How a Swallowed Planet Spun Up a Star ⚡ экспресс
The star GJ 504 – a Sun-like star, 2 billion years old – spins unusually fast (period 3.4 days) and shows strong magnetic activity, defying its evolutionary stage. Astronomers think a nearby giant planet, tugged by tides, plunged into the star and spun it up, rejuvenating its magnetic dynamo. Using spectropolarimetry and 3D wind modeling, they measured the rate at which the star loses angular momentum. Comparing with evolutionary models revealed that only a scenario where the planet was swallowed explains the observations. Interestingly, they found another candidate star facing a similar fate—perhaps such events aren’t rare.
The star GJ 504, a twin of our Sun in age, behaves like a true figure skater: it completes a rotation in 3.4 days, shining with X-ray light. Usually, stars of the Sun's age spin sluggishly, but this one seems to have received a cosmic doping.
The secret was revealed by modeling. Light analysis (spectroscopy) showed that normal braking by the stellar wind couldn't have slowed it down. The only explanation: in the past, the star swallowed a exoplanet the size of Jupiter. This 'dance partner' transferred its orbital momentum, and the star spun up like a figure skater after a lift. Without that, it would rotate lazily—a full revolution per month.
A similar 'dancer' has been found at HD 75332—it seems celestial choreography is more common than expected.
🎯 The star GJ 504 completes a full rotation in 3.4 days—seven times faster than our Sun.