Astronomers have found evidence of the presence of an exoplanet in Barnard’s star, the nearest single star to us. It belongs to the class of red dwarfs and is located in the constellation Ophiuchi approximately 6 light years from Earth. The conclusion about the presence of a star near the star of the planetary body of scientists has prompted anomalies that were observed in the movement of the star. The study of astronomers is reported in an article in the journal Nature.
Red dwarfs are much smaller and colder than our Sun, but at the same time they are able to demonstrate changing activity, then “fading”, then starting to throw star flares into the surrounding space. Researchers nevertheless note that Barnard’s star is one of the quietest red dwarfs ever discovered.
The relatively moderate activity of the star created an interest for scientists who were trying to find new exoplanets near it. However, for a very long time, it was not possible to do this, even despite the use of various search methods. And yet, scientists observed strange “fluctuations” in the motion of the star, which cannot be attributed to the usual error in observations. A team of international scientists headed by astrophysicist Ignacy Ribas decided to study the issue in more detail.
“This was not a revelation to us. In fact, back in 2015, we noted the presence of a signal in the archived observational data from various astronomical instruments. Nevertheless, statistical data in order to make an unequivocal conclusion was not enough, ”commented astrophysics of the Institute of Space Sciences Ignaci Ribas.
After a more careful study of the signal, the researchers got a clearer idea of what they actually see. Astronomers analyzed data on the radial velocity of a star collected over two decades using seven different spectrometers and carefully filtered all possible statistical errors and noises.
“We are almost certain that we see periodic oscillations with an amplitude of 1.2 meters per second with an interval of 233 days. This may indicate the presence in the system of the planet. At the same time, such anomalies can also be observed due to certain phenomena occurring on the surface of the star, ”explains Ribas.
To eliminate these phenomena and explain the observed anomalies, scientists conducted a variety of computer simulations. As a result, it turned out that the probability of observing a uniform signal every 233 days due to the activity of the star itself, namely star spots on the surfaces of the stars, which can actually create similar fluctuations in the movement of the star, will actually be less than 0.8 percent.
“After all the checks, we came to the conclusion that the Keplerian reflex movement noted in this case can be explained precisely by the presence of a planet in the system. At the moment, we are confident in this conclusion by 99.2 percent, ”adds Ribas.
Based on the data obtained, scientists make the assumption that they have discovered a potential super-Earth – a planet weighing more than Earth, but smaller in size than the same ice giant Uranus. The object is most likely located on the “snow boundary” of the Barnard star. We are talking about the distance from the star, at which the temperature becomes low enough so that simple volatile compounds (such as water, ammonia, methane, molecular nitrogen and chlorine) become solid, eventually forming a planet.
And yet, many details about the potential exoplanet are still unknown to scientists.
“We know almost nothing about its composition and characteristics. Mass, most likely, 4 times the earth. The planet can be both stony and belongs to the class of soft mini-Neptunes – the class of gas dwarfs. In any case, it should be a very cold world because its equilibrium temperature is about -170 degrees Celsius, ”the researchers note.
Ribas and his colleagues are going to continue the exploration of the star Barnard. Who knows, maybe this red dwarf is hiding some more planets.