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.

Comments

Known unknowns

[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

[ShanghaiBill]

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

[bondsbw]

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

And how has that information influenced scientific research?

Re:Known unknowns

[arcctgx]

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).

The first thing I think of

[The-Ixian]

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....

Re:The first thing I think of

[gstoddart]

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 lucky enough to get the right view of it to even see it.

It's basic science ... observe, hypothesize, observe some more, refine your hypothesis ... keep going.

I'm also sure nobody is saying the original researchers were faking it or did it wrong. It's just now several years later and we have better techniques.

If it was easy, everybody would be doing it.

Me, I read the summary and think "damn, this stuff is cool". Because it's only really around 20 years since we've been able to do this. Before that it was speculative science. Now people treat it like it's commonplace.

For me, as always, thanks to the people who keep the universe wondrous and awesome by showing us just how complex and amazing it really is.

Re:The first thing I think of

[mrchaotica]

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

Oh good

[U2xhc2hkb3QgU3Vja3M]

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.

Re:Oh good

[jfdavis668]

When men were real men, and women were real women, and small furry creatures from Alpha Centauri were real small furry creatures from Alpha Centauri.

Hyperspace Bypass

[Lead Butthead]

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?

Sid Meiers lied to me.

[Sowelu]

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

Not yet???

[Xtifr]

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).

Re:Wrong about that. Wrong about everything?

[HiThere]

When the other christians publicly accept those who do so as christian, then those who act that way ARE christian.

Your point, that some christians don't accept them as christian, is quite weak when all the recognized mouthpieces of the religion accept them as christian.

Now, personally, speaking as a non-christian gnostic, I don't consider that were I a christian I would accept many of the spokespeople chosen by the religion as valid christians. But historically, they're closer to christians as defined by the council of Nicea than the average. E.g., few of them support burning people alive.

Re:Wrong about that. Wrong about everything?

[Grishnakh]

Except that Catholics aren't real Christians, according to all the evangelicals in America.

They also prosecuted Galileo for supporting heliocentrism instead of geocentrism. How is that "always supporting science"? From Wikipedia: "In February 1616, an Inquisitorial commission declared heliocentrism to be 'foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture.'" Doesn't sound very scientific to me. He ended up spending the rest of his life under house arrest and his scientific opinions being silenced.

Maybe **you** should read up on history before defending a religion.