[Link]: KIC 8462852, aka WTF star, "the most mysterious star in our galaxy", ETI candidate, etc.

I'm not an astronomy expert either, but see section 2.6: "Limits on a companion". That reddit thread didn't seem to realize that section 2.6 actually lays out the case against an undetected binary based on doppler shifts.

The 20% dip requires a large occluder, about as large as the F-class star itself - or more likely even larger assuming it isn't perfectly opaque/cohesive. A star that big should be detectable unless it is close enough to be indistinguishable, because stars only get that big due to fusion overcoming gravity. The doppler analysis in section 2.6 rules out any large heavy close companion.

The other sections in general place geometric limits on the location of the occluder object(s) - within a range of 3 to 8 AUs.

Also, the hidden binary hypothesis doesn't much help explain the odd fractal complexity of the dip around 1540, which suggests a number of objects. The simpler single dip pattern at around 800 fits the profile of a single occluder clump about the size of the star or larger (partial occlusion), which of course is itself also weird. The second occlusion event at 1540 could be caused by the 800 clump plus additional smaller objects/clumps. For comparison, a more typical occlusion by a jupiter sized object creates a plateau shaped dip pattern of < 1%, like this.

The occluder clumps appear to be something about as large as the star, but of less mass, and they can't be very hot. They outline a full set of observational constraints in 4.4.1 which doesn't leave much room for known objects. The only things that seem to fit the full profile are swarms of stuff/debris/clouds bound to small objects, moving in tight formations (thus the swarm of disintegrating comets theory).

There is another oddity that the paper briefly mentions but does't even attempt to explain. There is a clear but small high frequency modulation in the light curve which they explain as the star's rotation period of 0.8 days. There is another larger longer term modulation on the order of 10-20 days which is present most of the time but strangely disappears in at least one time period:

We also report on the presence of a possible 10 – 20 day period (Figure 2), which, when present, is visible by eye in the light curve. We illustrate this in Figure 4, showing zoomed in regions of the Kepler light curve. The star’s 0.88 d period is evident in each section as the high-frequency flux variations. The panel second from the bottom ‘(c)’) shows no low-frequency (10 – 20 day) variations, but the rest do. We have no current hypothesis to explain this signal.

Assuming this isn't aliens, then perhaps this will turn out to be the stellar equivalent of ball lightning.

The probability that any specific observation is caused by aliens is so heavily influenced by priors/models that it's more interesting to consider conditionals such as P(aliens caused WTF | aliens exist) or P(WTF observations | aliens caused WTF).

What's the probability that this is caused by aliens?

What is your own probability estimate? I am not sure I can accurately distinguish between below 1/100,000 and between 1/10,000 and 1/100,000. With probabilities this small I am not sure that any estimate is useful

Can you put in an "I'd just like to see the results" option?

My guess is somewhere between .2% and 2%, depending on how many stars have actually been examined, a figure I don't know.

I just posted a comment on facebook that I'm going to lazily copy here:

At this point I have no idea what's going on and I'm basically just waiting for astrophysicists to weigh in. All I can say is that this is fascinating and I can't wait for more data to come in.

Two specific things I'm confused about:

1. Apparently other astronomers already looked at this data and didn't notice anything amiss. Schaefer quotes them as saying "the star did not do anything spectacular over the past 100 years." But as far as I can tell the only relevant difference between their work and Schaefer's is that he grouped the data into five year bins and they didn't. And sure, binning is great and all, and it makes trends easier to spot. But it's not magic. It can't manufacture statistical significance out of thin air. If the binned data has a significant trend then the unbinned data should as well. So I don't get why the first paper didn't find a dimming trend (unless they were just eyeballing the data and didn't even bother to do a linear fit, but why would they do that?). I mean, in the end Schaefer's plot looks pretty convincing, so I don't think this throws his work into doubt. But it still seems weird.

2. Any explanation for this has to kind of walk a tightrope walk - you need something that blocks out a significant amount of light to account for the data, but thermodynamics is pretty insistent that any light you absorb has to come out as infrared eventually. So if you posit something that blocks out too much light you run up against the problem of there being no infrared excess. The nice thing about the megastructure hypothesis was that it could explain the dips while still being small enough to not produce an infrared excess.

Now, though, we have to explain not just dips but progressive dimming. And yeah, progressive dimming certainly sounds consistent with a dyson swarm being built. But dyson swarms large enough to dim an entire star seem like the kind of thing that would definitely produce an infrared excess. And in fact it seems like any explanation for that much dimming would require an infrared excess, which we don't see.

I guess it all depends on the magnitude of the dimming, though. If it's not that much dimming, I guess there could be an intermediate-sized dyson swarm (or weird astrophysical phenomenon, it doesn't matter, they should all produce infrared) that was big enough to cause the dimming but not big enough to produce noticeable infrared excess.

For now I remain confused and fascinated.

That's less likely than that it's something aliens constructed to make their lives better.

The star is 1,480 light years away. Any aliens there will never affect us.