The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data

Bryson, Steve; Kunimoto, Michelle; Kopparapu, Ravi K.; Coughlin, Jeffrey L.; Borucki, William J.; Koch, David; Aguirre, Victor Silva; Allen, Christopher; Barentsen, Geert; Batalha, Natalie M.; Berger, Travis; Boss, Alan; Buchhave, Lars A.; Burke, Christopher J.; Caldwell, Douglas A.; Campbell, Jennifer R.; Catanzarite, Joseph; Chandrasekaran, Hema; Chaplin, William J.; Christiansen, Jessie L.; Christensen-Dalsgaard, Jorgen; Ciardi, David R.; Clarke, Bruce D.; Cochran, William D.; Dotson, Jessie L.; Doyle, Laurance R.; Duarte, Eduardo Seperuelo; Dunham, Edward W.; Dupree, Andrea K.; Endl, Michael; Fanson, James L.; Ford, Eric B.; Fujieh, Maura; Gautier III, Thomas N.; Geary, John C.; Gilliland, Ronald L.; Girouard, Forrest R.; Gould, Alan; Haas, Michael R.; Henze, Christopher E.; Holman, Matthew J.; Howard, Andrew W.; Howell, Steve B.; Huber, Daniel; Hunter, Roger C.; Jenkins, Jon M.; Kjeldsen, Hans; Kolodziejczak, Jeffery; Larson, Kipp; Latham, David W.; Li, Jie; Mathur, Savita; Meibom, Soren; Middour, Chris; Morris, Robert L.; Morton, Timothy D.; Mullally, Fergal; Mullally, Susan E.; Pletcher, David; Prsa, Andrej; Quinn, Samuel N.; Quintana, Elisa V.; Ragozzine, Darin; Ramirez, Solange V.; Sanderfer, Dwight T.; Sasselov, Dimitar; Seader, Shawn E.; Shabram, Megan; Shporer, Avi; Smith, Jeffrey C.; Steffen, Jason H.; Still, Martin; Torres, Guillermo; Troeltzsch, John; Twicken, Joseph D.; Uddin, Akm Kamal; Van Cleve, Jeffrey E.; Voss, Janice; Weiss, Lauren M.; Welsh, William F.; Wohler, Bill; Zamudio, Khadeejah A.
2021
ASTRONOMICAL JOURNAL
DOI
10.3847/1538-3881/abc418
We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define eta(circle plus) as the HZ occurrence of planets with radii between 0.5 and 1.5 R-circle plus orbiting stars with effective temperatures between 4800 and 6300 K. We find that eta(circle plus) for the conservative HZ is between 0.37(-0.21)(+0.48) (errors reflect 68% credible intervals) and 0.60(-0.36)(+0.90) planets per star, while the optimistic HZ occurrence is between 0.58(-0.33)(+0.73) and 0.88(-0.51)(+1.28) planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is similar to 6 pc away and there are similar to 4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun.