The Biggest Thing In The Universe Is So Gigantic It Shouldn’t Exist At All (HuffingtonPost.com)

Awesome, huge, gigantic…are now terms completely dwarfed by an amazing new discovery! Thanks to the nerdy folk over at The Huffington Post, we’re now all in the know.


What’s the biggest known structure in the universe?

Astronomers used to think it was a “filament” of galaxies known as the Sloan Great Wall. But recent research suggests a different structure is even bigger — and its size has astronomers scratching their heads.

Meet the Hercules-Corona Borealis Great Wall (Her-CrB GW). Check it out in the video above.

“The Her-CrB GW is larger than the theoretical upper limit on how big universal structures can be,” Dr. Jon Hakkila, an astrophysics professor at the College of Charleston in South Carolina and one of the astronomers who discovered the structure, told The Huffington Post in an email. “Thus, it is a conundrum: it shouldn’t exist but apparently does.”

Mysteries just like this are why astronomers scan the skies for a glimpse into the past, as they shed light not only on the early years of our universe, but also more about our galaxy, our solar system, and ultimately, ourselves.

“We are now mapping structures across the sky,” astronomer Dr. Jay M. Pasachoff, director of the Hopkins Observatory at Williams College in Williamstown, Mass., who was not involved in the great wall’s discovery, told The Huffington Post. “We’re learning how the universe grew up. So we’re learning about how our cluster of galaxies grew up and how our own galaxy grew up and how our sun formed, and how the Earth formed soon there after. We’re looking back at our history.”

Because astronomers are still mapping the sky, there just may be something even grander than the Hercules-Corona Borealis Great Wall in our universe.

“The danger of finding the biggest, or most distant, or the oldest things in the universe is always that sooner or later someone is likely to come along and find something bigger, more distant, or older than the thing you found,” Hakkila said. “So far we have not been upstaged, but it has only been about six months since we published.”

The finding was published in the journal Astronomy & Astrophysics.

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First Planet Discovered Orbiting a Brown Dwarf (TechnologyReview.com)

This is really interesting. Using a different detection technique, astronomers aren’t required to search for planets and stars based on brightness alone. I’d expect to see dozens of new brown dwarf planets to be found in the near future due to this discovery.

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Astronomers have long supposed that planets can form around brown dwarfs just as they do around ordinary stars. Now they’ve found the first example.

Astrophysical calculations show that any star that is smaller than about 1/10th of the mass of the sun cannot sustain hydrogen fusion reactions at its core. These failed stars never light up. Instead they wander the galaxy as warm, dark balls of hydrogen known as brown dwarfs.

Brown dwarfs probably form through the same process that lead to ordinary stars but merely on a smaller scale. If that’s correct, planets should also form in the protoplanetary disks of gas and dust around brown dwarfs. Indeed, astronomers have seen a number of protoplanetary disks of this type.

Until now, however, they’ve never seen a planet orbiting a brown dwarf. That’s not really surprising.

The standard methods for detecting planets look for the way a star wobbles as a planet orbits or at how its magnitude changes as a planet passes in front. But given that brown dwarfs are dim and difficult to see, these methods have yet to produce fruit.

All that changes today with the announcement by an international team of astronomers that they’ve discovered a planet orbiting a brown dwarf the first time. These guys have made their discovery using an entirely different method of detection called gravitational lensing. This occurs when one body passes in front of another and its gravity focuses light from the more distant object towards Earth. That works regardless of the brightnesses involved.

The brown dwarf in question is almost 6000 light years from Earth in the Fish Hook constellation. Astronomers first noticed an unusual change in its brightness in April 2012. Further investigation showed that this was indeed a lensing event.

These guys conclude that the brown dwarf is being orbited by a planet about twice the mass of Jupiter at a distance of just under one astronomical unit. The brown dwarf itself is about 10 times larger than its companion.

That’s the first time astronomers have found an object orbiting a brown dwarf that can be truly described as a planet. The technical definition of a planet is that it must have formed in the parent object’s protoplanetary disk.

Astronomers have seen other planet-sized objects orbiting brown dwarfs but only at distances of several tens of astronomical units. That’s too far to have been part of the protoplanetary disk. “Thus,…,they are not bona fide planets,” say the team.

So that’s a modest first for this team. It raises the question of what kind of conditions exist on such a planet and, of course, whether these could support life.

This planet almost certainly does not fall into that category but where there is one planet, there are almost certainly others. Astronomers can now have some fun speculating on the Goldilocks zones around brown dwarfs where conditions are just right for life and how to spot the interesting planets inside them.

Ref: arxiv.org/abs/1307.6335 : Microlensing Discovery Of A Tight, Low Mass-Ratio Planetary-Mass Object Around An Old, Field Brown Dwarf

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