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WASHINGTON — They are the most common type of planet observed in our Milky Way galaxy. It is two to three times the diameter of Earth but smaller than Neptune, and it orbits closer to its star than Mercury, the solar system’s innermost planet, does to the Sun.
Called “subneptunes,” they do not exist in our solar system, and their basic nature remains a mystery. But the discovery announced Wednesday of six planets in synchronous orbits around a star about 20% less massive than the sun may give astronomers an answer soon. It gives me hope.
Researchers confirmed that the six planets are in a rare condition called orbital resonance, where their synchronous orbits around the stars have not apparently changed since they formed some 4 billion years ago. This indicates that chaotic events such as giant impact events have not disrupted their orbits.
“The resonance aspect is very interesting, partly because of its mathematical beauty,” said Hugh Osborne, an astronomer at the University of Bern in Switzerland and one of the authors of the study published in Nature. Ta.
“The importance of this system is that it has the potential to unlock the secrets of these mysterious sub-Neptunian planets that we know little about,” Osborn added. “These are definitely not Earth-like planets.”
Hundreds of subneptunes have been discovered.
“What these sub-Neptunes are made of is an active topic of research in the field, because the combination of rock, water, and atmospheric compositions that can reproduce the planet’s bulk properties such as its mass, radius, and density is… There is more than one,” the university said. This is a paper by Chicago astronomer Rafael Luque, the lead author of the study.
Scientists have wondered whether the planets below Neptune are rocky planets with thick atmospheres of hydrogen and helium gases, rocky and icy planets with warm, water-rich atmospheres, or other planets. It’s here.
Earth, the largest of the solar system’s four rocky planets, is approximately 7,900 miles in diameter. Neptune is the smallest of her four gas planets, with a diameter of about 30,600 miles, about four times the diameter of Earth.
The newly discovered sub-Neptune ranges from 1.9 to 2.9 times the diameter of Earth. They all seem to have a great atmosphere. They and their star are about 100 light-years from Earth. One light year is the distance that light travels in one year, which is 5.9 trillion miles. The star, called HD110067, is visible in the northern constellation of Coma in Earth’s night sky.
The planet was detected by observing a small drop in the star’s brightness as it passed in front of the star from our vantage point.
The innermost planet takes about nine days to orbit the star. The outermost planets take about 54 days. Planets orbit stars between 6% and 20% of the distance between Earth and the Sun. However, because this star is smaller and less luminous than the Sun, it does not receive the same level of radiation as it would if it were orbiting close to a larger star.
Scientists call it the “habitable zone” around a star. This is the distance at which a rocky planet is thought to be neither too close nor too far away to support life. The Earth exists within the Sun’s “habitable zone.” But what about these six sub-Neptunes?
“None of them are in the nominal habitable zone for terrestrial planets. But the definition of the habitable zone for sub-Neptune planets could include much larger orbits. “Because they have atmospheres that can warm or cool the planet’s surface, we can tell how close or far away they are from their star,” Luque said.
Researchers hope that the James Webb Space Telescope, which began operating last year, can provide answers about these six planets and about sub-Neptune planets in general.
“Potential habitability south of Neptune is an active research topic in this field as well, and we expect promising results on this front, perhaps from the JWST of this planetary system,” Luque said.