Astronomers discover first second-generation planet orbiting a white dwarf
A research team led by the University of Warwick has identified a Jupiter-sized planet that formed from the debris expelled during the death of the white dwarf HS 0209+0832.
Discovery of a second-generation world
An international team of astronomers led by the University of Warwick has identified a planet formed from the ejected material of its dying host star. The study, published on 5 October 2026 in Nature Astronomy with backing from the European Research Council, documents the first known second-generation planet orbiting a white dwarf. Researchers from the Instituto de Astrofísica de Canarias and the University of Wisconsin-Madison also participated in the investigation. While astronomers previously suspected the existence of reborn worlds around pulsars, this detection confirms that such planetary formation can take place around white dwarf remnants.
Jamie Williams, the lead author from the University of Warwick's Department of Physics, described the rarity of finding a planet assembled from its own star's remnants.
Second-generation planets are worlds that form out of the material a star casts off as it dies. They're incredibly rare, and finding one around a white dwarf was completely unexpected. It's a bit like finding a planet that has risen from the ashes of the very star it once orbited.
Heavy elements in the stellar atmosphere
White dwarfs are dense, collapsed stellar cores left behind when stars deplete their nuclear fuel, a fate awaiting more than 90% of stars in the Milky Way. These remnants possess intense gravitational fields that draw in surrounding debris, depositing material onto their outer layers and altering their spectroscopic signatures. Most polluted white dwarfs display signatures dominated by standard rock-forming elements such as silicon and iron, matching the composition of rocky asteroids. The target white dwarf in this study, designated HS 0209+0832, revealed a different chemical profile when examined.
Analyses of HS 0209+0832 revealed elevated concentrations of zinc, copper, and niobium, with abundance levels more than 1,000 times higher than those measured in the Sun. The presence of niobium represents the first detection of this element in a white dwarf atmosphere. Nuclear models show that this specific elemental signature arises through the slow neutron-capture process, known as the s-process, which synthesizes heavy elements inside dying stars during their red giant phase.
- Hubble Space Telescope discovers white dwarf HS 0209+0832 with over 100 unidentified spectral lines
- Astronomers identify survivor planet TIC 365102760 b orbiting a dying star
- Nature Astronomy publishes study identifying the second-generation planet around HS 0209+0832
Orbital dynamics and atmospheric evaporation
The chemical abnormalities on HS 0209+0832 originate from an active accretion process involving an orbiting companion. Data collected by NASA's Transiting Exoplanet Survey Satellite (TESS) detected periodic brightness variations repeating every 4.4 days. These periodic fluctuations correspond to a Jupiter-sized gas giant situated in an orbit around the collapsed stellar core.
Because the gas giant orbits at such close proximity, stellar radiation continuously heats and evaporates its outer gaseous envelope. Portions of the vaporized planetary atmosphere escape the planet's gravitational pull and fall directly onto the surface of the white dwarf. This continuous deposition of enriched planetary material maintains the heavy element concentrations observed in the stellar spectrum.
Formation mechanisms and stellar evolution
Planetary creation from stellar ejection requires specific environmental conditions. In the HS 0209+0832 system, researchers suggest that a companion star played a decisive role by capturing part of the expelled matter during the red giant transition. This gravitational interaction facilitated the development of a protoplanetary accretion disk around the newly formed white dwarf, providing the raw material necessary to condense a gas giant.
The discovery broadens understanding of stellar evolution and post-main-sequence planetary systems. Unlike surviving first-generation planets that endure the expansion of a red giant, this system demonstrates that planetary birth can restart around dense stellar remnants. Researchers are utilizing spectral monitoring to assess whether similar accretion signatures exist around other catalogued white dwarfs.
