Kepler-138
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 21m 31.56798s |
| Declination | +43° 17′ 34.6810″ |
| Apparent magnitude (V) | 13.040±0.092 |
| Characteristics | |
| Spectral type | M1V |
| Apparent magnitude (V) | 13.040±0.092 |
| Apparent magnitude (Kepler) | 12.925 |
| Astrometry | |
| Radial velocity (Rv) | −37.25±0.72 km/s |
| Proper motion (μ) | RA: −20.461±0.012 mas/yr Dec.: 22.641±0.012 mas/yr |
| Parallax (π) | 14.9019±0.0097 mas |
| Distance | 218.9 ± 0.1 ly (67.11 ± 0.04 pc) |
| Absolute magnitude (MV) | 8.81 ± 0.28 |
| Details | |
| Mass | 0.535±0.012 M☉ |
| Radius | 0.535+0.013 −0.014 R☉ |
| Luminosity (bolometric) | 0.056±0.004 L☉ |
| Luminosity (visual, LV) | 0.026 ± 0.006 L☉ |
| Surface gravity (log g) | 4.71±0.03 cgs |
| Temperature | 3726+44 −40 K |
| Metallicity [Fe/H] | -0.28 ± 0.10 dex |
| Rotation | 19.394±0.013 days |
| Rotational velocity (v sin i) | ~3 km/s |
| Age | >1 Gyr |
| Other designations | |
| Kepler-138, KOI-314, KIC 7603200, TIC 159376971, 2MASS J19213157+4317347 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| KIC | data |
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Kepler-138, also known as KOI-314, is a red dwarf located in the constellation Lyra, 219 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets transiting their stars.
The star hosts three confirmed planets and a likely fourth, including the lowest-mass exoplanet with a measured mass and size discovered to date, Kepler-138b, with a mass comparable to that of Mars. Kepler-138d is remarkable for its low density; initially thought likely to be a gas dwarf, more recent observations as of 2022 show that it, as well as planet c, are likely to be ocean worlds.