Rebellious planets; Hunting the galaxy’s most mysterious realms
Rebellious or invisible planet, this name is in itself full of mystery. Synonyms such as starless planet, wandering planet or interstellar planet may be appropriate terms and good descriptions of these cosmic bodies, but still none of this diminishes the wonder of such worlds. A restless world moving alone in the darkness and vast expanse of the galaxy.
There are definitely “Wandering Planets” and our Milky Way galaxy may contain billions or even trillions of these objects. But we still have little information about these mysterious shrinkers, and according to astrophysicist Jacco Van Loon, scientists are trying to expand their human vision of these objects by hunting them down using creative techniques.
Most known planets, including most of the extrasolar planets discovered, orbit a star. These planets, including the Earth, use the heat and light of the stars, and it is the light emitted by the central stars that makes it possible for us to see the planets .
There are also invisible planets that are hidden from our view and float in the universe alone and abandoned. These lonely dark worlds have no stars to spin around, no light to shine on them, and no heat to radiate from their surface. These are the “Rogue Planets” that astronomers want to take a closer look at.
These types of planets are actually made from the remnants of a star. Scattered masses that orbit a young star in a thin plate of particles and gas and grow when small particles stick together and pull each other together until they clear their surroundings. Everything is chaotic in this world, and collisions between planetary or pre-planetary embryos are common.
In addition, stars tend not to form alone, but to form in clusters of hundreds or thousands of stars at a time, and the collision of new planetary systems causes more destruction and more intense gravitational interaction.
The young earth is thought to have been hit by a mass the size of Mars, and enough material to form the moon has been removed. But some planets faced a more severe fate; They were completely removed from their planet and condemned to live in vast interstellar space. These are free floating planets.
Rogue planets may also form apart from the gas and dust clouds of stars and go through a process similar to star formation. A small cloud of gas and dust can collapse by gravity to form a central planet instead of a star, and moons surround it instead of planets.
When the planets are still very young, for example only a few million years old (for example, the Earth is more than 4.5 billion years old), they still follow the formation and energy released by continuous gravitational contractions as well as radioactivity at their core. They are hot. Large specimens of these young but free-floating planets, which resemble objects from the early days of Jupiter, have thus been seen directly in areas where stars have just formed. But finding smaller rogue planets was almost impossible until a gravitational lens was discovered.
Gravitational lens
Everything that has mass bends the space and causes light to deviate from the direct path. So the object that has the mass focuses the light from the source behind it and, like a large magnifying glass, magnifies the image of the background mass. This phenomenon is called “Gravitational Lensing”.
This theory was predicted by Einstein’s general relativity and was first confirmed when, during the 1919 solar eclipse, stars moved away from their usual positions near the sun.
The effect of the gravitational lens on galaxies made up of trillions of stars has been clearly observed . Due to the presence of large amounts of matter in these galaxies and their stars, stars and other objects located in the background and parallel to them are magnified and distorted under certain conditions .
One observation was made in 2019 by a black hole in a massive galaxy called Messier 87 (M87). So even an invisible rogue planet, despite its low mass, can act as a gravitational lens, or better yet, a “micro-lens” because it has very little effect.
Last year, one of these micro-lens events led to the discovery of a new stray planet called OGLE-2016-BLG-1928 in the Milky Way. The observation of light amplification by an invisible star in the dense inner regions of the Milky Way galaxy lasted only 42 minutes, which means it must be a small object that is estimated to be a planet close to Earth.
This micro-lensed planet was not associated with any detected stars. Although rogue planets had previously been discovered by the gravitational lens method, this was one of the most compelling things. OGLE-2016-BLG-1928 In addition to being more similar to Earth, it was named the smallest wandering planet ever discovered.
Upcoming efforts with the Nancy Grace Roman Telescope
In addition to the current extensive work, new simulations show that NASA’s Nancy Grace Roman Space Space Telescope, which will be launched in the coming years, could detect a large number of rogue planets. According to NASA, studying these island worlds will help to understand how planetary systems form, evolve and decompose.
The Roman Space Telescope will detect rogue planets by conducting a large microlens scan. “The microlens signal from a wandering planet lasts only a few hours to a few days and then disappears forever,” said Matthew Penny, an assistant professor of physics and astronomy at Louisiana State University. This makes it difficult to observe them from the ground, even with multiple telescopes. “Roman, however, changes the game of searching for wandering planets.”
According to researchers, Roman can detect rogue planets with a mass as small as Mars. The telescope’s studies will also help refine planet-forming models because they will test the formation of planets and their evolutionary models that predict different types of these isolated worlds.
Thus, the number of stray planets provided by the Roman mission is at least 10 times more accurate than current estimates obtained with the help of ground-based telescopes, and vary from tens to trillions in the galaxy.