# How to calculate pulsar's wavelength by it's diameter and mass?

1. Feb 9, 2014

### Hyperion

Hello. I came to this forum to seek help for this question, since I cannot find it anywhere on the internet, nor even books. I have to calculate a maximum of a radiated wavelength of a neutron star. Sorry I don't know how else could I translate it from to English. All I was given is that it's mass M is 2,5 Ms (Sun masses), it's diameter R = 12km and it's surface temperature is T = 5,0*10^5 K. It's being observed from a spacefaring ship, which is travelling straight towards it, by a velocity of V = 0,5c. I also need to calculate the wavelength of the pulsar, if it's observed from a distant point, in which we can neglect it's gravitational force. Another task is to calculate it's wavelength that is falling upon the ship's photometer, and the last one is that the ship has decided to change it's course to fly to a different star, and I need to calculate the wavelength the ship will recognize in the moment of closest departure to the ship- in the moment when it'll fly at a right angle to a connecting line between the star and the ship?

Yes I'm on some astronomical/astrophysical competition, and I really have no idea where to seek help for this... Could anyone at least partially help me? Thank you

2. Feb 11, 2014