Doomed Planet Found Disintegrating with Every Orbit

Astronomers have identified a disintegrating exoplanet, BD+05 4868 Ab, orbiting an orange K-class star 140 light-years away. This planet, roughly the size of Jupiter, orbits extremely close to its star at 0.02 astronomical units, completing an orbit every 30.5 hours. The intense stellar radiation causes catastrophic mass loss, with the planet shedding approximately a Moon’s worth of material every million years, equivalent to a Mount Everest-sized mass per orbit. This debris forms a comet-like tail, consisting of a 9-million-kilometer trailing tail of fine, soot-like dust and a shorter leading tail of larger, sand-sized particles. The discovery, made using NASA’s Transiting Exoplanet Survey Satellite (TESS), shows asymmetrical light curves indicating dust clouds blocking about 1% of the star’s light.

Here's a bit more detail on these "disintegrating" or "evaporating" planets:

1. The Cause: These planets orbit extremely close to their host stars, much closer than Mercury orbits our Sun. This proximity results in incredibly high surface temperatures and intense stellar radiation.
2. The Process: The intense heat vaporizes the rocky material on the planet's surface. This vaporized rock and dust then escapes the planet's weak gravity.
3. The Mass Loss: The rate of material loss is indeed significant. Comparing it to "a Mount Everest's worth of material" per orbit is a vivid way to illustrate the scale, especially considering these planets often have orbital periods of less than a day!
4. The Comet-Like Tail: As the planet orbits, the escaping dust and gas form a massive cloud or tail that trails behind it, much like a comet. This tail is not made of ice like a typical comet's tail, but rather vaporized rock and minerals.
5. Detection: Astronomers detect these objects by observing the light from the host star. When the planet and its extensive dust cloud pass in front of the star (transit), they block a significant and often variable amount of starlight. The shape and depth of this dimming are unique compared to transits of solid planets, revealing the presence of the trailing debris cloud.
6. Doomed Fate: Because they are constantly shedding mass at such a high rate, these planets are indeed considered "doomed." They are expected to completely evaporate over astronomical (though relatively short compared to the star's lifetime) timescales, potentially leaving behind only a dense core, if anything.

Studying these objects gives astronomers valuable insights into the end-stages of planetary evolution under extreme conditions and the composition of rocky exoplanets. It's a dramatic example of the diverse and sometimes violent processes shaping planetary systems in the universe.