Potentially major ALMA array discovery? Options

[antipode]

This could be big. At the very least its an interesting discovery, but there's a chance it might change our view of the solar system.

http://arxiv.org/pdf/1512.02652.pdf

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[dtolman]

Based off the range of possibilities (large & dark TNO, Super-Earth at 300 AU, closest Brown Dwarf - or unsaid - a new type of object), this is going to be one of the major discoveries of 2015, no matter what it turns out to be.

[ZLD]

I'm going to stay cautiously optimistic here and say this looks great. However, this is extremely early for any real conclusions I think.

[Habukaz]

Mike Brown (and others) is rather dismissive:

Here's the danger of releasing un-peer-reviewed papers on arXiv. There are so many reasons why this is likely wrong.

Fun fact: if it is true that ALMA accidentally discovered a massive outer solar system object in its tiny tiny tiny field of view, ...

that would suggest that there are something like 200,000 earth sized planets in the outer solar system. Which, um, no.

even better: I just realized that this many earth sized planets existing would destabilize the entire solar system and we would all die.

https://twitter.com/plutokiller/status/674800207284928512

https://twitter.com/plutokiller/status/674804436150018048

It seems to boil down to that this would have to be a rather extreme chance discovery in order to be real.

[alan]

They are making this claim based on two observation?

Most of the asteroid searches use several observations to eliminate false positives from variable stars and other transients.

[JRehling]

Maybe I'm missing something, but making two observations of a signal near Alpha Centauri and concluding that it's an object in our solar system seems to me like making two observations of a signal near Jupiter and concluding that it's a satellite of the Earth.

[mcaplinger]

Maybe I'm missing something...

Did you read section 4.1? They certainly try to address why the object is not associated with alpha Cen. As I read it, the basic argument is that it's too bright to be at that distance and not have been seen previously.

Statistically I agree, the chance that the object just happened to be in line with alpha Cen but not associated with it seem very low.

Assuming this object is real, the most likely explanation can't be discussed here due to rule 1.3.

[antipode]

I agree that the chance alignment is worrying. I have no problem with an extreme TNO having a random inclination to the ecliptic, and I'm also open to the idea that WISE might have missed moving sources in crowded stellar fields, but what are the chances that this object just happens to be right next to the closest stellar pair in the sky when ALMA starts looking at it? That doesn't mean it couldn't be something very interesting (my favourite outcome would be a bigger-than-Pluto object at over a thousand AU) but what if its some weird instrumental glitch with this new instrument?

I wonder if this paper will get past pre-print and actually get published in a journal?

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[ZLD]

Assuming this object is real, the most likely explanation can't be discussed here due to rule 1.3.

Haha, is this some new way to get around the rule? 'It's probably a rule 1.3.'

Joking aside, I think it entirely possible for an object to go missed in past surveys. Completely possible and maybe even likely. Does it mean this object fits into that category? No way to know until many more readings are taken. I also do not think it should so quickly be dismissed as many have done. Its a question mark at the moment. Nonetheless, excitement that ends in disappointment due to faulty data can be bad for public outreach all the same though.

[Gsnorgathon]

What other instruments are there that might be able to confirm or disconfirm the ALMA team's findings? Is this the sort of thing where there might be existing data that could be analyzed? If ALMA's the only instrument that's capable of detecting this (putative) object, it's going to be a long wait to be sure it's not an artifact. (That is, an instrumental or methodological artifact, not a Rule 1.3.)

[elakdawalla]

Well, WISE has ruled out brown dwarfs within the solar system. Here's a SciAm article about the whole thing.

[scalbers]

Have yet to read all the text, though if it has the proper motion of A Centauri it should be associated with it. I wonder if it is something bright at millimeter wavelengths and dim at visible wavelengths. Some sort of companion in the Alpha Centauri system, like a large planet or brown dwarf? Maybe it's a brown dwarf that WISE couldn't see in the glare next to A Centauri.

[ZLD]

They do address WISE and question why it would only be detectable now, suggesting that there was too much glare from AC or that it may have been too cold for WISE to catch.I think they've covered the bases as to this being tenuous evidence. Supposing it actually exists and that it isn't in the Solar System because it can't be accounted for in models, maybe it is a very distant, very old dwarf or sorts that is traveling between the systems.

[JRehling]

Did you read section 4.1? They certainly try to address why the object is not associated with alpha Cen. As I read it, the basic argument is that it's too bright to be at that distance and not have been seen previously.

The signal-to-noise ratio for the two "detections" are about 3.6 and 2.1, and are in different locations. For Kepler, an SNR of 7.1 was used for most of the published work, and that ends up creating a lot of false detections. I think the simple explanation is that they took two spurious events which weren't even in the same location and concluded that they detected an object that moved and that has a spectral profile matching those two rather low SNRs.

SNRs of 2 to 4 ought to be occurring in lots of places where there is no real object. That's how noise works – sometimes it's more, and sometimes it's less. An SNR of 7 is hard to get without a real phenomenon behind it – and yet it's not impossible. An SNR<4 is not going to be very rare in a large data set. In Fig. 1 (left), we can see lots of non-black pixels almost as bright as the one they circled. In Fig. 1 (right), what they circle does indeed appear somewhat rare.

The fact that the two detections are in different locations should be taken as a source of doubt that a real object exists. The fact that four observations show no such object are yet more indication that there's no real object.

I suspect that if they created a Monte Carlo model of spurious detections, the possible reality of this "thing" would disappear like smoke. Moreover, I suspect that they detected it and not many more of them in other places of the sky precisely because they were looking at Alpha Centauri, and if they look at lots of other locations and cherry pick noise, they'll find lots more.

[Hungry4info]

I suspect that they detected it and not many more of them in other places of the sky precisely because they were looking at Alpha Centauri, and if they look at lots of other locations and cherry pick noise, they'll find lots more.

Exactly. Indeed, on the same day this second paper was reported, making a very similar claim, but this time toward W Aql.

The serendipitous discovery of a possible new solar system object with ALMA
http://arxiv.org/abs/1512.02650