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Thread: Young Sun's X-ray flares may have saved Earth

  1. #1 Young Sun's X-ray flares may have saved Earth 
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    The colossal X-ray flares generate turbulence in the dust disc, preventing young planets from spiralling inwards to their deaths


    Young Sun's X-ray flares may have saved Earth
    13:16 11 May 2005
    NewScientist.com news service
    Kelly Young


    Earth and its planetary neighbours may owe their existence to immense and violent X-ray flares produced by the Sun in its youth, new research on distant stars suggests.

    The observations indicate that massive flares from young stars are frequent. These would generate turbulence in the swirling dust disc around the stars, and help to prevent nascent planets from spiralling in towards the star, to their destruction.

    When solar flares are emitted by the Sun today, we think of them as a danger, or perhaps a nuisance, says Joan Najita, an astronomer with the National Optical Astronomy Observatory in Tucson, Arizona, US. They can knock out communication satellites and pose a hazard for astronauts. But solar flares could have played a very important role in the survival of our young planet, she says.

    Using the Chandra X-ray Observatory, an international team of astrophysicists observed 1400 embryonic stars in the Orion Nebula Cluster for almost two weeks. Of those stars, 28 were similar in size to the early Sun and about 14 of these suns may have planet-forming discs around them.

    The team, known as the Chandra Orion Ultradeep Project, found that many of these stars produce a prodigious amount of X-rays through solar flares. The stars are relatively young - between 1 and 10 million years old, compared to our 4.6-billion-year-old Sun - and so give clues as to how our star may have behaved as an infant.
    Stellar short-circuits

    The young stars have not had time to develop cores, so they are magnetically more unstable than their older relatives. This instability leads to short-circuiting, says Scott Wolk, an astrophysicist with the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, US, and one of the research team.

    The young stars are constantly spewing out thousands of small flares and, roughly once a week, these stars let loose a huge flare that bursts out to 10 times the star’s radius. These enormous flares dwarf anything seen from our Sun today in terms of in energy, size and frequency. (You can view an animation in .mov or .mpeg format).

    The core accretion model of planet formation suggest that dust particles in a disc around a young star begin to clump together into rocks, which then stick together to form planetary cores. But a problem with this model is that once the planet cores reach a certain mass, gravitational attraction should frequently cause them spiral in toward the central star.

    But massive solar flares early in a star’s history could help counteract this inward migration by generating turbulence, allowing terrestrial planets like Earth to survive. The flares flood the flat protoplanetary discs with X-rays, generating charged particles such as protons and ions. If you ionise a disc, it is widely believed it will make it a seething boiling mess, says Eric Feigelson, an astronomer at Penn State University in Pennsylvania, US. This could cause the gas in the disc to cluster here and there, which then pushes and pulls a protoplanet in a zigzag motion, slowing its spiral in towards the star.

    The results are scheduled to be published in the Astrophysical Journal Supplement later in 2005.

    Source here
    Understanding how mechanisms work within newly formed star systems is key to understanding how our system came to be. I would never have thought that flares were more violent nor that not having a fully formed core would influance this action in such a way, much less encourage of the protoplantary bodies to obtain stable orbit. This in turn may well explain why the planets for the most part have a roughly circular orbit and not an eccentric one. Barring such capture possibilites as Pluto in my mind this might go a long way towards explaining the idea.


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