b Centauri Exoplanet System

Distant mega-Jupiter orbiting a pair of massive blue stars // b Centauri (b Cen), also designated HD 129116, is a real exoplanet system located 325 light-years away in the constellation Centaurus. It consists of two high-mass stars—b Cen A and b Cen B—which together weigh up to 10 times that of the Sun. The primary component, b Cen A, is 5. 6 times the mass of the Sun and 2. 93 times its size. It is a hot bluish star of spectral type B2. 5V, shining at several hundred times the Sun's luminosity with an 18,445 K (18,172 °C) surface temperature. The other star, b Cen B, is the smaller secondary component with an upper mass estimate of 4. 4 solar masses. A distance of ~1. 0 AU separate the pair, but the shape of their orbits around each other is unknown. Although such massive stars are expected to have short lifespans, b Cen is also a very young system at only 15 million years, meaning that both stars are still firmly on the main sequence. By blocking out the stars’ glare using an instrument called a coronagraph, astronomers discovered a third body on the outskirts of b Cen in 2021. The object—designated b Cen (AB) b—is a circumbinary planet, meaning that it orbits around both central stars from afar. It is a massive gas giant of 10. 9 Jupiter masses, equivalent to over 3400 Earths. Still red-hot from the residual heat of its formation, b Cen (AB) b shines with an intrinsic luminosity one ten-thousandth that of the Sun. While certainly minuscule compared to a star's brightness, it is largely thanks to this glow that the planet could be seen. b Cen (AB) b’s distance to its host is projected at a vast 556 AU, about 19 times that of Neptune’s distance to the Sun. While the shape of its orbit is not well constrained, its orbital period is estimated at between 2650 and 7170 years. b Cen is one of the most massive star systems confirmed to host an exoplanet, challenging the traditional belief that the intense radiation and stellar winds of high-mass stars would quickly disperse pl