Magnetic storms may be the answer to a mystery that has puzzled astronomers for years. Developing stars give off far more infrared light than theories predict. A group of astronomers now believe they have detected the source of this additional infrared radiation.
Stars are born in vast clouds of gas and dust, that collapses over time. As the gas accumulates into a proto-star, there is a natural spin to the remaining material, which will coalesce into planets, comets, and asteroids. As these planetary disks take shape around stars, they are heated by their sun. This causes the gas and dust to glow in infrared wavelengths of electromagnetic radiation. In 2006, the Spitzer Space Telescope saw that radiation, as well as additional heating, produced by an unknown source.
Researchers believe clouds of gas and dust are trapped above the planet-forming disk. As energy is released by the star, it is trapped by the clouds, which then radiate the energy in the form of infrared waves. The effect might look familiar to a person who finds themselves in the alien star system.
"If you could somehow stand on one of these planet-forming disks and look at the star in the center through the disk atmosphere, you would see what looks like a sunset," Neal Turner, from Jet Propulsion Laboratory (JPL), said.
Collapse of the proto-planetary disk also causes the collapse of magnetic fields contained in the structure. Researchers found this can direct the flow of material, including plasma, generating arcs. These features then contribute to heating of the clouds, creating the excess radiation.
The idea of clouds, caught in the magnetic field of a star, has been theorized for a while. This is the first time such a system has been discussed as a means of explaining excess infrared energy from developing stellar groups.
This new theory could also explain some missing details surrounding the formation of planets from disks. Some astronomers speculated that a halo of material surrounded the planetary disk. Recent observations suggest disks are surrounded by fuzzy layers of low-density gas, traveling along magnetic field lines. The new study brings together these two ideas, and is able to account for all the excess energy measured by Spitzer.
"The starlight-intercepting material lies not in a halo, and not in a traditional disk either, but in a disk atmosphere supported by magnetic fields. Such magnetized atmospheres were predicted to form as the disk drives gas inward to crash onto the growing star," Turner said.