MASSIVE and violent solar flares may have saved a nascent Earth from spiralling into the sun during the early stages of planet formation.
In the most commonly accepted model of planet formation, dust particles in the protoplanetary disc around a young star clump together to form rocks, which then stick together to form planetary cores. But the model fails to explain how the cores, once they reach a certain mass, can resist gravitational attraction and keep from falling towards the host star.
That鈥檚 where solar flares come in, according to a team working on the Chandra Orion Ultradeep Project. The team studied 1400 embryonic stars in the Orion Nebula Cluster, using the Chandra orbiting X-ray observatory, and found 28 similar in size to the early sun, about 14 of which may have planet-forming discs around them. These stars are between a million and 10 million years old, and can provide clues as to how our 4.6-billion-year-old sun may have behaved as an infant.
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Roughly once a week, each of these stars lets loose a flare that reaches up to 10 times the star鈥檚 radius. These enormous flares dwarf anything our sun can eject today in terms of energy, size and frequency.
Such gigantic solar flares could have helped counteract the inward migration of planetary cores by generating turbulence in the protoplanetary disc, and may have allowed Earth to survive its precarious youth. The work will appear in a future issue of the Astrophysical Journal Supplement.
