This galaxy could have two spiral arms that make it look like a small galaxy, a new study indicates.
The study has not undergone peer review.
The Oort cloud originated from the leftover material of the giant planets in our solar system (Jupiter, Neptune, Uranus, and Saturn) when they formed approximately 4.6 billion years ago. Some of these leftover pieces are substantial enough to be classified as dwarf planets.
As the planets started orbiting the sun, they sent a large amount of leftover material beyond Pluto’s orbit, where it remains today. The inner edge of the Oort cloud is approximately 2,000 to 5,000 astronomical units from the sun, while its outer edge is situated between 10,000 and 100,000 astronomical units away. (One astronomical unit is roughly equivalent to 93 million miles or 150 million kilometers, about the average distance between Earth and the sun.)
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The enormous distance between us and the cloud makes the objects within it too small and distant to be clearly seen by even the most advanced telescopes. Most of what we know about these objects comes from observations of long-period comets, which are essentially “snowballs” of ice and dust that were kicked out of the cloud by gravitational disturbances and now orbit the sun.
Spirals within spirals?
Scientists have used computer simulations to incorporate both the gravitational forces within our solar system and those from outside our solar system to create a model of the Oort cloud’s structure.
A crucial factor in understanding the shape of the Oort cloud is “galactic tide” – the gravitational pulls exerted by nearby stars, black holes, and the center of our galaxy, which have a significant impact on the objects in the Oort cloud, although these effects are often obscured for objects closer to the sun by our star’s own gravitational force.
Scientists ran the model on NASA’s Pleiades supercomputer and discovered a structure within the inner part of the Oort cloud, located between 1,000 and 10,000 astronomical units from the sun. This densely populated region appears to resemble the spiral disk of the Milky Way galaxy, with the inner Oort cloud’s arms stretching approximately 15,000 astronomical units from end to end.
Researchers will need to verify this structure by observing the objects themselves or identifying the light reflected from them against all other background and foreground light sources. These tasks are extremely challenging and currently lack dedicated resources.
The researchers believe that studying these comets could provide insight into the origins of comets, the development of our solar system, and the ongoing influence of the cloud on the surrounding cosmos.
