HS 0209+0832 is a young white dwarf in the constellation Cetus.
Planetary system In 1999, Hubble Space Telescope observations in the far-ultraviolet detected the presence of carbon, aluminium, silicon, and other heavy elements in HS 0209+0832's atmosphere. The presence of these elements, alongside the helium-enriched atmosphere, suggested ongoing accretion, but no source was identified. In the 25 years since, several other similarly polluted white dwarfs were discovered to be planetary debris.
In a paper published on 5 October 2026, the detection of a second-generation exoplanet was announced in the journal Nature. NASA announced that the Hubble Space Telescope had been used to view HS 0209+0832 and had seen the unusual abundance of certain elements in the atmosphere; niobium, nickel, and calcium had been seen absorbing light, indicated by dips in the wavelengths of light.
HS 0209+0832 is the core of a star that burned through all of its nuclear fuel and its outer envelope of gas and dust were disassembled by outer space. This planet is a second generation planet that formed from the cast-off gas and dust. The planet is still hot and is full of radiation, which is the cause of the atmospheric collapse.
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