Kepler-78
Binary star in the constellation Cygnus
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Kepler-78 (formerly known as KIC 8435766) is a 12th magnitude star 407 light-years (125 parsecs) away in the constellation Cygnus. Initially classified as an eclipsing binary with orbital period 0.710015 days,[10] it was later re-classified as a single star with significant interaction between star magnetosphere and close-in planet.[11] The radius of the star is of about 74% of the Sun, and the effective temperature is about 5,100 K.
Artist's impression of the planet Kepler-78b around Kepler-78 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 34m 58.01374s[2] |
| Declination | +44° 26′ 53.9602″[2] |
| Apparent magnitude (V) | 11.72[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | K2.5V[4] |
| Astrometry | |
| Proper motion (μ) | RA: +38.195 mas/yr[2] Dec.: −16.309 mas/yr[2] |
| Parallax (π) | 8.0085±0.0104 mas[2] |
| Distance | 407.3 ± 0.5 ly (124.9 ± 0.2 pc) |
| Details | |
| Mass | 0.779+0.032 −0.046[5] M☉ |
| Radius | 0.7475+0.0077 −0.0078[5] R☉ |
| Luminosity | 0.31[6] L☉ |
| Surface gravity (log g) | 4.51[6] cgs |
| Temperature | 5,058±50[5] K |
| Metallicity [Fe/H] | −0.18±0.08[5] dex |
| Rotation | 12.53 days[7] |
| Rotational velocity (v sin i) | 3.1[8] km/s |
| Age | 240[7] Myr |
| Other designations | |
| Kepler-78, KIC 8435766, TYC 3147-188-1, 2MASS J19345800+4426539[9] | |
| Database references | |
| SIMBAD | data |
| KIC | data |
Planetary system
The Kepler-78 planetary system is composed of one known planet called Kepler-78b, a planet slightly bigger than Earth with an extremely close orbit to the parent star. The orbital period of this planet is about 8.5 hours because of its proximity to its star. While it has a similar density to the Earth (at 5.57 g/cm3), its surface temperature is about 1300 to 1500 K.[12]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 1.68±0.27 M🜨 | 0.00901+0.00012 −0.00019 |
0.35500745±0.00000008 | 0 | 75.2+2.6 −2.1° |
1.201±0.028 R🜨 |