Asteroseismology

StarDate: November 8, 2010

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Like a non-coffee drinker after a double espresso, stars have the jitters. Their surfaces vibrate at thousands or millions of different frequencies. The vibrations are produced by processes deep inside a star. So measuring the vibrations can reveal a lot about a star’s structure and its inner workings.

In one example, astronomers used the vibrations to plot a star’s magnetic cycle. As a star rotates, it generates a magnetic field. Over time, the field becomes entangled, producing dark “starspots” and powerful outbursts known as flares.

The Sun’s magnetic cycle lasts about 11 years. Several other stars show similar cycles.

But using observations from a European satellite named COROT, astronomers found that one star’s magnetic cycle lasts less than a year. The star is known as HD 49933. It’s about 100 light-years away, in Monoceros, the unicorn. The faint constellation rises in late evening right now, just below much-brighter Orion.

COROT measured the vibrations on the star’s surface. As the star’s magnetic cycle peaked, the vibrations got shorter and quieter. As the cycle waned, they got longer and stronger.

The observations are important not just because of HD 49933 itself. Because the star’s cycle is so short, it gives astronomers a chance to monitor many cycles in a short time. That can provide new insights into the magnetic cycles of all stars, including the Sun -- cycles that change the stars’ jittery surfaces.

 

Script by Damond Benningfield, Copyright 2010

 

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