Kepler-38
Kepler-38 is a binary star system in the constellation Lyra. These stars, called Kepler-38A and Kepler-38B have masses of 95% and 25% solar masses respectively. The brighter star is spectral class G while the secondary has spectral class M. They are separated by 0.147 AU, and complete an eccentric orbit around a common center of mass every 18.8 days.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 07m 19.2814s[1] |
| Declination | +42° 16′ 45.120″[1] |
| Characteristics | |
| Spectral type | G V[2] / M[3] |
| Astrometry | |
| Proper motion (μ) | RA: −4.648±0.026[1] mas/yr Dec.: −13.159±0.025[1] mas/yr |
| Parallax (π) | 0.8225 ± 0.0145 mas[1] |
| Distance | 3,970 ± 70 ly (1,220 ± 20 pc) |
| Orbit | |
| Primary | Kepler-38A |
| Companion | Kepler-38B |
| Period (P) | 18.79537 |
| Semi-major axis (a) | 0.1469 |
| Eccentricity (e) | 0.1032 |
| Details | |
| Kepler-38A | |
| Mass | 0.949 M☉ |
| Radius | 1.757 R☉ |
| Temperature | 5640 K |
| Metallicity | -0.11 |
| Kepler-38B | |
| Mass | 0.249 M☉ |
| Radius | 0.2724 R☉ |
| Metallicity | -0.11 |
| Other designations | |
| Database references | |
| SIMBAD | data |
| KIC | data |
Planetary system
In 2012, a circumbinary Neptune-sized planet was found transiting the brighter star. Follow-up radial velocity measurements did not give sufficient information to constrain the mass of the planet. The planet was confirmed via transit duration variation method.
It is likely that additional planets in the habitable zone exist, including rocky terrestrial planets, according to simulations of the formation of the Kepler-38 system; furthermore, the orbits of any such planets are probably stable.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | — | 0.4644 | 105.595 | — | — | 0.39 RJ |
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Orosz, Jerome A.; et al. (2012), "THE NEPTUNE-SIZED CIRCUMBINARY PLANET KEPLER-38b", The Astrophysical Journal, 758 (2): 87, arXiv:1208.3712, Bibcode:2012ApJ...758...87O, doi:10.1088/0004-637X/758/2/87, S2CID 119226095
- "Notes for star Kepler-38(AB)". Extrasolar Planets Encyclopaedia. 2012. Retrieved 29 April 2013.
- "Kepler-38". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 4 January 2017.
- Macau, E E N.; Domingos, R. C.; Izidoro, A.; Amarante, A.; Winter, O. C.; Barbosa, G. O. (2020), "Earth-size planet formation in the habitable zone of circumbinary stars", Monthly Notices of the Royal Astronomical Society, 494: 1045–1057, arXiv:2003.11682, doi:10.1093/mnras/staa757, S2CID 214667061
