The discussion around alien megastructures in the vicinity of the distant star KIC 8462852 flared up with renewed vigor after scientists refuted the hypothesis that the decrease in the luminosity of a celestial body could not be associated with a cloud of comets and asteroids. Where did aliens come from and how are they related to microwaves and snack-loving scientists?
For the first time, KIC 8462852 (a single star in the constellation Cygnus) was talked about in October 2015: scientists recorded that its luminosity dropped by 20 percent and remained at such a low level for various periods of time (from 5 to 80 days).
As an explanation for this phenomenon, some scientists have suggested that it may be surrounded by the Dyson sphere, which was created by an alien civilization living in its vicinity. Another point of view suggests that KIC 8462852 is surrounded by a cloud of many comets and asteroids. However, such formations are possible only near young stars, among which KIC 8462852 does not belong. Subsequently, the researchers assumed that it could be a swarm of comets that passed the star in a highly elongated (eccentric) orbit in 2011 and 2013.
To test the "alien" hypothesis, scientists used a 0.5-meter Newtonian reflector telescope installed at the SETI Optical Observatory in Boquete, Panama, to track laser signals from the star. However, they could not find them, so they had to say goodbye to the version of the aliens. The data obtained from the Spitzer telescope made it possible to reject the assumption of a collision of asteroids or planets, the fragments of which "block" the light from the star.
KIC 8462852
Image: NASA
Unwittingly, astronomer Bradley Schaefer from Louisiana State University gave a "second wind" to the version of aliens on a star: he published a preprint of an article stating that between 1890 and 1989, the luminosity of KIC 8462852 decreased by 20 percent. The scientist also tried to calculate the possible number of comets in the star.
To ensure the observed change in the brightness of KIC 8462852, 648 thousand comets would be required, the core of each of which would be at least 200 kilometers in diameter. Since the latter seems impossible, the scientist believes that the cometary explanation for the change in the luminosity of KIC 8462852 is incorrect. The astronomer is skeptical that an alien civilization could cover a fifth of the star's disk (and thus change its luminosity), but agrees that other explanations for this behavior of KIC 8462852 have not yet been found. Nevertheless, many media outlets took the astronomer's calculations solely as an indication that aliens live on KIC 8462852.
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Universal Wow
One of the first serious "alien" sensations associated with the Wow! It was recorded on August 15, 1977 by the Ohio State University Big Ear radio telescope and lasted 72 seconds. Signal Wow! (Russian "Oho!") corresponds approximately to the hydrogen line (with a frequency of about 1420 megahertz and with a wavelength of about 21 centimeters). Scientist Jerry Ehman (who coined the name Wow!) As part of the Search for Extraterrestrial Intelligence (SETI) project for the search for extraterrestrial civilizations received a strong narrow-band signal northwest of the globular cluster M55 in the constellation Sagittarius.
Such a powerful signal has never been observed. Since hydrogen is the most abundant chemical element in the Universe, and its radiation easily passes through the dense atmosphere of the Earth, some experts thought that Wow! could be a message from aliens.
Initially, scientists ruled out that other planets, near-earth satellites, asteroids and other bodies of the solar system could be the source of the signal. Taking advantage of this, journalists over the years continued to insist on the alien nature of the signal. This version was in demand among conspiracy theorists of all stripes.
The Ohio State University Radio Observatory and the North American Astrophysical Observatory
Over the years, science was able to put everything in its place. So, in a new study, the results of which are published in the Journal of the Washington Academy of Sciences, astronomers tried to debunk this point of view. According to them, the source of Wow! there could be comets 266P / Christensen and P / 2008 Y2 (Gibbs), the transit of which was observed in the period from July 27 to August 15, 1977 in the vicinity of the Chi group of the constellation Sagittarius.
The nucleus of each comet is surrounded by huge hydrogen clouds with a radius of several million kilometers. These celestial bodies were discovered after 2005 and were not taken into account when determining the sources of the extraterrestrial signal. Heavenly Source Wow! was in the area of comets. Astronomers believe that the radiation from their clouds could have caused the signal to be recorded.
Not all experts agree with such conclusions. In particular, James Bauer of the Jet Propulsion Laboratory in Pasadena believes that radiation from a comet cloud is generally not observed at a wavelength of 21 centimeters. Astronomers hope to test their hypothesis on January 25, 2017 (during transit 266P / Christensen) and January 7, 2018 (during transit P / 2008 Y2).
Microwave peritones
Another mystery, which turned out to have nothing to do with aliens, is the fast radio pulses. The first fast radio pulse was detected in 2001 by the Parks radio telescope in Australia, the data from which were processed only by 2007. Since then, the existence of 16 such radio pulses has been confirmed.
This flare, lasting milliseconds, led to the release into space of energy equivalent to radiation emitted by the Sun for several tens of thousands of years. The location of the signal source is unknown. The signal, like other fast radio pulses, was no longer observed.
Researchers led by Michael Hippke of the German Institute for Data Analysis in Neukirchen tried to answer the question about the nature of such radio pulses. They were engaged exclusively in science, but showed imprudence in comments to the media: the researchers said that along with fast radio bursts, peritons - short radio bursts - are observed. News about the "alien nature" of the bursts immediately hit the Internet.
Photo: John Sarkissian
A few days later, other scientists found out that ordinary microwaves were the source of peritones. If the microwave is near the radio telescope, and a person opens it at the wrong time, it emits a “radio cry” that exactly corresponds to the mysterious peryon - and the telescope hears this cry. However, microwave ovens cannot emit signals like fast radio pulses. From this and other features of the mysterious signals, scientists have confidently concluded their extraterrestrial and even extragalactic origin.
The sensation did not take place, and at the end of 2015, astrophysicists proposed an explanation of the nature of fast radio pulses, which had nothing to do with aliens.
Formalities
Let's finish the chase for aliens on a "mathematical note". To estimate the number of existing alien civilizations, the American astronomer Frank Drake proposed in 1960 a formula that was named after him.
According to this formula, the number of extraterrestrial civilizations can be estimated as
According to this formula, the number of extraterrestrial civilizations can be estimated as
N c = N * xf p xn e xf d x L c / t, where N * is the total number of stars in the Galaxy, f p is the proportion of stars with planetary systems, n e - the average number of planets with habitable conditions in each planetary system, f d is the probability that on a random suitable planet there is a civilization capable of making contact (this parameter often decomposes into several: the probability of the existence of life, intelligent life, communicative life), L c - the length of time during which the civilization was capable of contact, t - the lifetime of the galaxy.
Another common form of Drake's formula is
N c = R * xf p xn e xf d x L c, where R * is the average rate of formation of stars in the Galaxy.
Almost all parameters of the Drake equation cannot be estimated unambiguously or at least within narrow limits. As well as giving an exact answer to the question of whether there is life somewhere outside the Earth.
Vladimir Koryagin
