Study indicates that the death of a star does not mean the end of the entire planetary system

Analysis of a Planet in a Dead Star

The study focused on the exoplanet WD 1856 b, a giant located about 80 light-years from Earth. This planet has a size comparable to Jupiter, but its mass is significantly greater, ranging between four and eleven times that of Jupiter. The most notable aspect is its orbit: it circles a white dwarf every 1.4 days, remaining at only 0.02 astronomical units away, which corresponds to about three million kilometers.

Initially, it seemed impossible for the planet to be in this orbit, given that during the red giant phase of the progenitor star, it occupied a much larger area. Astronomers debated whether the planet would have survived inside the atmosphere of the red giant or if it would have migrated from a more distant initial position to the interior of the system after stellar death.

Contribution of the James Webb Telescope

To resolve this doubt, scientists used the NIRSpec spectrograph of the James Webb Telescope during a brief astronomical transit of the planet in front of the white dwarf. This phenomenon lasted only eight minutes, requiring extreme precision in the collected data.

Atmospheric and Thermal Discoveries

Observations revealed the presence of hydrocarbons, possibly methane, along with mist and clouds in the planet's atmosphere, indicating a notably high carbon concentration. This is the first atmospheric characterization of a planet orbiting a dead star. This chemical composition is valuable as it can indicate both materials incorporated during formation and compounds accumulated over billions of years.

However, the most crucial discovery was the planet's temperature, estimated at about 400 Kelvin (approximately 127°C), a value much higher than the 160 Kelvin expected if the energy were supplied solely by the faint white dwarf.

Historical Reconstruction of the Planet

By applying planetary cooling models, researchers were able to recreate the thermal history of WD 1856 b and determine its heating period. The result indicated that this heating occurred between 3 and 5.5 billion years after the star transformed into a white dwarf. This virtually eliminates the hypothesis of survival inside the red giant, as the heating would have coincided with the stellar death.

The most plausible explanation is that the planet remained in a safe and distant orbit for long periods. Only much later did gravitational interactions trigger a process of planetary migration, altering its trajectory and generating internal heat through tidal forces.

Implications for Solar Systems

This finding demonstrates that the evolution of a planetary system does not cease with the death of its star, but can continue for billions of years. Surviving gas giants can alter their orbits, undergo gravitational interactions, and migrate toward the stellar remnant long after the original star has disappeared.

Although it is unknown if something similar will happen in our Solar System, the case of WD 1856 b proves that Jupiter and other gas giants may have a much longer and more complex history than previously imagined. For the first time, astronomers have been able to observe and reconstruct a possible future for the Solar System, suggesting that the death of the Sun may be the beginning of a new cycle.