This is what an astral neighborhood looks like: of course there is our sun. Then come the eight planets of the solar system at various distances, and then a lot of icy little things. After about a light year, the solar system ends in all directions and then little or nothing comes first. If you are in the Southern Hemisphere and studying the constellation Centauri, you can see our closest neighbor glowing in the night sky: the Alpha Centauri triple star system. It is about 4.3 light years from Earth. This three-star system can now be expanded to include a new exoplanet. Researchers on the Breakthrough Watch astronomical program about Kevin Wagner of the University of Arizona want to find evidence of an exoplanet. They recently presented their findings in Nature Communications..
Alpha Centauri – is in neighbor with 3 stars
Our closest neighbor, Alpha Centauri, functions as a completely different star system from our solar system. Because in the solar system there is only one star, the sun, in the center. Alpha Centauri is made up of two sunlike stars, Alpha Centauri A and Alpha Centauri B, orbiting each other. They themselves form a binary star system. This double star beam is surrounded by a kind of appendix, the red dwarf Proxima Centauri, which is much smaller and less illuminated than the two Sunlike stars.
Two exoplanets are Proxima Centauri, and none for Alpha Centauri B.
What Proxima Centauri lacks in comparison to the two larger stars, the planet makes up for in exoplanets: in recent years, astronomers have already tracked two exoplanets around this red dwarf. Scientists on Earth recently received supposedly mysterious signals from this star’s neighborhood. A few years ago it was announced that a planet had been discovered around Alpha Centauri B. Unfortunately, a few years later it turned out that this was an interference signal. So it is Proxima Centauri So far the only star in the neighboring star system that has some exoplanets in its orbits.
Researchers are very interested in Alpha Centauri
However, researchers do not abandon the search for more planets in the three-star system. This is mainly because it would be very cool to find more planets out there. Astronomers were especially impressed by the habitable areas around the two Sunlike stars. Because in these areas there could be liquid water on the surface of a planet, which in turn would not exclude an exoplanet from the principle of habitability – see our Earth, which behaves well in the habitable zone around the sun and certainly above the surface of liquid water. Unfortunately, it is currently difficult to detect such planets with the available technical capabilities. These planets are very small and very faint, and their sunlike stars are very bright. Usual techniquesIn which researchers have so far found more than 4000 exoplanets in other star systems, they cannot be used in such Earth-like planets.
Alpha Centauri in focus from Breakthrough Watch
However, Alpha Centauri is close enough to Earth that researchers can test technologies that could one day be used with better telescopes of distant stars. This is exactly what Kevin Wagoner and his colleagues did as part of Breakthrough Watch. Breakthrough Watch, in turn, is part of Breakthrough Initiatives, a program initiated by entrepreneur Yuri Milner. His goal is to search for life outside the planet Earth. For this project, Breakthrough Watch worked with ESO European Southern Observatory They worked together. Thus the NEAR experiment can be performed on the VLT Very Large Telescope in the Chilean Atacama Desert.
Das NEAR-Experiment am a very large telescope
Through the NEAR experiment, the researchers were able to extend the VLT with a number of special tools, for example an ECG machine that blocks the light of a sunlike star. This could lead to a fainter exoplanet in its orbit. The researchers used a total of one hundred hours of observation from May 2019 to June 2019 to investigate Alpha Centauri A in more detail. These observations were made in the infrared region of the electromagnetic spectrum. In this wavelength range, the sunlike star does not appear as bright as it does in the visible range, while a potential exoplanet in its orbit in the habitable zone there shines brightly. This makes it possible to detect such a signal at all.
One hundred hours of observation, a possible exoplanet
Such an undertaking is still not easy. Out of a hundred valuable hours of observation, the researchers were unable to evaluate about 23 hours because the signal quality was not good enough. However, in the remaining hours, they filtered out an exciting signal, specifically that of a possible exoplanet around Alpha Centauri A. So far, it was nothing more than a mass of infrared pixels. If the signal turns out to be a planet, then it would be an exoplanet the size of Neptune, a gas planet. You can’t stand that. However, according to the researchers, the planet could lie directly on the outer edge of the habitable zone around Alpha Centauri A. This does not completely rule out the presence of liquid water on the surface.
Exoplanet filter instead of an exoplanet of the Alpha Centauri triple star system
However, the researchers also take care in their technical article to talk about only one candidate. Because they cannot be sure of the existence of this outer planet. So it’s also possible to imagine that they noticed a warm dust cloud orbiting Alpha Centauri A instead. Or, unknown interference signals in your experiment set a line through the exoplanet count. Another observation campaign could have been demonstrated with the Very Large Telescope in 2020. However, the global corona pandemic has disrupted telescopes on Earth, along with a few other things. Meanwhile, the scientists requested more observation time for the telescope. Other teams of scientists must also monitor Alpha Centauri using other methods to see if our sun-like neighbor Alpha Centauri A really has this exoplanet.