Rogue Brown Dwarf Lurks In Our Cosmic Neighborhood

astroengine writes "The UK Infrared Telescope in Hawaii has discovered a lone, cool brown dwarf called UGPSJ0722-05. As far as sub-stellar objects go, this is a strange one. For starters, it's the coolest brown dwarf ever discovered (and astronomers using the UKIRT should know; they are making a habit of finding cool brown dwarfs). Secondly, it's close. In fact, it's the closest brown dwarf to Earth, at a distance of only 10 light years. And thirdly, it has an odd spectroscopic signature, leading astronomers to think that this might be the discovery of a whole new class of brown dwarf."

Re:Hmmm...

[tmosley]

1/3rd of a light year. The brown dwarf is about 2.5 times further than the nearest bright star, Alpha Centauri. Definitely not inside of the solar system, but well within our cosmic neighborhood.

Pretty close...

[Notquitecajun]

This chart http://www.astro.wisc.edu/~dolan/constellations/extra/nearest.html [wisc.edu] lists the closest objects to earth. The brown dwarf (being a failed brown dwarf and found recently...howzabout calling it FAIL) is about the 12th closest object to our solar system.

Re:thats actually really close...

[linzeal]

Project Orion [wikipedia.org] is the only one I have ever heard of that claims such speeds.

Re:thats actually really close...

[Anonymous Coward]

Somebody mod him "insightful but doubtful".

A *LOT* of money would be saved by performing a flyby. This might be the only way it could be done. Not having to carry the fuel required to slow down cuts the cost by *more* than 50%.

Consider the Pioneer missions, Voyagers, and the current New Horizons, they're all flybys for one reason: it's cheaper to do a flyby. If you find something really interesting on the flyby, you can then justify funds for an expensive orbital mission.

Alternative tech like light sails might eventually change this, but for current, self fueled reaction drive technology, flybys are way cheaper than orbitals.

Re:Probably has water

[Frequency Domain]

It's not a star [wikipedia.org]. Brown dwarfs generate enough heat at their cores to maintain convection between the core and the surface, which keeps elements from differentiating (separating out), but they don't have enough mass to sustain fusion, which is required to be considered a star.

Re:thats actually really close...

[RockDoctor]

Even though it uses light and not solar winds, an equivalent concept of a Heliopause would probably still take effect (the closer you get to the other star the more its light counters Sol).

True, but not particularly important. Most of the benefit of the "launching lasers" you get by getting up to a high speed fairly soon, reducing your time of flight. If you're only (or largely) powered by launching lasers and solar sails, then you'll be expecting to have an asymmetric journey in both distance and time, because the high intensity of the "launching lasers" at the Sol end of the journey would need to be counteracted by the lower intensity of the light from the target star over a longer distance and duration.

Using an interstellar laser to push it isn't really practical as at those distances it becomes horribly difficult to aim the laser with such precision. Assuming your laser could aim precisely, by the time you realise you are pointing in the wrong direction and make a correction, it will take years for the correction to take effect, by which time the sail has already moved.

Your laser will have a certain divergence of beam, due to manufacture errors. As you get further away, the intensity will drop (this is part of the reason that you get up to speed as soon as possible, and will, indeed eventually the "launching lasers" will become useless. But regardless, you don't steer the ship by moving the laser, you steer it by tilting the sail.
With a solar sail, you get two types of drive. Some drive is from particles of solar wind travelling (more-or-less) radially out from Sol hitting the sail and sticking. These transfer their momentum vector directly to the sail, and hence to the towed payload. Their impulse on the sail will always be radial to the target star (to moderate precision). The other source of drive though is from photons that hit the sail and are reflected from the sail's surface. These, as a moment's consideration will tell you, will provide an impulse vector to the sail (and hence, to the payload) which is in the direction of the bisector of the angle between the direction of the incoming photon and the direction of the outgoing photon. In short, the sailor can "tack" his vessel against the light-wind from the "launching lasers". The control system is at the sailor's end, not the launching laser's end ; the launching laser jockey simply points his laser at the target star and leaves it up to the sailor to stay within the beam ; the sailor has to work out how to make the final cruise form the light beam to the target star, knowing that an error either kills everyone on board, or means an unnecessary year in the tin can (which is also likely to be a death sentence for the erring sailor).

Byproduct : if a solar sail powered probe is launched from star A to star B, then for a number of years before the arrival of the probe at star B, there will be an intense, monochromatic source of light shining from star A at star B. In short, a very bright warning light.
Reference reading : " The Mote in God's Eye (Orbit Books) (Paperback) by Larry Niven and Jerry Pournelle (Author) ; classic hard SF.
Byproduct 2 : if your solar sail-powered craft approaches the target star without being greeted or communicated with ... then the inhabitants are either dead, or live underground, or have yet to learn to bang the rocks together. Or just possibly use visual pigments that work in a very different part of the spectrum to your launching lasers.

Hmmm : multi-wavelength launching lasers. Possible? Helpful? Problematic? I'll have to think about that.