Free Astronomy Magazine July-August 2023

JULY-AUGUST 2023 The star eventually grows to entirely engulf the orbiting planet, triggering an outburts that can be detected from Earth. “With these revolutionary new opti- cal and infrared surveys, we are now witnessing such events happen in real time in our own Milky Way — a testament to our almost certain fu- ture as a planet,” said Kishalay De, an astronomer at the Massachusetts Institute of Technology and lead au- thor on the paper. The outburst from the engulfment lasted approximately 100 days and the characteristics of its lightcurve, as well as the ejected material, gave astronomers insight into the mass of the star and that of its engulfed planet. The ejected material con- sisted of about 33 Earth masses of hydrogen and about 0.33 Earth masses of dust. “That’s more star- and planet-forming material being recycled, or burped out, into the in- terstellar medium thanks to the star eating the planet,” said Lau. From this analysis, the team estimated that the progenitor star is about 0.8−1.5 times the mass of our Sun and the engulfed planet was 1−10 times the mass of Jupiter. Now that the signatures of a plane- tary engulfment have been identi- fied for the first time, astronomers have improved metrics they can use to search for similar events happen- ing elsewhere in the cosmos. This will be especially important when Vera C. Rubin Observatory comes on line in 2025. For instance, the ob- served effects of chemical pollution on the remnant star when seen else- where can hint that an engulfment has taken place. The interpretation of this event also provides evidence for a missing link in our understanding of the evolu- tion and final fates of planetary sys- tems, including our own. “I think there’s something pretty re- markable about these results that speaks to the transience of our exis- tence,” says Lau. “After the billions of years that span the lifetime of our Solar System, our own end stages will likely conclude in a final flash that lasts only a few months.” !