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Dozens of discoveries vault known exoplanet tally over 400

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New exoplanets include Gliese 667C bA suite of some 30 newly discovered planets in other solar systems, unveiled today, brings the catalogue of such extrasolar planets, or exoplanets, to more than 400.

The newfound bodies were turned up by the High Accuracy Radial Velocity Planetary Search (HARPS), a program designed to detect the presence of orbiting planets by tracking the motion of their host stars. As a star wobbles under the gravitational influence of a planet, it periodically moves closer to our solar system before drawing away again, imbuing its emitted light with telltale Doppler shifts.

The research team announced its findings today at an exoplanet conference in Porto, Portugal, hosted by the European Southern Observatory and the Center for Astrophysics at the University of Porto.

With the new influx from HARPS, the known population of exoplanets is now 403, according to the online Extrasolar Planets Encyclopaedia. (HARPS announced 32 new finds today, but the encyclopedia catalogued just 30 of them, characterizing the other two as brown dwarfs, failed stars too small to sustain fusion.)

The swelling planetary catalogue is still bereft of the ultimate goal of planet hunters, however: small, rocky planets at the right distance from their stars to potentially host life as we know it. Those planets may indeed be common throughout the galaxy, but most current detection methods tend to favor massive planets or planets in tight orbits around their host stars. (The smallest planet in the new group found by HARPS, for instance, is roughly 5.5 times the mass of Earth and is so close to its star that it completes an orbit in about four days.)

Ground-based telescopes such as that used by HARPS as well as space-based observatories are turning up ever smaller extrasolar planets, but the real payoff—an Earth-like planet orbiting a distant star—may have to wait until 2012 or 2013. That is when NASA’s Kepler spacecraft will have logged enough time in its dedicated search for planetary transits, or periodic dips in a star’s brightness as an orbiting planet partially obscures it, to have solid evidence for an Earth-like planet.

Artist’s impression of GJ 667C b, a newfound exoplanet that orbits a star 23 light-years from the sun in a triple-star system (the two companion stars to the exoplanet’s host star are depicted in the background): ESO





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  1. 1. bitflung 3:20 pm 10/19/2009

    wait – if we find exoplanets by watching for the star wobbling, then i want to know: how much does our own star wobble? are we missing exoplanets that happen to have other planets in their solar system, thus potentially obscuring the telltale wobble by averaging out the gravitational pull and spreading out the wobble to a slower less obvious ‘beat pulse’ remnant of the otherwise strong gravitational influences of those planets?

    -bit

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  2. 2. Rouge77 3:52 pm 10/19/2009

    Sun wobbles too and Jupiter’s influence on the Sun would be easy to find with an equipment similar to our own. Earth would be beyond the current capabilities with this method, but probably not for long. And yes, we are missing exoplanets because other planets in the same system hide their influence. There are cases where such at first "hiddden" planets have been found.

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  3. 3. Rouge77 3:52 pm 10/19/2009

    Sun wobbles too and Jupiter’s influence on the Sun would be easy to find with an equipment similar to our own. Earth would be beyond the current capabilities with this method, but probably not for long. And yes, we are missing exoplanets because other planets in the same system hide their influence. There are cases where such at first "hiddden" planets have been found.

    Link to this
  4. 4. bitflung 5:25 pm 10/19/2009

    @Rogue77
    cool, thanks for the clear and meaningful reply.

    Link to this
  5. 5. profpaul 8:05 pm 10/19/2009

    Many multi-planet systems can be detected by stellar "wobble" but the wobbles take on a sort of multi-harmonic. single planet systems have fairly singular wobbles, since closer planets move faster they can create faster "wobbles" than more distant planets. Doppler shifts then become overlays of two wobbles and reading the cycle can tell how many large planets are in the system — that make the star wobble. As mention small mass planets are still a way from being detected by this method.

    The Kepler probe is using a visual method to detect small planets transiting a star slightly dimming the light as it passes. But this relies on the stars planetary ecliptic to be aligned somewhat in our direction. Which makes this method somewhat long term. As we move around the galactic center we are hoping some of these alignments will work to our advantage.

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  6. 6. Innov8or 3:52 am 10/31/2009

    The doppler shift detection also detects only planets orbiting in a plane generally close to our viewpoint. At least within what, 45 degrees?

    The Kepler system requires that the planet orbit precisely between it’s star and us (less than 1 degree). Are the odds in our favour? Do our planets orbit in the same plane as our galaxy?

    Link to this
  7. 7. zaid 12:55 am 11/4/2009

    i agree with innov8or

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