Unusual light fluctuations of Tabby's Star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project.

The discovery was made from data collected by the Kepler space telescope, which observed changes in the brightness of distant stars to detect exoplanets.

[8] In September 2019, astronomers reported that the observed dimmings of Tabby's Star may have been produced by fragments resulting from the disruption of an orphaned exomoon.

During its primary and extended mission from 2009 to 2013 it continuously monitored the light curves of over 100,000 stars in a patch of sky in the constellations Cygnus and Lyra.

[38][43][44][45] By the end of the three-day dimming event,[46] a dozen observatories had taken spectra, with some astronomers having dropped their own projects to provide telescope time and resources.

[35] On 10 October 2017, an increasing brightening, lasting about two weeks, of the starlight from KIC 8462852 was noted by Bruce L. Gary of the Hereford Arizona Observatory[59] and Boyajian.

By 18 March 2018, the star was down in brightness by more than 1% in g-band, according to Bruce L. Gary,[33] and about 5% in r-band, making it the deepest dip observed since the Kepler Mission in 2013, according to Tabetha S.

[19][20] Teasing accurate magnitudes from long-term photographic archives is a complex procedure, however, requiring adjustment for equipment changes, and is strongly dependent on the choice of comparison stars.

Another study, examining the same photographic plates, concluded that the possible century-long dimming was likely a data artifact, and not a real astrophysical event.

[21] Another study from plates between 1895 and 1995 found strong evidence that the star has not dimmed, but kept a constant flux within a few percent, except an 8% dip on 24 October 1978, resulting in a period of the putative occulter of 738 days.

Originally, and until Kohler's work of 2017, it was thought that, based on the spectrum and stellar type of Tabby's Star, its changes in brightness could not be attributed to intrinsic variability.

[86] Some of the proposed explanations involve interstellar dust, a series of giant planets with very large ring structures,[87][88] a recently captured asteroid field,[2] the system undergoing Late Heavy Bombardment,[89][90] and an artificial megastructure orbiting the star.

[92][93] However, in September 2019, astronomers reported that the observed dimmings of Tabby's Star may have been produced by fragments resulting from the disruption of an orphaned exomoon.

[94][95] Meng et al. (2017) suggested that, based on observational data of Tabby's Star from the Swift Gamma-Ray Burst Mission, Spitzer Space Telescope, and Belgian AstroLAB IRIS Observatory, only "microscopic fine-dust screens", originating from "circumstellar material", are able to disperse the starlight in the way detected in their measurements.

[96] Although the explanation of a significant amount of small particles orbiting the star regards "long-term fading" as noted by Meng,[50] the explanation also seems consistent with the week-long fadings found by amateur astronomer Bruce L. Gary and the Tabby Team, coordinated by astronomer Tabetha S. Boyajian, in more recent dimming events.

[59][61][62][102] Dimming and brightening events of Tabby's Star continue to be monitored; related light curves are updated and released frequently.

[89][90] High-resolution spectroscopy and imaging observations have also been made, as well as spectral energy distribution analyses using the Nordic Optical Telescope in Spain.

[76] Other researchers think the planetary debris field explanation is unlikely, given the very low probability that Kepler would ever witness such an event due to the rarity of collisions of such size.

This absence of emission supports the hypothesis that a swarm of cold comets on an unusually eccentric orbit could be responsible for the star's unique light curve, but more studies are needed.

[89][6] In December 2016, a team of researchers proposed that Tabby's Star swallowed a planet, causing a temporary and unobserved increase in brightness due to the release of gravitational energy.

[111] Additionally, the researchers suggest that the consumed planet could have caused the star to increase in brightness up to 10,000 years ago, and its stellar flux is now returning to the normal state.

[111][112] Sucerquia et al. (2017) suggested that a large planet with oscillating rings may help explain the unusual dimmings associated with Tabby's Star.

The model predicts a discrete and short-lived event for the May 2017 dimming episode, corresponding to the secondary eclipse of the planet passing behind KIC 8246852, with about a 3% decrease in the stellar flux with a transit time of about 2 days.

Three other stars in the Kepler Input Catalog likewise exhibit similar "avalanche statistics" in their brightness variations, and all three are known to be magnetically active.

[7][91] The latest results have ruled out explanations involving only opaque objects such as stars, planets, swarms of asteroids, or alien megastructures.

Numeric simulations were performed of the migration of gas giant planets, and their large gaseous moons, during the first few hundred million years after the formation of the planetary system.

[91][121] In 2016, a Kickstarter fund-raising campaign was led by Tabetha Boyajian, the lead author of the initial study on the star's anomalous light curve.

[134] In October 2015, the SETI Institute used the Allen Telescope Array to look for radio emissions from possible intelligent extraterrestrial life in the vicinity of the star.

[135][136] After an initial two-week survey, the SETI Institute reported that it found no evidence of technology-related radio signals from the star system.

[140][141] In May 2017, a related search, based on laser light emissions, was reported, with no evidence found for technology-related signals from Tabby's Star.