effective temperature


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effective temperature

Symbol T eff, T e. The surface temperature of a star, expressed as the temperature of a black body (i.e. a perfect radiator) having the same radius as the star and radiating the same total amount of energy (E) per unit area per second. A star is thus being considered a black body and its effective temperature is thus given by Stefan's law:
T eff 4 = E /σ = L /4πR 2

σ is Stefan's constant and L and R are the star's luminosity and radius. Although accurate determinations of effective temperature are difficult, each spectral type has a characteristic range of T eff; the total range is from about 2500 to over 40 000 kelvin. The Sun's effective temperature is 5770 K. The effective temperature is the best measure of the actual temperature of the gas in a star's outer layers.

Radiation temperature, T r, is equivalent to the effective temperature measured not over the whole spectral range but over a narrow portion of the spectrum, for example at visible wavelengths, which gives the optical temperature.

effective temperature

[ə¦fek·tiv ′tem·prə·chər]
(astrophysics)
A measure of the temperature of a star, deduced by means of the Stefan-Boltzmann law, from the total energy that is emitted per unit area.
(meteorology)
The temperature at which motionless, saturated air would induce, in a sedentary worker wearing ordinary indoor clothing, the same sensation of comfort as that induced by the actual conditions of temperature, humidity, and air movement.
(statistical mechanics)
That temperature which can be inserted in the Boltzmann distribution formula to describe the relative populations of two energy levels which may or may not be in thermal equilibrium.

effective temperature

An index which combines into a single figure the effects of temperature, humidity, and air movement on the sensation of warmth or cold felt by the human body; numerically equal to the temperature of still, saturated air which induces an identical sensation.
References in periodicals archive ?
However, all the 95% confidence intervals of the differences between any 2 sums of effective temperatures do not include 0.
Further evidence that the decline in deaths is infrastructural is given in newer, southern cities, which have no mortality excursions at high effective temperature.
In air conditioned buildings, this reduction in effective temperature via HVLS fans also means lower building operating costs, since thermostats can be set higher without a loss of comfort.
The relationship between the effective temperature of a black body and its apparent colour to the eye has been calculated (8) and is illustrated in Figure 7.
Analysing the new observations, the team was then able to measure the mass of the planet, around 7 to 11 times the mass of Jupiter, and its effective temperature, between 1100 and 1700 Degrees C.
Among these stages, the equilibrium state refers to the state when the real temperature reaches the room temperature and effective temperature does not change any more.
The study is not only an indicator of sentiment in a relationship often muddled with mixed signals and misunderstandings, but an effective temperature gauge," Brain said.
Also make sure the thermocouple is placed close enough to the nozzle tip to provide effective temperature control.
The rubber injection molding unit features a screw with special intake toothing and compression zone, a plasticizing cylinder with intake pocket and effective temperature regulation, high injection pressure which continues into the mold without mentionable pressure loss due to the nozzle design, back pressure control and controlled temperature in the intake zone, according to the literature.

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