Abstract:
A new study published in the prestigious journal Nature suggests that roughly 8% of stars (one in 12) may have consumed a planet, based on spectroscopic analysis of 91 stellar pairs.
Methodology:
After engulfing a planet, a star's chemical composition can change in a process called planetary ingestion. By comparing the elemental makeup of two stars born together (known as co-natal stars), it is possible to detect signs of planetary ingestion in the stars, as they share a common composition from the same molecular cloud core. However, studying chemical differences in stars has previously been challenging.
In this study, lead author and corresponding author Fan Liu from Monash University in Australia, along with colleagues and collaborators, identified 91 close pairs (less than 106 astronomical units apart) of co-natal stars using the European Space Agency's Gaia satellite. The stars' spectra, covering 21 elements, were obtained from the Very Large Telescope, Magellan Telescope, and Keck Observatory. Upon comparison, the authors found that 8% of the stellar pairs showed evidence of planetary ingestion in one of the stars. They also found that the observed evidence is consistent with a model of planetary ingestion.
Conclusions:
The authors conclude that planetary ingestion could occur throughout the lifetime of stellar systems, while external perturbations (such as rogue icy planets or stellar flybys) could disrupt the system's equilibrium due to the introduction of high-abundance elements into the star. They propose that planetary ingestion may have been particularly prevalent in the first 100 million years of stellar system formation, but evidence of these early events may not be detectable.
