dark comet First Interstellar Object 1I/2017 U1 ‘A small object with no detected coma, similar to ‘Oumuamua, with large accelerations that can be explained by volatile outgassing. These objects represent a potentially widespread class of small objects that lie further in the continuum between asteroids and comets and whose active nature is inferred from their orbital motions. Michigan State University astronomer Darryl Seligman and his colleagues have now detected seven new dark comets, proving that there are two distinct populations of these objects.
This artist’s impression shows ‘Oumuamua, the first interstellar object discovered in the solar system. Recent observations show that the object is moving faster than predicted as it leaves the solar system. Astronomers speculate that the ejection of material from the surface due to solar heating is responsible for this behavior. This release of gas can be seen, in this artist’s impression, as a subtle cloud emitted from the side of the object facing the sun. Image credits: NASA / ESA / Hubble / ESO / M. Kohnmesser.
In 2003, astronomers noticed that asteroid 2003 RM’s orbit deviated slightly from its expected orbit. This motion cannot be explained by the acceleration typical of asteroids.
Then, in 2017, the interstellar object ‘Oumuamua passed through our solar system, leaving astronomers perplexed.
Like a typical asteroid or comet, it was moved in part by the gravity of other bodies in the solar system, such as the sun.
But astronomers also discovered that ‘Oumuamua is accelerating beyond that, likely due to the release of previously trapped gas.
The strength of the thrust added by such outgassing defied that of a typical asteroid and rivaled the speed of a comet.
problem? ‘Oumuamua lacked the bright dust tail that is characteristic of comets, so it could not be easily classified as an asteroid or comet.
In 2023, astronomers identified seven objects in our solar system that reflect the same unusual features as ‘Oumuamua.
These objects were classified into an entirely new class of objects: the first seven dark comets.
“One of the most important reasons we study small objects like asteroids and comets is because they tell us about how matter is transported around the solar system,” Seligman said. the doctor said.
“Dark comets are a new type of near-Earth object that may contain water, and could provide a new source of materials needed for the development of life to Earth.”
“The more we learn about them, the more we will understand their role in the origin of the Earth.”
Dr. Seligman and his co-authors not only discovered seven new dark comets, but also compared the total number of known comets and identified two different types.
The first type is called an outer dark comet. These are large objects with eccentric orbits similar to Jovian comets and may have originated outside the solar system.
The second type is called an internal dark comet. These are small celestial bodies with roughly circular orbits that move through the inner solar system close to Earth and may have originated in the asteroid belt.
“What’s interesting about these objects is that although they look like asteroids, their motion is similar to that of comets,” said Dr. David Farnochia, a navigation engineer at NASA’s Jet Propulsion Laboratory.
“This is a puzzle that challenges the way we have always classified objects as either asteroids or comets.”
Dr. Seligman said, “Expanding our knowledge of dark comets will help us understand the context in which ‘Oumuamua was a fortuitous event that has left the solar system and is no longer observable.”
“What many people might not normally think about is that the solar system is a chaotic place.”
“We don’t know where things came from, but with 14 currently known dark comets orbiting within our solar system, we will collect more data in the coming years and hopefully uncover answers. Opportunities are opening up: the formation of our own planet.”
This finding is reported in the following article: paper in Proceedings of the National Academy of Sciences.
_____
Darryl Z. Seligman others. 2024. Two distinct populations of dark comets, distinguished by orbit and size. PNAS 121 (51): e2406424121;doi: 10.1073/pnas.2406424121
Source: www.sci.news
