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 ?
To get a better understanding of how the thermal stresses and birefringence are built up, the evolution of the actual and effective temperatures during quenching of PS-PC-PS slab in 25[degrees]C water from the initial temperature of 170[degrees]C was investigated (Fig.
This effective temperature is related to the actual temperature through
The motion of magnetic and abrasive particles in the current magnetorheological polishing fluid between the surface of polished workpiece and polishing tool is considered as the flow of their mixtures in local equilibrium with the same effective temperatures, depending on the flow rate.
The head scientist assigned to the project, Rob Thompson, stated that they "aim to push effective temperatures down to 100 pico-Kelvin.
Tony Pacheco, Director of Quality and Aftermarket at Blue Giant said, If a facility doesn t have a HVAC system, our HVLS fans can act as a stand-alone cooling system, lowering effective temperatures by up to 8AF across the fan s coverage area .
From the effective temperatures we obtain spectral types F0 & K2, which are close to the estimates of Svechnikov & Kuznetsova, (3) F0 & G7IV.
Let t represent the lower developmental threshold, and let k represent the sum of effective temperatures required for completing a specified developmental stage.
It also addresses regulator concerns that effective temperatures for SCR operation are typically not achieved during startup or idling.
Products provide controlled flame-retardant and smoke-suppressant properties at various effective temperatures.
As per Tony Pacheco, director of quality and aftermarket for Blue Giant, If a facility doesn t have a HVAC system, our HVLS fans can act as a standalone cooling system, lowering effective temperatures by up to 8 degrees Fahrenheit across the fan s coverage area.
Converting these (V-R) colour indices to effective temperatures using the tables in reference 7, we find that the maximum and minimum effective temperatures of CQ Boo during a pulsation cycle are ~9000K and ~7700K, hence their ratio is ~1.

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