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takyon writes:

Proxima Centauri b confirmed as nearest exoworld

Four years ago, scientists made one of the most exciting exoplanet discoveries so far, a rocky planet similar in size to Earth orbiting the nearest star to the sun, Proxima Centauri. While the detection seemed solid, more confirmation is always good, and now the ESPRESSO spectrograph on the Very Large Telescope (VLT) in Chile has provided that extra and more detailed confirmation. The news was announced by the University of Geneva (UNIGE) on May 28, 2020.

[...] Proxima Centauri b is very similar in size to Earth, with a mass of 1.17 Earth masses. It orbits its star in only 11.2 days, in contrast to our Earth's year-long orbit around our sun. That means Proxima Centauri b is a lot closer to its star than Earth is to the sun. But, because the star is a red dwarf – much smaller and cooler than our sun – its orbit is indeed within the habitable zone of Proxima Centauri. Interestingly, Proxima Centauri b receives about the same amount of solar energy from its star that Earth does from our sun.

[...] The mass of Proxima b was previously estimated to be 1.3 Earth masses. The accuracy of the new measurement of 1.17 Earth masses is unprecedented, according to Michel Mayor, the "architect" of all ESPRESSO-type instruments:

ESPRESSO has made it possible to measure the mass of the planet with a precision of over one-tenth of the mass of Earth. It's completely unheard of.

The new confirmation of Proxima Centauri b is exciting, but there may be more surprises in store ... there is also possible evidence of another and smaller planet in the newest data. A secondary detection was also made, although it isn't certain whether it is actually a planet. If it is, it is even smaller than Proxima Centauri b. [...] If it is a planet, it would be more akin to Mars or Mercury in size and mass – estimated at a minimum Earth mass of 0.29 ± 0.08 – and orbits the star in only 5.15 days. It wouldn't be too surprising, though, in that low-mass stars like red dwarfs tend to have multiple planets in their systems. More observations will be required to either confirm or refute this possible second planet.

Journal Reference
Mascareño, A. Suárez, Faria, J. P., Figueira, P., et al. Revisiting Proxima with ESPRESSO, (https://arxiv.org/abs/2005.12114v1)

Proxima Centauri - Planetary system

Previously: ESO Confirms Reports of Proxima Centauri Exoplanet
Proxima b May Have Oceans
Dust Belts and Possible Additional Exoplanet Spotted Around Proxima Centauri
First Light for VLT's ESPRESSO Exoplanet Hunter
Very Large Telescope's ESPRESSO Combines Light From All Four Unit Telescopes for the First Time
Proxima Centauri's No Good, Very Bad Day
High Levels of Ultraviolet Radiation Should Not Preclude Life on Exoplanets
Icy second planet potentially spotted orbiting Proxima Centauri

Original Submission