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[Music] Rachel Osten: When I got the

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news on April 23rd, earlier this year,

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that a flare had been detected by Swift and it

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was coming from a nearby flare star called

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DG CVn, I was initially very surprised.

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Swift doesn't normally detect flares

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from nearby flare stars, and DG CVn

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is a relatively unknown star.

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Narrator: There are a few things we know about DG CVn. It is an

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M-class star, also called a red dwarf, and is located only about

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60 light years away. Rachel: It's a dim little red star, it has

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a luminosity that's about one-thousandth the luminosity of the sun.

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It has a mass that's about one-third the mass of the sun, 

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and a radius that's about one-third

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the radius of the sun. Narrator: The largest solar flare

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ever recorded happened on November 4th, 2003.

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It was so powerful that it overloaded the sensors measuring it, but

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later calculations put it at an an X45.

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Flares are classified according to their strength. The smallest ones are

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B-class, followed by C, M, and X, the largest.

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An X45 flare is a very powerful flare.

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DG CVn's flare, however, was much

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larger. Rachel: We can estimate

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how big the flare on DG CVn was with respect to

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the solar scale; it would have been an 

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X100,000. So this is several orders of 

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magnitude larger than the biggest solar flare we've ever seen.

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The flare that Swift triggered on from DG CVn

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was only the beginning of what turned out to be

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a fairly extended series of flares,

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a flare "event" if you will, that lasted

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almost 20 days. Steven Drake: This was a

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very different star than the sun, so we don't really have to worry about this happening

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in the present-day sun. The young sun, such large events may have

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occurred. In the present-day sun the activity levels are much

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lower. The fundamental reason that DG CVn is more active than the sun

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is it's a very young star--30 million years--it's rapidly rotating,

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young stars are born that way, and rapid rotation

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is one of the key ingredients which powers activity. The faster the rotation,

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the greater the activity. Narrator: While not a threat to us,

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the massive flares of red dwarf stars can help us better understand the flares produced

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by our own sun. They are also of interest because red dwarf stars

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a often orbited by planets. Some data suggest

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that 40 percent of red dwarfs have "super-Earth" type planets orbiting

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in a habitable zone, where liquid water is possible.

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If this is true, then they are good candidates for supporting life.

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However, the habitable zone around a cool, dim star like

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DG CVn is much closer to the star than the Earth is to the sun.

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Rachel: When planets are closer to their star,

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they're more susceptible to anything the star does. For instance,

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if the star flares, the planet is much closer to the

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star, and it can be hit by

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the radiation or the particles that get ejected

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from the star when this flare process happens. If you happened

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to be on a planet around an M dwarf,

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when one of these large flares went off, you'd be

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having a very bad day. [Beeping]

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[Beeping]

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[Beeping]