Let's separate out the facts from the speculation. It is a fact that ultra-fast frequency modulations have been observed in several stars in the Sloan survey.
The observed stars are in the spectral range F2 to K1. The spectral sequence for stars goes OBAFGKM and our sun is a type G2 star, so these stars are all 'fairly similar' to the sun. The F stars are of higher energy and the K stars are of lower energy (overall).
So the question arises as to what could cause this type of periodic (in frequency) change in intensity. The most obvious (to me) is some sort of resonance effect, which will produce exactly this type of signal. So where does the resonance come from? The original paper itself mentions the possibility of reflecting surfaces about 250 microns apart. To produce the signal seen, the reflectivity of those surfaces would be pretty low. Another possibility is resonance within the detecting device itself. But both of these explanations have the difficulty that only a few stars show this effect: only a couple hundred of the hundreds of thousands measured.
Another possible explanation comes from the way the data is processed. The data from the Sloan Survey aren't in frequency units, so the data has to be converted to such units before the Fourier analysis. A linear extrapolation between data points is used, which can itself give rise to periodic modulations. Again, though, the fact that such a signal is detected in only a few stars argues against this explanation.
The original paper proposes ETIs as a possible explanation. Given the wide range of physical effects that can produce a signal of this type, this seems premature. For example, it may be due to small scale turbulent layers in the atmospheres of a select collection of stars, possibly an effect that changes over time. Any type of resonant phenomenon anywhere along the data path could potentially be the source of this signal, especially if there is a resonance with just certain spectral types.
It should be noted that the spectral types reported for these stars are 'binned' and not evenly distributed. Also, preference in the surveys were for exactly the stars we are interested in (f through K). I also find it peculiar for the ETI hypothesis that 'signals' were found for type A stars also. These are typically considered to be too 'hot' for life to reasonably exist around them.
My personal guess is that this is an instrumental effect combined with a data processing effect. But that is a guess.
I also found another paper related to this suggesting the signal is actually an indirect detection of axion-like dark matter.
https://arxiv.org/pdf/1611.02586.pdf
My recommendation: wait an see what shakes out of this. I'd find it interesting if the same effects are found in the same stars in a subsequent survey using different hardware. Until then, there are just too many parameters to form a firm conclusion.
The observed stars are in the spectral range F2 to K1. The spectral sequence for stars goes OBAFGKM and our sun is a type G2 star, so these stars are all 'fairly similar' to the sun. The F stars are of higher energy and the K stars are of lower energy (overall).
So the question arises as to what could cause this type of periodic (in frequency) change in intensity. The most obvious (to me) is some sort of resonance effect, which will produce exactly this type of signal. So where does the resonance come from? The original paper itself mentions the possibility of reflecting surfaces about 250 microns apart. To produce the signal seen, the reflectivity of those surfaces would be pretty low. Another possibility is resonance within the detecting device itself. But both of these explanations have the difficulty that only a few stars show this effect: only a couple hundred of the hundreds of thousands measured.
Another possible explanation comes from the way the data is processed. The data from the Sloan Survey aren't in frequency units, so the data has to be converted to such units before the Fourier analysis. A linear extrapolation between data points is used, which can itself give rise to periodic modulations. Again, though, the fact that such a signal is detected in only a few stars argues against this explanation.
The original paper proposes ETIs as a possible explanation. Given the wide range of physical effects that can produce a signal of this type, this seems premature. For example, it may be due to small scale turbulent layers in the atmospheres of a select collection of stars, possibly an effect that changes over time. Any type of resonant phenomenon anywhere along the data path could potentially be the source of this signal, especially if there is a resonance with just certain spectral types.
It should be noted that the spectral types reported for these stars are 'binned' and not evenly distributed. Also, preference in the surveys were for exactly the stars we are interested in (f through K). I also find it peculiar for the ETI hypothesis that 'signals' were found for type A stars also. These are typically considered to be too 'hot' for life to reasonably exist around them.
My personal guess is that this is an instrumental effect combined with a data processing effect. But that is a guess.
I also found another paper related to this suggesting the signal is actually an indirect detection of axion-like dark matter.
https://arxiv.org/pdf/1611.02586.pdf
My recommendation: wait an see what shakes out of this. I'd find it interesting if the same effects are found in the same stars in a subsequent survey using different hardware. Until then, there are just too many parameters to form a firm conclusion.
