Planets orbiting the Sun-like stars of Alpha Centauri could be carbon-rich worlds with diamonds and graphite littered across their surfaces, say astronomers. Although the existence of such planets has not been confirmed, the team argue that modelling their hypothetical mineralogy, interior structure and atmosphere could guide future observations by shaping our understanding of what is possible.
Alpha Centauri is a multiple-star system just 4.3 light years away that features two Sun-like stars, designated A and B, plus the red dwarf Proxima Centauri. So far, astronomers have discovered one confirmed exoplanet (and two strong candidates) orbiting Proxima, but a 2012 “discovery” of a planet orbiting Centauri B was later disproven. A candidate planet for Centauri A is currently awaiting confirmation after its discovery in 2021.
Despite the lack of confirmed planets around Alpha Centauri A or B, a team led by Haiyang Wang of ETH Zürich, Switzerland and the Swiss National Center for Competence in Research PlanetS set themselves the challenge of modelling what any planets orbiting the two stars might be like. “The model is the first of its kind and has proven to be useful for estimating the bulk elemental compositions of habitable-zone terrestrial planets orbiting Sun-like stars,” Wang tells Physics World.
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