A mysterious star whose multiple bouts of darkening may be due to "extraterrestrial megastructures", according to some researchers, may now have more than a dozen colleagues exhibiting such mystifying behavior, a new study shows.
In addition, exploring all of these stars can help solve the puzzle of their stunning vibration, says the study's author.
In 2015, scientists noticed unusual fluctuations in light from a star named KIC 8462852. This otherwise normal F-type star, which is slightly larger and hotter than the earth's sun, sits about 1
These analyzes of KIC 8462852 – now nicknamed "The Star of Boyadzhian" (former Tabi star) after its discoverer – raised the possibility for astronomers to find signs of intelligent extraterrestrial life. In particular, researchers suggest that the star is surrounded by a Dyson sphere, a hypothetical mega-structure that is built around a star to capture as much of its light as possible. The mathematician and physicist Freeman Dyson suggested that such mega-structures could help power an advanced civilization. (Science fiction often depicts Dyson's spheres as solid wrappers around stars, but megastructures could also be globular swarms of giant solar panels.)
The mega-structure hypothesis is near the bottom of most astronomers' lists these days word for Boyajian's star, however; further analyzes indicate more prosaic explanations, such as dust clouds or comet fragments. However, scientists have not yet nailed the exact cause of the strange blackout. The answer remains partly elusive because Boyajian's star looked unique; there were no known colleagues to provide additional clues that could help the researchers solve this cosmic mystery.
The study's author, Edward Schmidt, an astrophysicist at the University of Nebraska-Lincoln, suggests that he may have discovered more than a dozen stars like the Boyadjian Star.
Schmidt sought colleagues from the Boyajian star using software that looked for similar eclipse events of about 14 million objects of varying brightness, observed in the Tracking of Variables in the Northern Sky from April 1999 to March 2000. It was followed by promising candidates by examining their long-term behavior, using All-Sky Automated Survey data for supernovae, excluding sources that may be obscured by conventional explanations, such as a dimming companion star or some inherent variability of brightness.
Schmidt identified 21 stars that showed possible unusual darkening. They fell into two separate categories: 15 were "slow beads" that darkened at speeds similar to the star of Boyadzhian, and six were "fast sins" that showed even greater variability in their rates of darkening.
"What surprised me most were those stars who had so much immersion, the ones I called 'fast sinkers,'" Schmidt told Space.com. "I expected more accidental dives like the Boyajian star."
Further analysis using data from the European Space Agency's Gaya Observatory found that these potential sinks are usually either conventional stars with a basic sequence of approximately the same mass as the sun or red giant stars with about twice the mass of the sun. Slow and rapid dives are observed in both groups, which may suggest that they represent different degrees of the same mechanism, Schmidt says.
Schmidt notes that the study of variables in the northern sky looked for potential colleagues of the Boyajian star, which do not contain records of the star himself, Boyajian darkens throughout the year with data in this catalog. This highlights how astronomers can easily miss stars that can darken this way if they only look at catalogs that observe stars for relatively short periods of time.
"Obviously, some of these stars are missing because of the catalogs available," Schmidt said. "As we look at more catalogs, we can get a better picture of what's happening, though it won't be a complete picture."
Future studies combined through more catalogs of stellar activity may find even more analogs to the Star of Boyagian, he said.
"I intend to try and track fast batteries," Schmidt said. "One thing I noticed with them is that at least one seems to be slowing down its immersion path over the five years of coverage we have from it. It would be interesting to find out what happened in his past, which can help give a better idea of what is going on with these stars. "
Schmidt details his findings July 18 in Astrophysical Journal of Letters.
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