Stellar Seismology: Listening To A Star's Secrets

CoRoT reveals a magnetic activity cycle in a Sun-like star: Using data captured by the CoRoT satellite, scientists have successfully probed a distant star, using a technique called stellar seismology to monitor the star's acoustic fluctuations. They detected "starspots"-areas of intense magnetic activity on the surface that are similar to sunspots. While scientists had previously observed these magnetic cycles in other stars, this was the first time they discovered such a cycle using stellar seismology.



Distant star's sound waves reveal cycle similar to the Sun's: In a bid to unlock longstanding mysteries of the Sun, including the impacts on Earth of its 11-year cycle, an international team of scientists has successfully probed a distant star. By monitoring the star's sound waves, the team has observed a magnetic cycle analogous to the Sun's solar cycle. The study, conducted by scientists at the National Center for Atmospheric Research (NCAR) and colleagues in France and Spain, is being published as a "Brevia" in Science.

Distant star's inner secrets revealed by sound waves. Using data captured by the Convection Rotation and planetary Transits (CoRoT) satellite, scientists have successfully probed a distant star, using a technique called stellar seismology to monitor changes in the star's sound waves. Using that technique, the international team detected "starspots"—areas of intense magnetic activity on the surface that are similar to sunspots. While scientists had previously observed these magnetic cycles in other stars, this was the first time astronomers have discovered such a cycle using stellar seismology.

This video includes observations of the Sun and animations illustrating the research findings. Observations have shown that the magnetism of the Sun is constantly rearranging itself, ejecting hot gas out into the solar system that can interfere with satellites and damage electrical grids on Earth. The Sun's magnetic field gets stronger and weaker on an 11-year cycle, and similar magnetic cycles have been observed in dozens of other stars.

The CoRoT satellite was launched in 2006 to study the oscillations of stars similar to our Sun, and to search for planets circling those stars. CoRoT monitored a star known as HD49933 for more than 180 days, revealing a magnetic cycle much shorter than the Sun's. It's the shortest cycle ever observed in another star—less than a year. In comparison, the Sun's cycle lasts 11 years; only about half of it is shown in this video.

The side-by-side animation compares the much shorter HD49933 cycle (at left) with about half of the 11-year solar cycle of our Sun (at right). The distant HD49933 is actually much larger than our nearby star, the Sun. If such short cycles turn out to be common, NASA's Kepler mission will find them in many more stars—providing valuable data to help astronomers understand the inner workings of our own star.