Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars

TL;DR

This study identified peculiar periodic spectral modulations in a small subset of solar-type stars, potentially indicating extraterrestrial intelligence signals, through Fourier analysis of millions of spectra from SDSS.

Contribution

It reports the discovery of unusual spectral modulations in a tiny fraction of stars, supporting a hypothesis of ETI signals, a novel finding not previously documented.

Findings

Signals found only in 234 stars within a narrow spectral range.

Signals match the predicted shape of ETI-generated light pulses.

Signals unlikely caused by instrumental effects or known astrophysical phenomena.

Abstract

A Fourier transform analysis of 2.5 million spectra in the Sloan Digital Sky Survey was carried out to detect periodic spectral modulations. Signals having the same period were found in only 234 stars overwhelmingly in the F2 to K1 spectral range. The signals cannot be caused by instrumental or data analysis effects because they are present in only a very small fraction of stars within a narrow spectral range and because signal to noise ratio considerations predict that the signal should mostly be detected in the brightest objects, while this is not the case. We consider several possibilities, such as rotational transitions in molecules, rapid pulsations, Fourier transform of spectral lines and signals generated by Extraterrestrial Intelligence (ETI). They cannot be generated by molecules or rapid pulsations. It is highly unlikely that they come from the Fourier transform of spectral lines because too many strong lines located at nearly periodic frequencies are needed. Finally we consider the possibility, predicted in a previous published paper, that the signals are caused by light pulses generated by Extraterrestrial Intelligence to makes us aware of their existence. We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis. The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the sun is also in agreement with the ETI hypothesis. However, at this stage, this hypothesis needs to be confirmed with further work. Although unlikely, there is also a possibility that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars.