Categories: White dwarf

White Dwarf Atmospheres Might Contain the Pulverized Crusts of Their Dead Planets

Astronomers have developed a new technique to search for exoplanets – by looking for their crushed up bones in the atmospheres of white dwarfs. And it’s working.

The search for planets outside the solar system, known as exoplanets, has one significant limitation: we can only find exoplanets that exist right now. But our universe has been hanging around for over 13 billion years, and many generations of planetary systems have come and gone in that vast expanse of cosmic time.

Unfortunately, when stars die they usually take their planets with them. Especially the most massive stars, which die as supernova – those deaths usually obliterate any orbiting planet completely. But even when less massive stars like the sun die, it’s generally bad news for their planets.

But as a new research paper has pointed out, that doesn’t remove all evidence of the planetary system off the galactic map. If any planets (or remnant cores of planets) survive, they can occasionally gravitationally scatter off of each other. This doesn’t usually happen in stable systems, but in the death throes of a star anything is possible (gravitationally speaking).

Some of those scattered objects can head inwards to the white dwarf, the leftover core of the parent star. That white dwarf is made of almost completely pure carbon and oxygen, surrounded by a dense but thin shell of hydrogen and helium. Naturally, any object passing too close will get torn to shreds by the extreme gravity of the white dwarf, with the debris making its way to the surface to mix and mingle with the hydrogen and helium.

Once there, any elements in the destroyed object, like lithium and calcium, can release their own light, giving a spectral fingerprint that astronomers can potentially spot. Most white dwarfs are too hot, though, and that light outshines any contamination. But the recent Gaia mission was able to map dozens of old, cool white dwarfs, and astronomers have detected the distinct signature of crushed up planets in their atmospheres.

The astronomers found that the abundance of enriched elements matches what we know from our own solar system, indicating that planetary systems like ours have been in the universe for a very, very long time.

Paul M. Sutter

Astrophysicist, Author, Host | pmsutter.com

Recent Posts

SpaceX Reveals the Beefed-Up Dragon That Will De-Orbit the ISS

The International Space Station (ISS) has been continuously orbiting Earth for more than 25 years…

23 hours ago

Gaia Hit by a Micrometeoroid AND Caught in a Solar Storm

For over ten years, the ESA's Gaia Observatory has monitored the proper motion, luminosity, temperature,…

2 days ago

Lunar Infrastructure Could Be Protected By Autonomously Building A Rock Wall

Lunar exploration equipment at any future lunar base is in danger from debris blasted toward…

2 days ago

Why is Jupiter’s Great Red Spot Shrinking? It’s Starving.

The largest storm in the Solar System is shrinking and planetary scientists think they have…

3 days ago

ESA is Building a Mission to Visit Asteroid Apophis, Joining it for its 2029 Earth Flyby

According to the ESA's Near-Earth Objects Coordination Center (NEOCC), 35,264 known asteroids regularly cross the…

3 days ago

The Most Dangerous Part of a Space Mission is Fire

Astronauts face multiple risks during space flight, such as microgravity and radiation exposure. Microgravity can…

3 days ago