There are 83 exoplanets in the habitable zone (HZ) in the currently known 694 exoplanets, but many exhibit wide elliptical orbits that take them just inside or outside the edges of the HZ during parts of their orbits. Those that stay within the HZ, instead of just crossing it, are more interesting candidates for habitable exoplanets and exomoons. Here we identified those that stay partially or continuously within the HZ. There are 119 that cross the HZ but only 33 that actually stay within the HZ throughout their orbits (Figure 1 and Table 1). This means that only 33, out of the original 83 exoplanets in the HZ, are better candidates for habitable exoplanets and exomoons.
There are many interesting cases that can be considered. For example, 16 Cyg B b is a gas giant exoplanet in the habitable zone (HZD between -1 and +1) but its wide elliptical orbit takes it outside the inner and outer edges of the HZ. Gliese 581 d and HD 85512 b, the only two known potentially habitable exoplanets, are not always within their HZ. This could impact their habitability. We will be presenting other interesting numbers, such as the range of equilibrium temperatures and time spent in the HZ, for the Habitable Exoplanets Catalog.
 Figure 1. Orbits of 694 exoplanets (some outside the range) in habitable zone units (HZU). In these units the HZ has a fixed size and the crossing orbits of exoplanets are easier to visualize. The HZ (light blue shaded area) correspond to HZD values between -1 and +1 HZU. Orbits of exoplanets outside the outer edge of the HZ are shown in blue and those outside the inner edge as red. Those that just cross the HZ are shown in light green and those continuously within the HZ in dark green.
Table 1. List of exoplanets partially crossing (black text) or continuously (red text) within the habitable zone. The table lists their mass (M), radius (R), period (P), mean distance (d), equilibrium temperature (Teq), habitable zone distance (HZD). Radius was estimated for many with a mass-radius relationship.
-------------------------------------------------------------------------------------- Name M(EU) R(EU) P(days) d(AU) Teq(K) HZD HZ -------------------------------------------------------------------------------------- 16 Cyg B b 533.90 7.44 800. 1.22 228. -0.10 Partial 24 Sex c 273.31 6.02 883. 1.99 353. -1.26 Partial 30 Ari B b 3139.86 13.02 335. 0.95 309. -0.96 Partial 47 Uma b 804.03 8.47 1078. 2.10 200. 0.53 Full 55 Cnc f 45.76 3.42 261. 0.78 252. -0.50 Full 61 Vir d 22.88 2.75 123. 0.45 354. -1.26 Partial BD-17 63 b 1620.78 10.56 656. 1.13 163. 1.54 Partial eps Eridani b 492.59 12.37 2502. 2.41 137. 3.11 Partial GJ 3021 b 1070.99 9.27 134. 0.42 357. -1.27 Partial Gl 581 d 6.04 1.81 67. 0.21 183. 0.62 Partial Gliese 876 b 723.19 8.19 61. 0.21 194. 0.33 Full Gliese 876 c 226.97 5.68 30. 0.13 250. -0.58 Full HAT-P-13 c 4608.10 14.70 448. 0.88 330. -1.13 Partial HD 106252 b 2402.57 11.96 1600. 2.38 172. 1.41 Partial HD 106270 b 3495.80 13.47 2890. 3.94 198. 0.52 Partial HD 10647 b 295.55 6.17 1003. 2.02 197. 0.64 Full HD 10697 b 2027.56 11.34 1076. 2.15 223. -0.01 Full HD 108874 b 432.21 6.96 395. 1.05 257. -0.55 Full HD 108874 c 323.52 6.35 1606. 2.59 163. 1.67 Partial HD 113538 b 85.81 4.18 263. 0.56 222. -0.12 Partial HD 114729 b 266.95 5.98 1135. 1.97 215. 0.14 Partial HD 114783 b 317.80 6.31 501. 1.19 182. 0.89 Partial HD 11506 b 1093.23 9.33 1270. 2.37 204. 0.45 Partial HD 11964 b 197.67 5.43 1945. 3.16 192. 0.61 Full HD 125612 b 953.40 8.93 502. 1.22 242. -0.30 Full HD 12661 b 730.94 8.21 264. 0.77 306. -0.97 Partial HD 126614 b 120.76 4.65 1244. 2.14 176. 1.22 Partial HD 128311 b 692.80 8.08 449. 1.06 181. 0.89 Partial HD 131496 b 699.16 8.10 883. 2.06 324. -1.12 Partial HD 134987 b 505.30 7.31 258. 0.79 319. -1.06 Partial HD 137388 b 70.87 3.93 330. 0.83 230. -0.18 Full HD 141937 b 3082.66 12.94 653. 1.39 228. -0.08 Partial HD 142 b 327.33 6.37 339. 0.93 262. -0.54 Partial HD 142245 b 603.82 7.73 1299. 2.62 303. -0.99 Partial HD 142415 b 514.84 7.35 386. 0.91 274. -0.70 Partial HD 147513 b 384.54 6.71 528. 1.27 223. -0.01 Full HD 148156 b 270.13 6.00 1010. 2.09 211. 0.31 Partial HD 153950 b 867.59 8.67 499. 1.20 283. -0.77 Partial HD 154672 b 1595.36 10.51 164. 0.48 412. -1.47 Partial HD 154857 b 572.04 7.60 409. 1.06 363. -1.30 Partial HD 156411 b 235.17 5.74 842. 1.83 282. -0.78 Partial HD 16175 b 1398.32 10.08 990. 1.70 278. -0.73 Partial HD 163607 c 727.76 8.20 1314. 2.40 201. 0.43 Full HD 164509 b 152.54 5.01 282. 0.84 292. -0.86 Partial HD 168443 c 5463.94 15.51 1750. 2.77 182. 0.99 Partial HD 169830 c 1283.91 9.81 2102. 3.40 203. 0.50 Partial HD 170469 b 212.93 5.56 1145. 2.23 190. 0.79 Partial HD 171028 b 629.24 7.83 550. 1.07 338. -1.18 Partial HD 183263 b 1166.33 9.52 626. 1.41 240. -0.28 Full HD 188015 b 400.43 6.79 456. 1.18 235. -0.24 Full HD 190984 b 985.18 9.03 4885. 4.52 154. 2.36 Partial HD 192310 c 23.83 2.79 526. 1.12 178. 1.05 Partial HD 196050 b 899.37 8.77 1316. 2.41 189. 0.82 Partial HD 196885 A b 947.04 8.91 1326. 2.28 248. -0.34 Partial HD 19994 b 533.90 7.44 536. 1.35 315. -1.03 Partial HD 202206 b 5529.72 15.57 256. 0.75 296. -0.90 Partial HD 202206 c 775.43 8.37 1383. 2.46 163. 1.77 Partial HD 20367 b 340.05 6.45 500. 1.22 266. -0.59 Full HD 2039 b 1557.22 10.43 1183. 1.63 226. -0.03 Partial HD 205739 b 435.39 6.97 280. 0.86 338. -1.16 Partial HD 20868 b 632.42 7.85 381. 0.63 237. -0.34 Partial HD 210277 b 390.89 6.74 442. 0.97 260. -0.57 Partial HD 213240 b 1430.10 10.15 951. 1.81 240. -0.26 Full HD 216435 b 400.43 6.79 1311. 2.55 225. -0.04 Full HD 216437 b 578.40 7.63 1256. 2.22 175. 1.25 Partial HD 216770 b 206.57 5.51 118. 0.43 354. -1.26 Partial HD 217786 b 4131.40 14.20 1319. 2.18 201. 0.51 Partial HD 218566 b 66.74 3.86 226. 0.66 243. -0.42 Full HD 222582 b 2462.95 12.06 572. 0.93 278. -0.75 Partial HD 23079 b 794.50 8.43 626. 1.50 224. -0.01 Full HD 23596 b 2574.18 12.23 1565. 2.75 226. -0.05 Full HD 28185 b 1811.46 10.94 383. 1.03 242. -0.35 Full HD 28254 b 368.65 6.62 1116. 1.26 271. -0.68 Partial HD 30562 b 409.96 6.84 1157. 1.49 270. -0.66 Partial HD 30856 b 572.04 7.60 912. 1.94 323. -1.11 Partial HD 31253 b 158.90 5.07 466. 1.20 313. -1.02 Partial HD 33564 b 2891.98 12.68 388. 1.03 284. -0.77 Partial HD 34445 b 251.06 5.86 1049. 1.99 214. 0.18 Full HD 37124 b 214.51 5.58 154. 0.53 307. -0.99 Partial HD 37124 c 207.21 5.52 886. 1.70 172. 1.36 Partial HD 38529 c 5625.06 15.65 2135. 3.45 211. 0.22 Partial HD 38801 b 3400.46 13.35 696. 1.70 281. -0.80 Full HD 39091 b 3273.34 13.19 2049. 2.60 233. -0.17 Partial HD 40979 b 1042.38 9.19 263. 0.80 336. -1.15 Partial HD 4203 b 657.85 7.95 432. 0.99 291. -0.86 Partial HD 43197 b 190.68 5.37 328. 0.51 339. -1.19 Partial HD 44219 b 184.32 5.32 472. 0.94 300. -0.93 Partial HD 45350 b 568.86 7.59 891. 1.21 260. -0.56 Partial HD 50554 b 1639.85 10.60 1293. 2.09 190. 0.81 Partial HD 5319 b 616.53 7.78 675. 1.74 305. -1.00 Partial HD 69830 d 18.43 2.57 197. 0.63 283. -0.82 Full HD 7199 b 92.16 4.27 615. 1.34 201. 0.40 Full HD 73267 b 972.47 8.99 1260. 2.12 164. 1.62 Partial HD 73526 c 794.50 8.43 378. 1.04 295. -0.90 Partial HD 73534 b 365.47 6.60 1800. 3.15 200. 0.36 Full HD 74156 c 2551.93 12.19 2476. 3.07 192. 0.75 Partial HD 7449 b 352.76 6.53 1275. 1.32 233. -0.14 Partial HD 75898 b 797.68 8.44 418. 1.18 309. -0.98 Partial HD 80606 b 1252.13 10.32 111. 0.16 614. -1.80 Partial HD 81040 b 2180.11 11.60 1002. 1.65 181. 1.03 Partial HD 82943 b 556.15 7.53 441. 1.16 254. -0.48 Full HD 82943 c 638.78 7.87 219. 0.70 328. -1.12 Partial HD 8535 b 216.10 5.59 1313. 2.42 190. 0.86 Partial HD 85512 b 3.50 1.52 58. 0.26 299. -0.96 Partial HD 86264 b 2224.60 11.68 1475. 2.04 263. -0.55 Partial HD 8673 b 4512.76 14.60 1634. 2.09 243. -0.26 Partial HD 92788 b 1226.71 9.67 326. 0.91 255. -0.51 Full HD 9446 c 578.40 7.63 193. 0.65 316. -1.04 Partial HD 96167 b 216.10 5.59 499. 0.92 363. -1.29 Partial HD 99706 b 444.92 7.02 868. 1.99 358. -1.28 Partial HIP 14810 c 406.78 6.83 148. 0.54 330. -1.14 Partial HIP 14810 d 181.15 5.29 962. 1.86 177. 1.13 Partial HIP 57050 b 94.70 4.31 41. 0.16 226. -0.26 Full HIP 57274 d 167.48 5.16 432. 0.97 171. 1.18 Partial kappa CrB b 572.04 7.60 1191. 2.65 292. -0.90 Partial Kepler-16 (AB) b 105.83 8.45 229. 0.70 188. 0.59 Full mu Ara b 532.63 7.43 643. 1.49 230. -0.14 Full mu Ara d 165.86 5.14 311. 0.92 293. -0.88 Full ups And d 3238.38 13.15 1303. 2.45 223. 0.05 Full -------------------------------------------------------------------------------------- |
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(CC) Planetary Habitability Laboratory @ UPR Arecibo, 2017