Our Sun is an ordinary star. It is 186,000 miles in diameter, and is an incandescent ball of mainly hydrogen gas. It does not rotate as a sold body, at the equator the rotation period is about 25 earth days.
The Sun is a G-type main-sequence star (G2V) based on spectral class and is informally referred to as a yellow dwarf, making it yellowish in colour. It has a regular sunspot cycle of 11 years (we are presently edging towards sunspot minimum). Up until now astronomers did not know for certain whether others stars like the Sun had a similar rotation period.
Dr. Martin Bo Nielsen of the International Max Planck Research School for Solar System Science, has for the first time been able to narrow in his thesis how much the rotation inside sun like stars changed. The change in rotation inside the sun is regarded as one of the principal mechanisms that drive the magnetic activity of the sun. Dr. Nielsen used current data from NASA’s Kepler satellite over several years. He determined the surface rotation by the movement of star spots and measured the rotation in deeper layers by studying vibrations inside the stars. By combining both methods, he succeeded for the first time to determine an upper limit on the change in rotation in depth and latitude of five sun-like stars.
Indeed the rotation period matched that of the Sun, which is significant. We now know that most sun type stars behave in a similar way, which helps astronomers in the hunt for Earth like habitable planets.
The thesis was supervised by Prof. Dr. Laurent Gizon from the Institute of Astrophysics of the University of Göttingen and Dr. Hannah Schunker from Göttingen Max Planck Institute for Solar System Research.
Fakultät für Physik – Studiendekanat