Question

The luminosity of the white dwarf Sirius B is 0.056 Lsun. If the luminosity of the sun is Lsun = 3.83 x 1026 Watts, then what is the luminosity of Sirius B in units of Watts? Give your result to 1 significant figure. Note: Write answers in scientific notation using the "e" notation. For example, an answer which is 8 x 1015 would be written as 8e15.

Answer 1

given

The luminosity of the white dwarf Sirius B is

L_ sirus B = 0.056 Lsun.

substitute 3.83* 10^26 W for Lsun in the above equation

L_ sirus B = 0.056(3.83* 10^26)

=2.1448 * 10^25 W

Rounding to one significant digit

L_ sirus B = 2.0 * 10^23

in scientific notation

L_ sirus B = 2e23