Scientists have found the best evidence yet for a star with a storm on it. Cloudy, windy storms are usually associated with planets. W1906+40, a distant dwarf star with some serious weather issues, is described in a study published recently in the Astrophysical Journal.
W1906+40 is small for a star -- about the same size as Jupiter -- and it's classified as an L-dwarf, which makes it close to planets on the planet-to-star spectrum. And yes, there's a spectrum: The coolest L-dwarf stars are known as brown dwarfs, and are sometimes referred to as "failed stars". They don't fuse atoms together to generate light the way most stars do, and they're quite similar to gas giant planets like Jupiter (which is arguably an overachieving planet). The biggest difference between star-like planets and planet-like stars is that they form very differently, and scientists often have to use the cosmic object's age to classify it correctly.
W1906+40 has a surface temperature of around 3,500 degrees Fahrenheit, so it might still have a little fusion going on — but not enough to make it too warm for clouds made of minerals to form in its atmosphere. It's not a total stellar failure, but it's probably pretty close.
But as is the case on Jupiter, that weird combination of star and planet qualities may have resulted in a massive storm -- which blurs the line between star and planet even further.
Jupiter's storm, called the Great Red Spot, has been raging for as long as humans have been watching it -- about 400 years. It's slowly shrinking, according to recent observations, but it's still about three times bigger than Earth.
"The star is the size of Jupiter, and its storm is the size of Jupiter's Great Red Spot," study author John Gizis of the University of Delaware said in a statement. "We know this newfound storm has lasted at least two years, and probably longer."
The cosmic forecast comes courtesy of Kepler, the great exoplanet hunting telescope. Kepler detects exoplanets by watching the dimming of distant stars, which scientists use to determine details about the objects passing in front of them. When Gizis and his colleagues looked at W1906+40, they saw a dark spot that didn't waver. That in itself isn't totally unusual: The most likely explanation would be a star spot. Known as sunspots when they happen on our own star, these patches of concentrated magnetic field can make dark blotches on a star's surface.
But further investigation in infrared light revealed that the dark spot had nothing to do with magnetic fields. The whopping storm makes a dark mark on top of the star, rotating around it about every nine hours. Scientists aren't sure why these storms last so long or how common they are, but the researchers involved in the study plan on seeking out more stormy dwarfs to learn more.