetic loop stretched outward from one of the stars making up the famous binary star system Algol, located in the constellation Perseus. “This is the first time we’ve seen a feature like this in the magnetic field of any star other than the Sun,” said William Peterson, of the University of Iowa.

The double star system, 93 light-years from Earth, includes a star about 3 times more massive than the Sun and a less-massive companion, orbiting it at a distance of 5.8 million miles, only about six percent of the distance between Earth and the Sun. The newly-discovered magnetic loop emerges from the poles of the less-massive star and stretches outward in the direction of the primary star. As the secondary star orbits its companion, one side — the side with the magnetic loop — constantly faces the more-massive star, just as the same side of our Moon always faces the Earth.

The scientists detected the magnetic loop by making extremely detailed images of the system using an intercontinental set of radio telescopes, including the National Science Foundation’s Very Long Baseline Array, Very Large Array, and Robert C. Byrd Green Bank Telescope, along with the Effelsberg radio telescope in Germany. These radio telescopes were used as a single observing system that offered both great detail, or resolving power, and high sensitivity to detect very faint radio waves. When working together, these telescopes are known as the High Sensitivity Array.

Algol is visible to the naked eye and well-known to amateur astronomers. As seen from Earth, the two stars regularly pass in front of each other, causing a notable change in brightness. The pair completes a cycle of such eclipses in less than three days, making it a popular object for amateur observers. The variability in brightness was discovered by an Italian astronomer in 1667, and the eclipsing-binary explanation was confirmed in 1889.

The newly-discovered magnetic loop helps explain phenomena seen in earlier observations of the Algol system at X-ray and radio wavelengths, the scientists said. In addition, they now believe there may be similar magnetic features in other double-star systems.

Source: EurekAlert


Nancy Atkinson is currently Universe Today's Contributing Editor. Previously she served as UT's Senior Editor and lead writer, and has worked with Astronomy Cast and 365 Days of Astronomy. Nancy is also a NASA/JPL Solar System Ambassador.

Comments on this entry are closed.

  • ND January 14, 2010, 8:16 PM

    Oh and Anaconda, happy anniversary! It’s been a year since we’ve been, erm, engaged in these dialogues of absurdity.

    I *heart* Anaconda.

    (I hope that weirds you out as much as it does me :-)

  • DrFlimmer January 15, 2010, 5:41 AM

    What was this topic about?

  • Anaconda January 15, 2010, 9:59 AM



    Read the post it states that “magnetic loops” were detected between these two stars.

    And if you review the paper I provided, you will see that magnetic fields in space are explained.

    And many other electro-magnetic, plasma phenomenon as well.

    Many of which havealready been observed & measured in situ by satellite probes in our solar system.

    That’s the facts — as much as others don’t want to hear it.

    This is a science website.

  • IVAN3MAN January 15, 2010, 1:02 PM