Created By : awnish

Reviewed By : Rajashekhar Valipishetty

Last Updated : Apr 10, 2023

Utilize the flexible and handy Luminosity Calculator tool to find the amount of energy emitted by the celestial bodies and how bright they appear from the earth. Simply give star radius, temperature to find the luminosity and distance from the earth to the star and hit the calculate button to get the apparent magnitude details in less time.

Choose a Calculation
Star radius(r):

Step by Step Process to Calculate Luminosity

Below given are the simple steps to find the sun luminosity. Follow these guiding principles to pbtain the result.

  • Check the radius and temperature of the star
  • Divide the star radius by the radius of the sun.
  • Divide the star temperature by the sun's temperature.
  • Find the square of both values and multiply them.
  • Multiply the result with the luminosity of the sun to get the output.

Luminosity Equation | Abosulte and Apparent Magnitude

Luminosity is the absolute measure of radiated electromagnetic power or the radiant power emitted by the light-emitting object. It depends on the object temperature and radius.

The luminosity formula is given as

L/LΓÿë = (R/RΓÿë)² * (T/TΓÿë)Γü┤


L is the luminosity of the star

LΓÿë is the luminosity of the sun and is equal to 3.828 x 1026 W

R is the star radius

RΓÿë is the radius of the sun and equal to 695700 km

T is the star temperature

TΓÿë is the temperature of the sun and it is 5778 K

Absolute magnitude is a way of finding luminosity. It uses a logarithm scale to calculate it

The formula of absolute magnitude is M = -2.5 x log10(L/L₀)


M is the absolute magnitude of the star

L₀ is the zero-point luminosity and its value is 3.0128 x 1028 W

Apparent magnitude is used to measure the brightness of stars when seen from Earth. Its equation is m = M - 5 + 5log10(D)


m is the apparent magnitude of the star

D is the distance between star and Earth


Question: Find the luminosity of a star having the radius 598250 km and temperature is 6500 K.


Given that,

Radius of the star R = 598250 km

temperature of the star T = 6500 K

The luminosity of star formula is L/LΓÿë = (R/RΓÿë)² * (T/TΓÿë)Γü┤

L/3.828 x 1026 = (598250/695700)² * (6500/5778)Γü┤

L = (0.85)² x (1.12)Γü┤ x 3.828 x 1026

= 1.18

Therefore, the luminosity of the star is 1.18 W.

Stay tuned to our website Physicscalc.Com to learn more physics concepts. Make use of these instant calculator tools to find the accurate answer easily in fraction of seconds.

FAQ's on Luminosity Calculator

1. How to use the luminosity formula?

The luminosity equation is used to measure the energy emitted by a body per unit time. It can be derived from the Stefan-Boltzmann law. The formula of luminosity is L/LΓÿë = (R/RΓÿë)² * (T/TΓÿë)Γü┤

2. How to find the luminosity of a star?

Divide the radius of the star by sun and temperature of star by sun. Square both the values and multiply it with the luminosity of the sun to get the star luminosity.

3. What is luminosity?

Luminosity is the total amount of energy produced by various celestial bodies per unit of time. The factors affecting the luminosity is the size of the star, temperature of the star. and It is measured in joules per second or watts.

4. Why measuring the luminosity of stars difficult?

Measuring the luminosity of stars is difficult because the distance of stars relative to Earth makes it difficult to measure the brightness.

5. What is the luminosity of the sun?

The sun's luminosity value is 3.828 x 1026 W.