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Storm similar to Jupiter’s Great Red Spot detected on low mass star

Star Storm

An artist’s rendering of a storm on a cool, star-like body such as a brown dwarf. L-dwarfs are a step above brown dwarfs in that they have some fusion occurring in the core. Image Credit: JPL / NASA

A large, cloudy storm has been detected on a tiny, cool star known as W1906+40 by scientists using NASA’s Spitzer and Kepler space telescopes. The finding marks the first time clouds and a storm similar to Jupiter’s Great Red Spot have been found on a star rather than on a planet.

John Gizis, a noted scientist at the University of Delaware, Newark, said the star is known as an L-dwarf. W1906+40 is low mass, thermally cool, and approximately the size of Jupiter.

Gizis, who is the lead author of a study about the storm published in The Astrophysical Journal, said the storm is located near the star’s north pole and is about the same size as Jupiter’s Great Red Spot. It has been around for at least two years.

L-dwarfs usually conduct at least some fusion in their cores and generate their own light, which is why they are considered stars. W1906+40 has an estimated temperature of 3,500 °F (2,200 K), cool enough for clouds composed of tiny minerals to form in its atmosphere.

An artist illustration showing a raging storm near one of the pols of W1906+40. Image Credit: JPL / NASA

An artist’s illustration showing a raging storm near one of the poles of W1906+40. Image Credit: JPL / NASA

Brown dwarfs are one step below L-dwarfs in stellar classification because the former either fail to conduct fusion in their cores or do so just briefly fusing deuterium – an isotope of hydrogen, rather than hydrogen itself.

Clouds and storms have previously been observed on brown dwarfs.

W1906+40 was discovered in 2011 by scientists using NASA’s Wide-field Infrared Survey Explorer (WISE). When Gizis realized the star was located in the same part of the sky where Kepler is searching for exoplanets, he had the planet-hunting observatory look towards it, then followed-up those observations by using Spitzer to look at the star in infrared wavelengths.

After the star was discovered, Gizis and his team studied its atmospheric changes for two years.

Kepler searches for orbiting planets by looking for regular dips in stars’ light as their planets transit in front of them. The telescope can also identify star spots, dark regions on a star’s surface caused by magnetic fields, much like sunspots on the Sun, which cause dimming as they rotate around the star.

While Kepler did find a dark spot on W1906+40, which was initially thought to be a star spot, Spitzer’s follow up, which measured the star in two infrared wavelengths and observed different layers of its atmosphere, revealed the dark spot was a large, cloudy storm that rotates around the star approximately every nine hours.

Scientists combined Spitzer’s infrared data with Kepler’s visible light data to confirm the dark spot as a storm large enough to hold three Earths.

“We don’t know if this kind of star storm is unique or common, and we don’t why it persists for so long,” Gizis said.

His team hopes to find answers by using Kepler and Spitzer to search for similar storms on other L-dwarfs and brown dwarfs.

Video courtesy of NASA Spitzer


Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.

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