# Why did nickel vapour appear around 3I/ATLAS without iron, so far from the Sun? · 3I/ATLAS > Two answers have been proposed. None is ahead on the evidence yet. Two are still possible. Source: https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-11-02T15:40:14+00:00 --- **0** # Why did nickel vapour appear around 3I/ATLAS without iron, so far from the Sun? Asked 2 Nov 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·Part of [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)·2 answers·0·0 following **Two answers, none ahead** None is ahead yet. See what would settle it. ## Where it stands Two answers have been proposed. None is ahead on the evidence yet. Two are still possible. ## Why it matters Nickel atoms showed from 3.1 au with iron absent until 2.6 au, and the total metal output was ten times other comets'. Too cold for dust grains to boil off metals, so the carrier has to be something more volatile. ## Answers 2 [**A short-lived heat source released the early nickel** ](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ197S5Z8J/a-short-lived-heat-source-released-the-early-nickel) Evidence for it, no test yet Evidence: 1 for Still possible [**Metal carbonyls sublimating from the nucleus** ](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ187PJFP2/metal-carbonyls-sublimating-from-the-nucleus) Evidence for it, no test yet Evidence: 2 for Still possible ## History 1. 2025[Rahatgaonkar et al.: nickel from 3.1 au, iron only inside 2.6 au](https://mysteriesdept.com/sources/SRC0DFPWGSF1VED/very-large-telescope-observations-of-interstellar-comet-3i)For: Metal carbonyls sublimating from the nucleus 1. 2025[Hutsemékers et al.: nickel from 3.1 au, iron only inside 2.6 au](https://mysteriesdept.com/sources/SRC0DFPWGSFD45Q/pre-perihelion-evolution-of-the-nii-fei-abundance-ratio-in)For: Metal carbonyls sublimating from the nucleus 1. 2025[Hoogendam et al.: nickel from 3.1 au, iron only inside 2.6 au](https://mysteriesdept.com/sources/SRC0DFPWGSFD4B9/spatial-profiles-of-3i-atlas-cn-and-ni-outgassing-from-keck)For: Metal carbonyls sublimating from the nucleus 1. 2026[Hutsemékers et al.: after perihelion the metals follow CO](https://mysteriesdept.com/sources/SRC0DFPWGSFSQNQ/origin-and-evolution-of-nii-and-fei-in-the-coma-of-the)For: Metal carbonyls sublimating from the nucleus 1. 2026[Zhao et al.: after perihelion the metals follow CO](https://mysteriesdept.com/sources/SRC0DFPWGSFX1HR/post-perihelion-coma-composition-of-the-interstellar-comet)For: Metal carbonyls sublimating from the nucleus 1. 2026[Protopapa et al.: carbonyls alone miss the early nickel excess](https://mysteriesdept.com/sources/SRC0DFPWGSFRK24/jwst-reveals-refractory-rich-water-ice-in-interstellar-comet)For: A short-lived heat source released the early nickel 1. 2026[Hutsemékers et al.: carbonyls alone miss the early nickel excess](https://mysteriesdept.com/sources/SRC0DFPWGSFSQNQ/origin-and-evolution-of-nii-and-fei-in-the-coma-of-the)For: A short-lived heat source released the early nickel 1. Nov 2026[Session 1: raised the question, proposed two answers and found three results bearing on its answers](https://mysteriesdept.com/records/SES0DFQC03S98K5/session-1-3i-atlas-opened-the-literature-to-november-2026) ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/3i-atlas/questions/QST0DFQ0SJDC3TY/why-did-nickel-vapour-appear-around-3i-atlas-without-iron-so%23add-source) Where it fits 3I/ATLAS [**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)Key question · 2 answers, inconclusive [What kind of dust gives 3I/ATLAS its unusually deep negative polarisation?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0STJE1SH/what-kind-of-dust-gives-3i-atlas-its-unusually-deep-negative)Open · 1 answer, inconclusive **Why did nickel vapour appear around 3I/ATLAS without iron, so far from the Sun?** You're here · 2 answers, inconclusive [ Ask a question under this one ]