DESI side project reveals the spectra of disintegrated exoplanets
Using spectral data from the Dark Energy Spectroscopic Instrument (DESI), astronomers have gained some of the clearest evidence yet that white dwarf stars are accreting debris from disintegrating exoplanets. Captured while DESI was unable to study its primary targets: distant galaxies, the results provide unprecedented insights into the chemical makeup of rocky exoplanets, revealing compositions…
The Dark Energy Spectroscopic Instrument (DESI), originally designed to study distant galaxies, has unexpectedly provided crucial insights into the composition of disintegrated exoplanets. By analyzing spectral data from white dwarfs—stars that leave behind hot, dense cores after their life cycles—a team of astronomers has discovered evidence of planetary debris accreting onto these stellar remnants.
This side project of DESI has revealed that between 20% and 50% of observed white dwarfs carry signatures of metals in their stellar spectra, indicating the presence of accreted rocky bodies. Among the 12 highly metal-enriched white dwarfs studied in detail by the DESI collaboration, the composition of accreted debris mirrors that of our own solar system, featuring elements such as oxygen, magnesium, silicon, calcium, and iron.
Six of the examined spectra were detailed enough to support further compositional analysis, indicating either dry, rock-forming compositions or potentially water-rich, oxide-bearing planetesimals. This discovery underscores the value of DESI as a tool for studying metal-rich white dwarfs and offers new avenues for understanding planet formation in different star systems, shedding light on the thousands of rocky exoplanets already discovered.
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