The main interest of this workshop is to see how we can get values for the Sun's luminosity and surface temperature, by using simple methods. The participants will share experiments in which the Sun's radiation is measured, leading to the value for the Sun's luminosity.
Again, for simplicity, let's figure out the luminosity for stars that have a higher and a lower surface temperature than that of our Sun, but with the same solar radius. If you know the surface temperature of any star relative Sun's, you can figure the star's luminosity relative to solar luminosity. In the equation below L = luminosity and T ...
Sun Fact Sheet. Sun/Earth Comparison. Bulk parameters Sun Earth Ratio (Sun/Earth) ... Luminosity (10 24 J/s) 382.8 : Mass conversion rate (10 6 kg/s) 4260. Mean ... of photosphere): 0.868 mb Pressure at bottom of photosphere (optical depth = 1): 125 mb Effective temperature: 5772 K Temperature at top of photosphere: 4400 K Temperature at bottom ...
The solar luminosity, L ☉, is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.One nominal solar luminosity is defined by the International Astronomical Union to be 3.828 × 10 26 W. This does not include the solar neutrino luminosity ...
A star's luminosity can be determined from two stellar characteristics: size and effective temperature. The former is typically represented in terms of solar radii, R ⊙, while the latter is represented in kelvins, but in most cases neither can be measured directly.To determine a star's radius, two other metrics are needed: the star's angular diameter and its distance from Earth.
As temperature decreases, luminosity will also decrease As radius increases (and with it surface area, but radius is a much easier to work with if you're trying to compare stars so we usually say ...
Calculating luminosity: an example. Let's analyze Sun with this luminosity calculator to investigate its absolute and apparent magnitude. Input the radius and temperature of the Sun into the calculator. The radius is equal to R☉ = 695700 km, and the temperature to T☉ = 5778 K.
Hertzsprung-Russel (HR) diagram. When stars are plotted on a luminosity vs surface temperature diagram (), several interesting patterns emerge:Most stars fall on the Main Sequence. On the Main Sequence, the more massive stars are bigger, hotter, more luminous, and die faster.
For example, if a star has the same surface temperature as the sun and a radius that is twice as big, its luminosity must be L = (2 R) 2 (T) 4 = 4 L. One can experiment with the relationships between luminosity, temperature (spectral type), and radius with the Stellar Luminosity Calculator. Use the calculator to answer the following questions.
L is the luminosity of the Sun in Watts, R is the radius of the Sun in meters, σ is a constant of physics known as the Stefan-Boltzmann constant (σ = 5.67 x 10-8 watt/m 2 /degree 4), and T is the surface temperature of the Sun in degrees Kelvin (degrees above absolute zero).