Question

You want to observe individual stars in a globular cluster; this cluster has 106 stars distributed within a sphere of characteristic radius of 1 parsec. Estimate the distance, in kiloparsecs (kpc), out to which the Hubble Space Telescope (HST) ought to be able to resolve individual stars within the cluster. You should assume that the HST has a mirror of diameter 2.4 m, and works at a wavelength of λ = 0.5 μm. (You will need to look up how to compute the angular resolution of a telescope ... and you will need to think through how closely the stars in this cluster are spaced ... To do the latter, you will need to come up with a model for the spatial distribution of stars in this cluster – however, I don’t expect you to construct a full theory for this distribution (!!), but am willing to accept even the most coarse model – you get to devise your own cluster model! A word to the wise: simpler is definitely better ...

Answer 1