NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered three worlds orbiting around a neighboring star (TOI-270). And that’s what TESS was looking for.
So, the new-found worlds orbit a red dwarf star just 73 light-years away from Earth in the constellation of Pictor. Astronomers call the new star system TOI-270 (TESS Object of Interest).
Stephen Kane, a UC Riverside associate professor of planetary astrophysics, says the new star system is exactly what the satellite was designed to find.
One planet is rocky and slightly larger than Earth, while the two others are gaseous and roughly twice Earth’s size.
What’s more interesting is that the TOI-270 star is nearby, making it brighter for viewing. The star is also “quiet.” That means it has few flares and allows scientists to observe it and its orbiting planets more easily.
“We’ve found very few planets like this in the habitable zone, and many fewer around a quiet star, so this is rare,” said Kane. “We don’t have a planet quite like this in our solar system.”
The planets of our solar system are either small, rocky ones like Earth, Mercury, Venus, and Mars, or much larger planets like Saturn, Jupiter, Uranus, and Neptune that are dominated by gas rather than land. Planets half the size of Neptune are very common around other stars, but we don’t have anything like that in our solar system.
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“There are a lot of little pieces of the puzzle that we can solve with this system,” study lead author Maximilian Günther, a postdoctoral researcher at the Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research, said in a statement. “You can really do all the things you want to do in exoplanet science with this system.”
Based on the available data, the team believes that all three worlds are tidally locked. This means they always present the same side to their parent star, just like the Earth-Moon system.
“TOI-270 will soon allow us to study this ‘missing link’ between rocky Earth-like planets and gas-dominant mini-Neptunes because here all of these types formed in the same system,” said Günther.
The rocky super-Earth is planet b, which orbits its star in just three days. The sub-Neptunes, planets c, and d, complete orbits of the star every five and 11 days, respectively.
Normally, this kind of star would be active, sending out flares and enduring solar storms. But this older star is quiet and provides its planets with a steady brightness. It’s only about half as hot as our zone.
TOI-270 is the perfect target for the upcoming NASA’s $8.9 billion James Webb Space Telescope. It will be able to measure the composition of the planets’ atmospheres for oxygen, hydrogen, and carbon monoxide.
Kane says these kinds of observations can help determine whether a planet has ever had a liquid water ocean and whether any of the planets have conditions suitable for life as we know it.
Scientists have described their work in a paper published today in the journal Nature Astronomy.