Stars and cloudy storms aren’t something you usually see in an article. Yet, here we are. Astronomers took a peek at data from NASA’s Spitzer and Kepler space telescopes. They found what appears to be a tiny star with a giant cloudy storm at its pole.
The concept of storms on stars isn’t a new one. Last year, observations from the Spitzer Space Telescope suggested most brown dwarf stars have one or more planet-size storms. Brown dwarf stars are often referred to as ‘failed stars.’ They just don’t have the mass to fuse atoms continually and become full stars.
Artist concept of storms raging on a brown dwarf star. Credit: NASA
The latest observation centers around a star dubbed W1906+40. It’s in a class of stars that includes brown dwarfs, called L-dwarfs. These stars are known for being much cooler than your average star. Based on estimates of W1906’s age, scientists believe it is a star (unlike a brown dwarf star). The older an L-dwarf star is, the more likely it’s a star.
W1906+40’s clouds don’t offer any reprieve from the heat. Temperatures on the star are estimated to be about 3,500 degrees Fahrenheit. That’s downright chilly compared to most stars, and it’s cool enough for clouds to form in its atmosphere.
Two years of study
W1906+40 was first spotted by NASA’s Wide-field Infrared Survey Explorer in 2011. Gizis and his team noticed the star was in the same part of the sky Kepler hunts for planets in.
How does a telescope looking for planets help find a storm on a star? Remember, Kepler is always on the lookout for dips in a star’s brightness. And the team of astronomers saw them on W1906+40. Brightness dips don’t have to come from planets. In fact, the researchers knew planets were not responsible for these dips. The most likely explanation was star spots. But follow-up observations with Spitzer ruled out star spots and pointed to a huge, cloudy storm.
The data tells us this storm rotates around the star about every 9 hours. If we could somehow travel there, it would look like a giant dark spot near the top pole.
Are these storms common?
That’s a question researchers plan to tackle in the future. Kepler data can find stars with dips in brightness. And Spitzer can use its infrared measurements to figure out if the changes in brightness are due to star spots, or something else.
“We don’t know if this kind of star storm is unique or common, and we don’t know why it persists for so long,” says Gizis. We know W1906+40’s storm has been around for at least two years and may be much older.