Thursday, 26 September 2013

Strange Failed Star Found Hiding Nearby

Stars form when giant clouds of interstellar dust and gas collapse under their own gravity. Steadily gathering into swirling spheres of raw elements, they grow denser and denser, hotter and hotter, until eventually they are hot and massive enough to begin fusing hydrogen into helium inside their cores and whoosh — a star is born.
But sometimes there’s not enough material to get to that point. The protostar, for whatever reason, doesn’t get massive enough to begin the hydrogen fusing process inside it. It’s collected all the dust and gas that was available but it still not enough to ignite. Falling short of full-blown stardom, it’s doomed to drift through the galaxy as a cool, dark brown dwarf… and there’s one right in our stellar neighborhood.

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Brown dwarf VVV BD001 located 55 light-years away.
This image reveals such a failed star, located a mere 55 light-years from our own solar system (although that’s still about 323.1 trillion miles away.) At the very center of the picture lies a brown dwarf — unofficially named VVV BD001 — that was spotted with the European Southern Observatory’s 4.1-meter VISTA telescope during the VVV survey.
The VVV survey (which stands for VISTA Variables in the Via Lactea, i.e., “Milky Way”) searches the area of the sky near the central bulge of our galaxy in near-infrared wavelengths. It’s in these heat-generated emissions that hidden brown dwarfs are most easily found, as they are otherwise optically very dim.
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Despite the name, brown dwarfs aren’t actually brown. But VVV BD001 is even less so (well, kinda sorta) — it’s one of a curious breed known as “unusually blue brown dwarfs.” These emit shorter-wavelength infrared light than most brown dwarfs for reasons not entirely understood (but then, wouldn’t necessarily look blue to our eyes either.) Regardless, it makes VVV BD001 an extra-special find! (Read more on this here.)
In addition, since astronomers don’t usually look for brown dwarfs near the bright, crowded galactic center, VVV BD001 — the first object of its type identified by the survey — was located purely by chance.
Makes one wonder how many others may be out there, and how close they might be…
Source: ESO news release
Credit: ESO, and D. Minniti and J. C. Beamín (Pontificia Universidad Católica de Chile). The team’s paper was published online in the August 27 edition of Astronomy & Astrophysics.