This page summarises the information held within TEPCat for the transiting planetary system K2-138b. Please see here for descriptions of the quantities given below.
| Quantity | Value | Unit |
|---|---|---|
| Reference of discovery paper | 2018AJ....155...57C | |
| Date of discovery paper | 2018 / 1 / 12 | y / m / d |
| Data/telescope used for discovery | K2 | |
| Right ascension | 23 15 47.77 | h m s |
| Declination | −10 50 58.9 | d m s |
| Right ascension (decimal) | 348.94904 | degrees |
| Declination (decimal) | -10.84969 | degrees |
| V-band apparent magnitude | 12.21 | mag |
| K-band apparent magnitude | 10.31 | mag |
| Transit duration | 0.0721 ( 1.730 ) | day hour |
| Transit depth | 0.03 | % |
| Time of mid-transit | 2457773.31683 ± 0.00091 | HJD or BJD |
| Orbital period | 2.353179 ± 0.000073 | days |
| Reference for orbital ephemeris | 2026A+A...711A.221L |
| Quantity | Value | Unit |
|---|---|---|
| Stellar effective temperature | 5275 ± 67 | K |
| Stellar metal abundance ([Fe/H] or [M/H]) | +0.06 ± 0.05 | dex |
| Stellar mass | 0.862 ± 0.034 | Msun |
| Stellar radius | 0.845 ± 0.006 | Rsun |
| Stellar logarithmic surface gravity | 4.51 ± 0.03 | c.g.s. |
| Stellar mean density | 1.429 ± 0.064 ( 2.016 ± 0.090 ) | ρsun g cm-3 |
| Orbital eccentricity | 0.0017 +0.0024 −0.0011 | |
| Orbital semimajor axis | 0.03385 +0.00023 −0.00029 | AU |
| Planetary mass | 0.0133 +0.0009 −0.0008 ( 4.23 +0.29 −0.25 ) | Mjup Mearth |
| Planetary radius | 0.1375 +0.0050 −0.0043 ( 1.541 +0.056 −0.048 ) | Rjup Rearth |
| Planetary surface gravity | m/s2 | |
| Planetary mean density | 4.72 +0.66 −0.41 ( 6.26 +0.88 −0.54 ) | ρjup g cm-3 |
| Planetary equilibrium temperature | 1308 +24 −20 | K |
| Reference of detailed study | 2026A+A...711A.221L |
K2-138b does not have an entry in the catalogue of orbital obliquity measurements.
Page generated on 2026/10/04 John Southworth (Keele University, UK)