What would be the luminosity of the Sun if its surface temperature were 4000 K and its radius were 2.0 AU ?

0.04558

Explanation:

Luminosity is defined as the total amount of energy a star can produce in a second. Luminosity is given by the formula

σ * A * T⁴

where;

σ = Stefan-Boltzmann constant

= 5.670367 * 10⁻⁸

A= Surface Area

=4πr²

T= Temperature in Kelvin

In the question,

Temperature= 4000K

Radius= 2.0 A.U

Substituting the variables into the equation,

0.000000056704 * 4(3.14)(2.0²) * 4000⁴

= 0.000000056704 * 50.24 * 16000

= 0.04558