NASA Discovers Three New Exoplanets Orbiting a Dwarf Star: Could There be Life on Their 'Dark Sides?'
NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered a dwarf star, dubbed TOI-270, with three exoplanets – TOI 270B, C, and D, in respective increasing distance from the star – in tight orbit around it. The system is located 73 light years from the Sun in the constellation Pictor. TESS' latest discovery was announced yesterday in a press release from NASA. In a research paper published in Nature Astronomy journal, TOI 270C and TOI 270D are described as "sub-Netpune sized," while the innermost planet, TOI 70B, is described as a rocky super Earth.
Of the three, TOI 270D is the only one that appears remotely temperate, with an estimated surface temperature of 150 degrees Fahrenheit (66 degrees C). The others, as depicted in the animation below, are described as "ovenhot."
NASA notes, however, that "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." One wonders, then, if the "dark" sides of these planets could sustain life.
But the possibilities of life on the "dark side" are not what have scientists intrigued. Instead, they are focusing on how two sub-Neptunes, both more than twice the size of Earth, were formed alongside a nearly Earth-sized planet: an event that researchers say is relatively rare. The discovery has some outlets calling TOI 270B (the super-Earth closest to the star) "the missing link" in planet formation. "We've found very few planets like this in the habitable zone, and many fewer around a quiet star, so this is rare," said U.C. Riverside Associate Professor Stephen Kane in a statement. "We don't have a planet quite like this in our solar system."
"An interesting aspect of this system is that its planets straddle a well-established gap in known planetary sizes," said article co-author Fran Pozuelos. "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. TOI 270 is an excellent laboratory for studying the margins of this gap and will help us better understand how planetary systems form and evolve."