Coronix: Forbidden Fe XIV Coronal Line
Cosmology & the Sky arc, page 150 of 193. Back to The Pixelated Physics Universe
Who they are
Coronix, a knight in blackened iron, wears a crown of 13 broken spikes against an eclipsed Sun, each tip burning coronal green.
Coronix is a character of the Cosmology & the Sky arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
The green coronal line at 530.3 nm (5302.86 Å in air), seen at total eclipses, was blamed on an unknown element, “coronium”. Walter Grotrian (1939) matched the red 637.4 nm line to Fe X, and Bengt Edlén (announced 1941, full paper in Z. Astrophys. 22, 30, 1942) identified the green line as Fe XIV: iron with 13 of its 26 electrons stripped away, Fe¹³⁺. The transition is the magnetic-dipole decay ²P°3/2 → ²P°1/2 inside the 3s²3p ground term, a fine-structure flip that an electric dipole cannot drive.Fe + 13 ionisations → Fe¹³⁺ (Fe XIV)χ(Fe¹²⁺ → Fe¹³⁺) ≈ 361 eV ≫ kBTphotosphere ≈ 0.5 eV Fe XIV: spectroscopic notation for the ion with 13 electrons removed (Roman numeral = charge + 1) χ: ionisation energy needed to remove the 13th electron (eV) kB: Boltzmann constant, 1.380 649 × 10⁻²³ J K⁻¹ (exact) Tphotosphere: temperature of the visible solar surface, about 5800 K Making Fe¹³⁺ in collisional equilibrium needs electron temperatures of about a million kelvin or more, so the identification proved the corona is far hotter than the surface below it.
No single equation is shown for this character; the physics above is stated in words because it is an observation or a piece of history, and we do not invent formulas.
Honest caveat: Why the corona is so hot (the coronal heating problem) is still unsolved; wave heating and many small reconnection events (“nanoflares”) are both studied. The ionisation-energy figure is from the NIST database and rounded.The glow is the approximate line colour: a pure spectral colour lies outside the sRGB range a print can show.In characterThirteen spikes, thirteen electrons surrendered to a million-kelvin crown. They named me coronium. I am iron that refused to stay cool.
Status: part of this topic is unsolved, unconfirmed or debated. The text above says which part; treat it as an open question, not settled fact.
Crossovers
Coronix meets Alfvena (Alfvén Waves). Alfvena's waves run along magnetic field lines in the solar corona. Coronix's green line shows the corona is above a million kelvin. Wave heating is one candidate for keeping it that hot, and the question is unsolved.
Coronix meets Viridael (Forbidden [O I] 557.7 nm Green Aurora Line). Coronix and Viridael both glow green with forbidden lines. Coronix's comes from highly ionised iron in the million-kelvin corona; Viridael's comes from neutral oxygen in Earth's upper atmosphere.
Wear the lore
Concept keywords: Forbidden Fe XIV Coronal Line, Coronix, Cosmology & the Sky, physics lore, Pixelated Physics