According to a new study, astronomers have discovered two exoplanets from the super Earth orbiting a star 11 light-years away from Earth. There is also a third potential planet that orbits a little further from the star, according to the researchers.
The proximity of this intriguing nearby planetary system will allow for further study in the future, the researchers said.
The star, Gliese 887, is a small faint red dwarf star with about half the mass of our sun. But given its proximity, it is the brightest red dwarf in the sky. It is also one of the closest stars to our sun, although it is far from the reach of any spacecraft technology we have today.
A team of astronomers working on the Red Dots project, which tries to find terrestrial exoplanets closer to our sun, observed the star using the European Southern Observatory in Chile. The team observed the star every night for three months. The high-precision radial velocity planet finder, known as the HARPS spectrograph, detected two planets around Gliese 887.
The spectrograph was able to detect the planets using a technique that astronomers call the “Doppler wobble” or radial velocity method. This so-called oscillation occurs when the star moves back and forth due to the gravitational pull of the orbiting planets. The HARPS instrument can measure these small oscillations.
These data were combined with other archival data, including measurements of the star dating back 20 years.
Astronomers named the planets Gliese 887b and Gliese 887c. The first planet completes an orbit around the star every 9.3 Earth days, while the second planet takes 21.8 Earth days to complete an orbit.
They also detected a signal beyond that could correspond to a planet that takes 50 Earth days to complete an orbit around the star.
This study published Thursday in the journal Science.
Planets are known as super-Earths because they are larger than Earth but even smaller than planets like Uranus and Neptune. And both are close to the star’s habitable zone, a place where terrestrial planets can support liquid water on their surfaces.
Since the star is much colder than our sun, its habitable zone is much closer to the star’s range, meaning that the planets that orbit it are also potentially within that range. However, the two super-Earths are too close for comfort, which means they are too hot to keep the water liquid.
Both receive between 2.5 and eight times more energy from their star than the Earth from the Sun.
Favorable conditions
But the third potential planet, which could also be a super Earth, could exist in the star’s habitable zone.
By observing and studying the star, the researchers discovered some good news.
“The host star is the best star that is very close to the Sun because it is an unusual star silent star, “said Sandra Jeffers, lead author of the study and a professor at the Institute of Astrophysics at the University of Göttingen in Germany, in an email to CNN.” By a silent star, I mean it doesn’t have dark stars or energetic outbursts [flares] that we see in the sun. “
If the star were as active as our sun, its stellar wind would erode and sweep away the planets’ atmospheres. The researchers believe that since the star is silent, the planets around it may have retained their atmospheres. They may have thicker atmospheres than Earth’s.
“If someone had to live around a red dwarf, they would want to choose a calmer star like GJ 887,” wrote Melvyn Davies, professor of astronomy in the department of astronomy and theoretical physics at Lund University in Sweden, in an article by Related perspective. . Davies was not involved in the study.
The star’s brightness is also very constant, which means it could be easier to detect the potential atmospheres of these planets, making them perfect targets for upcoming missions like NASA’s James Webb Space Telescope. The telescope, to be launched next year, can peer through the atmospheres of exoplanets and help characterize their compositions.
“By studying the atmospheres of these planets, scientists will be able to understand if conditions are favorable for life,” said Jeffers.
Previously, the Red Dots team found other exoplanets near our sun, such as the orbiting planets Proxima Centauri and Barnard’s star. Studying these nearby exoplanets could help astronomers learn more about the formation and evolution of stars and planets, as well as search for life beyond Earth.
Going forward, Jeffers and his team want to observe Gliese 887 more to determine if the third signal belongs to a planet.
“If other observations confirm the presence of the third planet in the habitable zone, then GJ 887 could become one of the most studied planetary systems in the Solar neighborhood,” Davies wrote.
