Talk:Solar luminosity

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I don't understand

12×10¹²/1387/0.33.

Does it mean

(12×10¹²/1387)/0.33

or

12×10¹²/(1387/0.33)

or something else? Michael Hardy 19:08, 5 Sep 2004 (UTC)

Reference?

The following reference:

Sackmann, I.-Juliana; Boothroyd, Arnold I; Kraemer, Kathleen E. (1993). "Our Sun. III. Present and Future". Astrophysical Journal. 418: 457–468. Retrieved 2008-03-19.

lists the solar luminosity as 3.854×10³³ erg s^-1, which doesn't match the value on this page.—RJH (talk) 23:00, 19 March 2008 (UTC)[reply]

Value of luminosity

I changed it because a 2007 publication lists it at the 3.839 value —Preceding unsigned comment added by 69.38.230.2 (talk) 04:22, 15 April 2008 (UTC)[reply]

Reference

I tried to cite it... this is my first ever edit, sorry! 69.38.230.2 (talk) —Preceding comment was added at 04:25, 15 April 2008 (UTC)[reply]

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The number of photons

In the article, it says, "This does not include the solar neutrino luminosity, which would add 0.023 L☉, or 8.8×1024 W, i.e. a total of 3.916×1026 W (the mean energy of the solar photons is 26 MeV and that of the solar neutrinos 0.59 MeV, i.e. 2.27%; the Sun emits 9.2×1037 photons and as many neutrinos each second, of which 6.5×1014 per m2 reach the Earth each second)."

This is inconsistent. The part that talks of "and as many neutrinos" is talking about the photons emitted in the core from the fusion reactions (gamma rays). However, the part that talks of "reaching the earth" is clearly talking about the much lower energy photons that escape the sun's surface (mainly visible and infrared light). 2601:45:500:5BA0:AC1E:79F8:C908:120D (talk) 20:56, 29 December 2022 (UTC)[reply]

Average solar photon energy??

The article says "The mean energy of the solar photons is 26 MeV." That works out from the numbers given: 3.828×10^26 W ÷ 9.2×10^37 photons/s = 4.1609x10^-12 J/photon. Result ÷ 1.602176634x10^-19 J/ev = 2.597x10^7 eV/photon. ☑

But that seems way too high. (I assume this average includes only photons actually leaving the Sun, given the article title "Solar luminosity".)

Other sources give very different numbers (derived differently). I searched Google Books for "average energy" "solar photon":

"The average energy of one solar photon is about T_S ÷ T_E = 6000K ÷ 288K = 20.83 times larger than average energy of one thermal [infrared] photon [emitted by] Earth." The Wien approximation says the peak emission is at 2898 μm⋅K ÷ T. Applying that gives Earth: 2898000 nm⋅K ÷ 288K = 10062nm (10.062µm) [0.1232eV] (infrared). Sun: 2898000 nm⋅K ÷ 6000K = 483nm [2.567eV] (cyan).

"The average energy of a solar photon may be taken to be that of green light of wavelength 550 nm." [2.25eV]

"... we obtain the average energy carried by one solar photon 1.45 eV." [855nm] (infrared). (This is from a book on photovoltaic cells, so they are probably looking at the arriving solar photons, with UV and gamma naturally filtered out.)

Some might confuse mean energy with energy of the peak emission. But the difference (a factor of 10^7) seems irreconcilable. The number of watts emitted must be too large, and/or the number of photons/s emitted must be too small. -A876 (talk) 04:50, 17 April 2023 (UTC)[reply]

The solar luminosity is the radiation leaving the surface of the sun. The 26 Mev is the energy released in the solar core by one method of combining 4 protons into one helium nucleus, and is not a single gamma ray. That energy is reabsorbed and remitted as well as transported by convection for about 100,00 years before it reaches the sun and leaves the surface. So not relevant for this article. I am removing it. StarryGrandma (talk) 06:15, 17 April 2023 (UTC)[reply]