Disintegrating Exoplanet Offers Rare Glimpse Into Exoplanet Geology
Astronomers have discovered a rocky, disintegrating exoplanet that is slowly disintegrating as it orbits dangerously close to its star. The intense stellar heat is vaporising its surface, forming a long tail of mineral dust that stretches up to 5.6 million miles (9 million kilometres) behind it.
A Rare Planetary Phenomenon
Named BD+05 4868 Ab, the planet is one of only four known exoplanets observed to be breaking apart while in orbit. It is the closest of its kind to our solar system, located around 140 light years away in the Pegasus constellation.
This proximity offers scientists a rare chance to study the disintegration of a planet in real time. As the planet orbits its host star, it sheds material equivalent to the mass of Mount Everest with each pass. The resulting dust tail wraps halfway around the star, forming a dramatic and telling spectacle.
Extreme Conditions and Runaway Disintegration
The planet’s surface is thought to have melted into magma due to temperatures near 3,000°F (1,600°C). Its orbit is extremely tight, completing a full revolution around its star every 30.5 hours. This distance is roughly 20 times closer than Mercury’s orbit around the Sun.
The host star is an orange dwarf, cooler and dimmer than the Sun. It has about 70% of the Sun’s mass and diameter, and emits only 20% of its light. These factors contribute to the planet’s severe conditions.
According to lead researcher Marc Hon from MIT, BD+05 4868 Ab is expected to vanish completely in about a million years. As more of its surface turns to dust, the disintegration speeds up.
A Unique Chance for Scientific Discovery
The dust tail contains mineral grains, possibly from the planet’s crust, mantle, or even its core. Scientists hope upcoming studies using NASA’s James Webb Space Telescope will reveal the mineral makeup of this dust.
This could unlock new insights into the structure and composition of rocky planets beyond our solar system. The discovery also holds importance for the broader search for life. Rocky planets in a star’s habitable zone are prime targets, and learning more about their geology helps define their potential for hosting life.
BD+05 4868 Ab was identified using the transit method, detecting slight dips in the star’s brightness when the planet passes in front of it. The NASA TESS telescope played a key role in the discovery.
The origin of the planet’s tight orbit remains uncertain. It may have once orbited farther out and was later pulled closer by the gravitational force of another body.
This rare find offers scientists a valuable chance to study how planets break apart and what their interiors might be made of—something even harder to determine within our own solar system.
with inputs from Reuters
