years, inclination between 128 and 157 degrees, and eccentricity smaller than 0.4. The SPHERE images show the planet has approximately 0.01% the solar luminosity, a relic of its recent formation. From this luminosity and the age of the system, cooling models predict it has a mass of about 11 times the mass of Jupiter. The mass ratio between b Cen (AB)b and the central binary star is 0.10—0.17%, which is similar to the Sun-Jupiter system and is consistent to the expectations that more massive stars tend to have more massive planets. The formation mechanism for b Cen (AB)b is uncertain. It is believed that most giant planets are formed via core accretion, in which a rocky core, after growing to a critical mass, starts rapidly accreting the surrounding gas of the circumstellar disc. This mechanism cannot explain b Cen (AB)b, because core accretion becomes less efficient at large distances from the star, and massive stars like b Centauri A cause the disc to dissipate much quicker. It's more probable that the planet formed directly from the circumstellar gas, through a mechanism known as gravitational instability. This process is much faster than core accretion and can act even at separations of hundreds of astronomical units. Another possibility is that the planet formed closer to the central stars and was subsequently ejected to its current orbit through interactions with another body, but this is disfavored by the lack of evidence of other planets in the system and by the low eccentricity of b Cen (AB)b. The discovery of b Cen (AB)b showed that planets can exist even around massive stars. Previous studies had shown that planet occurrence rate starts to drop for stars over 2 and reaches almost zero for 3 stars, but this result is valid only for close in planets, which the radial velocity method can detect. The discovers of b Cen (AB)b argued that the short lifetime of the circumstellar discs around massive stars may prevent planets from migrating closer to their stars, but allows the existence of distant planets like b Cen (AB)b. References External links B-type main-sequence stars Centauri, b Centaurus (constellation) Durchmusterung objects 129116 071865 5471 Binary stars Planetary systems with one confirmed planet