Astronomers have discovered two potentially habitable worlds in our cosmic backyard orbiting a red dwarf star. The extra-solar planets or “exoplanets” are only 16 light-years away and have masses similar to our planet.
They are in the “habitable zone” of their star, GJ 1002, defined as the shell around a star that is neither too hot nor too cold to support liquid water, an essential ingredient for life.
“Nature seems to want to show us that Earth-like planets are very common,” study author Alejandro Suárez Mascareño of the Instituto de Astrofisica de Canarias (IAC) said in a statement.
(opens in new tab). “With these two, we now know of seven in planetary systems that are quite close to the sun.”
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Because liquid water is essential to the existence of life, planets in habitable zones are the focus of our search for life elsewhere in the universe, although being in a habitable zone is no guarantee that we can support life. For example, in the solar system, both Venus and Mars are in the sun’s habitable zone, but neither could currently support life.
Because GJ 1002 is a relatively cool red dwarf, its habitable zone — and these two new exoplanets — are much closer to it than Earth is to the sun. The inner planet, designated GJ 1002b, takes only about 10 days to orbit the star, while the outer planet, GJ 1002c, completes an orbit in 21 days.
Infographic comparing the relative distance between the discovered planets and their star to the inner planets of the solar system. The area marked in green represents the habitable zone of the two planetary systems. (Image credit: Design: Alejandro Suárez Mascareño (IAC). Planets of the Solar System: NASA)
“GJ 1002 is a red dwarf star, with barely one-eighth the mass of the sun,” study co-author and IAC researcher Vera María Passegger said in the statement. “It’s a pretty cool, faint star. This means the habitability zone is very close to the star.”
The proximity of both planets to Earth means they could be excellent targets for astronomers looking to study the atmospheres of Earth-like worlds beyond the solar system.
The exoplanets were discovered as a result of a collaboration between the European Southern Observatory’s (ESO) instrument ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations), installed on the Very Large Telescope (VLT) in the Atacama Desert region of northern Chile, and CARMENES (Calar Alto high-resolution search for M dwarfs with Exoearths using near-infrared and Échelle optical spectrographs) at the Calar Alto Observatory in Andalusia, southern Spain.
The two instruments observed the planet’s parent star during two separate periods, CARMENES studying GJ 1002 between 2017 and 2019, while ESPRESSO collected data from the red dwarf between 2019 and 2021.
CARMENES’ sensitivity over a wide range of near-infrared wavelengths makes it well suited for detecting variations in the velocities of stars that may indicate orbiting planets.
“Because of the low temperature, the visible light of GJ 1002 is too weak to measure the variations in velocity with most spectrographs,” explains a researcher at the Institute of Space Sciences (ICE-CSIC), Ignasi Ribas.
While ESPRESSO and the VLT’s light-gathering ability enabled astronomers to make observations of the system that no other telescope on Earth would have been able to achieve, it was the combination of these two powerful instruments that yielded results that individually have struggled to test. reach and lead to the discovery of these exoplanets.
“Each of the two groups would have had a lot of problems if they had tackled this work independently,” concluded Suárez Mascareño. “Together we have come much further than we would independently.”
The astronomers now hope to use the ANDES spectrograph on the under-construction Extremely Large Telescope in the atmosphere of GJ 1002c.
The team’s research is published in the journal
Astronomy & Astrophysics. (opens in new tab)
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