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Why did nickel vapour appear around 3I/ATLAS without iron, so far from the Sun?

Asked 2 Nov 2026 by ·Part of What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?·2 answers·0·0 following
Two answers, none aheadNone 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

Evidence: 1 for
Still possible
Evidence: 2 for
Still possible

History

  1. Rahatgaonkar et al.: nickel from 3.1 au, iron only inside 2.6 auFor: Metal carbonyls sublimating from the nucleus
  2. Hutsemékers et al.: nickel from 3.1 au, iron only inside 2.6 auFor: Metal carbonyls sublimating from the nucleus
  3. Hoogendam et al.: nickel from 3.1 au, iron only inside 2.6 auFor: Metal carbonyls sublimating from the nucleus
  4. Hutsemékers et al.: after perihelion the metals follow COFor: Metal carbonyls sublimating from the nucleus
  5. Zhao et al.: after perihelion the metals follow COFor: Metal carbonyls sublimating from the nucleus
  6. Protopapa et al.: carbonyls alone miss the early nickel excessFor: A short-lived heat source released the early nickel
  7. Hutsemékers et al.: carbonyls alone miss the early nickel excessFor: A short-lived heat source released the early nickel
  8. Session 1: raised the question, proposed two answers and found three results bearing on its answers
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