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ESPRESSO instrument confirms presence of Earth-like star in closest star system

An artistic rendering imagines what the surface of the exoplanet Proxima b might look like. The planet's sun, the red dwarf star Proxima Centauri seen just above the horizon, is the closest star to our own solar system. Photo by ESO/M. Kornmesser
An artistic rendering imagines what the surface of the exoplanet Proxima b might look like. The planet's sun, the red dwarf star Proxima Centauri seen just above the horizon, is the closest star to our own solar system. Photo by ESO/M. Kornmesser

May 28 (UPI) -- Astronomers have confirmed the presence of an Earth-like exoplanet in the star system closest to our own, Proxima Centauri.

Scientists identified the planet, Proxima b, with the help of ESPRESSO, a spectrograph mounted on the European Southern Observatory's Very Large Telescope in Chile.

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The rocky planet boasts a mass of 1.17 Earth masses. Though the planet enjoys an intimate orbit around its host star, completing an orbit every 11.2 days, because Proxima Centauri is a small, low-mass star, the Earth-like world remains within the habitable zone. If there is water on Proxima b, it could persist in liquid form.

Proxima b was first spotted by an older spectrograph called HARPS, but the latest observations provided researchers with more precise data regarding the exoplanet's size and the timing of its orbit.

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"We were already very happy with the performance of HARPS, which has been responsible for discovering hundreds of exoplanets over the last 17 years," Francesco Pepe, leader of the ESPRESSO research team and a professor of astronomy at the University of Geneva in Switzerland, said in a news release. "We're really pleased that ESPRESSO can produce even better measurements, and it's gratifying and just reward for the teamwork lasting nearly 10 years."

Securing precise measurements of the exoplanet's size is an important first step in gauging the odds of finding life on Proxima b.

"ESPRESSO has made it possible to measure the mass of the planet with a precision of over one-tenth of the mass of Earth," said Nobel Prize-winner Michel Mayor, who lead the design of the ESPRESSO spectrograph. "It's completely unheard of."

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But while the latest data -- published online this week -- confirmed that temperatures on Proxima b are right for liquid water, the conditions on the exoplanet's surface could be too harsh for life if the alien world is without an atmosphere. Proxima Centauri, an active red dwarf, blasts Proxima b with heavy doses of X-rays, 400 times more X-radiation than hits the Earth.

Scientists hope the next generation of VLT instruments will help them continue to study the habitability of Proxima b.

"Is there an atmosphere that protects the planet from these deadly rays?" said UNIGE researcher Christophe Lovis, who works on ESPRESSO's scientific performance and data processing. "And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favorable conditions existed? We're going to tackle all these questions, especially with the help of future instruments."

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