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Space

Alpha Centauri Turns Out Not To Have a Planet After All. At Least, Not Yet (forbes.com) 91

StartsWithABang writes: In 2012, astronomers announced that the nearest star system to us, the Alpha Centauri system, possessed at least one exoplanet around it. A periodic signal that recurred just every 3.24 days was consistent with an Earth-sized exoplanet orbiting and gravitationally tugging on the second largest member of the star system: Alpha Centauri B. That planet, named Alpha Centauri Bb, turns out not to actually be there. A reanalysis of the data shows that a combination of stellar properties and the times at which the observations were made conspired to produce this spurious signal: a signal that goes away if the data is handled correctly. Accounting for everything correctly reveals something else of interest, a periodic 20-day signal, which may turn out — with better observations — to be Alpha Centauri's first exoplanet after all.
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Alpha Centauri Turns Out Not To Have a Planet After All. At Least, Not Yet

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  • Known unknowns (Score:2, Insightful)

    by Anonymous Coward
    handling data correctly got rid of the 3 day signal, but another 20 day signal showed up. So they measured it wrong? Or did they measure it wrong the second time?
    • Re:Known unknowns (Score:4, Insightful)

      by ShanghaiBill ( 739463 ) on Tuesday January 05, 2016 @04:44PM (#51243707)

      Since 2012, we have much greater experience with exoplanets, more data, and better algorithms. So a mistake today is less likely than a mistake 4 years ago.

      • Re:Known unknowns (Score:4, Interesting)

        by bondsbw ( 888959 ) on Tuesday January 05, 2016 @04:50PM (#51243739)

        And how many exoplanets discovered to date are the result of handling data incorrectly?

        And how has that information influenced scientific research?

        • And how many exoplanets discovered to date are the result of handling data incorrectly?

          And how has that information influenced scientific research?

          Depends on what you mean by "discovered". If you mean any instance where somebody suspects there may be an exoplanet, then somewhere over 50% are false positives. That's probably why they typically require multiple confirmations from different sources before they actually consider something an exoplanet.

    • Re:Known unknowns (Score:5, Interesting)

      by arcctgx ( 607542 ) on Tuesday January 05, 2016 @05:02PM (#51243815)

      It's noisy data. In the plots in TFA, you'll see that the residuals are expressed in meters per second. Meters! It's at the limit of detection even for our best spectrographs.

      It's very hard to work with noisy data. If you work on bad data the results get extremely dependent on methods of analysis. How do you prepare the data? Do you reject outlying measurements before you even get to analysis? If so, how? Why reject *this* point, but leave *that* one? Are you doing any filtering of the data (and how)? Any windowing? Smoothing? There's a lot of tricks you can use to make bad data appear acceptable. But in the end, it's garbage in, garbage out. That other signal can very well be an artifact. Or could be real, but not a planet. Or indeed a planet. We have no way of knowing without getting more observations of better quality (which is difficult and costs a lot of $$$).

      On the other hand, if the data is good, then any data analysis method will give you consistent results (provided that the method is used correctly).

      • by Anonymous Coward

        And all of this is a good reason for making the data (raw and processed) publicly available so that others can look at it.

    • by Anonymous Coward

      handling data correctly got rid of the 3 day signal, but another 20 day signal showed up. So they measured it wrong? Or did they measure it wrong the second time?

      The first signal was from the still fresh debris of a destroyed planet while it was dispersing. The new signal they've found is from the Deathstar that destroyed it.

      The good news is that the Rebel Base is no longer near us so we may be spared. Unless...

  • by The-Ixian ( 168184 ) on Tuesday January 05, 2016 @04:24PM (#51243621)

    when I read that summary is: How do we know that *this* time the data was handled correctly?

    I am sure that the original researchers thought they were handling the data correctly too....

    • Well, look at it this way ... if it exhibits a periodic dimming, then either something is orbiting it, or some feature of the star has a periodicity which needs to be explained.

      People forget that they're mostly inferring based on what they can see of the light from the star dimming in some interval (something transiting in front of it), or in measuring a wobble in the star (again light, suggesting gravity is at work and deflecting the star).

      It's not like they can directly photograph it, and we have to be lu

      • This one was detected with doppler shift, not dimming.

      • Now see, I had you pegged as a grumpy old man with an onion on his belt. The façade has cracked slightly and I see the awe and wonder. Nice.

      • It gets better. most of the planets discovered to date, have orbits of their star that is closer to venus than earth.

    • The first thing I thought of was "why the fuck is this scientific topic linking to an article from Forbes, of all places?"

      • That was my second thought.

      • by Opyros ( 1153335 )
        We need a new tag for stories like this: ohnoitsethan
      • by dywolf ( 2673597 )

        not even Forbes.

        its a forbes.com/sites/ page, ie, a blog, though they don't call it that.
        forbes.com is notorious for giving anyone a voice under /sites/
        Sometimes sane, frequently not.
        But being under forbes they also get a little bit of authority that they don't necessarily qualify for.

    • by Tablizer ( 95088 )

      I believe they announce a "find" when a certain statistical confidence level is reached.

      For example, if the statistical confidence threshold is 95%, then they have to be at least 95% confident, based on statistical analysis of the data, before they formally announce.

      But that would also mean that the "new" find, when formally announced, has a 5% chance of being wrong.

      If the press or public complains often about false finds, they may decide to raise the threshold. (I don't know the actual current target level

    • by Kjella ( 173770 )

      when I read that summary is: How do we know that *this* time the data was handled correctly?

      I am sure that the original researchers thought they were handling the data correctly too....

      Nothing is absolutely certain, even mathematical proofs depend on them actually being correct. I'm sure a lot of people here have introduced a new bug when fixing an old one. All we can do is see what stands up to scrutiny...

    • by iris-n ( 1276146 )

      Well, I'm very confident that they were careful not to repeat the same mistake the original researches made, so it is at least a less wrong analysis =)

    • by dywolf ( 2673597 )

      First thing I thought of was "dammit, the arcologys are already on their way".

  • Oh good (Score:4, Funny)

    by U2xhc2hkb3QgU3Vja3M ( 4212163 ) on Tuesday January 05, 2016 @04:24PM (#51243625)

    We'll finally be able to go our local planning department to see if there's any planning charts or demolition orders for our solar system.

    Or at least, see if there's any small furry creatures living there.

  • by Sowelu ( 713889 ) on Tuesday January 05, 2016 @04:34PM (#51243671)

    Either that, or the Transcendence ending was really, really hardcore.

  • It has (maybe) a planet around it, not an exoplanet.

  • Alpha Centauri B is just trying planets on, looking for one that doesn't make her look fat.

  • BB-8 @ Alpha Centauri

  • Crap. I hope I can get a refund on this ticket I bought.
    • by Tablizer ( 95088 )

      Crap. I hope I can get a refund on this ticket I bought.

      Good luck with that; the mailing address is on the "missing" planet.

  • Aw shit.
  • Not yet??? (Score:5, Insightful)

    by Xtifr ( 1323 ) on Tuesday January 05, 2016 @05:32PM (#51244027) Homepage

    Wow, I think that may be one of the worst headlines I've seen on Slashdot, and that's saying something. "Not yet" does not mean "we're not sure yet." And "turns out not to have a planet" does not mean "we don't know if it does, but our earlier assumption turns out to be wrong."

    From the headline, I assumed that they'd managed to establish that Alpha C. actually did not have a planet, but did have coalescing clouds that would soon (in astronomical terms) become one. That would be an extremely cool discovery! Unfortunately, neither of those things appears to be true (or if it is, we haven't established it).

    How about "Reports of Alpha Centauri's Planet Proven to be Premature"? It's even got some nice alliterism to it. And, possibly more importantly, it's got some relationship to the facts (at least as presented in TFS).

  • by Anonymous Coward

    The crew of the Jupiter II is really lost in space now!

    CAP === 'Danger Will Robinson!'

  • You know, so many problems with science could be solved if peer review was mandatory precondition prior to blabbing to the press.

  • Alpha Centaurs, 2012: Come to our star system! We can haz Class M planet.

    Alpha Centaurs, 2016: j/k

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