Question

3. [9 marks] You have access to a small professional telescope that is able to record the ultraviolet through infrared spectrum of a star in the constellation of Orion. You determine that the wavelength of light at the peak of the spectrum is 922.93 nm. The star’s apparent magnitude is m = 0.45. a) [2 marks] Determine the star’s surface temperature in units of Kelvin (K). b) [3 marks] Using the solar constant and the Sun’s apparent magnitude, determine the star’s brightness in units of Watts per square metre (W/m2 ). c) [2 marks] Using the star’s parallax (we’ll talk about this a little later in the course), you determine that its distance is 643 light years. Calculate the star’s luminosity in units of Watts (W). d) [2 marks] Determine the star’s radius in metres, and compare it with the size of the Sun.

Answer 1