“We find a hot spot that covers half of the surface of the star like a giant lighthouse that rotates in and out of our field of view,” said Berger. The team also observed soft x-ray emission and an x-ray flare.Īlso for the first time, the group charted optical hydrogen-alpha emission with a period of two hours that matches the two-hour rotation period of the star. These flares come from the catastrophic collisions and merging of the magnetic fields in the corona of the star these actions drive the annihilation of magnetic energy like a giant short-circuits in the fields.
The star’s steady radio emission is interrupted with spectacular fireworks displays of minute-long flares.
“With such a unique set of observations you always expect to find the unexpected,” said Berger, “but we were shocked at the level of complexity that this object exhibits.” The study is part of a program that looks at the origins of magnetic fields in ultracool dwarfs, stars that astronomers always assumed were simple, quiet, and more tranquil than their hotter and more massive siblings. This is the first time that such a powerful set of telescopes has been trained on one of the smallest known stars. The team’s observations of TVLM513-46546 combine radio data from the Very Large Array, optical spectra from the Gemini North 8-meter telescope, ultraviolet images from the orbiting Swift observatory and x-ray data from NASA’s Chandra X-ray Observatory. Edo Berger, a Carnegie-Princeton postdoctoral fellow at Princeton University, is using these observations to explain the flamboyant activity of this M-type dwarf that lies about 35 light-years away in the constellation Boötes. Simultaneous observations made by four of the most powerful Earth- and space-based telescopes revealed an unusually active magnetic field on the ultracool low-mass star TVLM513-46546.
Princeton dwarf star with a surprisingly magnetic personality and a huge hot spot covering half its surface area is showing astronomers that life as a cool dwarf is not necessarily as simple and quiet as they once assumed.
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