NASA’s Kepler mission has revolutionized the study of exoplanets and distant celestial bodies. To date, it has observed approximately 530,000 stars and identified over 2,600 exoplanets. Among these countless stars, one in particular stands out due to its unusual behavior: KIC 8462852, commonly referred to as Tabby’s Star or Boyajian’s Star. This star exhibits some of the most perplexing characteristics in the universe, with its brightness decreasing by nearly 25%—a magnitude far greater than what a typical exoplanet orbiting its host star would cause. Additionally, it has shown a gradual fading over decades, with sporadic brightening events and a conspicuous lack of infrared emissions—something commonly associated with stars that experience significant flux dips.
These anomalies have baffled scientists, leading to numerous hypotheses, including the possibility of an advanced extraterrestrial structure. However, new developments have further complicated the mystery. The star has now entered a prolonged dimming phase of about 1%, deviating from its usual short-lived but dramatic dips. Kepler’s data previously recorded drops of up to 22%, each lasting only a few days, whereas the current dimming has persisted for nearly a month. Unlike previous dips, this phase exhibits occasional brief recoveries, forming an inverse pattern of its typical behavior. The shallow nature of this dimming also stands out, as the star’s brightness variations have become less pronounced over time. This phenomenon has been linked to a collision scenario, such as icy comets disintegrating in orbit, a theory proposed by Dr. Boyajian early in the star’s investigation. However, this explanation would require an improbably high number of comets or an exceptionally large one disintegrating in a way that no current models have successfully predicted.
A particularly intriguing recent observation suggests that during this dimming event, the material obscuring the star temporarily became optically thick. This was determined by analyzing different wavelengths of light, indicating that the dust cloud briefly increased in density before thinning again. If confirmed, this suggests the dust was thick enough to obscure the star’s brightness but changed density unpredictably, challenging current theories. While some have speculated about a large solid object, such as an alien megastructure, the more likely explanation remains an unusual dust cloud behaving in ways not yet fully understood.
One of the biggest challenges in solving this puzzle is the persistence of dust within the system. The long-term dimming of Tabby’s Star suggests a link between its gradual fading and the short-term brightness dips. It is unlikely that two independent dimming phenomena would coincide without being related. However, spectral analysis indicates that the dust particles are incredibly small—submicron in size—meaning they should be expelled from the system rather quickly. The fact that the dust remains suggests a replenishing mechanism that contradicts existing collision-based models. At the same time, the shallower dips compared to Kepler’s initial observations could support a collisional scenario where the debris is dispersing over time.
Another significant breakthrough involves a correlation between the dimming events and a possible periodic cycle. Identifying periodicity is crucial in determining whether this phenomenon results from interstellar dust passing in front of our viewpoint or if it is bound to the star’s orbit. The former seems unlikely, as such an effect should also be visible in nearby stars, much like a cloud in the night sky obscuring multiple stars at once. However, the observed dimming is isolated to Tabby’s Star, implying that the dust is in orbit around it. Furthermore, it appears to reside within the star’s habitable zone, which only deepens the mystery.
Another confounding factor is the absence of infrared emissions. Given the dust’s small size, it should be heated and emit infrared radiation, yet no such emissions have been detected. The star’s dimming trend has persisted for at least a century, suggesting that some of this material remains in the system and should be radiating heat, but it is not. Establishing periodicity could provide crucial insights into whether the dust is exceptionally cold or if an entirely different mechanism is at play.
The leading natural explanation remains a collisional model, in which cascading material collisions generate continuous dust clouds. However, maintaining such a process over extended periods is difficult to justify. Historical sky surveys from the 1930s to the 1970s, along with Kepler’s observations, indicate that this phenomenon has been ongoing for nearly a century. Whatever mechanism is responsible appears to be continuous and long-term, making it even more perplexing.
Recent research by Edward Schmidt has added a new dimension to the mystery. He has analyzed historical sky surveys to identify other stars exhibiting similar behavior. Remarkably, he found multiple candidates, suggesting that Tabby’s Star may belong to a small cluster of around 15 stars displaying comparable brightness variations. These “slow dippers” have light curves eerily similar to Tabby’s Star, but their exact nature remains uncertain. Two particularly striking patterns have emerged from this data that suggest these stars are not just random anomalies.
The first pattern reveals that these stars appear to cluster spatially, with many located in the same region as KIC 8462852. Such clustering is unexpected if these stars were randomly distributed throughout the galaxy. This raises the intriguing possibility of an artificial cause, as one would expect such a pattern from an expanding extraterrestrial civilization. Could this be a sign of an advanced technological presence?
The second pattern adds to the strangeness: these candidate stars are not only clustered in space but also by spectral type. They are either Type F stars, like Tabby’s Star, or Type G stars, like our Sun. Larger or smaller stars do not appear to exhibit the same phenomenon. This is unusual, as one might expect similar dimming behaviors to occur across different stellar types. One possibility is that smaller and larger stars might be more efficient at dispersing dust, preventing such long-term dimming events. However, this remains speculative. Interestingly, Type G stars are known to be ideal for life, and while Type F stars have shorter lifespans, they are relatively stable—potentially making them suitable for extraterrestrial habitation or utilization.
Given these peculiar findings, the study suggests that these candidate stars warrant further investigation, including potential searches for techno signatures by SETI. Regardless of whether the explanation is natural or artificial, this phenomenon presents a compelling and unresolved astronomical mystery that demands continued study.
