Planet K2-18 b
| Name | K2-18 b | ||
| Planet Status | Confirmed | ||
| Discovered in | 2015 | ||
| Mass | 0.02807 ( -0.00503 +0.00535 ) MJ |  |
|
| Mass*sin(i) | — | |
|
| Semi-Major Axis | 0.1429 ( -0.0065 +0.006 ) AU | |
|
| Orbital Period | 32.939623 ( -0.0001 +9.5e-05 ) day | |
|
| Eccentricity | 0.2 (± 0.08) | |
|
| ω | -5.7 ( -33.8 +46.4 ) deg | |
|
| Tperi | — | ||
| Radius | 0.211 ( -0.02 +0.02 ) RJ | |
|
| Inclination | 89.5785 ( -0.0088 +0.0079 ) deg | ||
| Update | 2021-02-05 | ||
| Detection Method | Primary Transit | ||
| Mass Detection Method | Theoretical | ||
| Radius Detection Method | Primary Transit | ||
| Primary transit | 2457264.39144 (± 0.00065) JD | ||
| Secondary transit | — | ||
| λ | — | ||
| Impact Parameter b | — | ||
| Time Vr=0 | — | ||
| Velocity Semiamplitude K | 3.55 ( -0.58 +0.57 ) m/s | ||
| Calculated temperature | 284.0 ( -15.0 +15.0 ) K | |
|
| Measured temperature | — | ||
| Hottest point longitude | — | ||
| Geometric albedo | — | ||
| Surface gravity log(g/gH) | — | ||
| Alternate Names | EPIC 201912552 b, 2MASS J11301450+0735180 b, EPIC 201912552.01, WISE J113014.45+073516.8 b |
Star
K2-18| Name | K2-18 | ||
| Distance | 38.07 ( -0.08 +0.08 ) pc | ||
| Spectral type | M2.5 V | ||
| Apparent magnitude V | 13.5 | ||
| Mass | 0.36 ( -0.05 +0.05 ) MSun | ||
| Age | — | ||
| Effective temperature | 3457.0 ( -39.0 +39.0 ) K | ||
| Radius | 0.41 ( -0.04 +0.04 ) RSun | ||
| Metallicity [Fe/H] | 0.12 ( -0.16 +0.16 ) | ||
| Detected Disc | — | ||
| Magnetic Field | — | ||
| RA2000 | 11:30:14.5 | ||
| Dec2000 | +07:35:18 | ||
| Alternate Names | EPIC 201912552, 2MASS J11301450+0735180, WISE J113014.45+073516.8 | ||
| Planetary system | 2 planets |
Atmospheric parameters
Temperatures
| Data Source | Type | Result Value | Result Figure | Notes | Reference |
Molecules
| Molecule | Data Source | Type | Result Value | Result Figure | Notes | Reference |
| CH4 | Measurements | Detected | 2020 - MADHUSUDHAN N. | |||
| H2O | Measurements | Detected | 2020 - MADHUSUDHAN N. | |||
| Measurements | Detected | 2019 - BENNEKE B. | ||||
| Measurements | Detected | 2019 - TSIARAS A. | ||||
| NH3 | Measurements | Detected | 2020 - MADHUSUDHAN N. | |||
Observability Predictor 
Related publications
Modeling the Transmission and Emission Spectra of K2-18b: Determining the Surfaces of Exoplanets with Hydrogen Dominated Atmospheres
2023
NICHOLSON L., HOOD C., FORTNEY J. & YU X.
Res. Notes AAS, 7, 87
paper
Characterising atmospheres of cloudy temperate mini-neptunes with JWST
2022
CONSTANTINOU S. & MADHUSUDHAN N.
MNRAS, 514, 2073
paper
CAMEMBERT: A Mini-Neptunes General Circulation Model Intercomparison, Protocol Version 1.0.A CUISINES Model Intercomparison Project
2022
CHRISTIE D., MEE A., INNES H., NOTI P., CHARNAY B. et al.
Plan. Sci. J., 3, 261
paper
Revisiting Radial Velocity Measurements of the K2-18 System with the Line-by-Line Framework
2022
RADICA M., ARTIGAU E., LEFRENIERE D., CADIEUX Ch., COOK N. et al.
MNRAS, 517, 5050
paper arxiv
1D atmospheric study of the temperate sub-Neptune K2-18b
2021
BLAIN D., CHARNAY B. & BEZARD B.
Astron. & Astrophys., 646, A15
paper
How to identify exoplanet surfaces using atmospheric trace species in hydrogen-dominated atmospheres
2021
YU X., MOSES J., FORTNEY J. & ZHANG X.
ApJ, 914, 38
paper arxiv
Deep Characterization of the Atmosphere of a Temperate Sub-Neptune
2021
HU R. et al.
JWST GO Programme
abstract
Chemical Disequilibrium in a Temperate Sub-Neptune
2021
MADHUSUDHAB N.
JWST GO Programme
abstract
How Deep Is the Ocean? Exploring the phase structure of water-rich sub-Neptunes
2021
NIXON M. & MADHUSUDHAN N.
MNRAS, 505, 3414
paper arxiv
Unveiling shrouded oceans on temperate sub-Neptunes via transit signatures of solubility equilibria vs. gas thermochemistry
2021
HU R., DAMIANIO M., SCHEUCHER M., KITE E., SEAGER S. & RAUER H.
ApJ. Letters, 921, L8
paper arxiv
Stellar surface inhomogeneities as a potential source of the atmospheric signal detected in the K2-18 b transmission spectrum
2021
BARCLAY Th., KOSTOV V., COLON K., QUINTANA E., SCHLIEDER J. et al.
Astron. J., accepted
arxiv
Photochemistry and Spectral Characterization of Temperate and Gas-rich Exoplanets
2021
HU R.
ApJ, 921, 27
paper
The interior and atmosphere of the habitable-zone exoplanet K2-18b
2020
MADHUSUDHAN N., NIXON M., WELBANKS L., PIETTE A. & BOOTH R.
ApJ. Letters, accepted
arxiv
Disentangling Atmospheric Compositions of K2-18 b with Next Generation Facilities
2020
CHANGEAT Q., EDWARDS B., AL-REFAIE A., TSIARAS A., WALDMANN I. & TINETTI G.
ApJ, submitted
arxiv
Formation of secondary atmospheres on terrestrial planets by late disk accretion
2020
KRAL Q., DAVOULT J. & CHARNAY B.
Nature Astronomy, 4, 769
paper arxiv
Consistently Simulating a Wide Range of Atmospheric Scenarios for K2-18b with a Flexible Radiative Transfer Module
2020
SCHEUCHER M., WUNDERLICH F., GRENFELL J., GODOLT M., SCHREIER F. et al.
ApJ., 898, 44
paper arxiv
Tidal evolution of exoplanetary systems hosting potentially habitable exoplanets. The cases of LHS-1140 b-c and K2-18 b-c
2020
GOMES G. & FERRAZ-MELLO S.
MNRAS, 494, 5082
paper arxiv
On the Temperature Profiles and Emission Spectra of Mini-Neptune Atmospheres
2020
PIETTE A. & MADHUSUDHAN N.
ApJ, accepted
arxiv
The high-energy environment and atmospheric escape of the mini-Neptune K2-18 b
2020
dos SANTOS L., EHRENREICH D., BOURRIER V., ASTUDILLO-DEFRU N., BONFILS X. et al.
Astron. & Astrophys., 634, L4
paper arxiv
Water vapour in the atmosphere of the habitable-
zone eight-Earth-mass planet K2-18 b
2019
TSIARAS A., WALDMANN I., TINETTI G., TENNYSON J. & YOURCHENKO S.
Nature Astronomy, in press, 3
paper arxiv
The weight of a world
2019
Anonymous
Nature Astronomy, 3, 875
paper
The K2-18b Planetary System: Estimates of the Age and X-UV Irradiances of a Habitable Zone "Wet" Sub-Neptune Planet
2019
GUINAN E. & ENGIE S.
Res. Notes AAS, 3, 189
paper
Mass-Radius relationship for M dwarf exoplanets: Comparing nonparametric and parametric methods
2019
KANODIA Sh., WOLFGANG A., STEFANSSON G., NING B. & MAHADEVAN S.
ApJ, submitted
arxiv
Water Vapor on the Habitable-Zone Exoplanet K2-18b
2019
BENNEKE B., WONG I., PIAULET C., KNUTSON H., CROSSFIELD I. et al.
ApJ. Letters, 887, L14
paper arxiv
The CARMENES search for exoplanets around M dwarfs: A low-mass planet in the temperate zone of the nearby K2-18
2018
PAULA S., HENNING Th., MARTIN K., TRIFON T., ZECHMEISTER L., et al.
Astron. J., accepted
arxiv
The CARMENES Search for Exoplanets around M Dwarfs: A Low-mass Planet in the Temperate Zone of the Nearby K2-18
2018
SARKIS P., HENNING Th., KÜRSTER M., TRIFONOV T., ZECHMEISTER M. et al.
Astron. J., 155, 257
arxiv
Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit
2017
CLOUTIER R., ASTUDILLO-DEFRU N., DOYON R., BONFILS X., ALMENARA J. et al.
Astron. & Astrophys., 608, A35
paper arxiv
ADS
Spitzer Observations Confirm and Rescue the Habitable-Zone Super-Earth K2-18b for Future Characterization
2016
BENNEKE B., WERNER M., PETIGURA E., KNUTSON H., DRESSING C. et al.
ApJ, 834, 187
paper arxiv
ADS
Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Systems, Including a Planet Receiving Earth-like Insolation
2015
MONTET B., MORTON T., FOREMAN-MACKEY D., JOHNSON J., HOGG D. et 4 additional authors
ApJ, 809, 25
arxiv
paper
ADS
