The mass-luminosity relation describes the mathematical relationship between luminosity and mass for main sequence stars.  It describes how a star with a luminosity of 280 L⊙ would have a mass of ______ M⊙.

Betelgeuse is a nearby supergiant that will eventually explode into a supernova. Let's see how awesome it would look. At peak brightness, the supernova will have a luminosity of about 10 billion times the Sun. It is 600 light-years away. All stellar brightnesses are compared with Vega, which has an intrinsic luminosity of about 60 times the Sun, a distance of 25 light-years, an absolute magnitude of 0.6 and an apparent magnitude of 0 (by definition). a) At peak brightness, how many times brighter will Betelgeuse be than Vega? b) Approximately what apparent magnitude does this correspond to? c) The Sun is about -26.5 apparent magnitude. What fraction of the Sun's brightness will Betelgeuse be?

If an X-ray binary consists of a 16 solar mass star and a neutron Star orbiting each other every 15.4 days, what is their average separation? (Hint: Use the version of Keller's third law for binary stars, Ma + Mb = a^3 /p^2 ; make sure you express quantities in unites of AU, solar masses, and years. Assume the mass of a neutron Star is 1.6 solar masses.)  ___________ AU

Do this in 10 min. I will give like on answer

A star has a radius of 2RO and has a temperature of 3TO. Calculate the luminosity in solar units.

Question A4 a) A star has a temperature T = 15000K, mass M = 0.25M and luminosity L = 0.02L. Sketch the position of this star on the Hertzsprung-Russell diagram relative to the main sequence. b) Using the given properties of the star, derive expressions for the star's radius R and mean density p. Calculate values for these in units of R. and kg m-³, respectively. c) Starting from the equation for hydrostatic equilibrium, derive an approximate expression for the central pressure Pc of the star in terms of its density p and radius R, assuming uniform ρ density. d) Assuming that the star is made of ordinary gas material such as the Sun, calculate an estimate of the central temperature of the star. From this value and the luminosity, briefly explain what can be inferred about the nuclear processes in the star. Discuss very briefly why your estimate for the central temperature may be too large.

RR Lyrae stars have essentially the same luminosity curve, with periods of up to 1 day.     False     True   47

Consider two stars on the main sequence, A and B. Star A has a mass of 6 M⊙. Star B has a mass of 0.3 M⊙.  Compute the ratio of main sequence lifetimes for the two stars, TB/TA .

Question 41 .Suppose you are looking at H-R diagrams of two similar star clusters. The most luminous main sequence stars in the Porcini cluster are much more luminous than the most luminous main sequence stars in the Morel cluster. What can you conclude? O the Porcini cluster is younger than the Morel cluster O the Porcini cluster is farther away than the Morel cluster O the Porcini cluster is lower in metallicity than the Morel cluster O the Porcini cluster is larger in diameter than the Morel cluster

A Type Ia Supernova is an example of a: