By Will Dunham
WASHINGTON (Reuters) – Scientists have long grappled with the mysterious nature of sub-Neptunes – the most common type of planet in the Milky Way galaxy. These planets, about two to three times the size of Earth but smaller than Neptune, orbit closer to their stars than Mercury does to the sun.
The recent discovery of six sub-Neptunes, all orbiting in synchronized patterns around a star significantly smaller than the sun, is raising optimism among astronomers. The findings, published in the journal Nature, reveal that these planets have been in orbital resonance – a rare condition where their synchronized orbits have remained unchanged for approximately 4 billion years.
Astronomer Hugh Osborn of the University of Bern in Switzerland, one of the researchers involved in the discovery, noted the mathematical beauty of the orbital resonance. “The key thing about this system is its potential to unlock the secrets of these mysterious sub-Neptune planets, which we know so little about,” Osborn said. “These are definitely not Earth-like planets.”
Lead author of the study, Rafael Luque, mentioned that the composition of sub-Neptunes remains a subject of active research. Scientists continue to debate whether these planets are rocky with thick hydrogen and helium atmospheres, or made of rock and ice with warm, water-rich atmospheres.
Compared to Earth’s 7,900-mile diameter, these newly discovered sub-Neptunes range from 1.9 to 2.9 times Earth’s size, all possessing large atmospheres. They and their star, HD110067, are located approximately 100 light-years from Earth.
Though not within the habitable zone for terrestrial planets, sub-Neptunes may have atmospheres that can regulate surface temperatures, providing potential for habitability. The researchers are hopeful that the James Webb Space Telescope (JWST) can provide more insights into these six planets and sub-Neptunes in general.
(Reporting by Will Dunham, Editing by Rosalba O’Brien)
