Astronomers Say They've Found a Brown Dwarf With Its Own Planet for the First Time in History

Tuesday, 27 March 2018 - 1:51PM
Science News
Tuesday, 27 March 2018 - 1:51PM
Astronomers Say They've Found a Brown Dwarf With Its Own Planet for the First Time in History
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Image credit: NASA/Outer Places
What's the difference between a planet and a star?

This isn't a set-up for a dumb joke, but rather a genuine question that astronomers are struggling to answer. The planet/star debate isn't black and white; there exists a grey area (or rather, a brown area) in between these terms.

A brown dwarf is either a large, gassy planet, or a small, failed star, depending on your perspective. Jupiter could potentially be described as a brown dwarf, but most of the time, this classification is reserved for larger bodies that are similar to the biggest planet in our solar system, but on a much larger scale.

Brown dwarfs don't have quite enough energy to burst forth in brilliant glory like regular stars - essentially, they're the kernels that don't quite manage to pop in the microwave popcorn bag that is the universe.

In the past, scientists have observed large planets orbiting brown dwarfs, but these appear to have formed at the same time as the bodies they orbit, creating a binary planet system.

Now, though, for the first time, astronomers have spotted a planet revolving around a brown dwarf that was created in the traditional manner; forming out of dust and debris that circled the failed star in the wake of its initial creation.

This is a big deal for the entire astronomical society. Essentially, this planet proves that brown dwarfs aren't entirely dissimilar to regular stars and that they can give off enough material initially after creation to be able to form planets of their own.

The challenge with studying brown dwarfs, in general, is the fact that they give off very little light. It's estimated that these kinds of cosmic bodies could be relatively common in the universe, but we'd never know it because we can't see any of them.

The scientists who managed to make this new discovery (and who've named their find OGLE-2017-BLG-1522) were only able to spot the brown dwarf and its baby when the pair passed in front of a brighter star. This temporary fluctuation in light from the star allowed astronomers to extrapolate the specific dimensions of the brown dwarf, which is approximately 46 times larger than Jupiter; and its baby, which is 60 times smaller than the brown dwarf itself.

There are still some uncertainties surrounding this discovery that need to be cleared up. At present, scientists estimate that there's only around a 76 percent chance that their calculations are correct and that OGLE-2017-BLG-1522 really is a dwarf star. The paper containing these findings has not yet passed through a peer review system, which will be crucial to verifying the assertions contained within.

If this does hold up to peer pressure, the discovery could change the way astronomers approach both brown dwarfs and stars in general—we'll finally have a little more understanding of how stars form, and what causes a planet to take shape in the orbit of a celestial body.

Certainly, this will make it more likely that brown dwarfs count as stars rather than planets. Clearly, the universe really doesn't care about our classification systems.
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