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This composite Hubble Space Telescope image shows the debris ring around the star Fomalhaut, along with the CS1 and cs2 bright dust clouds. For comparison, Dust Cloud CS1, painted in 2012, is pictured with Dust Cloud CS2, painted in 2023. Credit: NASA, ESA, Paul Kalas (UC Berkeley)
Astronomers hoping to observe a planet around a nearby star have witnessed a very rare “unprecedented celestial event,” the team said: the violent result of not one, but two collisions between the planets’ rocky building blocks.
Over the past two decades, astronomers have observed two separate catastrophic collisions around the star Fomalhaut, 25 light-years away in the constellation Piscis Austrinus. The discovery happened later on much larger scales than planetesimals (rocky fragments of rejected planets). The asteroid that killed the dinosaurs Smashed into each other in a great cloud of glowing debris.
The Fomalhaut system is no stranger to such mishaps. It is known as the “Eye of Sauron” because of its resemblance to JRR Tolkien’s fiery, all-seeing eye. Lord of the Rings suffrage This similarity comes from the spectacular dust belt that surrounds Fomalhaut at a distance of 133 astronomical units (AU), with one AU equal to 93 million miles (150 million km)—the average distance between. the sun and the earth.
Made up of countless rocky, icy collisions, this belt of dust and debris provides a dusty analog of our early solar system that formed 4 billion years ago, the team said — offering a glimpse into our neighborhood’s chaotic infancy, when planets were forming. Create, destroy, and reassemble.
Wrong planet syndrome
A new study, conducted and led by an international team of researchers Paul KalasAn astronomer at the University of California, Berkeley, described these two collision events in devastating detail to help solve the mystery of the planet.
In the early 2000s, astronomers observing the Fomalhaut system discovered a large, bright object that many assumed was a dust-covered exoplanet reflecting light. They called this exoplanet candidate Fomalhaut b.
But even when it is considered The existence of the planet came out And as another bright point of light appeared nearby, about 20 years later, researchers realized they weren’t looking at planets, but clouds of glowing debris they called “cosmic fender benders.”
An artist’s illustration tracks the formation of the dust cloud CS2 around the star Fomalhaut. In panel 1, the star appears in the upper left corner while the two white dots in the lower right corner represent larger objects about to collide. In panel 2, the objects approach each other. In panel 3, they collide. In panel 4, the dust cloud CS2 is visible and the starlight pushes the dust grains away. | Credit: NASA, ESA, STScI, Ralf Crawford (STScI)
Fomalhaut Forensics: A History of Catastrophic Accidents
The two collision events, now called Fomalhaut cs1 and Fomalhaut cs2, seem incredibly serendipitous. Theory suggests that collisions of this size should occur only once every 100,000 years, but the Fomalhaut system surprised scientists with two such smash-ups in just 20 years.
In fact, based on this timeline, the study estimates that 22 million similar events may have occurred so far in the Fomalhaut system’s relatively young, 440-million-year life. Even if one could only rewind the past 3,000 years, “Fomalhout’s planetary system would be sparkling with these collisions,” Callas explained in one. statement.
Reverse engineering the collisions based on factors such as the mass of the debris cloud and the size of the dust grains suggests that Fomalhaut cs1 and cs2 were the result of collisions with planets around 37 miles (60 km) in diameter, or four to six times the size of the asteroid. Non-avian dinosaurs 66 million years ago.
It’s an exotic phenomenon with a relevant twist: “These large bodies are similar to the large bodies that surround our own asteroids and Kuiper Belts“Study co-author Jason Wangan astronomer at Northwestern University told Live Science via email.
And there are many of these bodies. Based on their reconstruction of the event, the researchers suggest that the Fomalhaut system could host 1.8 Earth masses of these primitive planets. It may be around 300 million such bodies according to a separate statement.
Furthermore, the system holds another 1.8 Earth masses in smaller bodies measuring less than 0.186 miles (0.3 km). These relativistic races continuously fill tiny dust grains, most a few 10,000ths of an inch in size, that swirl and shine in Fomalhaut’s dust belt. Without this rocky reservoir, the dust belt would disappear as its grains are blown out of the system by the stellar wind or engulfed by its star.
Illustration of a violent collision between two planets orbiting Fomalhaut. | Credit: NASA, ESA, STScI, Ralf Crawford (STScI)
A planet that never was, may still be
Although Fomalhaut b no longer exists—as a planet, at least—it “The planet that never was“There may actually still be hidden within the system.
The researchers calculated that, given the particular circumstances, there is about a 10% chance that Fomalhaut cs1 and cs2 are not random collisions. Their similar timing and location may indicate a hidden influence, such as a ghostly gravitational pull of the invisible. exoplanet.
“For example, something — like the planets — must be responsible for carving planets into the dust belts we see,” Wang told LiveScience. “Additionally, we speculate that the proximity in location of the cs1 and cs2 impact sites may be driven by a planet that preferentially collides with planets there.”
Playing planetary peek-a-boo
This exoplanetary illusion highlights an important consideration for planet-hunters and next-generation facilities. NASA’s Observatory for Habitable Worlds which is designed to directly image habitable-zone exoplanets in the nearby Universe: “Fomalhaut cs2 looks exactly like an extrasolar planet reflecting light from a star,” Callas explained.
As a result, this unique study will not only inform our ideas about planetary composition, such as collision rates and debris belt mechanics, but it may help astronomers more accurately identify planetary bodies among all the other bright astronomical objects the universe constantly dazzles us with.
