HEC: Data of Potentially Habitable Worlds

Last Update: January 13, 2016

The database of potentially habitable worlds (also known as small planets in the habitable zone) of the Habitable Exoplanets Catalog (HEC) identifies objects of interest for follow-up observations and for statistical studies, including both confirmed and unconfirmed exoplanets. The database is updated with corrections and additions as new results are available. The HEC corrects or model many of the planetary properties combining different databases, so the numbers might not necessarily match those of a particular exoplanets database.

Potentially Habitable Exoplanets (Main Database)


These are potentially habitable exoplanets discovered by different ground or space observatories, some still unconfirmed. They are divided into a conservative sample (i.e. those more likely to be rocky and support surface liquid water) and an optimistic sample (i.e. those less likely to be rocky or support surface liquid water)Mass or radius for an iron, rocky, and water composition are given when not available for comparison purposes (Seager et al., 2007). Equilibrium temperatures are calculated assuming a 0.3 bond albedo. All planets are sorted by an Earth Similarity Index (ESI) based on how similar they are to Earth's stellar flux and size (either measured from mass or radius). This is a working list and data might be constantly revised.



Figure A-1. All planets in and near the habitable zone. Those less than 2.5 Earth radii are labeled. A mass-radius relation was used to illustrate RV planets.

Table A-1. Conservative sample of potentially habitable planets.

Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. GJ 667C c M-Warm Terran ≥ 3.8 1.1 - 1.5 - 2.0 0.88 247 28.1 24 0.84
002. Kepler-442 b K-Warm Terran 8.2 - 2.3 - 1.0 1.3 0.70 233 112.3 1115 0.84
003. GJ 667C f* M-Warm Terran ≥ 2.7 1.0 - 1.4 - 1.8 0.56 221 39.0 24 0.77
004. Wolf 1061 c (N) M-Warm Terran ≥ 4.3 1.1 - 1.6 - 2.0 0.60 223 17.9 14 0.76
005. Kapteyn b* M-Warm Terran ≥ 4.8 1.2 - 1.6 - 2.1 0.43 205 48.6 13 0.67
006. Kepler-62 f K-Warm Terran 10.2 - 2.8 - 1.2 1.4 0.39 201 267.3 1200 0.67
007. Kepler-186 f M-Warm Terran 4.7 - 1.5 - 0.6 1.2 0.29 188 129.9 561 0.61
008. GJ 667C e* M-Warm Terran ≥ 2.7 1.0 - 1.4 - 1.8 0.30 189 62.2 24 0.60

* planet canditate/unconfirmed, (N) = new addition to the catalog













 
Table A-2. Optimistic sample of potentially habitable planets.
 
Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. Kepler-438 b M-Warm Terran 4.0 - 1.3 - 0.6 1.1 1.38 276 35.2 473 0.88
002. Kepler-296 e M-Warm Terran 12.5 - 3.3 - 1.4 1.5 1.22 267 34.1 737 0.85
003. Kepler-62 e K-Warm Superterran 18.7 - 4.5 - 1.9 1.6 1.10 261 122.4 1200 0.83
004. Kepler-452 b G-Warm Superterran 19.8 - 4.7 - 1.9 1.6 1.11 261 384.8 1402 0.83
005. GJ 832 c M-Warm Superterran ≥ 5.4 1.2 - 1.7 - 2.2 1.00 253 35.7 16 0.81
006. K2-3 d M-Warm Terran 11.1 1.5 1.46 280 44.6 137 0.80
007. Kepler-283 c K-Warm Superterran 35.3 - 7.0 - 2.8 1.8 0.90 248 92.7 1741 0.79
008. tau Cet e* G-Warm Terran ≥ 4.3 1.1 - 1.6 - 2.0 1.51 282 168.1 12 0.78
009. GJ 180 c* M-Warm Superterran ≥ 6.4 1.3 - 1.8 - 2.3 0.79 239 24.3 38 0.77
010. Kepler-440 b K-Warm Superterran 41.2 - 7.7 - 3.1 1.9 1.43 273 101.1 851 0.75
011. GJ 180 b* M-Warm Superterran ≥ 8.3 1.3 - 1.9 - 2.4 1.23 268 17.4 38 0.75
012. GJ 163 c M-Warm Superterran ≥ 7.3 1.3 - 1.8 - 2.4 1.40 277 25.6 49 0.75
013. HD 40307 g* K-Warm Superterran ≥ 7.1 1.3 - 1.8 - 2.3 0.68 227 197.8 42 0.74
014. K2-18 b M-Warm Superterran ? - 16.5 - 6.0 2.2 0.94 251 32.9 111 0.73
015. Kepler-61 b K-Warm Superterran ? - 13.8 - 5.2 2.2 1.27 267 59.9 1063 0.73
016. Kepler-443 b K-Warm Superterran ? - 19.5 - 7.0 2.3 0.89 247 177.7 2540 0.71
017. Kepler-22 b G-Warm Superterran ? - 20.4 - 7.2 2.4 1.11 261 289.9 619 0.71
018. GJ 422 b* M-Warm Superterran ≥ 9.9 1.4 - 2.0 - 2.6 0.68 231 26.2 41 0.71
019. GJ 3293 c* M-Warm Superterran ≥ 8.6 1.4 - 1.9 - 2.5 0.60 223 48.1 59 0.70
020. Kepler-298 d K-Warm Superterran ? - 26.8 - 9.1 2.5 1.29 271 77.5 1545 0.68
021. Kepler-174 d K-Warm Superterran ? - 14.8 - 5.5 2.2 0.43 206 247.4 1174 0.61
022. Kepler-296 f M-Warm Superterran 28.7 - 6.1 - 2.5 1.8 0.34 194 63.3 737 0.60
023. GJ 682 c* M-Warm Superterran ≥ 8.7 1.4 - 1.9 - 2.5 0.37 198 57.3 17 0.59
024. KOI-4427 b* M-Warm Superterran 38.5 - 7.4 - 3.0 1.8 0.24 179 147.7 782 0.52

* planet canditate/unconfirmed, (N) = new addition to the catalog










 

Potentially Habitable Exoplanets (NASA Kepler Objects of Interest)


These are exoplanets discovered by the NASA Kepler primary mission (Q1-Q17 DR 24 KOI Catalog). Those already confirmed are listed by their Kepler names. They are divided into a conservative sample (i.e. those more likely to be rocky and support surface liquid water) and an optimistic sample (i.e. those less likely to be rocky or support surface liquid water)Estimated masses for a pure iron, rocky, and water composition, respectively, are given for comparison purposes (Seager et al., 2007)All planets are sorted by an Earth Similarity Index (ESI) based on how similar they are to Earth's radius and stellar flux. Equilibrium temperatures are calculated assuming a 0.3 bond albedo. Values for some objects might be different from other published results since this list is based on a fully automated dispositioning processEstimates for the distance from Earth are only approximate. This is a working list and data might be constantly revised.


Figure K-1. Kepler (Q1-Q17 DR 24) planets in and near the habitable zone. Those less than 2.5 Earth radii are labeled.


Table K-1. Kepler (Q1-Q17 DR 24) conservative sample of potentially habitable planets.

Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. Kepler-296 e M-Warm Terran 3.5 - 1.1 - 0.5 1.1 0.84 244 34.1 707 0.93
002. KOI-7235.01* G-Warm Terran 4.4 - 1.4 - 0.6 1.1 0.75 237 299.7 2121 0.89
003. KOI-2626.01* M-Warm Terran 4.0 - 1.3 - 0.6 1.1 0.65 229 38.1 659 0.84
004. KOI-6425.01* G-Warm Terran 13.3 - 3.5 - 1.5 1.5 0.68 231 521.1 2308 0.80
005. Kepler-452 b G-Warm Terran 4.1 - 1.3 - 0.6 1.1 0.56 220 384.8 1216 0.80
006. Kepler-62 f K-Warm Terran 10.4 - 2.9 - 1.2 1.4 0.41 204 267.3 848 0.68
007. KOI-3138.01* M-Warm Subterran 0.4 - 0.1 - 0.1 0.6 0.47 211 8.7 232 0.68
008. Kepler-296 f M-Warm Terran 5.8 - 1.7 - 0.8 1.2 0.37 199 63.3 707 0.67
009. Kepler-440 b M-Warm Terran 12.2 - 3.2 - 1.4 1.5 0.39 201 101.1 747 0.66
010. KOI-2418.01* M-Warm Terran 4.0 - 1.3 - 0.6 1.1 0.35 196 86.8 723 0.66
011. KOI-7591.01* K-Warm Terran 7.2 - 2.1 - 0.9 1.3 0.33 193 328.3 1582 0.63

* planet canditate/unconfirmed, (N) = new addition to the catalog













 
Table K-2. Kepler (Q1-Q17 DR 24) optimistic sample of potentially habitable planets.

Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. Kepler-395 c M-Warm Terran 6.1 - 1.8 - 0.8 1.2 1.15 264 35.0 889 0.91
002. Kepler-438 b M-Warm Terran 2.4 - 0.8 - 0.4 1.0 1.31 273 35.2 500 0.90
003. KOI-7179.01* G-Warm Terran 4.9 - 1.5 - 0.7 1.2 1.30 272 407.1 1911 0.89
004. KOI-3010.01* K-Warm Superterran 16.0 - 4.0 - 1.7 1.6 0.93 250 60.9 1142 0.84
005. Kepler-442 b K-Warm Superterran 16.0 - 4.0 - 1.7 1.6 1.08 260 112.3 1366 0.84
006. KOI-463.01* M-Warm Superterran 16.5 - 4.1 - 1.7 1.6 1.27 270 18.5 305 0.82
007. KOI-4550.01* K-Warm Superterran 26.9 - 5.9 - 2.4 1.7 1.04 257 140.3 1953 0.81
008. Kepler-62 e K-Warm Superterran 26.9 - 5.9 - 2.4 1.7 1.18 265 122.4 848 0.80
009. KOI-4036.01* K-Warm Superterran 37.2 - 7.3 - 2.9 1.8 1.02 256 168.8 1200 0.79
010. KOI-6676.01* F-Warm Superterran 34.8 - 7.0 - 2.8 1.8 1.18 266 439.2 2637 0.79
011. Kepler-155 c K-Warm Superterran 29.6 - 6.3 - 2.5 1.8 1.28 271 52.7 618 0.79
012. KOI-5475.01* F-Warm Superterran 21.7 - 5.0 - 2.1 1.7 0.68 232 448.3 1265 0.78
013. KOI-5856.01* G-Warm Superterran 24.5 - 5.5 - 2.2 1.7 1.48 281 259.3 2689 0.77
014. Kepler-235 e M-Warm Superterran 55.0 - 9.1 - 3.6 1.9 1.16 265 46.2 1137 0.77
015. Kepler-436 b K-Warm Superterran 47.4 - 8.4 - 3.3 1.9 1.28 271 64.0 1416 0.76
016. KOI-7554.01* F-Warm Superterran 64.4 - 9.9 - 3.8 2.0 1.13 262 482.6 3548 0.76
017. KOI-7223.01* G-Warm Superterran 14.6 - 3.7 - 1.6 1.5 0.57 221 317.1 1803 0.76
018. KOI-5236.01* F-Warm Superterran 64.4 - 9.9 - 3.8 2.0 0.79 240 550.9 1697 0.75
019. KOI-3282.01* M-Warm Superterran 61.9 - 9.7 - 3.8 2.0 1.30 272 49.3 1230 0.75
020. Kepler-69 c G-Warm Superterran 27.8 - 6.0 - 2.4 1.7 1.60 286 242.5 1711 0.75
021. KOI-4450.01* G-Warm Superterran 64.4 - 9.9 - 3.8 2.0 1.38 276 196.4 2700 0.74
022. KOI-4103.01* K-Warm Superterran ? - 14.4 - 5.4 2.2 0.95 251 184.8 1735 0.74
023. KOI-4054.01* G-Warm Superterran 67.2 - 10.1 - 3.9 2.0 1.41 278 169.1 1872 0.74
024. KOI-5202.01* F-Warm Superterran 37.2 - 7.3 - 2.9 1.8 0.63 227 535.9 3029 0.74
025. KOI-7587.01* G-Warm Superterran ? - 14.9 - 5.5 2.2 1.03 257 366.1 716 0.74
026. KOI-1871.01* K-Warm Superterran ? - 13.8 - 5.2 2.1 1.21 267 92.7 1236 0.73
027. Kepler-22 b G-Warm Superterran ? - 14.4 - 5.4 2.2 1.21 267 289.9 684 0.73
028. Kepler-443 b K-Warm Superterran ? - 15.2 - 5.6 2.2 0.87 246 177.7 2711 0.73
029. KOI-2020.01* K-Warm Superterran ? - 13.1 - 4.9 2.1 0.77 239 111.0 1370 0.73
030. Kepler-26 e M-Warm Superterran ? - 12.8 - 4.8 2.1 1.32 273 46.8 1007 0.73
031. KOI-854.01* M-Warm Superterran 59.4 - 9.5 - 3.7 2.0 0.65 228 56.1 907 0.72
032. Kepler-61 b K-Warm Superterran ? - 14.4 - 5.4 2.2 1.30 272 59.9 970 0.72
033. KOI-6343.01* F-Warm Superterran 47.4 - 8.4 - 3.3 1.9 0.61 225 569.5 2910 0.72
034. KOI-1876.01* K-Warm Superterran ? - 18.1 - 6.5 2.3 0.96 252 82.5 1105 0.72
035. KOI-7470.01* K-Warm Superterran 47.4 - 8.4 - 3.3 1.9 0.60 225 392.5 1568 0.72
036. KOI-5276.01* K-Warm Superterran ? - 15.2 - 5.6 2.2 0.72 235 220.7 2728 0.71
037. KOI-7345.01* F-Warm Superterran ? - 21.1 - 7.5 2.4 1.19 266 377.5 3963 0.71
038. KOI-4016.01* K-Warm Superterran ? - 18.5 - 6.7 2.3 0.76 238 125.4 807 0.70
039. KOI-2834.01* K-Warm Superterran ? - 23.6 - 8.2 2.4 0.94 251 136.2 2213 0.70
040. KOI-4458.01* F-Warm Superterran ? - 25.9 - 8.9 2.5 1.11 262 358.8 2078 0.70
041. Kepler-439 b G-Warm Superterran ? - 19.5 - 7.0 2.3 1.55 284 178.1 2025 0.68
042. KOI-6734.01* G-Warm Superterran ? - 13.1 - 4.9 2.1 0.50 214 498.3 3708 0.65
043. KOI-7136.01* G-Warm Superterran ? - 17.4 - 6.3 2.3 0.52 217 441.2 3654 0.65
044. KOI-3946.01* F-Warm Superterran ? - 20.7 - 7.3 2.4 1.87 298 308.5 1873 0.64
045. KOI-7040.01* F-Warm Superterran ? - 14.7 - 5.5 2.2 0.48 212 502.2 2626 0.64
046. Kepler-309 c M-Warm Superterran ? - 12.3 - 4.7 2.1 0.40 203 105.4 803 0.61
047. Kepler-441 b K-Warm Superterran 52.9 - 8.9 - 3.5 1.9 0.34 194 207.2 1224 0.58
048. KOI-2770.01* K-Warm Superterran ? - 18.8 - 6.8 2.3 0.39 201 205.4 1598 0.58
049. Kepler-174 d K-Warm Superterran ? - 12.6 - 4.8 2.1 0.34 194 247.4 916 0.57
050. KOI-4356.01* K-Warm Superterran 49.2 - 8.6 - 3.4 1.9 0.29 187 174.5 1311 0.55
051. KOI-959.01* M-Warm Superterran ? - 18.8 - 6.8 2.3 0.26 181 12.7 35 0.50

* planet canditate/unconfirmed, (N) = new addition to the catalog













 

Potentially Habitable Exoplanets (NASA Kepler K2 Mission)


These are exoplanets discovered by the NASA Kepler K2 mission (K2 Catalog). Those already confirmed are listed by their K2 names. They are divided into a conservative sample (i.e. those more likely to be rocky and support surface liquid water) and an optimistic sample (i.e. those less likely to be rocky or support surface liquid water)Estimated masses for a pure iron, rocky, and water composition, respectively, are given for comparison purposes (Seager et al., 2007)All planets are sorted by an Earth Similarity Index (ESI) based on how similar they are to Earth's radius and stellar flux. Equilibrium temperatures are calculated assuming a 0.3 bond albedo. Estimates for stellar flux and distance from Earth are only approximate. This is a working list and data might be constantly revised.


Figure K2-1. Kepler (K2) planets in and near the habitable zone. Those less than 2.5 Earth radii are labeled.

Table K2-1. Kepler (K2) conservative sample of potentially habitable planets.

Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. EPIC 203823381.01* M-Warm Subterran 0.8 - 0.3 - 0.1 0.7 0.40 203 8.3 10 0.68

* planet canditate/unconfirmed, (N) = new addition to the catalog

 
Table K2-2. Kepler (K2) optimistic sample of potentially habitable planets.

Name Type Mass
(ME)
Radius
(RE)
Flux
(SE)
Teq
(K)
Period
(days)
Distance
(ly)
ESI
001. K2-9 b M-Warm Superterran 18.0 - 4.4 - 1.8 1.6 1.13 263 18.4 61 0.83
002. K2-18 b M-Warm Superterran ? - 16.5 - 6.0 2.2 1.05 258 32.9 30 0.73

* planet canditate/unconfirmed, (N) = new addition to the catalog

 

Note: K2-3 d was not included since it has not been added to the NASA K2 Catalog yet. It is included in the main database.



Tables Legend


  • Name - Name of the planet. This links to the data of the planet at the Extrasolar Planets Encyclopaedia or NASA Exoplanet Archive.
  • Type - PHL's classification of planets that includes host star spectral type (F, G, K, M), habitable zone location (hot, warm, cold) and size (miniterran, subterran, terran, superterran, jovian, neptunian) (e.g. Earth = G-Warm Terran, Venus = G-Hot Terran, Mars = G-Warm Subterran).
  • Mass - Minimum mass of the planet in Earth masses (Earth = 1.0 ME). Estimated for a pure iron, rocky, and water composition, respectively, when not available. 
  • Radius - Radius of planet in Earth radii (Earth = 1.0 RE). Estimated for a pure iron, rocky, and water composition, respectively, when not available.
  • Flux - Average stellar flux of the planet in Earth fluxes (Earth = 1.0 SE).
  • Teq - Equilibrium temperature in kelvins (K) assuming a 0.3 bond albedo (Earth = 255 K). Actual surface temperatures are expected to be larger than the equilibrium temperature depending on the atmosphere of the planets, which are currently unknown (e.g. Earth mean global surface temperature is about 288 K or 15°C).
  • Period - Orbital period in days (Earth = 365 days).
  • Distance - Distance from Earth in light years (ly).
  • ESI - Earth Similarity Index, a measure of similarity to Earth that summarizes how similar are these planets to the stellar flux, mass, and radius of Earth (Earth = 1.0). Results are sorted by this number. Planets more similar to Earth based on only these parameters are not necessarily more habitable.