{"product_id":"sanguora-pixel-hoodie","title":"Sanguora – The Forbidden [O I] 630.0 nm Red Aurora Line Pixel Hoodie","description":"\u003cp\u003eSanguora, a tall oracle on a high spire, trails a slow red veil of light far above a thin band of green aurora.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eAtomic oxygen’s red auroral doublet at 630.0 nm and 636.4 nm is the forbidden ¹D₂ → ³P transition (to ³P₂ for 630.0 nm and ³P₁ for 636.4 nm), mainly magnetic dipole. The ¹D₂ level lives about 110 s, around 150 times longer than the green line’s upper level. Collisions therefore quench it everywhere below roughly 200 km, and the red aurora shines only from the thinnest high air. ¹D₂ is also the lower level of the 557.7 nm green line, so each green photon leaves an atom ready to emit red.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eτ(¹D₂) ≈ 110 s\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eI\u003csub\u003e630\u003c\/sub\u003e ∝ P(¹D₂) · A\u003csub\u003e630\u003c\/sub\u003e \/ (A\u003csub\u003etot\u003c\/sub\u003e + k\u003csub\u003eq\u003c\/sub\u003e[M])\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eτ: radiative lifetime of ¹D₂ (s)\u003c\/li\u003e\n\u003cli\u003eI\u003csub\u003e630\u003c\/sub\u003e: 630.0 nm emission rate per unit volume (photons m⁻³ s⁻¹)\u003c\/li\u003e\n\u003cli\u003eP(¹D₂): production rate of ¹D₂ atoms (m⁻³ s⁻¹)\u003c\/li\u003e\n\u003cli\u003eA\u003csub\u003e630\u003c\/sub\u003e: Einstein coefficient of the 630.0 nm branch (s⁻¹)\u003c\/li\u003e\n\u003cli\u003eA\u003csub\u003etot\u003c\/sub\u003e: total radiative decay rate of ¹D₂, = 1\/τ (s⁻¹)\u003c\/li\u003e\n\u003cli\u003ek\u003csub\u003eq\u003c\/sub\u003e[M]: collisional quenching rate per atom (s⁻¹)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eSources: \u003cem\u003eAstron. \u0026amp; Geophys.\u003c\/em\u003e 47, 1.11 (2006), doi:10.1111\/j.1468-4004.2006.47111.x; Stoffregen \u0026amp; Derblom, “Life-time of the atomic oxygen 6300 Å line”, \u003cem\u003eNature\u003c\/em\u003e 185, 28 (1960), doi:10.1038\/185028a0.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The green cascade is not the only source of ¹D₂: slow electrons and chemical reactions populate it directly. “Above about 200 km” is approximate and varies with solar activity.\u003c\/p\u003e\u003cp\u003eThe glow is the approximate line colour: a pure spectral colour lies outside the sRGB range a print can show.\u003c\/p\u003e\u003ch3\u003eIn character\u003c\/h3\u003e\u003cp\u003e\u003cem\u003eDown there the air is loud. Up here I have a hundred and ten seconds of silence, and I spend every one of them on red.\u003c\/em\u003e\u003c\/p\u003e\u003ch3\u003eOn the hoodie\u003c\/h3\u003e\u003cp\u003eFront: a red veil curl over a ¹D→³P ladder. Back: Sanguora in full pixel art with “FORBIDDEN. OBSERVED ANYWAY.” and “110 SECONDS, OR NOTHING.” Gildan 18500 Heavy Blend hoodie, Black, S to 5XL.\u003c\/p\u003e\u003cp\u003ePart of the \u003cstrong\u003eForbidden Transitions\u003c\/strong\u003e set with \u003ca href=\"\/hi\/products\/nebulia-pixel-hoodie\"\u003eNebulia\u003c\/a\u003e, \u003ca href=\"\/hi\/products\/coronix-pixel-hoodie\"\u003eCoronix\u003c\/a\u003e, \u003ca href=\"\/hi\/products\/flipwarden-pixel-hoodie\"\u003eFlipwarden\u003c\/a\u003e, \u003ca href=\"\/hi\/products\/viridael-pixel-hoodie\"\u003eViridael\u003c\/a\u003e, \u003ca href=\"\/hi\/products\/sulphra-pixel-hoodie\"\u003eSulphra\u003c\/a\u003e. Browse all \u003ca href=\"\/hi\/collections\/hoodies\"\u003ephysics hoodies\u003c\/a\u003e, more \u003ca href=\"\/hi\/collections\/astrophysics\"\u003eastrophysics \u0026amp; cosmology designs\u003c\/a\u003e, or the \u003ca href=\"\/hi\/collections\/deep-cuts\"\u003eDeep Cuts\u003c\/a\u003e.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"Black \/ S","offer_id":50964466434151,"sku":"31589461466487302190","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ M","offer_id":50964466466919,"sku":"13976056328637914017","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ L","offer_id":50964466499687,"sku":"26675432088594547446","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ XL","offer_id":50964466532455,"sku":"11314529587195495811","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 2XL","offer_id":50964466565223,"sku":"29213941198584587947","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 3XL","offer_id":50964466597991,"sku":"33598749605627957709","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 4XL","offer_id":50964466630759,"sku":"13981346293377287018","price":64.99,"currency_code":"USD","in_stock":true},{"title":"Black \/ 5XL","offer_id":50964466663527,"sku":"94709181752167870614","price":64.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/03_H15.png?v=1793678396","url":"https:\/\/pixelatedphysics.com\/hi\/products\/sanguora-pixel-hoodie","provider":"Pixelated Physics","version":"1.0","type":"link"}