Slashdot Mirror
Alpha Centauri Turns Out Not To Have a Planet After All. At Least, Not Yet (forbes.com)
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.
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.
Has it occurred to you that perhaps the planet isn't there because the Vogons had erroneously demolished it after having mistaken it for Earth?
ELOI, ELOI, LAMA SABACHTHANI!?
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.
And how many exoplanets discovered to date are the result of handling data incorrectly?
And how has that information influenced scientific research?
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
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).
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).