The dayside of TRAPPIST-1b, the innermost planet in the seven-planet system TRAPPIST-1, has a temperature of about 227 degrees Celsius (441 degrees Fahrenheit), according to an analysis of data from the Mid-Infrared Instrument (MIRI) onboard the NASA/ESA/CSA James Webb Space Telescope.
TRAPPIST-1 is an ultracool M-dwarf star located 38.8 light-years away in the constellation of Aquarius.
Also known as K2-112 or TIC 278892590, the star is barely larger than Jupiter and has just 8% of our Sun’s mass.
In February 2017, astronomers announced that the star hosts at least seven planets: TRAPPIST-1b, c, d, e, f, g and h.
All these planets are similar in size to Earth and Venus, or slightly smaller, and have very short orbital periods: 1.51, 2.42, 4.04, 6.06, 9.21, 12.35 and 20 days, respectively.
Three of these planets lay in the star’s habitable zone, meaning they may harbor suitable conditions for life.
TRAPPIST-1b, the innermost planet, has an orbital distance about one hundredth that of Earth’s and receives about four times the amount of energy that Earth gets from the Sun.
Although it is not within the habitable zone, observations of the planet can provide important information about its sibling planets, as well as those of other red-dwarf systems.
“There are 10 times as many of these stars in the Milky Way as there are stars like the Sun, and they are twice as likely to have rocky planets as stars like the Sun,” said Dr. Thomas Greene, an astrophysicist at NASA’s Ames Research Center.
“But they are also very active — they are very bright when they’re young, and they give off flares and X-rays that can wipe out an atmosphere.”
“It’s easier to characterize terrestrial planets around smaller, cooler stars,” said Dr. Elsa Ducrot, a researcher at the Université Paris-Saclay.
“If we want to understand habitability around M-dwarf stars, the TRAPPIST-1 system is a great laboratory. These are the best targets we have for looking at the…
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