| 1 | The apparent expansion rate of the Crab Nebula is 0.23 arcsec per year. The apparent size of the Crab Nebula is about 4 by 6 arcmin. If the expansion rate remains constant, calculate how long it will be until the long axis of the Crab nebula has the same apparent size as full moon. |
| 2 | In an X-ray burster, the surface of a neutron star 10 km in radius is heated to a temperature of 3 x 107K. (a) Determine the wavelength of maximum emission of the heated surface ( which you may treat as a blackbody ). In what part of the electromagnetic spectrum does this lie? (See Figure5-7.) (b) Find the luminosity of the heated neutron star. Give your answer in watts and in terms of the luminosity of the Sun (the luminosity of Sun is 3.86 x 1026W). How does this compare with the peak luminosity of a nova? Of a Type Ia supernova? |
| 3 | An X-ray binary contains a 2M⊙ star and a 1.5M⊙ neutron star. If their orbital period is 1 day, what is the separatin between the two stars? Use AU in expressing your answer. If the orbital period is 20 minutes, what is the separation? |
