Mystery Object Defies Astronomical Classification
Posted by Xeno on April 8, 2010
A mysterious object discovered near a brown dwarf doesn’t fit into any known astronomical category.
The newly discovered mystery companion forms a binary system with the brown dwarf, located 460 light-years away in the Taurus star-forming system. The object is too light to be another brown dwarf, but it’s too young to have formed by accretion, the way a typical planet does.
“Although this small companion appears to have a mass that is comparable to the mass of planets around stars, we don’t think it formed like a planet,” said astronomer Kevin Luhman of Penn State University, co-author of the study April 5 in The Astrophysical Journal. “This seems to indicate that there are two different ways for nature to make small companions.”
Luhman’s team made the discovery with the Hubble Space Telescope and the Gemini Observatory.
The new object and its companion brown dwarf are orbiting as a binary pair, 15 astronomical units from each other. If they were superimposed on our solar system, the companion would be orbiting midway between Saturn and Uranus. The oddball object’s mass is somewhere between five and 10 Jupiter masses, making it too small to fuse deuterium. The International Astronomical Union currently uses this fusion line, which occurs at about 13 Jupiter masses, as the defining characteristic of a brown dwarf.
But the object appears to be around the same age as its binary partner, which doesn’t fit conventional ideas about planet formation. Traditional theories describe planets forming from the gaseous disk that swirls around the equator of a newly formed star. Particles in the gas and dust cloud collide, and gradually accrete into larger objects, eventually becoming planets. These rocky planets can grow into sizes up to 10 Earth masses before they become gas giants.
And 1 million years is much shorter than the expected time for a planet to be born this way. Planets can form this quickly when there is a gravitational instability in the gaseous disk, but the brown dwarf’s disk probably didn’t have enough material to form a planet larger than a single Jupiter mass.
“It looks like this new system formed by the collapse and fragmentation process that forms binary star systems,” Alan Boss, president of the IAU Commission on Extrasolar Planets said in an e-mail to Wired.com. Boss theorized that these sorts of planet-sized objects exist in a paper published in 2001. …
Of course, I love the idea that this could be a Dyson Sphere. See: how to create a Dyson Sphere.
… The great advantage to a Dyson Sphere is twofold: One, the species inhabiting the sphere can theoretically use 100% of their sun’s power, and two, the sphere’s inner surface provides an enormous habitable area for, potentially, an entire species. In terms of figures, the Earth has a surface area of roughly 789 million square miles (assuming it where a perfect sphere), while a human-made Dyson Sphere would theoretically have an area of approximately 252 quadrillion square miles. If we assume that the habitable to non-habitable area ratio remains the same from the Earth to the sphere, our living space would be multipied some 319 million times. Of course, our population would also be much larger, but each citizen could still probably be gauranteed a good swatch of space if he wanted it.
Given this huge amount of space, humanity would be able to reestablish rain forests and other heavily damaged/destroyed ecosystems from Earth, and still have room for habitation. Large industrial complexes would ring the upper and lower portions of the sphere, using solar collectors to gather the energy necessary for all our large scale manufacturing needs (i.e. replacement sphere pieces, spacecraft, etc.) while fusion reactors or distributed solar power would provide energy for the populace. …