Scientists have discovered a ‘Super Earth’ that is believed to revolve around one of the oldest stars in the Milky Way galaxy. The exoplanet gets its title because it is thought to be about three times the mass of Earth, with a size 50% larger than our home planet.
The planet, known as TOI-561b, was described in a new study accepted for publication in The Astronomical Journal. Despite the mass of the planet, its density is about the same as that of the Earth, astronomers found in the study.
“We report the discovery of TOI-561, a multi-planetary system in the galactic hard disk that contains a rocky, ultra-short-period planet (USP),” the study said.
The planet gets its name from the planet-chasing Transiting Exoplanet Survey Satellite (TESS) mission conducted by NASA in 2018. The “TOI” in TOI-561b stands for TESS Object of Interest. It is located outside the solar system, in the thick Milky Way disk, explains a CNN report. Because of its proximity to the host, it only takes less than half the earth to complete one orbit around it.
“For every day you are on earth, this planet orbits its star twice,” Stephen Kane, co-author and astrophysicist at the University of California, Riverside, said in a statement. The researchers determined the planet’s mass, radius and density using the WM Keck Observatory in Hawaii.
(Representative image: Reuters)
This proximity of the ‘super-Earth’ results in the average surface temperature on the planet exceeding 2,000 Kelvin, or 3,140 degrees Fahrenheit. TOI-561b is therefore too hot to be habitable. Although astronomers know that the rocky planet and its star form a 10 billion year old system, they wonder if the planet has ever been alive in its past.
“TOI-561b is one of the oldest rocky planets yet to be discovered,” lead study author Lauren Weiss said in a statement. “Its existence shows that the universe has formed rocky planets since its inception 14 billion years ago.” By comparison, our sun is only 4.5 billion years old.
Such older planets are found to be less dense than the more recently formed planets. This is because there were not so many heavy elements present in the universe at that time. Such elements were eventually created by stars that reached their end in a supernova.
The study highlights two other planets orbiting the star, both of which are likely to be gaseous and larger than TOI-561b.