Alpha Centauri is the closest star system to our sun. The inset image shows the two main stars, A and B (3rd star, Proxima, lies a distance away). A new study shows that a planet could lie within the Alpha Centauri A cultivated zone. Photos via Zdenek Bardon and NASA / CXC / Univ. of Colorado / T. Ayres et al.
Astronauts have an image something near the Alpha Centauri A star, in the star system next door to our sun, just 4.4 light-years away. Is it an asteroid, or a dust, or an image glitch, or… planet? If it is a planet, it is the first known planet designed directly in a star’s living zone, the region of a star system in which melt water can exist and therefore in which life can be as we know it will happen.
The astronaut team is calling out what they thought was a “planet candidate. ”This team is part of a near-Earth experiment in the Alpha Centauri Division (NEAR) experiment, with the specific goal of depicting low-mass (Earthlike) planets in the astronomical zones of the stars. The group made the comments in May and June of 2019 and reported them in the magazine Nature Communication on February 10, 2021.
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Due to its proximity (just 26 trillion miles, or 42 trillion km), Alpha Centauri A is a logical target for the research. Alpha Centauri A is one of two large stars in this system, and the two stars – A and B – orbit each other in an approximate orbit the size of Saturn. The stars are similar in size and temperature to our sun. The residential zone, where meltwater is possible, will be at the same speed as the Earth’s arable zone.
The astronauts used the Very Large Telescope in Chile to find planets in the mid-infrared range of the electromagnetic spectrum. Earth-like medium planets glow in this wave. But the image was still challenging, because at 4.4 light-years away, any planet in the Alpha Centauri A cultivation zone would be just 1 arc second from its home star. So the team put together 100 hours of observation time to extract the most sensitive image ever taken from the residential realm of the Alpha Centauri star system.
With this amazing improvement in imaging capabilities, the team believes they can find Neptune-sized planets within the star’s arable zone. The astronomers’ goal was to see if there are planets around the arable zones of the stars could be directly pictured, and now they may have found their first evidence of one.
In image b on the right – extended image of left – the broken white circle represents the inner edge of the arable zone. The clear field with the name C1 is the candidate of the planet. Image via Nature Communications / NEAR.
The speck of light they found is between the size of Neptune and Saturn and lies about 1 celestial unit, or the distance between the Earth and the sun, away from its own star. The astronomers know that the planet’s candidate turned out to be something as unstable as a defect or artifact in the data, but they are excited by the possibility that they may find one in their experiment to see the it could be done. They also hope to be able to image smaller planets, closer to the size of Earth.
Team member Kevin Wagner of the University of Arizona posted the video below, which summarizes NEAR’s test intentions and the methods he used to discover the candidate planet.
Their results must be verified before a definite call can be made for a new planet.
At least 50 planets orbiting other stars have been oriented, just none in this “Goldilocks” orbit near (but not too close to) the home star. The same telescope used in this study also made the first ever image of an exoplanet in 2004, when a speck around a brown dwarf was seen. Last year the telescope saw the first ever multi-planet system around a star.
So far, images have just worked best for planets that are a long way from their parent stars. It has also become easier to see planets that do not pass in front or behind the star from our point of view. This new mid-infrared imaging approach could open up new avenues for finding planets that support water and life.
Bottom line: Astronomers may have photographed the first ever planet within a star-dwelling zone. The Alpha star is Centauri A, just 4.4 light-years away, in the star system closest to our sun.
Source: Illustration of low mass planets within the Alpha Centauri arable zone
