Table 1
Definition of the three types of exoplanets with their occurrence rate considered in this work: rocky planets within the opt HZ, rocky planets within the con HZ, and exo-Earth candidates (ECCs).
| Name | Rp (R⊕) | Fp (F⊕) | ηhab2min | ηhab2max | ζhab2min | ζhab2max |
|---|---|---|---|---|---|---|
| opt HZ | 0.5–1.5 | 0.320–1.776(a) |  |
 |
 |
 |
| con HZ | 0.5–1.5 | 0.356–1.107(b) |  |
 |
 |
 |
| EEC | 0.8(c)–1.4 | 0.356–1.107(b) |  |
 |
 |
 |
Notes. Shown are the average number of planets per Sun-like (η) and FGK-type (ζ) star in the hab2min and hab2max planet populations. Rp denotes the planet radius and Fp denotes the planet instellation flux. Occurrence rates are averaged over our input catalog for the given range of spectral types. Because the stellar flux range and the underlying occurrence rate model is depends on spectral type, the number of objects falling within this range, and hence the occurrence rate, varies with spectral type as well. (a)Dependent on spectral type according to the “Early Mars” and “Recent Venus” scenarios in Kopparapu et al. (2014). (b)Dependent on spectral type according to the “Maximum Greenhouse” and “Runaway Greenhouse” scenarios in Kopparapu et al. (2014); only the values for 1 M⊕ planets are adopted here. (c)For EECs, the lower limit of the radius range depends on the separation from the host star; 
, where ap is the planet semi-major axis in units of au (see Stark et al. 2019).
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