Two decades after originally discovering brown dwarfs, scientists still aren’t certain exactly why these so-called “little starlets” fail to grow into stars, but new research led by experts at the York Plasma Institute at the University of York may soon help solve the mystery.
Brown dwarfs are a sort of a hybrid of very low mass stars and planets, sharing characteristics of each, and scientists believe that the physics of how dense plasmas merge within them plays a key role in explaining why they form. To investigate, the York-led team created plasma “lumps” as a way to simulate the conditions found deep within actual brown dwarfs.
Working along with experts from the UK’s Science and Technology Facilities Council’s (STFC) Central Laser Facility, they used one of the world’s most powerful lasers—the Vulcan Petawatt in the STFC’s Oxfordshire laser laboratory, to create the first-ever test of viscosity and resistivity in a brown dwarf. Their findings have been published in the journal Nature Communications.
“Brown dwarfs are really difficult to observe because they are cool and our atmosphere absorbs the emissions from cool objects,” Professor Nigel Woolsey from the York Department of Physics explained in a statement Friday. “One of the issues you have in brown dwarfs with dense matter is how this material comes together and how hot it gets.”
Research could reveal how brown dwarfs transport energy
Even though their small size and cool temperature makes these “starlets” difficult to find, they can be detected by measuring the x-rays emitted by the objects, the study authors explained. By doing so, they were able to come up with a profile of how dense plasmas form within the brown dwarfs, thus bringing scientists one step closer to understanding the unusual objects.
“This basic research is furthering our understanding of matter in extreme environments and furthering our understanding of exotic objects,” said Woolsey. “We don’t know because we can’t see them, but we think there are lots of brown dwarfs about. There is a suggestion there is at least as many brown dwarfs as there are stars. There’s more than a billion stars in our galaxy.”
“The Vulcan Petawatt laser is one of the few places on Earth where we can produce conditions close to those at the centre of a brown dwarf,” added lead author Dr Nicola Booth, a scientist at the STFC’s Central Laser Facility who previously studied at York. “We hope that with the predicted future observations of brown dwarfs, our experiments can help with the understanding of how energy is transported in these ‘starlets’.”
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Feature Image: NASA artist’s concept
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