# High carbon and nitrogen isotope ratios in CN

> VLT spectra of CN give 12C/13C of 151 and 14N/15N of 363, both high for a comet, though the 3-sigma ranges are wide.

Source: https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ3T4VZPQZ/high-carbon-and-nitrogen-isotope-ratios-in-cn  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[3I/ATLAS](https://mysteriesdept.com/mysteries/3i-atlas)Evidence

Evidence · 3I/ATLAS

# High carbon and nitrogen isotope ratios in CN

VLT spectra of CN give 12C/13C of 151 and 14N/15N of 363, both high for a comet, though the 3-sigma ranges are wide.

Suggestive0

## What it means

Key question[What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0HS0K7SD/what-is-3i-atlas-made-of-and-why-is-its-chemistry-so-unlike)

No answer ahead yet

**Open** unchanged

Answer this evidence bears on[An icy body from a cold, metal-poor disc around an old star](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ178MEYWB/an-icy-body-from-a-cold-metal-poor-disc-around-an-old-star)

Supports6 for, none against

**Still possible** unchanged

What it implies
1.

Carbon and nitrogen also point to a birthplace unlike the young Solar System.For the key question: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?

## Next steps 2

1

Compare gas lost with crust depth

Could shiftFair odds~20 h

[On: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0HS0K7SD/what-is-3i-atlas-made-of-and-why-is-its-chemistry-so-unlike)

**11** score

Details

Use the compiled production rates (Frincke and Seligman's table) to date when more than 20 m of surface had gone, and check whether the composition changed then. A change at that point favours the crust; a change well before or after weakens it.

2

Test whether a cosmic-ray crust can raise D/H to 1 per cent

Could shiftFair odds~30 h

[On: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0HS0K7SD/what-is-3i-atlas-made-of-and-why-is-its-chemistry-so-unlike)

**8** score

Details

Run the cosmic-ray processing model forward to predict how much a 20-m processed crust changes water D/H and 12C/13C. If processing cannot reach the measured ratios, the birthplace reading is strengthened; if it can, the isotopes no longer date the body.

Ranked by how likely each is to move the key question, for the time it takes

## Sources 2

[High nitrogen and carbon isotopic ratios in the interstellar comet 3I/ATLAS](https://mysteriesdept.com/sources/SRC0DFPWGSFTSQF/high-nitrogen-and-carbon-isotopic-ratios-in-the-interstellar)

Opitom et al. 2026

SRC

[Older than the Sun: Astronomers find new clues to the origin of interstellar comet 3I/ATLAS](https://mysteriesdept.com/sources/SRC0DFPZ6F4QJ60/older-than-the-sun-astronomers-find-new-clues-to-the-origin)

ESO 2026

SRC

## Cite it

```
Mysteries Department. (2026). High carbon and nitrogen isotope ratios in CN [Evidence EVD0DFQ3T4VZPQZ]. https://mysteriesdept.com/r/EVD0DFQ3T4VZPQZ
```

Key

**EVD** 0DFQ3T4VZPQZ

Kind

Evidence

Tier

Suggestive

Found in

[Session 1](https://mysteriesdept.com/mysteries/3i-atlas/sessions/SES0DFQC03S98K5/session-1-3i-atlas-opened-the-literature-to-november-2026) · 2 Nov 2026

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