A star named Tabby is an anomaly that has sparked a surge of interest in astro-engineering projects for extraterrestrial supercivilizations.
The finds of the largest planet hunter, the Kepler space telescope, are continually attracting interest. But a small publication in September 2015 caused a storm. The observational data for the star KIC 8462852 did not resemble anything seen before. Usually, the planet passing between the star and us makes it slightly and for a short time, although regularly, lose its luster. KIC 8462852 behaves extremely strange: it fades very strongly, losing up to 85% of brightness, and at irregular intervals. None of the 150,000 stars that Kepler observed showed anything like this.
Astronomers, faced with such an anomalous light curve, fussed about. A meticulous check of the technique showed that neither the telescope's equipment nor the algorithms for processing its data could give such a picture. Calculations made it possible to discard the hypothesis that the anomaly can be created by unstable processes taking place in the star itself. There are only three options left. Firstly, the unstable brilliance of the star KIC 8462852 can give a swarm of small, chaotically moving celestial bodies, the remnants of the protoplanetary cloud from which it was formed. However, the star is not young enough for this, and additional observations in the infrared range did not find any traces of protoplanetary "debris".
Secondly, the blackout can cause a thick cloud of comets or asteroids, somehow intercepted from a passing star. However, there are no indications of this, and the cloud will not survive for such a long time: most of its bodies in some thousands of years should finally fall onto the star. It turns out that we see a unique, rare case? It's hard to believe in this.
There remains one more version, which was voiced by the authors of the famous article: the flickering of KIC 8462852 may be associated with a giant astro-engineering structure, which was erected by its existing civilization. However … is that possible? “Aliens should remain the very last hypothesis to take into account,” said American astronomer Jason Wright on this matter. "But what we see here is exactly what we can expect from an extraterrestrial civilization." There are two possibilities to discover the cosmic existence of "other" civilizations. First, accept the signals they send. Second, discover the "miracle." With this term Shklovsky designated phenomena that cannot happen "by themselves", that is, phenomena that are inexplicable from the point of view of astronomy. "Miracles" would not be deliberate signals, the purpose of which is to notify possible observers in space about the presence of life, but only a by-product of the activity of a highly developed civilization accompanying it, just as a glow in the night sky accompanies a large city. A simple calculation shows that such phenomena can be observed from distances of hundreds (if not tens) of light years, provided that they correspond to energy costs equal to the powers of stars.
In short, only manifestations of "stellar engineering" can be astronomically observable. The emergence of such activity in one form or another at a certain stage of development is considered quite probable by all authors (Dyson, Sagan, von Horner, Bracewell, as well as Shklovsky himself).
To understand what astrophysicists are talking about, we will have to go back half a century - in the golden era of the beginning of astronautics, the craze for the stars and confidence in the imminent exit of man to the vastness of the Universe.In those years, all kinds of projects for radio observations of distant space and hunting for signals from "brothers in mind" were only comprehended at the conceptual level. Arguing about the prospects for the development of mankind and contact with other planets, astronomer Nikolai Kardashev found an extremely adequate approach to formalize the possible levels of technological development of civilization - here or under any other star.
Nikolai Semenovich Kardashev is a Soviet astrophysicist, academician of the Russian Academy of Sciences and a living classic of radio astronomy. One of the founders of radio interferometry with ultra-long bases, a participant in the creation of RATAN-600 and other large radio telescopes, long-term head of the FIAN Radio Astronomy Station in Pushchino, Moscow Region. Researcher of the nature and evolution of active galactic nuclei, dark matter, one of the pioneers of the search for extraterrestrial civilizations. Laureate of the State Prize, Demidov Prize, etc.
The main criterion in the Kardashev scale is the ability to use energy: a Type I civilization must put all the available resources of its home planet at its service; type II civilization - all the energy of its star; finally, type III gains power over the whole galaxy. Subsequently, this classification was developed and supplemented by the famous American astronomer Carl Sagan, who translated these estimates into watts and made the scale fractional. In such a refined form, the development of our civilization by the beginning of the twentieth century. reached 0, 58 on the Kardashev scale, and 0, 72 - in 2010. The annual energy consumption of earthlings today is more than 16 * 1012 watts.
For comparison: a full-fledged type I civilization, according to Sagan's calculations, should produce about 10 ^ 16 watts, type II - 10 ^ 26, type III - 10 ^ 37 watts. It is assumed that a type IV civilization can also develop, the energy consumption of which is comparable to the power of the Universe and already reaches 10 ^ 100 W and more, but we are still hardly able to talk about it. Our immediate plans are to overcome the first line and transition to a type II civilization. Here we at least have a ground for hypotheses.
So, it is logical to assume that the ability to use the energy of a star to the fullest extent will require the construction and operation of cyclopean structures, including power generating capacities and other infrastructure. Engineers and scientists, science fiction writers and other dreamers have come up with a lot of options for us, ranging from the Tsiolkovsky space elevator to the Stanford Torus, a hypothetical space settlement with artificial gravity. However, the most famous astro-engineering project is much larger than all of them put together, and it will lead us back to the mysterious star Tabby.
Star Power Plant
According to Freeman Dyson's assumption, any advanced civilization will sooner or later face the problem of a lack of living space and energy on its home planet. And the natural solution for it will be to go beyond its cradle - to build a mega-structure on the scale of the entire planetary system. The thin spherical shell surrounding the parent star will allow it to capture its radiation, diverging in all directions, and at the same time will provide huge areas for settlement and exploitation.
Freeman John Dyson is an English and American theoretical physicist, one of the founders of the quantum theory of electromagnetic interactions, a researcher of the evolution of pulsars and neutron stars. Winner of numerous scientific awards, member of the Royal Society of London, the American National Academy of Sciences and the Russian Academy of Sciences. Author of a number of futurological projects, including the "Dyson Sphere" and the Orion nuclear-powered spacecraft, which was developed by NASA in 1950-1960.
In its minimal form - in the form of a ring - the Dyson sphere appears in the popular science fiction novels by Larry Niven, the action of which develops in a huge ring that encircles a star at a decent distance.By the way, the total mass of the fictional superdense material "skrit" from which the "Niven ring" is made is about 300 times the mass of the Earth and is close to the mass of Jupiter. Such estimates are also given by rough calculations for the Dyson sphere around our Sun: it will take as much matter as the largest planet in the solar system contains.
The appearance of the "Niven ring" is no coincidence. Calculations show that due to the uneven acceleration at the equator and at the poles, the Dyson hard sphere will experience dangerous overloads, and the engineers of the Kardash type II civilization will have to find some solutions to this problem. The ring may be one of them, but other options have been proposed, including open structures and even something resembling a shell. But whatever such an astroengineering structure may be, at this stage one thing is important to us: it must be huge.
It is the cyclopean dimensions and the need to capture the lion's share of the energy of the parent star that give us the theoretical opportunity to detect Dyson spheres, if they are in the foreseeable space of space. By absorbing radiation and partially heating up, the sphere should have a rather unusual spectral profile. And the search for such anomalies has already been carried out within the framework of the SETI project - for many years and so far to no avail. And then the star KIC 8462852 returns to the stage.
Back on Tabby
As we already know, the idea that a large-scale space construction was unfolding in the vicinity of KIC 8462852 was announced as soon as astronomers noted the anomalousness of its brightness. And immediately received a flurry of criticism, so that even one of the inspirers of the SETI Institute and the famous enthusiast of the search for extraterrestrial intelligence Seth Shostak made a very cautious statement that "it would be prudent to double-check everything again." This is exactly what astronomers are doing today: the strangeness of the star needs an explanation. Enthusiasts and professionals involved in the AAVSO variable star program are not mixing lenses with KIC 8462852, noticing new oddities. So, on May 23, 2016, the star darkened by as much as 24%, but after 1, 5 hours it returned to normal: the usual transit of the planet lasts much longer and does not manifest itself so sharply. Oil on the fire of discussions around KIC 8462852 was poured by the work of American Bradley Schaefer, published in January 2016. After analyzing the images of the star on old astronomical photographic plates stored at Harvard University, he found that the brightness of KIC 8462852 over the past century has dropped by 0.16 magnitude - as if the unknown builders had noticeably moved forward, additionally shielding the star. And although Schaefer's results are regularly criticized, something is definitely wrong with KIC 8462852.
Theorists recalculate over and over again the effect that an irregular cloud of dust, a swarm of asteroids or tailed comets can have on the spectrum of a star - there is still no convincing explanation for the anomaly. Tabeta Boyajian and her colleagues at Yale University continue to work more actively than others. In the summer of 2016, scientists managed to collect $ 100,000 in a matter of weeks to buy working hours for LCOGT (Las Cumbres Observatory Global Telescope Network) telescopes. The funding was provided by the sensation and the support of thousands of enthusiasts who invested in the project through the Kickstarter crowdfunding platform. “According to our initial plans, observations will be carried out throughout the year. Every night two hours will be given to our star,”Boyajyan said. So far, long-term observations of the mysterious "star Tabby" have shown that its irregular fluctuations in brightness, probably, can not be associated either with the planet or with the construction work of an extraterrestrial civilization. During the observation period from 2016 to December 2017, the researchers tracked several separate episodes of changes in the brightness of the "Tabby Star". Multispectral analysis showed the extreme heterogeneity of this process.In other words, at some wavelengths the brightness dropped much more than at others, indicating a partially transparent object resembling a gas and dust cloud that shields it. However, having partially rejected the options with a planet, a Dyson sphere, etc., experts still do not give an answer to the question about the nature of the mysterious, irregular and powerful jumps in the brightness of the star.