Astrophysics (Index)About

surface temperature

(temperature of the surface of a star or planet)

The term surface temperature is used in astronomy for stars an planets.

In the case of stars, the effective temperature is generally used/quoted as the surface temperature. In fact, the exact location of the surface of a star is located is unclear as the star is gas or plasma and beyond the star is additional gas/plasma. The surface is generally taken as what appears to us to be the outside of the star, i.e., that part which produces the light we see, a layer of the star called the photosphere. As opposed to the center or deeper regions of the star, the photosphere is the portion whose temperature determines the spectrum and therefore color of the star. The photosphere has a some depth and the emerging light comes from a range of depths at a range of temperatures. The effective temperature is a relatively easy-to-determine quantity used to approximate this temperature range. Spectral lines, whose form and magnitude depend on temperature, can be used to determine more accurately the photosphere's temperature at different depths.

For planets, the surface temperature is more defined, especially for rocky planets. The reflection of electromagnetic radiation affects observed spectrum, such that the effective temperature is not such a good indicator of surface temperature. The spectrum must be further-analyzed, presuming there is a black body contribution from the solid surface and the atmosphere produces temperature-dependent spectral signatures such as absorption lines. Another issue is that the surface temperature of a planet invariably varies over its surface. A mean surface temperature is of interest. Such surface temperatures can also vary over the course of the planet's orbit. The planet's calculated equilibrium temperature is often taken as an approximation.


(stars,planets,temperature)
Further reading:
https://en.wikipedia.org/wiki/Photosphere
https://en.wikipedia.org/wiki/Effective_temperature
https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature
https://ui.adsabs.harvard.edu/abs/2015AGUFM.P33B2130W/abstract
https://earthobservatory.nasa.gov/global-maps/MOD_LSTD_M

Referenced by pages:
A-type star (A)
B-type star (B)
color index
data cube
Earth
effective temperature (Teff)
equilibrium temperature (Teq)
exotic star
F-type star (F)
G-type star (G)
greenhouse effect
HD 209458 b
K-type star (K)
kelvin (K)
L-type star (L)
M-type star (M)
Mars
O-type star (O)
O5 spectral type (O5)
red clump (RC)
red dwarf
stellar temperature determination
temperature
Venus
white dwarf (WD)
Wilson-Bappu effect
Y-type star (Y)

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