Aging Sun‑like Stars Could Be Swallowing Nearby Planets

As stars like our Sun advance through their life cycles, they may do more than just fade gracefully into the backdrop of the cosmos — they may actively devour the planets orbiting close to them.

The stellar change‑up

Stars similar to the Sun spend billions of years in the so‑called “main sequence” phase, burning hydrogen in their cores. When the hydrogen runs out, the star’s core contracts while its outer layers expand and cool. The star enters the red‑giant phase, ballooning in size and altering the dynamics of its planetary system.
The Royal Astronomical Society

Evidence of planetary destruction

A recent large‑scale study by teams at University College London and University of Warwick finds clear statistical evidence that many planets that once orbited close to aging stars are now missing.

The researchers examined nearly half a million stars in the early post‑main‑sequence phase.

Among these, they identified about 130 planets or planet candidates in very close orbits.

The fraction of stars with such nearby planets drops dramatically once the star is well into the red‑giant stage — from about 0.35% to as low as 0.11%.

How does it happen?

The key mechanism appears to be tidal interaction. As the star expands, it exerts stronger tidal forces on nearby planets. These forces act to slow the planet’s orbit, causing it to spiral inward until it is either torn apart or swallowed by the star.
The Royal Astronomical Society

Additionally, the star’s outer layers expanding outward raise the possibility of direct engulfment — the planet may end up inside the star’s envelope.

What this means for our Solar System

While the planets in the referenced study are typically giant planets in very tight orbits, the findings do raise questions about the future of our own system. In roughly five billion years, the Sun will become a red giant. The study suggests close‑in planets are likely to be engulfed in such cases.

However, the study also indicates that planets farther out — like Earth, Mars and beyond — may survive longer (though not indefinitely) under some conditions.

Why this discovery matters

It gives empirical support to long‑standing theories about what happens to planetary systems as their stars age.

It helps refine models of planet survival and destruction, which in turn informs our search for exoplanets and potentially habitable worlds.