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Internal heat is the heat source from the interior of celestial objects, such as stars, brown dwarfs, planets, moons, dwarf planets, and (in the early history of the Solar System) even asteroids such as Vesta, resulting from contraction caused by gravity (the Kelvin–Helmholtz mechanism), nuclear fusion, tidal heating, core solidification (heat of fusion released as molten core material ...
By selectively radiating heat in the infrared atmospheric window, a range of frequencies in which the atmosphere is unusually transparent, an object can effectively use outer space as a heat sink, and cool to well below ambient air temperature. [40] [41] [42]
The molar heat capacity is the heat capacity per unit amount (SI unit: mole) of a pure substance, and the specific heat capacity, often called simply specific heat, is the heat capacity per unit mass of a material. Heat capacity is a physical property of a substance, which means that it depends on the state and properties of the substance under ...
Passive daytime radiative cooling uses a material that fluoresces in the infrared atmospheric window, a frequency range where the atmosphere is unusually transparent, so that the energy goes straight out to space. This can cool the heat-fluorescent object to below ambient air temperature, even in full sun. [14] [15] [16]
Primordial heat is the heat lost by the Earth as it continues to cool from its original formation, and this is in contrast to its still actively-produced radiogenic heat. The Earth core's heat flow—heat leaving the core and flowing into the overlying mantle—is thought to be due to primordial heat, and is estimated at 5–15 TW. [23]
Earth's atmosphere is partly transparent to visible light, and the light reaching the surface is absorbed or reflected. Earth's surface emits the absorbed radiation, approximating the behavior of a black body at 300 K with spectral peak at f max. At these lower frequencies, the atmosphere is largely opaque and radiation from Earth's surface is ...
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
The law was formulated by Josef Stefan in 1879 and later derived by Ludwig Boltzmann. The formula E = σT 4 is given, where E is the radiant heat emitted from a unit of area per unit time, T is the absolute temperature, and σ = 5.670 367 × 10 −8 W·m −2 ⋅K −4 is the Stefan–Boltzmann constant. [28]