For the first time a powerful laser has been used tofurther our understanding of some of the most mysterious celestial objects justbeyond the solar system - brown dwarfs.
Despite being discovered 20 years ago, very little is knownabout brown dwarfs – notably why they fail to grow into stars.Scientistssay part of the answer probably lies in the physics of how dense plasmas mergeinside them.
Now researchers, led by the York Plasma Institute at theUniversity of York and the Central Laser Facility (CLF), have created “lumps” of plasma to recreate theconditions similar to those found deep inside brown dwarfs.
They were able to do this in the laboratory using one of theworld’s most powerful lasers, the CLF's Vulcan Petawatt, to create the first test of resistivity and viscosityfound in brown dwarfs.
Credit: Gemini Observatory/Artwork by JonLomberg
Dr Nicola Booth, an experimental research scientist atthe CLF, who led the test, said: “The Vulcan Petawattlaser is one of the few places on Earth where we can produce conditions closeto those at the centre of a brown dwarf.
“We hope that with the predicted future observations ofbrown dwarfs, our experiments can help with the understanding of how energy istransported in these ‘starlets’.”
Brown dwarfs bridge the gap between very low mass stars andplanets and share characteristics with both.Despitebeing numerous, these little “starlets” are hard to spot because they are smalland cool so tend to be faint and difficult to record.
But by measuring the x-rays emitted from these objects, theresearchers were able to build up a profile of how dense plasmas form insidebrown dwarfs.
The results, published in Nature Communications, pavethe way towards furthering our understanding of these celestial objects.Professor Nigel Woolsey from the University of York, andlead investigator on the project, said: “Brown dwarfs are really difficult toobserve because they are cool and our atmosphere absorbs the emissions fromcool objects.
“One of the issues you have in brown dwarfs with densematter is how this material comes together and how hot it gets. This basicresearch is furthering our understanding of matter in extreme environments andfurthering our understanding of exotic objects.
“We think, but we don’t know because we can’t seethem, but we think there are lots of brown dwarfs about. There is a suggestionthere is at least as many brown dwarfs as there are stars. There’s morethan a billion stars in our galaxy.”
It is hoped NASA’s premier observatory, the James Webb SpaceTelescope currently under construction in the U.S, will help scientistsunderstand brown dwarfs in the future.
The research was led by the University of York and STFC, incollaboration with researchers from the University of Oxford, University ofNevada, Instituto Nazionale di Optica, and Queen’s University Belfast.
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