Mass of each Star/Wind Particle

Patrick Koh
  • 4 Oct '15

Across multiple subhalos, I computed the average mass per stellar/wind particle by dividing the "mass_stars" by "len_stars" but I don't get consistent values. Could someone explain this for me? I ultimately want to determine the mass of each stellar particle for any subhalo.

Dylan Nelson
  • 3 Nov '15

Hi Patrick,

Two points, both of which are relevant here:

  • The masses of star particles are variable (because they are spawned from gas cells with variable mass). So, the average star particle mass may differ from subhalo to subhalo (although probably not significantly).
  • "mass_stars" includes the mass of only true star particles, excluding wind particles. You see this in the documentation under SubhaloMassType ("Note: Wind phase cells are counted as gas (type 0) for SubhaloMassType."). However, "len_stars" gives the total number of all PartType4 particles, so therefore both true star and wind particles. As a result, the mean mass of true star particles cannot be computed just from these two numbers
  • Page 1 of 1