‘Second Earth’ Proxima b’s star is more like our Sun than thought


#ProximaB #Earth‘Second Earth’ Proxima b’s star is more like our Sun than thought : In August, astronomers declared to great fanfare that they had discovered a ‘second Earth’ orbiting nearby star Proxima Centauri, four light-years away.

Orbiting in the star’s habitable zone, the Earth-sized planet Proxima b piqued the interests of experts because they believe it has a temperature suitable for liquid water to exist on its surface.

Although this, of course, doesn’t guarantee it could host alien life, evidence of water could increase the chances of it significantly. Now, further to this, researchers from Harvard have found Proxima Centauri may be more like our own Sun than previously thought.

On first appearance, Proxima Centauri seems nothing like our Sun. It’s a small, cool, red dwarf star only one-tenth as massive and one-thousandth as luminous. However, it is sunlike in one surprising way: it has a regular cycle of starspots.

Starspots (like sunspots) are “blotches” on a star’s surface where the temperature is a little cooler than the surrounding area. These areas are driven by magnetic fields which can restrict the plasma on the surface and create spots. The more the magnetic field changes, the more this affects the number and distribution of starspots.

Credit : ESO/M. Kornmesser

Our Sun goes through an 11-year activity cycle. At the solar minimum, the Sun is practically spot-free. At solar maximum, typically more than 100 sunspots cover less than one percent of the Sun’s surface, on average.

The study shows that Proxima Centauri goes through a similar cycle lasting seven years from peak to peak. But it’s much more dramatic. At least one-fifth of the star’s surface is covered in spots at any one tie and some of those spots are much larger relative to the star’s size than the spots on our Sun.