A special star system is discovered in the galactic neighborhood of the sun: It is home to two so-called super-Earths. And the conditions are favorable for studying the atmospheres of the rocky giants more closely. Could there be life there too?
An international research team has discovered a new planetary system with two super-Earths. The special thing about it: The multi-planet system is only 33 light-years away from Earth and thus one of the closest among those known to date. Large rocky planets outside of our solar system are called super-Earths. However, this says nothing about whether these planets - like Earth - can also accommodate life.
And in this case, the researchers also consider it quite unlikely: Because the two large rocky worlds orbit in very narrow orbits around their home star, a cool dwarf star called HD 260655. However, it is hot enough to warm up the surface temperatures of the two planets to estimated 284 degrees and 435 degrees to heat. Far too hot for liquid surface water to exist there - a prerequisite for life as we know it.
The two sibling planets HD 260655 b and HD 260655 c were discovered with the help of NASA's planet hunter, the "Transiting Exoplanet Survey Satellite" ("TESS"). The researchers were able to use further measurements to determine the size and density of the two planets. This confirmed that they are rocky worlds that are only slightly larger and more massive than Earth. Planet b is about 1.2 times and planet c 1.5 times the size of Earth. And the scientists are now hoping to find out more about the planets - for example about the composition of their atmospheres.
"Due to the relatively high apparent brightness of the host star, the newly discovered planets are excellent targets for further atmospheric studies," said Karan Molaverdikhani from the University Observatory of the Ludwig Maximilian University of Munich, according to a statement. Molaverdikhani is part of the international research team that tracked down the super-Earths. "At 33 light-years, the planets are relatively close to us. Their star, while smaller than our Sun, is one of the brightest in its class." Good conditions for being able to capture light from the star, which shines through the atmospheres of these planets, for example with the new James Webb Space Telescope and perhaps even the Hubble Space Telescope.
Our sun has a radius of ten parsecs, which corresponds to 33 light years, more than 400 stars and a constantly growing number of exoplanets to its direct neighbors. The planet hunter "TESS" is tracking down more and more of these exoplanets by looking out for so-called transits. A transit is when a planet passes in front of its star from the Earth's point of view. Then there is a measurable slight drop in the star's brightness, which in turn provides information about the diameter of the planet. To confirm a discovery, astronomers use other telescopes on Earth. These then measure the slight wobbling of a star, which is caused by the gravitational forces of the planets orbiting it - from this the mass of the planets can be calculated.
(This article was first published on Friday, June 17, 2022.)