Evaporating planet explains gaseous disk formation around white dwarf WD J0914+1914

Star system: WD J0914+1914 | Distance from the Sun: 1393 light years

The white dwarf WD J0914+1914 is surrounded by a ring of gas containing hydrogen, oxygen, and sulfur. This material originates from a nearby Neptune-like or super-puff planet—a planet with a very low density—that is losing its atmosphere due to intense radiation from the star. The escaping gas forms a disk around the star, which is then slowly pulled onto the white dwarf's surface, creating the unique light signals observed by instruments.

Advanced simulations were used to model the atmosphere of these planets when blasted by extreme ultraviolet radiation from the white dwarf. These 3D models calculated the mass-loss rate as the planet evaporates, tracking how this gas travels to form the surrounding disk. The model also used viscous disk evolution, which describes how the gas spreads and moves within the disk over time.

The findings confirm that a planet orbiting at a distance of 15 solar radii is the likely source of this material. The gas-rich planet undergoes continuous photoevaporation, creating a stable gaseous disk. In contrast to previous ideas, the new data shows that this disk actually extends further out than the orbit of the planet itself, providing a precise explanation for the spectral patterns seen in the system.

Key findings
- The planet loses mass at a rate of 1.8 to 4 trillion grams per second.
- A gas-rich planet at 15 solar radii naturally produces the observed disk.
- The circumstellar disk reaches a stable state in less than 100,000 years.
- The disk structure extends beyond the path of the orbiting planet.

Scientific study

Planetary atmospheric escape and disk formation around WDJ0914+1914 (external link)