Astronomers observe a star absorbing an exoplanet for the first time

For the first time in history, scientists observed a dying star swallowing a planet, according to a publication in the journal Nature. Several telescopes were used in the investigation, including LCO's Magellan twins.

Astronomers have recorded for the first time the absorption of a giant exoplanet by a Sun-like star. Such events can occur several times a year, according to the scientists. The discovery was published in the journal Nature.

Gemini/NOIRLab/NSF/AURA/P. Marenfeld

Gemini/NOIRLab/NSF/AURA/P. Marenfeld

It is now known that many exoplanets have short orbital periods around their stars and, as the stars evolve, they can expand and absorb nearby planets. For example, our Earth, too, is expected to be absorbed by the Sun within a few billion years.

Although scientists have observed exoplanets about to fall onto a star and planetary debris on white dwarfs, this is the first record of the destruction of an exoplanet by a star.

A flash

Astronomers led by Kishalay De of the Kavli Institute for Astrophysics and Space Research reported that they discovered the ZTF SLRN-2020 flare in archived observational data from the Zwicky Transient Facility 2020 system. In addition, they used data collected from the UKIRT survey, the NEOWISE telescopes, Gemini South, the Magellan Telescopes at Las Campanas Observatory, Swift, and the Keck Observatory.

The event was found in the disk of the Milky Way, at a distance of about 12 thousand light-years from the Sun. At first it showed a rapid increase in optical brightness until a maximum about 10 days after onset. After that its brightness faded for 6 months.

The flare was characterized by an exceptionally low luminosity in the optical range and an increase in source brightness in the mid-infrared range, starting about 7 months before the optical outburst and lasting at least 15 months.

Red subluminous novae

The researchers concluded that this event is best described by a model in which a Sun-like star swallows a giant exoplanet. The body would have had a mass of less than 10 Jupiters, and generated an ejection of dust and gas. This event constitutes a "missing link" in our understanding of the evolution of planetary systems.

Scientists have called such events "subluminous red novae" and estimate that they occur between 0.1 and several times a year. Now that we know what they can look like, we can find many more. Kishalay comments that "for decades, we have been able to see the before and after, what we lacked was to capture the star in the act."

It is also believed that ZTF SLRN-2020 could help us understand the effect of planetary dipping on the brightness, chemical composition, and rotation rate of late-stage stars.

This finding is really exciting. We rarely have information about the wild process that occurs when a star devours a planet.

Scientific Publication

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