Exoplanets · Space Codex
Kepler-16 b
A cold, Saturn-like planet orbiting a pair of stars that eclipse each other every 41 days: the first confirmed transiting circumbinary planet.
A real world with two suns
Artist's concept. No telescope has seen Kepler-16 b as more than a point of light, and most exoplanets not even that. What we know comes from how a planet dims or tugs its star. Any picture of its surface, colour or sky, anywhere, is an illustration, not an observation.
At a glance
Key points
- Orbits two stars at once
- First confirmed transiting circumbinary planet
- Cold and Saturn-like
How it was found
Kepler saw the two stars eclipse each other every 41 days, and then extra dips that did not fit: a third body crossing first one star, then the other. Its gravity also shifted the timing of the stellar eclipses slightly, so Laurance Doyle's team could weigh all three bodies from the light curve alone. The September 2011 Science paper made it the first clear case of a planet transiting two stars, quickly nicknamed after Tatooine in Star Wars.
Weighed again from the ground
In 2022 the BEBOP survey, using the SOPHIE spectrograph at Haute-Provence, the observatory where 51 Pegasi b was found, measured the brighter star's wobble with a precision of 1.5 m/s. Separating the planet's tug from the stars' own orbit gave 0.31 Jupiter masses, matching the eclipse-timing value and showing circumbinary planets can be found without transits.
A flat, cold system
The planet and both stars move within half a degree of a single plane, a strong hint that it formed in a disc of gas and dust surrounding the pair. At 0.7 AU from two dim stars it is cold, with an equilibrium temperature far below freezing.
Double sunsets
Any observer on a moon of Kepler-16 b would see two suns, a larger orange one and a smaller red one, and cast two shadows. Because both stars move, the planet's transits change in length and timing from one orbit to the next.
Missions
- 2009–2018
Kepler / K2
NASACompletedTransit survey that showed small planets are common.
Related entries
- Exoplanets: the censusPlanets around other stars
Sources
- NASA Exoplanet Archive: Kepler-16 overview (opens in a new tab)
- Doyle et al. 2011, Science 333:1602 (arXiv) (opens in a new tab)
- Triaud et al. 2022, MNRAS, BEBOP III (arXiv) (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.