Star Seen Swallowing A Planet For The First Time, May Herald A Possible Fate Of Earth

The event, which has been named ZTF SLRN-2020, appears to have taken place in our own galaxy, some 12,000 light-years away, near the eagle-like constellation Aquila.

When a star nears the end of its life, it expands to several times its size, and swallows up everything in its wake, including planets. This is what will happen to our Sun, although that is still a long time away (5 billion years). When that happens, the Sun will absorb its nearest two planets (Mercury and Venus) and possibly even Earth.

All this is understood from theory, and has been deduced from the remnants of many giant red stars that astronomers have identified over the years. What had never been observed until now, however, is the actual process of a dying star consuming a planet. Now, this has finally happened.

In a study published in Nature on Wednesday, astronomers have described the first observation of an ageing star swallowing a planet. A statement from NASA describes the process: “After running out of fuel in its core, the star began to grow in size, shrinking the gap with its neighbouring planet, eventually consuming it entirely.”

The event, which has been named ZTF SLRN-2020, appears to have taken place in our own galaxy, some 12,000 light-years away, near the eagle-like constellation Aquila, according to details published by MIT, whose researchers were involved in the study. The planet has been estimated to be about the size of Jupiter, and its orbit is even closer to its star than Mercury’s orbit is to our Sun. 

Researchers described the event based on observations from multiple ground-based observatories and NASA’s NEOWISE spacecraft. 

The star was first seen expanding, and its outer atmosphere spread out, eventually engulfing the planet. The planet slowed down and its orbit shrank, and eventually it went below the star’s visible surface.

Although the star is dying, it has several years left. The final phase of its life (red giant phase) has begun, and this can sometimes last more than 100,000 years.

After consuming the planet, the star temporarily increased in size and became a few hundred times brighter, NASA said. Recent observations show the star has returned to the size and brightness it was before merging with the planet, it added.

NASA quoted MIT astronomer Kishalay De, lead author of the study in Nature, as saying: “This type of event has been predicted for decades, but until now we have never actually observed how this process plays out.”

When this happens to the Sun in five billion years, with the Sun consuming at least Mercury and Venus and possibly Earth too, the “light show” is expected to be much more subdued, NASA said, quoting De. These three planets in our Solar System are several times smaller than the one that was observed being consumed.