Astronomers have confirmed the existence of a three-star exoplanet located 1,800 light-years from Earth. Planets parked in multi-star systems are rare, but this object is particularly unusual due to its inexplicably strange orbital alignment.
The first trace of KOI-5Ab was detected by NASA’s Kepler space telescope in 2009, but it was very early in the mission, so the exoplanetary candidate was left out. in favor of easier goals. It was not a terrible decision, as Kepler, over the course of his illustrious nine-year career, detected 4,760 candidates for the exoplanet.s, of which about half have yet to be confirmed.
“The KOI-5Ab was abandoned because it was complicated and we had thousands of candidates,” David Ciardi, chief scientist at NASA’s Exoplanet Science Institute, told NASA. statement. “There were easier selections than KOI-5Ab and every day we learned something new from Kepler, so KOI-5 was mostly forgotten.”
Ciardi, along with his colleagues, have now contemplated KOI-5Ab with new eyes, specifically NASA’s Transiting Exoplanet Survey Satellite and several ground-based telescopes, including the Keck Observatory in Hawaii The team was finally able to confirmed KOI-5Ab as a bona fide exoplanet and, in the process, discovered some fascinating, if not completely baffling, aspects of its stellar environment. Ciardi, a Caltech research astronomer, recently presented his team’s findings to a virtual meeting of the American Astronomical Society.
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Confirmation of KOI-5Ab was done with the proven transit method, in which a planet in orbit passes in front of its star from our perspective, causing a brief attenuation. The confirmation was further validated with another technique, the rocking method, in which the slight gravitational pull of a planet in orbit causes a detectable shock to the host star. TESS was used for the transit method, while Keck was used to detect hesitation. The combined data allowed researchers to rule out other possibilities, such as a fourth star.
Probably KOI-5Ab is a gas giant, similar to Neptune in terms of size. It resides in a three-star system, and while its orbit is a bit strange, its overall environment is less chaotic than it may seem.
Despite having three stellar companions, KOI-5Ab orbits a single star, KOI-5A, once every five days. This host star is trapped in a mutual orbit with a nearby star called KOI-5B, and the two revolve around each other every 30 years. A farther star, KOI-5C orbits this pair once every 400 years.
The problem has to do with the orbital alignment of KOI-5Ab relative to KOI-5B. The two objects do not share the same orbital plane, which is an unexpected result, one that calls into question conventional theories of planetary formation, such as how these objects are believed to be. form of a single protostellar disk.
“We don’t know many planets that exist in three-star systems, and this one is very special because its orbit is skewed,” Ciardi said. “We still have a lot of questions about how and when planets can form in multi-star systems and how their properties are compared to planets in single-star systems. By studying this system in more detail, we may be able to get an idea of how the universe makes planets ”.
Ciardi and colleagues do not know the reason for the misalignment, but their working theory is that KOI-5B exerted a gravitational shrinkage during the development of the system, disrupting the orbit of KOI-5Ba and causing it to migrate to the host star.
About 10% of all stellar systems involve three stars, according to NASA. The planets have been seen in three-star systems before, and also within binary star systems, but these discoveries remain rare. It seems that various stellar systems do not usually host many planets. This could mean that the conditions for planet formation are not ideal in these environments, but it could be the result of an observational selection effect, as it could be more difficult for astronomers to detect planets in multi-star systems. comparison with stellar systems.
The answer to this question is important, as it has serious implications for the pursuit of extraterrestrial life. There are multiple star systems more than 85% of all the star systems in the Milky Way galaxy. If confirmed that multi-star systems tend to have far fewer planets and, consequently, fewer life-sustaining planets, SETI astrobiologists and scientists should focus their attention on single-star systems.
This list can be further reduced. A huge quarter of the stars in the Milky Way are red dwarfs, which, due to their propensity to explosion nearby planets with solar flares, could also be poor candidates in search of alien life.
Given these factors, it’s easy to get the feeling that life must be exceptionally rare in the galaxy. That good might be the case, but it’s important to remember that the Milky Way has about 100 billion stars. This still leaves us a lot to choose from, a handful of which could host civilizations by asking the same questions as these.