Artist's impression of red dwarf star TVLM 513-46546. ALMA observations suggest that it has an amazingly powerful magnetic field (shown by the blue lines), potentially associated with a flurry of solar-flare-like eruptions.
Take TVLM 513-46546 for example. It’s a small M-class red dwarf, a star that belongs to the most populous stellar group in the galaxy. But TVLM 513-46546 would find it hard blending in with the crowd.
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As observed by the Atacama Large Millimeter/submillimeter Array (ALMA), this little star was found to have an extremely powerful magnetic field, rivaling the most powerful magnetically active regions on our sun. It is so active, argue astronomers, that if our planet was in orbit around this star, satellites would not function.
“If we lived around a star like this one, we wouldn’t have any satellite communications. In fact, it might be extremely difficult for life to evolve at all in such a stormy environment,” said Peter Williams, of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. and lead author of the study published in the Astrophysical Journal.
TVLM 513-46546 is located some 35 light-years from Earth in the constellation Boötes. It is a teeny tiny star is only 10 percent the mass of our sun, so tiny in fact that it is on the cusp of the bridging gap between what constitutes a star and what constitutes a planet. If the star were any smaller, there would be insufficient pressure in its core to ignite fusion, making it a brown dwarf, or a “failed star.” But a brown dwarf TVLM 513-46546 is not, it is a magnetic powerhouse and one of the most violent stellar objects we’ve seen in the Milky Way.
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The red dwarf is spinning rapidly, taking only 2 hours to spin a full rotation — by comparison, our sun takes 25 days to complete one rotation — and this rotation rate could be the root as to why TVLM 513-46546′s magnetic field is so strong.
“This star is a very different beast from our sun, magnetically speaking,” said coauthor Edo Berger, also from the CfA.
When studying the object with ALMA, the researchers detected powerful radio signals that betrayed the star’s magnetic personality. They measured a signal at 95 GHz, a high-frequency radiation produced by a process known as synchrotron emission, which is generated by high-energy electrons rapidly accelerated by intense magnetic fields. From this measured frequency, the researchers realized the star had a global magnetic field hundreds of times more powerful than the average magnetic field observed in our sun. Although our sun can muster the strength to occasionally generate synchrotron emissions at these frequencies, only the most powerful solar flares can generate them.
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As ALMA only observed TVLM 513-46546 for a short, 4 hour period, and it was generating these powerful radio emissions for the entire time, astronomers were able to deduce that this star is constantly erupting, blasting superflares into space.
This is yet another example of why red dwarfs may not be the best locations for potentially habitable planets to spawn life. The constant stellar flare ups would wash the local interplanetary environment with radiation, continually destroying hypothetical atmospheres and any biospheres that have the potential to evolve within. Also, as TVLM 513-46546 is so tiny and cool, any planet orbiting within the star’s habitable zone (the region surrounding a star that is neither too hot or too cold for liquid water to persist on the planet’s surface) would be extremely close to the red dwarf, making the likelihood of life (at least, life as we know it) extremely slim.
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