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Scientists now have a second example of a strange stellar phenomenon speculatively related to extraterrestrial intelligence in 2015
A distant star in the southern sky sparkles in a strange way, suggesting that a strange cloud of matter – or something still strange – is in orbit. Discovered by astronomers using a telescope in Chile, the star recalls two other enigmatic astrophysical objects, the one thinking to house a planet with rings 200 times larger than those of Saturn, the other the most famous for the distant possibility that he is surrounded by "an extraterrestrial". Megastructures. The new star could help illuminate one or two of these confusing objects.
In 2010, the Variables Vista survey in the Via Lactea (VVV) study began its project to create a three-dimensional map of variable stars near the center of the Milky Way. As part of this project, astronomer Roberto Saito of the Federal University of Santa Catarina analyzed the telescope data for eruptive explosions of hundreds of millions of monitored stars. But the most remarkable thing he found was not an explosion at all, it was a mysteriously dark star on several days in 2012. He and his colleagues reported their findings in an article recently published in the Monthly Notices from the Royal Astronomical Society.
Known as VVV-WIT-07, the star looks much older and redder than our sun, although the amount of interstellar dust lying between our solar system and the star's house, closer to the galactic center makes the exact classification and distance very difficult. What is certain is that in the summer of 2012, the brightness of the object has slightly faded for 11 days, then dropped over the next 48 days, which suggests that something has blocked more than three quarters of the light of the star going towards the Earth. But what can this "something" be?
According to Eric Mamajek, an astrophysicist from the University of Rochester, not affiliated with the VVV survey, such a low degree of gradation suggests that an object or group of objects of excessive size blocks light. "It must be more than a million miles wide and be very dense to block as much starlight," he says. Mamajek should know it: he led the team that discovered J1407, another strange star periodically eclipsed by an object the size of a planet supposed to boast of owning a massive ring system 200 times wider than that of Saturn. In the latter case, he says, the strange VVV-WIT-07 signals could come from aggregates or clouds of material passing between the Earth and the star, although he warned that the data was preliminary. and that additional observations were necessary.
Tabetha Boyajian agrees. Mr. Boyajian, an astronomer at Louisiana State University, was the lead author of the 2015 newspaper announcing the strange darkening of KIC 8462852, also known as Tabby's Star, an atypical object first discovered by the telescope Kepler space from NASA. VVV-WIT-07 is expected to host "a very special type of dust cloud to create this type of trough," says Boyajian. Boyajian's study has helped to generate renewed public interest in the Tabby Star, as its unusual attenuation could be seen as evidence of an extraterrestrial civilization constructing an artificial structure that absorbs its light. More conventional explanations include a swarm of comets or fragments of a broken planet, both of which would create large clouds of dust and debris that could also block the light of the star. But, until now, no simple and simple explanation corresponds to the complexity of the decrease in brightness observed around the star; the researchers fail to understand the true nature of the strange obscuration of Tabby's Star.
Astronomers detect these troughs by tracing the light intensity of a star in time, a figure called "light curve". The J1407 light curve shows that its massive rings can sometimes block up to about 95% of the star's light, while The Tabby's light curve Star suggests that, whatever either its orbit, it covers only about 20% of the light emission of this star. This makes VVV-WIT-07 an intermediate case, says Saito. "Our object is similar in that we also try to explain the behavior of the light curve depending on the material surrounding the star," he explains.
Based on their data, including the follow-up observations made in 2016, Saito and his colleagues speculate that the star could continue to flicker in 2019, potentially displaying four additional mitigating events all over the world. throughout the year as the mysterious light – blocking material continues its orbit around the star. If these predictions are confirmed, they may be essential to solving not only the mysteries behind VVV-WIT-07, but also those surrounding Tabby's Star.
"With a sample of two, we can have two stars to study instead of one to try to unify a theory of what's going on," says Boyajian. If both stellar gradations are caused by the same natural process, it is less likely that an unusual event will occur, such as oversized cosmic construction projects.
There is hope that more of these particular twinkling stars may appear in the near future. Saito says that it is possible that the VVV survey may discover more, even though it is not optimized to identify such systems. The large synoptic geoptic telescope (LSST), an 8.4-meter instrument under construction in Chile, could bring in more members of the record collection when it begins to operate in the 2020s.
"I think we'll start finding more items like this in the LSST era," says Mamajek. "We will probably start to discover a strange variable [stars]which have not been seen before. "
For the time being, Saito and his colleagues plan to continue to observe VVV-WIT-07 with infrared instruments on the ESO's new technology telescope and the astrophysics research telescope south of the National Observatory of Astronomy both of which contributed to the 2016 team's observations. The intrinsic spark of the star, as well as the attenuation of its light over vast galactic distances, means that it is better observed in the lengths of light. near-infrared waves, where interference from interstellar dust is minimal. Although the VVV survey ended last year, an extensive survey still observes the galactic center and may reveal other missed eclipses in the initial observations.
Hopefully these observations will help to better understand the cause of the strange gradation of VVV-WIT-07. "This is certainly not a common phenomenon," says Mamajek. "I can not wait to see future results."
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