SUB EARTH: Did Scientists Just Discover Another Earth ???
New Delhi, May 4: Scientists believe they have found a new planet that could have oceans of liquid water orbiting the closest star to Earth, Proxima Centauri, according to a new study.
This potential planet, Proxima Centauri d, is referred to as a “sub-Earth” or a planet substantially less massive than Earth or Venus, by researchers. Since astronomers conventionally wait for independent confirmation before officially introducing new planets into their catalogues, Proxima Centauri d is currently only a “planet candidate.”
Authors of the study, which appears in the Feb. 10 edition of the Astronomy & Astrophysics journal, have high confidence in their detection.
A team lead by astronomer João Faria measured tiny shifts in the spectrum of light from the star as the planet’s gravity pulled at it during orbit, using the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO). This state-of-the-art device is located at the Very Large Telescope, a system of four 8.2-metre telescopes at the European Southern Observatory in Cerro Paranal, Chile.
“I knew that ESPRESSO could do this, but I was still surprised to see it showing up,” said Faria.
The space object they found is smaller than a planet found to be orbiting Proxima Centauri in 2016, known as Proxima Centauri b.
“Our results bring new interest to the planetary system around Proxima,” said authors of the new study. “The star is now the likely host of three low-mass planets.”
Proxima Centauri b is around 1.3 times the mass of Earth and takes 11.2 days to orbit around Proxima Centauri, said the Nature journal. Proxima Centauri d is most likely smaller than Earth and takes an estimated five days to orbit its sun.
While Proxima Centauri b is considered to be in the habitable zone of the star, Proxima Centauri d is not.
“The search for life starts now,” said Guillem Anglada-Escudé, an astronomer at Queen Mary University of London and leader of the team that discovered Proxima Centauri b around six years ago.
“The habitability conditions of Proxima b…have been extensively studied,” said researchers. “On the other hand, the candidate Proxima d orbits much closer to the star and outside the [habitable zone] range.”
However, the new finding has only made scientists more interested in the Proxima Centauri system.
“It’s showing that the nearest star probably has a very rich planetary system,” says Anglada-Escudé.
“It is fascinating to know that our Sun’s nearest stellar neighbor is the host to three small planets,” says Elisa Quintana, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Their proximity make this a prime system for further study, to understand their nature and how they likely formed.”
Although Proxima Centauri – a red dwarf and the dimmest star in the Alpha Centauri star system – is the closest star to our Sun, it is still around 40.2 trillion km away, according to NASA.
Even so, data about possibly habitable planets orbiting the star “fulfils a longstanding dream of science-fiction writers – a potentially habitable world that is close enough for humans to send their first interstellar spacecraft,” according to the Nature journal.
“It does make you wonder,” said Faria, who explained that interstellar travel is still in the realm of science fiction as of the discovery of Proxima Centauri d.
