NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered a strange star system, where a giant gassy planet is tightly orbiting a tiny white dwarf. Not only is this the first time such an arrangement has been seen, but it raises some very odd questions about how the planet survived the star’s expansive “death” in the first place.
The planet, named WD 1856 b, is roughly the size of Jupiter, making it about seven times bigger than the star it’s orbiting, named WD 1856+534. That’s a huge disparity – stars are normally much bigger than planets. In our own solar system, for example, you could squeeze about 1,000 Jupiters into the Sun.
The difference is that WD 1856+534 is a white dwarf star, a tiny remnant of what was once a Sun-like star. This one is only about 40 percent bigger than Earth and half the Sun’s mass. The planet, which is roughly the size of Jupiter, is so close that it orbits the white dwarf every 34 hours, which is 60 times faster than Mercury’s orbit around the Sun.
All of that is bizarre enough by itself. We’ve never seen such a huge planet orbiting such a tiny star, let alone that closely. Previous gas giants orbiting white dwarfs have been smaller and seem to be evaporating. But the really weird part is that it’s hard to explain just how this system came to be in this arrangement.
The team says that the most likely explanation is that the planet originally formed much further out from the star, beyond the reach of its red giant phase. Later on, the gravitational influence of other objects could have slowly nudged it into a closer orbit. The prime suspects are other gas giant planets born in the same system, but other candidates include two other nearby stars, or even a rogue star swinging through at some point.
Short video:
https://youtu.be/fDhG0ppvQ2g
https://newatlas.com/space/giant-planet-orbiting-tiny-star/