| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Parent star | ||
| Star | Kepler-16 | |
| Constellation | Cygnus | |
| Apparent magnitude | (mV) | 11.5 |
| Distance | 200[1] ly (61 pc) |
|
| Mass | (m) | 0.69 / 0.2026 M☉ |
| Radius | (r) | 0.649 / 0.2262 R☉ |
| Temperature | (T) | 4450 ± 150 (A) K |
| Metallicity | [Fe/H] | -0.3 ± 0.2 (A) |
| Orbital elements Epoch BJD 2455212.12316 |
||
| Semimajor axis | (a) | 0.7048 ± 0.0011 AU |
| Eccentricity | (e) | 0.0069 ± 0.0015 |
| Orbital period | (P) | 228.776 ± 0.037 d |
| Inclination | (i) | 90.0322 ± 0.0023° |
| Longitude of the node | (Ω) | 0.003 ± 0.013° |
| Argument of periastron |
(ω) | 318 ± 22° |
| Mean longitude | (λ) | 106.51 ± 0.32° |
| Physical characteristics | ||
| Mass | (m) | 0.333 ± 0.015 MJ |
| Radius | (r) | 0.7538 ± 0.0025 RJ |
| Density | (ρ) | 0.964 ± 0.047 g cm-3 |
| Surface gravity | (g) | 14.52 ± 0.7 m/s² |
| Temperature | (T) | 170 - 200 K |
| Discovery information | ||
| Discovery date | 07.07.2011 | |
| Discoverer(s) | Laurance Doyle[1] | |
| Detection method | Transit (Kepler Mission) | |
| Discovery status | Published | |
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
Kepler-16b (formally Kepler-16 (AB)-b, unofficially referred to as Tatooine) is an extrasolar planet. It is a Saturn-mass planet consisting of half rock and half gas,[2] and it orbits a binary star, Kepler-16, with a period of 229 days.[1] "[It] is the first confirmed, unambiguous example of a circumbinary planet – a planet orbiting not one, but two stars," said Josh Carter of the Harvard-Smithsonian Center for Astrophysics, one of the discovery team.[3]
The planet was discovered using the space observatory aboard NASA's Kepler spacecraft.[4] Scientists were able to detect the planet using the transit method, when they noticed the dimming of one of the system's stars even when the other was not eclipsing it.[4] Furthermore, timing all the eclipses and transits of the planet and stars in the system has allowed for unusually high precision in the calculations of the sizes and masses of objects in the Kepler-16 system.[5] The leader of the planet's discovery team, Laurance Doyle of the SETI Institute in Mountain View, California, said of this precision, "I believe this is the best-measured planet outside the solar system."[5] For example, the planet's radius is known to within 0.3%, better than that of any other known exoplanet (as of September 2011).[6]
Kepler-16b is also unusual in that it falls inside the radius that was thought to be the inner limit for planet formation in a binary star system.[5] According to Sara Seager, a planetary expert at the Massachusetts Institute of Technology, it was thought that for a planet to have a stable orbit around such a system, it would need to be at least seven times as far from the stars as the stars are from each other.[5] Kepler-16b's orbit is only about half that distance.[5]
As seen from Earth, the planet will cease transiting one star as soon as 2014, and will stop crossing the second and brighter star in 2018. After that, the planet will remain undetectable using the transit method until around 2042.[5]
The planet orbits on the outer edge of the habitable zone[7], however it is likely a gas giant with surface temperatures around -100 to -70 °C (-150 to -94 °F).
In the announcement paper, the discovery team stated: "Following the convention of Ref. 22,[8] we can denote the third body Kepler-16 (AB)-b, or simply “b” when there is no ambiguity."[1] It is listed as Kepler-16 (AB)-b on the SIMBAD Astronomical Database.[9] The Extrasolar Planets Encyclopaedia lists it as Kepler-16 (AB) b.[10]
Astronomers have informally referred to Kepler-16b as "Tatooine," after the fictional planet orbiting two suns that is a key setting in the Star Wars film series.[5] "Again and again we see that the science is stranger and weirder than fiction" said John Knoll, a visual effects supervisor at Industrial Light & Magic who worked on several of the movies.[5]