3I/ATLASEvidence
Evidence · 3I/ATLAS
Models reproduce the water at low metallicity
Astrochemical models reproduce 3I's water D/H most readily at less than half the Sun's metallicity and densities near 10^4 per cubic centimetre, and a composition model places its host between [Fe/H] -0.8 and 0.0.
What it means
Key questionWhat is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?
No answer ahead yet
Openunchanged
Answer this evidence bears onAn icy body from a cold, metal-poor disc around an old star
Supports6 for, none against
Still possibleunchanged
What it implies
- A metal-poor host can produce the measured chemistry without exotic processes.For the key question: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?
- Metal-poor hosts are more common among older stars.For: Where in the Galaxy, and how long ago, did 3I/ATLAS form?
Next steps 2
1
Compare gas lost with crust depth
Could shiftFair odds~20 h
11score
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
8score
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
SRC
On the Compositions of Interstellar Objects
SRCHopkins et al. 2026
Cite it
Mysteries Department. (2026). Models reproduce the water at low metallicity [Evidence EVD0DFQ3TH6PKZY]. https://mysteriesdept.com/r/EVD0DFQ3TH6PKZY
@misc{mysteriesdept_evd0dfq3th6pkzy,
title = {Models reproduce the water at low metallicity},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DFQ3TH6PKZY},
url = {https://mysteriesdept.com/r/EVD0DFQ3TH6PKZY}
}