Editing Openai/6946e998-79f0-8007-9a65-19828450838d (section)

==== Now apply stricter physical filters instead of just “all 0.5–1.5 R⊕ in that band.” ====

You can reasonably do:
# Radius cut: - Only count 0.8–1.4 R⊕ (or even 0.8–1.2 R⊕) to avoid: - sub-Mars, likely to lose atmosphere - super-Earths / mini-Neptunes with deep volatile envelopes
# Mass-density cut (where known): - For planets with measured mass and radius, only keep rocky densities (say ≳ 4–5 g/cm³). - This explicitly rejects planets with large H/He envelopes that happen to be “Earth-size-ish.”
# Spectral-type cut: - If you want to be conservative regarding flares and pre-main-sequence stripping, you might: - focus on FGK stars (Sun-like and somewhat cooler/warmer), - or, at minimum, down-weight M-dwarfs, where a big fraction of nominal HZ planets may have had their atmospheres cooked off.

Together, these cuts likely:
* Reduce the raw η⊕ (FGK) to the lower end of typical estimates (say 0.1–0.3 per star, not 0.5–1.0).
* Reduce the effective contribution from M dwarfs by some factor (maybe treat their η⊕ as, say, 0.05–0.2 instead of 0.2–0.4, to reflect the risk that many are bare rocks).

The exact numbers are not well measured yet, but conceptually, that’s the effect.