Kepler-16
Binary star system in the constellation Cygnus
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Kepler-16 is an eclipsing binary star system in the constellation of Cygnus that was targeted by the Kepler spacecraft. Both stars are smaller than the Sun; the primary, Kepler-16A, is a K-type main-sequence star and the secondary, Kepler-16B, is an M-type red dwarf. They are separated by 0.23 AU, and complete an orbit around a common center of mass every 41 days. The system is host to one known extrasolar planet in circumbinary orbit: the Saturn-sized Kepler-16b.
An artist's rendering of the Kepler-16 system, showing the binary star being orbited by Kepler-16b. Credit: NASA/JPL-Caltech | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 16m 18.1759s[2] |
| Declination | +51° 45′ 26.778″[2] |
| Characteristics | |
| Spectral type | K7V[3] |
| Astrometry | |
| Proper motion (μ) | RA: 14.041±0.054[2] mas/yr Dec.: −48.601±0.051[2] mas/yr |
| Parallax (π) | 13.2893±0.0271 mas[2] |
| Distance | 245.4 ± 0.5 ly (75.2 ± 0.2 pc) |
| Orbit[4] | |
| Primary | Kepler-16A |
| Name | Kepler-16B |
| Period (P) | 41.077777±0.000035 days |
| Semi-major axis (a) | 0.2257±0.0010 AU |
| Eccentricity (e) | 0.15962±0.00037 |
| Inclination (i) | 90.30401±0.0019[5]° |
| Longitude of the node (Ω) | 0[5]° |
| Periastron epoch (T) | BJD 2457573.0995±0.0032 |
| Argument of periastron (ω) (secondary) | 263.67±0.02° |
| Semi-amplitude (K1) (primary) | 13.6787±0.0015 km/s |
| Semi-amplitude (K2) (secondary) | 46.88±0.28 km/s |
| Details | |
| Kepler-16A | |
| Mass | 0.704±0.011[4] M☉ |
| Radius | 0.6489±0.0013[5] R☉ |
| Luminosity | 0.148[6] L☉ |
| Surface gravity (log g) | 4.6527±0.0017[5] cgs |
| Temperature | 4,450±150)[5] K |
| Metallicity [Fe/H] | −0.3±0.2[5] dex |
| Rotation | 35.1±1.0 days[7] |
| Kepler-16B | |
| Mass | 0.2054±0.0019[4] M☉ |
| Radius | 0.22623±0.00059[5] R☉ |
| Luminosity | ~0.0057[6] L☉ |
| Surface gravity (log g) | 5.0358±0.0017[5] cgs |
| Temperature | ~3,311[6] K |
| Other designations | |
| KOI-1611, KIC 12644769, GSC 03554-01147, 2MASS J19161817+5145267, Gaia DR2 2133476355197071616[8] | |
| Database references | |
| SIMBAD | data |
| KIC | data |
Eclipses
The Kepler-16 system is almost edge-on to Earth and the two stars eclipse each other as they orbit. The larger and brighter primary star is partially eclipsed by the secondary for about six hours and the brightness drops by about 0.15 magnitudes. The secondary star is completely occulted by the primary star for about two hours, but the overall brightness only drops by about 0.02 magnitudes.
There are also shallow eclipses caused by a large exoplanet. When this transits across the primary star, the brightness drops by slightly more than the secondary eclipse. When it transits the secondary star, the brightness drops by 0.001 magnitudes.[5]
Planetary system
Kepler-16b is a gas giant that orbits the two stars in the Kepler-16 system.[5] The planet is a third of Jupiter's mass and slightly smaller than Saturn at 0.7538 Jupiter radii, but is more dense. Kepler-16b completes a nearly circular orbit every 228.776 days.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.333 MJ | 0.7048 | 228.776 | 0.0069 | 90.032° | 0.7538 RJ |