M31 · HELGA Dust Components
Herschel HELGA · Viaene+2014 SED decomposition · Seraphim v18.3
n(C) = 3.561 + 3.506 × C · C_eff = (n − 3.561) / 3.506
| Component |
T_dust (K) |
λ_peak (μm) |
n |
C_eff |
Δ from n_H |
Position |
Framework interpretation
Condensation zone (where grains FORM): n ≈ 91.3–94.0 · C_eff ≈ 25.0–25.8
HELGA cold dust (grain EMISSION): n ≈ 100.5–103.1 · C_eff ≈ 27.6–28.4 · 8–11 oct above condensation zone
WISE mid-IR (warm grain emission): n ≈ 74–83 · C_eff ≈ 20–23 · 9–18 oct below condensation zone
The elemental condensation ceiling (n_H = 92.19) sits exactly between WISE warm emission and HELGA cold emission.
Dust grain formation occupies a 2.66-octave window. The grains then radiate on either side of it.