In astronomy, luminosity is the total amount of energy emitted per unit of time by a star, galaxy, or other astronomical object. As a term for energy emitted per unit time, luminosity is synonymous with power.. In SI units luminosity is measured in joules per second or watts.Values for luminosity are often given in the terms of the luminosity of the Sun, L ⊙.
Stars can also change in luminosity over time. The North Star or Polaris, for example, could have been as much as 4.6 times brighter in ancient times than it was today. A 2014 study noted that the ...
The luminosity of any star is the product of the radius squared times the surface temperature raised to the fourth power. Given a star whose radius is 3 solar and a surface temperature that’s 2 ...
In astronomy, luminosity is the total amount of energy emitted by a star, galaxy, or other astronomical object per unit time. It is related to brightness, which is the luminosity of an object in a given spectral region. It has been shown that the luminosity of a star (assuming the star is a black body, which is a good approximation) is also related to temperature and radius of the star by the ...
Thus if a star is twice is luminous as the Sun, L * /L sol = 2. This approach is convenient as the luminosity of stars varies over a huge range from less than 10-4 to about 10 6 times that of the Sun so an order of magnitude ratio is often sufficient. What Determines a Star's Luminosity?
What is luminosity? Luminosity is a measure of the energy radiated by an object, for example a star or a galaxy. For the stars of the main sequence, luminosity is directly related to their temperature - the hotter a star is, the more luminous it is. On the other hand, cooler stars emit less energy - hence, it's more difficult to spot them in the night sky.
Luminosity is the total energy that a star produces in one second. It depends on both the radius of the star and on its surface temperature. One can calculate luminosity by finding the product of 1) how much energy each section of the surface of a star is producing (σ T 4, the Stefan-Boltzmann Law) and 2) the entire surface area of the star (4π R 2).
The luminosity that matters when it comes to understanding what's powering an object, from stars to quasars, is the intrinsic luminosity. That's a measure of the amount of energy it actually emits in all directions each second regardless of where it lies in the universe.
The luminosity of a star, on the other hand, is the amount of light it emits from its surface. The difference between luminosity and apparent brightness depends on distance. Another way to look at these quantities is that the luminosity is an intrinsic property of the star, which means that everyone who has some means of measuring the ...