Scientists found a possible new dwarf planet — it could spell bad news for Planet 9 fans – Space
Source: Space.com
“It’s very rare to discover an object both large and with an exotic orbit.”
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A potential new dwarf planet has been discovered in the outer reaches of the solar system, and its existence poses the greatest challenge yet to the hypothesis that a ninth planet lurks far from the sun.
“We were very excited to discover 2017 OF201 because it was not expected at all,” study leader Sihao Cheng of the Institute for Advanced Study in Princeton, told Space.com. “It’s very rare to discover an object both large and with an exotic orbit.”
“The object’s aphelion — the farthest point on the orbit from the sun – is more than 1,600 times that of the Earth’s orbit,” Cheng explained in a statement. “Meanwhile its perihelion — the closest point on its orbit to the sun — is 44.5 times that of the Earth’s orbit, similar to Pluto’s orbit.”
We’re learning more and more about the outer solar system. Beyond Neptune is the Kuiper Belt; a ring of icy cometary nuclei and planetesimals dominated by Pluto and Charon. The Kuiper Belt begins about 30 astronomical units (AU) from the sun (one AU is the distance of Earth from the sun), its inner edge guarded by Neptune, and extends out to 50 AU. NASA’s New Horizons spacecraft is currently exploring the Kuiper Belt.
Meanwhile, the twin Voyager spacecraft have already sped through the Kuiper Belt and have entered a realm called the Scattered Disk, which is thought to go all through way out to more than 1,000 AU and is home to icy bodies on highly elongated and highly inclined orbits. These objects were literally scattered in the region through gravitational interactions with Neptune, and have had their orbits further modified via torques induced by the gravity of passing stars, or the “galactic tide” (the overall gravitational field of the Milky Way galaxy). Beyond the Scattered Disk is the Oort Cloud, which is an immense volume of space that possibly stretches up to a light-year from the sun and is the source of long-period comets.
However, much about the Scattered Disk is still unknown, and besides those long-period comets that venture this way every now and then, no Oort Cloud object has ever been seen — they are too far away and too small. This is why every discovery of a trans-Neptunian object (TNO) on a greatly elongated orbit is vital for piecing together the mystery of the outer solar system.
Around 5,000 TNOs have been discovered until now, but the latest discovery may be one of the most important. Known as 2017 OF201, it is currently 90.5 AU away from the sun, but its orbit brings it as close as 4.14 billion miles (6.66 billion kilometers) from our star and as far away as a whopping 157 billion miles (244 billion kilometers). from the sun. For the vast majority of its 24,256-year orbit, 2017 OF201 is too far away to be seen with current telescopes; it could only be discovered because its last perihelion came in 1930, and that it’s still relatively close.
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The object’s last perihelion also came, coincidentally, during the same year that Clyde Tombaugh discovered Pluto with a 13-inch (330mm) telescope at Lowell Observatory in Arizona. Would it have been possible for Tombaugh to have also found 2017 OF201? Probably not — at magnitude +20.1, this object would have been four magnitudes fainter than Pluto, and it is even fainter today.
Fortunately, telescopic technology has come a long way in the past 95 years, with deep surveys that can capture the passage of a faint object. For example, the Dark Energy Survey (DES) has identified about 800 TNOs — and that’s even though DES is ostensibly a cosmological survey. In the same vein, Cheng, along with Jiaxuan Li and Eritas Yang of Princeton University, have been scrutinizing observations made by the Dark Energy Camera Legacy Survey (DECaLS) on the Victor M. Blanco 13-foot (4-meter) telescope at the Cerro Tololo Inter-American Observatory in Chile. They discovered 2017 OF201 in archive data going back to 2017 from DECaLS, and also spotted it in old data dating from 2011–12 captured by the 11.7-foot) (3.58-meter) Canada–France–Hawaii Telescope on Mauna Kea.
Based on its brightness and its expected albedo of 0.15 (meaning it would reflect just 15% of the sunlight incident upon it), Cheng’s team calculated that 2017 OF201 is probably about 435 miles (700 kilometers)) across. This would make it the second largest object found on such an elongated orbit. Although it is substantially smaller than Pluto, which is 1,477 miles (2,377 km) across, 2017 OF201 is nevertheless large enough to be classified as a dwarf planet.
However, 2017 OF201’s existence contradicts the Planet Nine hypothesis, based on our best guess as to Planet Nine’s orbit. Planet Nine is a concept that was introduced in 2016 by Caltech astronomers Michael Brown and Konstantin Batygin to explain a per
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