29.10.2020
20:08
It is the smallest planet of its kind ever detected. To observe it, the scientists had to use a “gravitational microlensing” effect to take light from a distant star and reflect it like a giant magnifying glass onto the celestial body.
By Jorge CantilloOctober 29, 2020 Share on FacebookShare Share on TwitterTweet Share on WhatsAppShare
The smallest rogue planet ever detected was discovered thanks to an astronomical effect known as gravitational microlensing. Credit: Jan Skowron / Astronomical Observatory, University of Warsaw
Astronomers from the United States and Poland discovered a planet similar in size to Earth that roams the Milky Way without a parent star to put it in orbit around it.
They have dubbed it a “rebel planet” and, although it is not the first of its kind to be discovered, it is the smallest detected so far.
According to what we know of the universe, there are planets -those that are within our solar system and orbit around the Sun, its mother star-, exoplanets -which orbit around other mother stars inside and outside the Solar System- and “rebellious planets. “, Which do not follow the orbit of any ruling star.
The latter could be thousands or millions. There might even be more of them than stars in the Milky Way. However, detecting them is not easy as they do not have their own light and do not follow any orbit.
In 2011, this same team of scientists had found 10 such objects, each the size of Jupiter, the largest planet in the entire Solar System. None had a parent star within 10 astronomical units, which is a measurement based on the distance between the Earth and the Sun.
This new “rogue planet” was detected taking advantage of an astronomical phenomenon known as ‘ gravitational microlensing’, which consists of bending the light of the stars most distant to it to create a giant magnifying glass effect and to be able to observe this celestial body.
The effect in question is very rare, as it requires the astronomer’s telescope to be in near perfect alignment with both the object to be observed and the star being used as the light source.
The gravity of a free-floating planet can deflect and focus light from a distant star as it passes close to it. Due to the distorted image, the star temporarily appears much brighter. Credit: Jan Skowron / Astronomical Observatory, University of Warsaw
The microlensing is the result of Einstein’s theory of general relativity: a massive object (the lens) can deflect light from a bright background object (the source). The gravity of the lens acts like a huge magnifying glass that bends and magnifies the light from distant stars.
This was stated by Przemek Mroz of the California Institute of Technology, astronomer and main author of the article in which the discovery of the “rogue planet” was reported.
“If a massive object (a star or planet) passes between a terrestrial observer and a distant source star, its gravity can deflect and focus the light from the source. The observer will measure a brief brightness of the source star ”, he details.
The massive object was detected in a region of the Milky Way known as the “Galactic Bulb”, which is located in the central part of the galaxy. The observation was made by the Warsaw telescope, at the Las Campanas Observatory, in Chile.
The disk of the Milky Way is seen on the University of Warsaw Telescope at the Las Campanas Observatory in Chile in an artistic recreation (Jan Skowron / University of Warsaw via REUTERS)
According to the researchers, this latest rogue planet, named OGLE-2016-BLG-1928 , is the smallest ever detected. Its mass would be similar to that of Earth or Mars , which is close in size but smaller than our planet.
The massiveness of the objects observed by the microlensing effect is determined by the duration of the event. As most of those registered belong to stars, these usually last several days. When rogue floating planets have been detected, the event lasts for a few hours. But in the latter case it only lasted 42 minutes.
“When we first saw this event, it was clear that it must have been caused by an extremely small object,” said another article author and astronomer Radoslaw Poleski from the University of Warsaw in Poland.
They concluded that it is one of the “rogue planets” because, if it were rotating around a star, it would also have influenced the microlensing event. Something that didn’t happen
” We can rule out that the planet has a star within about eight astronomical units , ” he added.
The gravity of a free-floating planet can deflect and focus light from a distant star as it passes close to it. Due to the distorted image, the star temporarily appears much brighter. Credit: Jan Skowron / Astronomical Observatory, University of Warsaw
One of the theory that astronomers have about these types of planets is that spinning disks of dense gas and dust were formed around the stars (just like ordinary planets), and were violently ejected from their original planetary systems after interactions. gravitational with other bodies (such as other planets in the system) , so they float freely through the galaxy.
These data are relevant to understanding the turbulent past of our own Solar System or similar planetary systems.
The search for free-floating planets is one of the scientific engines of the Roman Nancy Grace Space Telescope, which is currently being built by NASA. The project is scheduled to begin operations in the middle of this decade.
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