“The star is the size of Jupiter, and its storm is the size of Jupiter’s Great Red Spot,” said John Gizis of the University of Delaware, Newark.
“We know this newfound storm has lasted at least two years, and probably longer.”
Gizis is the lead author of a new study describing the phenomenon and published in The Astrophysical Journal. The observations were made using data from NASA’s Spitzer and Kepler space telescopes.
“While planets have been known to have cloudy storms, this is the best evidence yet for a star that has one,” Gizis said.
The star, known as W1906+40, is thought to be of a type known as an L-dwarf. Some of these fuse atoms and generate light but others, called brown dwarfs, are known as “failed stars” for their lack of atomic fusion.
W1906+40, is thought to be the former given its temperature of about 1,900 °C (2,200 Kelvin) – cool in star temperature terms.
Gizis says it is this relative coolness that allows clouds of tiny minerals to form.
In the past Spitzer has observed storms on cloudy brown dwarfs that have lasted for days at most. In the case of W1906+40, which was first spotted in 2011, the phenomenon has been going on for two years.
“We don’t know if this kind of star storm is unique or common, and we don’t why it persists for so long,” said Gizis.