Artist’s conception of this research showing an imagined time sequence as a star passes behind a TNO with an atmosphere.
NAOJ
Beyond Neptune is the Kuiper Belt, a doughnut-shaped region icy bodies and dwarf planets often called Trans-Neptunian Objects. Most famously, there’s Pluto, but also Eris, Haumea, Makemake, Gonggong and Arrokoth. About 80 have been found, with potentially thousands more, but humanity’s ever more powerful telescopes and techniques.
Another has just been found and, impossibly, it appears to have an atmosphere. Called 2002 XV93, this small object in the far reaches of the solar system may possess a thin atmosphere, despite being far too small to sustain one according to current scientific theories.
Scientists have long believed that only the largest TNOs, such as Pluto, could maintain atmospheres due to their stronger gravity and volatile-rich surfaces. Pluto’s thin, tenuous atmosphere of nitrogen, methane and carbon monoxide is around 100,000 times less dense than Earth’s.
About 310 miles (500 kilometers) in diameter, 2002 XV93 is much smaller than Pluto, which measures about 1,473 miles (2,370 kilometers) across. Its weak gravity and frigid environment should make it nearly impossible for gases to remain trapped around the object for long periods.
MORE FOR YOU
The discovery was made possible by a rare astronomical event known as a stellar occultation. On Jan. 10, 2024, 2002 XV93 passed directly in front of a distant star as viewed from Japan, where a research team from the National Astronomical Observatory of Japan coordinated observations from both professional and amateur astronomers across the country.
How the star’s light changed as the TNO moved across it would tells scientists a lot about its atmosphere. If it had no atmosphere, the star’s light would disappear abruptly as it slipped behind 2002 XV93’s solid surface. Instead, the observations showed a gradual dimming effect, suggesting that starlight was passing through a thin layer of gas before vanishing.
Researchers — who published a paper in Nature in early May — say calculations indicate that any atmosphere should only survive for less than 1,000 years unless constantly replenished. One way that might happen is for frozen gases on the surface to warm slightly and turn into vapor; Pluto’s atmosphere is thought to expand and contract during its 248 year-long orbit of the sun. When it’s closer to the sun, the temperature of Pluto's solid surface increases, causing the ice to sublimate into gas, according to researchers.
However, observations of 2002 XV93 using the James Webb Space Telescope in 2022 found no evidence of frozen gases on its surface — but did find water ice.
2002 XV93's orbital path as shown on NASA's Small-Body Database Lookup.
NASA/JPL/SSD
One theory is that material from deep inside 2002 XV93 object may have recently reached the surface through geological activity, releasing trapped gases into space. Another possibility is that a comet or other impactor struck 2002 XV93, temporarily releasing gas and dust that created the observed atmosphere.
If either explanation is true, the outer solar system may be more active and dynamic than previously believed.
Wishing you clear skies and wide eyes.
此内容由惯性聚合(RSS阅读器)自动聚合整理，仅供阅读参考。 原文来自 — 版权归原作者所有。