Dwarf Star Blasts out Stunningly Powerful Flares
A
nearby star smaller than Jupiter punches far above its weight, firing
off surprisingly intense flares that regularly triple its total
brightness, scientists say.
Dwarf Star Blasts out Stunningly Powerful Flares
By Mike Wall | SPACE.com – 16 hrs ago
A nearby star smaller than Jupiter punches far above its weight, firing
off surprisingly intense flares that regularly triple its total
brightness, scientists say.
The dwarf star, which lies 53 light-years from Earth, has an intrinisic
brightness just 0.02 percent that of our own much larger sun. But the
dwarf still manages to unleash dazzlingly bright flares comparable in
energy to the most powerful solar flares that erupt from our star, a new study reports.
"It would be like the sun suddenly, in a minute, became three times
brighter and then gradually faded over the next few hours," astronomer John Gizis
of the University of Delaware told reporters today (June 3) at the
222nd meeting of the American Astronomical Society in Indianapolis. [The Worst Solar Storms in History]
Gizis and his team discovered the powerhouse L dwarf star, known as
W1906+40, two years ago. It's just 90 percent as wide as the planet Jupiter, with a cool (for a star) average temperature of about 3,700 degrees Fahrenheit (2,038 degrees Celsius).
But observations by NASA's planet-hunting Kepler space telescope
have revealed that, every week or so, W1906+40 blasts out a flare that
heats the star up to 14,000 degrees Fahrenheit (7,760 degrees Celsius).
"The energy is something like, if I've calculated it correctly —
something like 4 billion megatons of TNT," Gizis said. For comparison,
the nuclear bomb the United States dropped on the Japanese city of
Hiroshima during World War II had an explosive yield of about 13
kilotons of TNT. (There are 1,000 kilotons in a megaton.)While the new findings have substantial gee-whiz appeal on their own, they could also help astronomers address broader questions, Gizik said.
For example, studying W1906+40's superflares could contribute to a better understanding of how flares work on stars in general and on our sun in particular. And they could shed light on the potential of dwarf-star systems to host extraterrestrial life.
"Some people have been arguing that you could put habitable planets next to L dwarfs, although personally I think it's arguably a far-fetched idea," Gizik said. "Of course, the flares are somewhat bad news for that kind of scenario, but more calculations would be needed."
As the new study shows, astronomers have also been using Kepler's precise measurements to study the stars themselves, learning more about stellar variability and outbursts such as flares.
Last month, however, NASA officials announced that the second of Kepler's four orientation-maintaining reaction wheels had failed, robbing the spacecraft of its precise pointing ability. Mission engineers are trying to recover at least one of the failed wheels; if they cannot do so, Kepler's planet-hunting days are almost certainly over.
The new study will be published in an upcoming issue of The Astrophysical Journal.
Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.
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Dwarf Star Blasts out Stunningly Powerful Flares
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