3I/ATLAS's Coma Proves Another Cometary Formation Theory

Universe Today ^ | October 06, 2025 | Andy Tomaswick

[SunkenCiv]

...Scientists have been keeping a close watch on those changes, both to ensure there’s nothing unexplainable by our current understanding, but also to compare 3I/ATLAS to both previous interstellar visitors as well as comets in our own solar system. A recent paper from European researchers describes how the changes in a particular material ratio in 3I/ATLAS’ coma fit with our current understanding of cometary geology.

That ratio is the nickel to iron (Ni/FE) abundance ratio. It has been measured for two decades, including on twenty in-system comets as well as 2I/Borisov, the last known interstellar visitor our solar system had. However, the fact that either of those materials is even present at all in the coma has puzzled scientists, as the temperatures on their surfaces typically aren’t enough to sublimate the silicates or sulfides that are thought to hold these metals on cometary surfaces.

The Ni/Fe ratio from studying 2I/Borisov were similar to those of in-system comets. But that ratio is also about 10 times higher than the Ni/Fe of the Sun itself. So the fact that one of our interstellar visitors and our in-system comets had the same high ratio pointed to some common process in cometary formation that was agnostic to the materials available in the star it formed around...

They noted that the spectral absorption line for nickel captured by the VLT’s UV-Visual Echelle Spectrograph (UVES) was present the entire time. However, the absorption lines for iron only appeared once 3I/ATLAS got within 2.64 AU of the Sun. This discrepancy caused a Ni/Fe ratio much higher than those seen in previous comets, but it was actively changing dramatically as 3I/ATLAS got closer to the Sun. No other study had shown that much of a dramatic change.

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TOPICS: Astronomy; Science
KEYWORDS: 3eyedatlas; 3iatlas; andytomaswick; astronomy; comet; comets; frasercain; iron; ironsun; nickel; physics; science; xplanets

[SunkenCiv]

Iron Appears on 3I/ATLAS // Starship Flight 11 
// DNA Could Survive on Mars | 20:05 

• Fraser Cain | 478K subscribers | 8,458 views | October 17, 2025

[SunkenCiv]

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Google news searches: exoplanet · exosolar · extrasolar ·

[SunkenCiv]

The rest of the 'iron sun' keyword, sorted:

• Violent Past: Young sun withstood a supernova blast [10/27/2013]
• Pole flips tied to plate tectonics [11/26/2011]
• Messenger from Mercury: Orbiter returns images of odd landforms on innermost planet [11/26/2011]
• Astronomy Picture of the Day -- SDSS J102915+172927: A Star That Should Not Exist [09/07/2011]
• Solar Flare Activity Prompting NASA to Convene a News Briefing Thursday in Washington [08/18/2011]
• Evolved stars locked in fatalistic dance [07/14/2011]
• Really Hot Doin's Discovered on the Sun [01/10/2011]
• Study Peels Back More of the Magnetic Sun [03/12/2010]
• Eclipses yield first images of elusive iron line in the solar corona [01/04/2010]
• To Find New Planets, Look for the Lithium? [headline wrong -- s/b look for low lithium levels] [11/15/2009]
• Theory of the sun's role in formation of the solar system questioned [09/09/2008]
• The Surface Of The Sun [08/29/2008]
• Biggest stars produce strongest magnets [01/30/2005]
• Scientific maverick's theory on Earth's core up for a test [12/05/2004]
• Magnetic Stars [10/15/2004]
• Is Iron Causing All the Flares? [11/19/2003]
• The Sun: A Great Ball of Iron? [07/17/2002]

[Does so]

If space physicists had termed it “comma” instead of “coma”, wouldn’t everybody conjure the same image?

[roving]

NASA won’t release the high definition pictures. Their excuses? The government is shut down.

[MarlonRando]

I trust our government as far as I can throw it. These series of interstellar visitors are really terrible interesting. I love the fact that we know next to nothing about them. That’s the only way you learn. Pity we don’t have probes lying around to shoot at them.

[quantim]

"However, the fact that either of those materials is even present at all in the coma has puzzled scientists,"

Maybe this is just a writer and not an astrophysicist? Usually kids are taught the basics of the elementary table by 5th grade including Fe and Ni formed by supernovae. Also these two "materials" are not referred to as "elements" like it should be. Not nitpicking but it just reminded me of today's college byproducts. The nuns that taught me this in public school over 50 years ago left a mark LOL!

[Empire_of_Liberty]

These objects are as interstellar as Percival Lowell’s canals were made in Barsoom.

Fortunately, we still have the data for science’s emergence from the dark ages of Climate Change.

[SunkenCiv]

Oh yeah, *they* don’t want us to know the *truth*, such as the pictures from every non-US source.

[SunkenCiv]

Comma chameleon?

[PIF]

Images taken before the official discovery indicate it is 12-14 miles in diameter and is more likely an asteroid than a comet.

Two news reports: one from August 24th and the other from May/June.

August 24th
Modern Keck Twin 2 10 meter telescope in Hawaii took these images [ it made the first direct image of a planetary system in orbit around another star.

Images of 3I taken on Aug 24 2025 - at a distance of 2.5-2.6AU. Hubble took an image a month before this if the object, KCWI with wavelength range of .3425 to 0.55 micrometers to get a spectrographic analysis of what king of materials are in the coma. The anti-tail is still present in the Keck image a month after the Hubble image

The authors reasoned that the nickel tetracarbonyl took place naturally, but no explanation on how. The ratio of nickel to cyanide showed a central concentration of nickel relative to cyanide, indicating a possible direct relationship between the two. Cyanide is related to living organisms, while nickel is treated to industrial processes. Why is that found here?

The Keck detected the plume of nickel out to an exponential radius of 600 km and 849 km for cyanide. They found the trace loss mass for 3.9 grams/sec cyanide and 0.9 grams/sec for nickel. This shows how precise the Keck is to detect that little metal escaping form an object thousands of kilometers away out of a total mass loss of 150 kilograms/sec: 87% of CO2, 9% of CO, and 4% H2O.

Recently before 3I disappeared behind the Sun, a huge gush of water was emitted, but the gush had no effect on 3I’s speed or trajectory. A never before seen action by any comet ever. Meanwhile, the coma remains in front of the object, even though the sun and solar wind are quite active recently, and despite being hit by a CME.

May/June 2025
In the research notes of a separate study of the American Astronomical Society, stated that in the data from NASA’s Transiting Exoplanet Survey Satellite TESS observatory on May/June 2025 observations. More than 9,000 TESS images where analyzed by stacking them into composite frames to search for any signs of a coma.

Why they found was that 3I’s profile was almost identical to four different ASTROIDS with no coma detected. 3I’s profile is slightly below the 4 astroids’ profile, but still remained bright, indicating it might be 12-14 km in diameter. The team suggested the material being ejected was as low as 10 meters/second which would account for the forward facing coma. This is a reach, but they are trying to find some sort of explanation for the absence of a coma.

But all in all, the object more closely resembles the 4 astroids, but not a comet.

We should wait for more information before declaring it a comet when it has so many un-comet like features. If it is an interstellar astroid, why not call it that? What is the fixation on calling it a comet, when it does not look like a comet?

The Juno probe stands the best chance of getting a detailed look at the object. Perhaps the most unscientific thing anyone an do is to leap to conclusions before getting more detailed information.

References on request.