Mysterious interstellar object 3I/ATLAS has come and — mostly — gone.
Scientists have been fascinated by the intriguing lump of ice and dust as it careened into the inner solar system last year, making its closest pass of the Sun in the fall and careening by the Earth on its way out. In the upcoming weeks, it’s expected to have a close encounter with Jupiter before it leaves our star system for good.
Meanwhile, researchers are continuing to pore over the wealth of data gathered by ground- and space-based telescopes about the rare visitor, which was only the third interstellar object to be spotted passing through our solar system.
As detailed in a new paper published in The Astrophysical Journal Letters, an international team of researchers including NASA scientists examined observations of the object made with the Atacama Large Millimeter/submillimeter Array (ALMA) between August and October, the months leading up to its closest pass of the Sun, or perihelion. That’s the point when comets, including 3I/ATLAS, become most active and release the most gas and dust as they’re heated up by solar radiation.
They found that 3I/ATLAS was teeming with an unusually large amount of methanol, a type of alcohol, exceeding almost all known comets in our solar system.
“Observing 3I/ATLAS is like taking a fingerprint from another solar system,” said lead author and American University physics assistant professor Nathan Roth in a statement. “The details reveal what it’s made of, and it’s bursting with methanol in a way we just don’t usually see in comets in our own solar system.”
That makes any residue left behind by the comet a particularly poor choice for a drink after a long day at work, since while methanol can get you drunk, it also causes a raft of disturbing health effects ranging from dizziness and agitation to vision loss and bloody urine to liver dysfunction and death.
The ALMA telescope analyzed the comet’s coma, or the glowing halo around its core, revealing the chemical fingerprints found within it. The researchers honed in on two molecules specifically: methanol and hydrogen cyanide, a commonly found organic molecule in comets. They measured the methanol-to-hydrogen cyanide ratio of 3I/ATLAS and found that it was among the highest of any comets ever studied.
That means 3I/ATLAS experienced very different conditions than the more familiar ones in the solar system. Other observations of the interstellar object have also found that its coma was dominated by carbon dioxide ice when it was much further from the Sun, adding to the mystery.
The authors of the latest paper also determined that the methanol was emanating from both the comet’s core and coma, yet another intriguing piece of the interstellar puzzle.
For now, scientists will have to content themselves with a treasure chest of data from an extremely rare glimpse of a distant star system. Fortunately, more powerful space telescopes could soon allow us to discover even more interstellar objects cruising through our solar system, which could help explain 3I/ATLAS’ unusual chemical makeup.
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