Stellar weather

Stars might also experience weather, report Oleg Kochukhov and co-workers.Their study challenges current models of structure formation within stellar atmospheres.
By tracking mercury clouds on alpha Andromedae over a seven-year period, the researchers discovered cloud dynamics similar to the weather patterns that exist on Earth and the giant gas planets. Other stars also host chemical and temperature spots, but astronomers generally believe that a star’s magnetic field is responsible for its surface structure — this explanation applies to sunspots on the Sun, for instance. But alpha Andromedae is non-magnetic, hence its cloud formation and evolution cannot be magnetic-field driven. Rather, the researchers’ analysis suggests that the same dynamical and self-organization processes that govern our weather are also responsible for those mercury clouds.
The abundance of heavy elements, such as mercury, in the atmosphere is used as a measure of a star’s evolution, but the diversity of the observed heavy-element concentration between stars of similar mass and age has puzzled astronomers. This study could help explain that variation.
Author contact:
Oleg Kochukhov (Uppsala University, Sweden)
Tel: +46 18 471 5993; E-mail: Oleg.Kochukhov@astro.uu.se