Monday, August 17, 2009

Tiny star's giant planet a 'spare gas tank' - nasa space information

The discovery of a giant planet orbiting the tiny star VB10 made headlines earlier this year as the smallest star ever to be found harboring a planet. But Greg Laughlin, an astronomer at the University of California, Santa Cruz, suggests that the VB10 system could also be a glimpse into the very distant future of our own galaxy.

"VB10 is the lowest-mass star we know of and is about as low-mass as a star can be," says Laughlin, co-writer of the book "The Five Ages of the Universe," which deals with the far-off future of our Milky Way galaxy. "Stars that small are very stingy with their energy production and burn so slowly that VB10 will be shining for the next 10 trillion years."

By the time VB10 runs out of fuel, Laughlin explains, the galaxy will have become a very different place. "Most of the other stars in the galaxy will have burned out," including our own sun, Laughlin says. "Stars like VB10 will be all that's left shining."

Over its lengthy lifetime, VB10 and its companion planet will witness spectacular changes in the neighborhood. "The Milky Way and Andromeda are on track to collide in about 5 billion years," Laughlin says. "Because stars are all so far apart --picture grains of sand separated by miles of empty space --there won't be any stellar collisions. But the gas clouds in each galaxy will smack into each other and create an intense burst of star formation."

This period, in which the galactic average of one new star a year will increase to between 10 and 50, will be, "the last baby boom" of the new combination galaxy, Laughlin says. As star formation decreases and old stars burn out, "the backdrop will slowly fade away, leaving behind stars that are 'built to last' like VB10," he says.

And as if 10 trillion years weren't a long enough lifespan, Laughlin explains that the gigantic planet orbiting VB10, which is 6.4 times the size of Jupiter, will eventually serve, quite literally, as the star's "extra gas tank."

"VB10 b's orbit will slowly tighten, and the planet will eventually merge with its star," Laughlin says. "The planet's gas will be a shot of fresh hydrogen to VB10 and should give it enough fuel to burn another 100 billion years -- basically forever."

VB10 was the first system to be discovered using astrometry, and Laughlin is hopeful that future astrometric missions, such as NASA's SIM Lite, will be able to find many similar systems. "SIM will be able to find a ton of objects like this," he says.

With their incredible endurance and "extra gas tank" planets, stars like VB10 ensure that, several quadrillion years from now and long after most other objects have faded into darkness, there will still be stars twinkling in the sky.

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