Spitzer and Kepler detect Jupiter-like storm on small star

December 10, 2015, NASA
This illustration shows a cool star, called W1906+40, marked by a raging storm near one of its poles. Credit: NASA/JPL-Caltech

Astronomers have discovered what appears to be a tiny star with a giant, cloudy storm, using data from NASA's Spitzer and Kepler space telescopes. The dark storm is akin to Jupiter's Great Red Spot: a persistent, raging storm larger than Earth.

"The star is the size of Jupiter, and its 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 appearing in The Astrophysical Journal.

While planets have been known to have cloudy storms, this is the best evidence yet for a star that has one. The star, referred to as W1906+40, belongs to a thermally cool class of objects called L-dwarfs. Some L-dwarfs are considered because they fuse atoms and generate light, as our sun does, while others, called , are known as "failed stars" for their lack of atomic fusion.

The L-dwarf in the study, W1906+40, is thought to be a star based on estimates of its age (the older the L-dwarf, the more likely it is a star). Its temperature is about 3,500 degrees Fahrenheit (2,200 Kelvin). That may sound scorching hot, but as far as stars go, it is relatively cool. Cool enough, in fact, for clouds to form in its atmosphere.

"The L-dwarf's clouds are made of tiny minerals," said Gizis.

Spitzer has observed other cloudy brown dwarfs before, finding evidence for short-lived storms lasting hours and perhaps days.

In the new study, the astronomers were able to study changes in the atmosphere of W1906+40 for two years. The L-dwarf had initially been discovered by NASA's Wide-field Infrared Survey Explorer in 2011. Later, Gizis and his team realized that this object happened to be located in the same area of the sky where NASA's Kepler mission had been staring at stars for years to hunt for planets.

Kepler identifies planets by looking for dips in starlight as planets pass in front of their stars. In this case, astronomers knew observed dips in starlight weren't coming from planets, but they thought they might be looking at a star spot—which, like our sun's "sunspots," are a result of concentrated magnetic fields. Star spots would also cause dips in starlight as they rotate around the star.

Follow-up observations with Spitzer, which detects infrared light, revealed that the dark patch was not a magnetic star spot but a colossal, cloudy storm with a diameter that could hold three Earths. The storm rotates around the star about every 9 hours. Spitzer's infrared measurements at two infrared wavelengths probed different layers of the atmosphere and, together with the Kepler visible-light data, helped reveal the presence of the storm.

While this storm looks different when viewed at various wavelengths, astronomers say that if we could somehow travel there in a starship, it would look like a dark mark near the polar top of the star.

The researchers plan to look for other stormy stars and brown dwarfs using Spitzer and Kepler in the future.

"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.

Explore further: Kepler provides insights into unusual dwarf star

More information: "Kepler Monitoring of an L Dwarf II. Clouds with Multiyear Lifetimes," John E. Gizis et al., 2015 Nov. 10, Astrophysical Journal, iopscience.iop.org/article/10. … /0004-637X/813/2/104 , On Arxiv: arxiv.org/abs/1509.07186

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wduckss
1.8 / 5 (5) Dec 11, 2015
If the rotation W1906 + 40 is 8.9 hours it is not enough that the body size of Jupiter has a temperature of 2,200 Kelvin. Weight and size of the body must be much bigger than Jupiter.
nkalanaga
5 / 5 (6) Dec 11, 2015
You're right. The diameter of the smallest stars is about the same as Jupiter, but the mass is about 80 times higher, giving the stars much higher densities. Interestingly, all brown dwarfs are about the diameter of Jupiter. Jupiter's mass is about where density starts increasing much faster than mass, so extra mass doesn't mean a larger diameter.
wduckss
1 / 5 (6) Dec 12, 2015
It is not realistic to expect a large discrepancy between the mass and radius. Magma has a temperature from 700 to 1300 ° C, the density at these temperatures is 2180-2800 kg / m3. Juppiter has a density of 1,326 kg / m3.
This indicates that the radius of the body must be higher because the higher temperature (of 1,300 ° C) is lower dense.
nkalanaga
5 / 5 (4) Dec 12, 2015
Jupiter is mostly gas, while magma is mostly silicates and metal oxides/sulfides. Gas is less dense than rock. It also compresses more easily, allowing the density to climb quickly as the mass increases.

Main-sequence stars, like red dwarfs, the Sun, and other hydrogen-fusing stars, are inflated by radiation pressure. Once the Sun runs out of fuel, it will be a white dwarf, with about the diameter of the Earth, about half its current mass, and a ridiculously high density.
wduckss
1 / 5 (4) Dec 12, 2015
I understand your vision, but the reality is different. If the body has a temperature of 2,200 Kelvin has a red color and can be small, medium and giant stars.
Small stars are transit stars, moving from planet in star, and the results are somewhat different but still within the universality within the Universe. You represent official position, I statistics.
See: The causal relation between a star and its temperature, gravity, radius and color http://www.svemir...tml#ring

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