18 Wolf 359 is a red dwarf star. The distance of the star from Earth was first determined from parallax measurements made by the astronomer Max Wolf. (a) (i) The parallax angle was 2.01 x 10-rad. Calculate the distance, in metres, of Wolf 359 from Earth. mean distance from Earth to Sun = 1.50 x 10"m (2) Distance of Wolf 359 from Earth = (ii) Explain why parallax measurements can only be used to determine the distances to a relatively small number of stars. (2)(b) The graph shows how the intensity of radiation from the star Wolf 359 varies with wavelength. Intensity 1.0 2.0 3.0 4/um (i) Show that the surface temperature of Wolf 359 is about 2700K. (3)(ii) The radius of the Sun is R. . The radius of Wolf 359 is 0.16R. . It is claimed that the luminosity of Wolf 359 is less than 0.1% of the luminosity of the Sun, Lam Deduce whether this claim is correct. R.= 6.96 x 10'm Lem = 3.83 x 1026 W T = 2700K (3) (Total for Question 18 = 10 marks)