WR 68a is a relatively newly discovered (2015) double-lined spectroscopic binary. It has an orbital pe- iod of 5.22 days, a nearly circular orbit, and photometric light curves that are fit best using an inclination, 80°. Spectral lines show maximum Doppler shifts in the two components of K = 144 km/s and Kp = 295 m/s. Find the masses of the two components. Your answers should be given in units of Mo

2GM What is the escape velocity (in km/s) from the surface of a 1.6 Mo neutron star? From a 3.0 M. neutron star? (Hint: Use the formula for escape velocity, V. ; make sure to express quantities in units of meters, kilograms, and seconds. Assume a neutron star has a radius of 11 km and assume the mass of the Sun is 1.99 x 1030 kg.) 1.6 Mo neutron star km/s 3.0 Me neutron star km/s

The star HD 93250 in the Carina Nebula is a bright O-type star. It has a reported apparent magnitude in the V band of mV = 7.41 and V band absolute magnitude of MV = −6.14. Using these values calculate the distance to HD 93250 in parsec. The distance to HD 93250 has been measured by other means as 2350 pc. Compare your calculated value of the distance with the measured value, and give a possible explanation for any difference. Calculate the value of the interstellar extinction in the V band AV that would account for the difference in the distances. The parameter E(B − V ) = AB − AV , where AB and AV are the extinctions in the B and V bands, is often used to characterize interstellar extinction. For the star HD 93250 the value E(B − V ) = 0.48 has been measured. Given the above value of E(B − V ) for HD 93250, calculate the extinction in the B band, and explain why the parameter E(B − V ) is often called the “reddening.” The B band apparent magnitude of HD 93250 is mB = 8.12. Calculate…

Let's compare the acceleration due to gravity at the surface of a Sun-like star to a white dwarf of similar mass. We know that the force of gravity comes from F= G*m_1*m_2/r^2 and that F = m * a from some of Newton's laws. As such, we know that the acceleration due to gravity is given by a_g = G*m/r^2. With that in mind, let's say that we have a white dwarf star is approximately the size of the Earth which is 1/100 radius of the Sun (0.01 R Sun) and that the white dwarf has a mass that is approximately half the mass of the Sun (0.5 M_Sun). What is the ratio of the acceleration due to gravity at the surface of the white dwarf star (aka the surface gravity) compared to the surface gravity of the Sun-like star (assume its mass is 1 M_sun and radius is 1 R_Sun).?