Fogg, 1992

3.1 Stellar ParametersStars occu over a wide range of mass, ftom about ^O.1 Mo to-100 Mo. Lighter sta$ are the more abundafl and here thedistribution is modelledby the Scalo initial mass spectrum [l5]:dN/dM (t Ma (3)whee M is the stellar mass ir solm units and T = 1.94 + 0.94Loc(M.For a star to possess terrestrial planeb it would have to haveformed ftom a nebula contaioing suf6cient heavy olemeDts.The star would have to be Population I and younger theo the ageoffomation ofthe galactic disc (-10 G}{). Overthis period, themetallicity of the inte$tellar medium has risen due to theFoducts of nuclesynthesis ft om successive genemtions of stars.The canonical model 116,17l of galactic chemical evolution isassumed to hold in the solar neighbou*ood which describes aroughly lioear increase in metnllicity, z, with age, T/G),i. Anequation which fits the model isiz = 0.13(10 - T) + 0_3 zo, (4)where zo - 0.02 is the heavy element fraction of the Sun. Tbepropotio! of balo Population II stars in the solar Deighbourhoodis a miniscule - 1/800 and so, assuding a constant starformation mte [17], the ages of the geatFeponderurc€ of starsnear the Sun can be assumed to be distributed evenly between0 - 10 Cyr.A [u0ctioo for calculating 6e sle ll ar zero age main seque0celumhosity wilhiD the mass range 0.1 - 2.0 l"{o was derived fiomthe theoretical models of lben [18]:LzAr{s = 0.71(IVI/MJ' L6, (5)where for {0.7 Mo < M < 2.0 Me): n = 4.75 and for {0. I Mo