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takyon [soylentnews.org] writes:

Earth-like planet spotted orbiting Sun's closest star [nature.com]

Astronomers have discovered a third planet orbiting Proxima Centauri, the star closest to the Sun. Dubbed Proxima Centauri d, the newly spotted world is probably a bit smaller than Earth, and well within the habitable zone of its host star — meaning that it could have oceans of liquid water that can potentially harbour life.

"It's showing that the nearest star probably has a very rich planetary system," says Guillem Anglada-Escudé, an astronomer at the Institute for Space Sciences in Barcelona, Spain, who led the team that in 2016 discovered the first planet to be seen orbiting Proxima Centauri [nature.com].

Astronomer João Faria and his collaborators detected Proxima Centauri d by measuring tiny shifts in the spectrum of the star's light as the planet's gravity pulled it during orbit. The team used a state-of-the art spectrograph called ESPRESSO at the Very Large Telescope, a system of four 8.2-metre telescopes at the European Southern Observatory in Cerro Paranal, Chile. The results were published on 10 February in Astronomy & Astrophysics.

A candidate short-period sub-Earth orbiting Proxima Centauri [aanda.org]

We detect a signal at 5.12 ± 0.04 days with a semi-amplitude of 39 ± 7 cm s⁻¹. The analysis of subsets of the ESPRESSO data, the activity indicators, and chromatic RVs suggest that this signal is not caused by stellar variability but instead by a planetary companion with a minimum mass of 0.26 ± 0.05 M_⊕ (about twice the mass of Mars) orbiting at 0.029 au from the star. The orbital eccentricity is well constrained and compatible with a circular orbit.

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