Free Range Brown Dwarfs

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Using two of the world’s largest optical-infrared telescopes, the Subaru Telescope in Hawaii and the Very Large Telescope (VLT) in Chile, an international team of astronomers has discovered more than two dozen brown dwarf stars floating around in two galactic clusters. During the Substellar Objects in Nearby Young Clusters (SONYC) survey, these “failed stars” came to their attention by showing up in extremely deep images of the NGC 1333 and rho Ophiuchi star clusters at both optical and infrared wavelengths. To make the findings even more exciting, these stellar curiosities outnumbered the “normal” stars in one cluster!

“Our findings suggest once again that objects not much bigger than Jupiter could form the same way as stars do. In other words, nature appears to have more than one trick up its sleeve for producing planetary mass objects,” says Professor Ray Jayawardhana, Canada Research Chair in Observational Astrophysics at the University of Toronto and leader of the international team. Their discovery will be published in two upcoming papers in the Astrophysical Journal and will be presented this week at a scientific conference in Garching, Germany.

Using spectroscopy, the researchers were able to separate candidate brown dwarfs by their red color. But there’s more to the story than just hues. In this case, it’s the identification of one that’s only about six times more massive than Jupiter. Located in NGC 1333, it is the smallest known free-floating object to date. What does that mean? “Its mass is comparable to those of giant planets, yet it doesn’t circle a star. How it formed is a mystery,” said Aleks Scholz of the Dublin Institute for Advanced Studies in Ireland, lead author of the first paper.

Brown dwarfs are indeed unusual. They walk a fine line between planet and star – and may have once been in stellar orbit, only to be ejected at some point in time. But in this circumstance, all of the brown dwarfs found in this particular cluster have very low mass – only about twenty times that of Jupiter. “Brown dwarfs seem to be more common in NGC 1333 than in other young star clusters. That difference may be hinting at how different environmental conditions affect their formation,” said Koraljka Muzic of the University of Toronto in Canada, lead author of the second paper.

“We could not have made these exciting discoveries if not for the remarkable capabilities of Subaru and the VLT. Instruments that can image large patches of the sky and take hundreds of spectra at once are key to our success,” said Motohide Tamura of the National Astronomical Observatory of Japan.

Free-range brown dwarfs? I’ll take mine over easy…

Original Story Source: Subaru Telescope News.