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.