Most stars are born in groups that can number in the thousands, in what are known as stellar nurseries. The Sun's life is thought to have started this way, 4.57 billion years ago. Recent research suggests that over 50 percent of all Sun-like stars are in binary pairs.
HD186302 is not just a stellar sibling, but a special one, uncannily similar to the Sun. It's a G-type main-sequence star just a bit bigger than the Sun, and around about the same surface temperature and luminosity. It also has extremely similar chemical abundances, and is around the same age - about 4.5 billion years old. It's an even closer match than F-type star HD162826, identified as a stellar sibling in 2014.
That means the size, age, temperature, luminosity and chemical composition of the Sun are all compatible with life “as we know it.” It is plausible that planets orbiting other stars with these same qualities - stellar siblings - could host life-forms similar to ours… and a stellar twin represents an even more hopeful option. If our sibling candidate has a planet, and the planet is a rocky type, in the habitable zone, and if this planet was 'contaminated' by the life seeds from Earth, then we have a dream scenario - an Earth 2.0, orbiting a Sun 2.0.
That's a lot of ifs, but however slim the chance, all these things could plausibly have come to pass. IA astronomers are now making plans to look very hard for signs of any planets that may be orbiting HD186302.
The team's research has been published in the journal Astronomy & Astrophysics.
Image credit: CDS Portal/Simbad