Scientists say they have discovered three new planets outside our solar system that orbit a star situated 73 light years away from Earth. If made of rock, this planet may be around twice Earth's size. One planet initially showed a habitable zone that could support water; TESS scientists later confirmed the planet's atmosphere is thick and will generate uninhabitable temperatures.
This infographic illustrates key features of the TOI 270 system, located about 73 light-years away in the southern constellation Pictor.
All three new worlds are orbiting an old star just a stone's throw from our own solar system. It orbits 11 times closer to its star than Mercury does our Sun.
"We describe GJ 357 b as a 'hot Earth, '" explains co-author Enric Pallé, an astrophysicist at the IAC and Luque's doctoral supervisor.
TOI 270 b is the closest planet to its host star, and it's thought to be a bit larger than Earth.
That process is what enabled researchers to find GJ 357 d.
An artist's illustration of the potentially habitable exoplanet GJ 357 d.
Without an atmosphere, it has an equilibrium temperature of -64 F (-53 C), which would make the planet seem more glacial than habitable. "It is uncommon for planets to have sizes between 1.5 and two times that of Earth for reasons likely related to the way planets form, but this is still a highly controversial topic".
Even through TESS monitored the star for about a month, Luque's team predicts any transit would have occurred outside the TESS observing window. TOI 270 c and TOI 270 d, respectively, register as 2.4 and 2.1 times larger than Earth.
"All of the planets are expected to be tidally locked to the star, which means they only rotate once every orbit and keep the same side facing the star at all times, just as the moon does in its orbit around Earth". The next step is for ground-based telescopes to examine the stars that these planets might be orbiting and detect whether the planets indeed exert a gravitational pull.
"This system is exactly what TESS was created to find - small, temperate planets that pass, or transit, in front of an inactive host star, one lacking excessive stellar activity, such as flares", said lead researcher Maximilian Gunther, a postdoctoral fellow at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research in Cambridge.
In a new paper in the The Astrophysical Journal Letters, a team led by Lisa Kaltenegger, associate professor of astronomy and director of Cornell's Carl Sagan Institute, models the conditions under which the planet - discovered in early 2019 - could sustain life.
This NASA graphic shows the GJ 357 star system and its three planets. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore.