Proxima Centauri Might be More Similar to Our Sun Than Previously Thought
A new study revealed that the tiny, red dwarf star Proxima Centauri is actually more sun-like than what astronomers have previously thought.
Previously, astronomers thought that Proxima Centauri is nothing like our Sun. There are not to blame for assuming so because the cool red dwarf star is only about one-thousandths as luminous and one-tenths as massive as our sun. However, a study published in the journal Monthly Notices of the Royal Astronomical Society showed that Proxima Centauri has a regular cycle of starspots just like our sun.
Starspots, just like sunspots, are dark blotches on the surface of a star that are driven by magnetic fields. These magnetic fields can restrict the flow of ionized gases called plasma. By restricting the flow of plasma, magnetic fields create spots in the star's surface that are cooler than the surrounding area. The number and distribution of spots across the star's surface is affected by the changes in the star's magnetic fields.
"The existence of a cycle in Proxima Centauri shows that we don't understand how stars' magnetic fields are generated as well as we thought we did," said co-author Jeremy Drake, of Smithsonian, in a statement.
Unlike our Sun that have an 11-year activity cycle and more than 100 sunspots at one percent of its surface during solar maximum, Proxima Centauri experiences a seven year cycle with at least one-fifth of the star's surface covered in starspots all at once. Additionally, the starspots observed in Proxima Centauri appear to be bigger relative to the star's size compared to our Sun.
The researchers at Harvard-Smithsonian Center for Astrophysics were baffled by their discovery. As oppose to our Sun that experience a rolling motion called convection in its outer third, while the interior remains relatively still, Proxima Centauri is believed to experience convection all the way into its core. The difference in the speed of rotation between the inner and outer regions of our Sun is responsible for its magnetic fields. However, there is no such difference in the rotation of the inner and outer regions of Proxima Centauri, suggesting that it should not experience regular cycle of activity.