Too tight perhaps?
Could light pollution possibly be the reason for the decrease of the light curve of KIC 8462 and EPIC 916?
http://www.cnn.com/2016/06/11/health/light-pollution-atlas-milky-way-irpt/index.html
It matters which way the rings spin as to how stable they are: http://up-ship.com/blog/?p=33346
Retrograde rings seem to calm down after a bit.
A recent paper entitled “Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars” by Borra and Trottier (2016), Université Laval, Quebec, reports the detection of periodic spectral modulations in 234 out of 2.5 million stars observed by the Sloan Digital Sky Survey (SDSS). Authors Borra and Trottier state that the signal is consistent with a prediction from an earlier paper by Borra, for signals from extraterrestrial civilizations broadcasting extremely rapid (shorter than 0.1 nanoseconds) optical pulses superimposed on the light of the host stars.
The one in 10,000 objects with unusual spectra seen by Borra and Trottier are certainly worthy of additional study. However, extraordinary claims require extraordinary evidence. It is too early to unequivocally attribute these purported signals to the activities of extraterrestrial civilizations. Internationally agreed-upon protocols for searches for evidence of advanced life beyond Earth (SETI) require candidates to be confirmed by independent groups using their own telescopes, and for all natural explanations to be exhausted before invoking extraterrestrial agents as an explanation. Careful work must be undertaken to determine false positive rates, to rule out natural and instrumental explanations, and most importantly, to confirm detections using two or more independent telescopes.
Peaks in Fourier analysis of stellar spectra, such as those discussed by Borra and Trottier, can be caused by instrumental optics or introduced during data reduction. Data artifacts, fringing, and inconsistencies in the manufacture of detectors are known to users of high resolution spectrographs to cause minute patterns to appear in the resulting spectra. The movement of the telescope, variations in observing conditions, and the process of wavelength calibration can easily introduce undesired signals at levels that are only barely detectable. It is therefore important to check the claimed signal using a different telescope and instrument.
If KIC 8462852 was simply a comet fly-by, Tabby's Star wouldn't be getting this much attention.
234 stars are claimed to exhibit spectral modulation that could be artificial.
More here: https://seti.berkeley.edu/bl_sdss_seti_2016.pdf
Needs confirmation, of course, and there might well be systematic explanations that don't invoke LGM.
Good explanations for the unusual light curve of Boyajian’s Star have been hard to find. Recent results by Montet & Simon lend strength and plausibility to the conclusion of Schaefer that in addition to short-term dimmings, the star also experiences large, secular decreases in brightness on decadal timescales. This, combined with a lack of long-wavelength excess in the star’s spectral energy distribution, strongly constrains scenarios involving circumstellar material, including hypotheses invoking a spherical cloud of artifacts. We show that the timings of the deepest dimmings appear consistent with being randomly distributed, and that the star’s reddening and narrow sodium absorption is consistent with the total, long-term dimming observed. Following Montet & Simon’s encouragement to generate alternative hypotheses, we attempt to circumscribe the space of possible explanations with a range of plausibilities, including: a cloud in the outer solar system, structure in the ISM, natural and artificial material orbiting Boyajian’s Star, an intervening object with a large disk, and variations in Boyajian’s Star itself. We find the ISM and intervening disk models more plausible than the other natural models
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