Astronomers discover youngest known planet ever: Study

Chennai (Tamil Nadu) [India], September 17 (ANI): Astronomers have confirmed the existence of a Jupiter-sized planet that is less than a million years old. Named Elias 2-24 b, it is the youngest known planet, offering scientists a rare opportunity to observe a world in the early stages of its formation.
Its surprisingly rapid formation challenges leading theories about how giant planets come together, especially so far from their stars.
Astronomers have confirmed the youngest known planet yet, a world less than 1 million years old that is still surrounded by the gas and dust from which it formed.
According to the Science Daily website, the planet, called Elias 2-24 b, was identified using observations preserved in NASA-funded archives. It is still orbiting within its young star's dusty disk, giving scientists a rare opportunity to study planet formation while it is still happening.
"Our planet-formation models already struggled to explain the previous record holders for the youngest known planet -- a four-way tie between two planets orbiting the star PDS 70 and two planets orbiting the star WISPIT 2 -- which are all more than 5 million years old," said Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile and co-author of a paper detailing the results, as quoted by the website of Science Daily.
"Elias 2-24 b shows us that even our best planet-formation models are still missing some important processes," added Cieza. 
In a study published September 16 in The Astrophysical Journal Letters, researchers led by Andrea Bernardi, a doctoral candidate at the Universidad Diego Portales in Chile, examined archived observations of seven young stars.
The stars were observed using the coronagraph at the W. M. Keck Observatory in Hawaii, which collaborates with NASA under a cooperative agreement. Surrounding each star is a debris disk containing dust, gas, and fragments of ice and rock. Gaps and other features within these disks may indicate that planets are in the process of forming.
A coronagraph blocks much of a star's bright light, making it easier to search for much fainter objects nearby. Using that technique, astronomers looked for planets hidden inside the dusty disks. Planets orbiting stars beyond our solar system are known as exoplanets.
"The planets should be found within the gaps, since they are carving them," Bernardi said. "And that's exactly where we found Elias 2-24 b."
Elias 2-24 b is roughly as massive as Jupiter and orbits a star about 450 light-years from Earth. Because the system is so young, studying it gives astronomers a glimpse of what our own solar system may have looked like billions of years ago.
Stars form inside vast clouds of gas and dust. Planets can then grow from material left over around the newborn star, gradually gathering matter and shaping paths through the surrounding disk.
But observing planets during these earliest stages is extremely difficult because thick dust can hide them from view.
Most confirmed exoplanets have instead been found through transits. A transit occurs when a planet passes in front of its star and causes a small temporary drop in the starlight seen from Earth.
That method becomes much harder to use when planets are still buried in dust or orbit very far from their stars.
As a result, most of the roughly 6,000 confirmed exoplanets are billions of years old and orbit relatively close to their stars.
Scientists currently build planet formation models using theories, computer simulations, and observations of young stars surrounded by disks where forming planets are often too difficult to detect directly. Discoveries such as Elias 2-24 b can provide crucial real-world tests for those models.
"The galaxy churns out new stars and planets continuously, so there are many in every stage of evolution," Cieza said. "That means we can see the entire process in theory, but there is a large gap in what most telescopes can detect. We are mostly blind to these baby planets right now."
A Decade-Old Mystery Comes Into Focus
The new confirmation also resolves a question astronomers have been debating for about 10 years.
Earlier observations from ALMA (Atacama Large Millimeter/submillimeter Array) in Chile revealed a gap in the dusty disk surrounding the young star Elias 2-24. Later, the European Southern Observatory's Very Large Telescope in Chile spotted a faint point of light inside that gap, according to the Science Daily website. 
Scientists wondered whether the object could be a planet. The problem was that existing planet formation theories suggested a large planet should not have been able to form so quickly, especially at such a great distance from its star.
Current models suggest that forming a Jupiter-size planet at Jupiter's distance from the Sun (which is just over five times larger than the distance of Earth to the Sun) takes about 5 million years. A giant planet much farther out should take even longer.
Yet the faint object in the Elias 2-24 system sits about 55 times farther from its star than Earth is from the Sun and was already showing signs of being a forming planet.
To investigate further, Bernardi and colleagues searched the Keck Observatory Archive, a NASA-funded collaboration between Keck Observatory and the NASA Exoplanet Science Institute at Caltech/IPAC.
That analysis ultimately confirmed the object as Elias 2-24 b.
"We usually hear about telescopes working separately, but this confirmation was possible only by using multiple telescopes together," Bernardi said. "Elias 2-24 b is at the limit of what current telescopes can detect, but with new instruments like NASA's Nancy Grace Roman Space Telescope, such detections should become easier."
They found the same faint object in observations collected in 2018 and 2020. By combining the observations and tracking how the object moved over time, the team determined that it behaved much more like a planet orbiting the star than an imaging artifact or a distant background star. (ANI)