In a recent study published in the prestigious journal Nature, researchers analyzed the spectra of 91 pairs of stars and found that the "diet" of stars reveals that about 8% of them (1 in 12) may have consumed a planet.
Planetary ingestion refers to the alteration of a star's chemical composition after it engulfs a planet. By comparing the elemental compositions of two stars that were born together (known as co-natal stars), researchers can potentially detect signs of these ingested planets because the stars share a common composition from their birth molecular cloud core. However, studying differences in stellar chemistry has been challenging.
For this study, the lead author, Fan Liu of Monash University in Australia, along with colleagues and collaborators, identified 91 pairs of close (less than 106 astronomical units apart) co-natal stars using the European Space Agency's Gaia satellite. The stars' spectra, covering 21 elements, were obtained from the Very Large Telescope, the Magellan Telescopes, and the Keck Observatory. Upon comparison, the authors identified indications of planetary ingestion in 8% of the star pairs. They also found that the observed evidence is consistent with a model of planetary ingestion.
The authors conclude that planetary ingestion could occur throughout a star system's lifetime, with external perturbations (such as stray icy planets or stellar fly-bys) potentially disrupting the system's balance by introducing elements in higher concentrations to the star. They suggest that planetary ingestion may be particularly prevalent in the first 100 million years of a star system's formation, but evidence for these early events may not be detectable.
