National Center for Atmospheric Research | 26 Aug 2010
CoRoT reveals a magnetic activity cycle in a Sun-like star - RA Garcia et alIn 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 this week as a “Brevia” in Science.
The scientists studied a star known as HD49933, which is located 100 light years from Earth in the constellation Monoceros, the Unicorn, just east of Orion. The team examined the star’s acoustic fluctuations, using a technique called “stellar seismology.” They detected the signature of “starspots,” areas of intense magnetic activity on the surface that are similar to sunspots. While scientists have previously observed these magnetic cycles in other stars, this was the first time they have discovered such a cycle using stellar seismology.
Studying many stars with stellar seismology could help scientists better understand how magnetic activity cycles can differ from star to star, as well as the processes behind such cycles. The work could especially shed light on the magnetic processes that go on within the Sun, furthering our understanding of its influence on Earth’s climate. It may also lead to better predictions of the solar cycle and resulting geomagnetic storms that can cause major disruption to power grids and communication networks.
The scientists examined 187 days of data captured by the international Convection Rotation and Planetary Transits (CoRoT) space mission.
The study authors found that HD49933 is much bigger and hotter than the Sun, and its magnetic cycle is much shorter. Whereas past surveys of stars have found cycles similar to the 11-year cycle of the Sun, this star has a cycle of less than a year.
This short cycle is important to scientists because it may enable them to observe an entire cycle more quickly, thereby gleaning more information about magnetic patterns than if they could only observe part of a longer cycle.
- Science Brevia 329 5995 (27 Aug 2010) DOI: 10.1126/science.1191064