HS 0209+0832 System (Artist’s Concept)

This artist’s concept depicts a possible explanation for the unusual chemical abundances NASA’s Hubble Space Telescope detected in the HS 0209+0832 system: a second-generation planet orbiting the white dwarf star.

The white dwarf is the “dead” core of a star that burned through all of its nuclear fuel and lost its outer envelope of gas and dust to space. The second-generation planet formed from that cast-off gas and dust, which is why its chemical content is very different from a planet that formed as its host star was forming.

The white dwarf is still hot and is blasting the planet with radiation, causing it to lose atmosphere to space. That atmospheric material is flowing back toward the white dwarf, forming a disk and then falling back onto its surface, which is how Hubble detected the planetary chemical signatures when studying the star.