Asteroids Near White Dwarfs Break Into Large Fragments

Asteroids that venture too close to white dwarfs do not immediately disintegrate into microscopic dust, according to a modeling study published in The Astrophysical Journal Letters and reported by El Heraldo elheraldo.co. Researchers Jordan Steckloff, Kathryn Volk, and Dimitri Veras, affiliated with the Planetary Science Institute and partner universities across the United States and the United Kingdom, analyzed tidal disruption dynamics in these dense stellar remnants elheraldo.co.

White dwarfs concentrate a mass comparable to the Sun into a volume roughly the size of Earth, continuing to emit residual heat and radiation for billions of years after nuclear fusion halts elheraldo.co. When small celestial bodies approach such remnants, extreme gravitational tidal forces exceed the internal structural cohesion of the objects elheraldo.co. Many asteroids are not monolithic rocks but rubble piles bound by mutual self-gravity and weak surface interactions elheraldo.co.

The Role of Cohesive Forces

The research team accounted for inter-particle Van der Waals forces alongside gravitational attraction within their structural models elheraldo.co. Incorporating these microscale interactions changed the predicted outcome of gravitational destruction elheraldo.co. Instead of producing a cloud of uniform, fine debris, the modeled disruption preserved a significant fraction of the initial asteroid mass in macroscopic segments elheraldo.co.

According to the numerical simulations, large portions of the progenitor bodies remain clustered into fragments measuring between 100 meters and 1 kilometer across elheraldo.co. This structural survival challenges earlier assumptions that tidal disruption instantaneously crushes rubble-pile asteroids down to fine dust grains elheraldo.co.

Implications for Debris Disks

The presence of kilometer-scale remnants alters how scientists interpret the circumstellar disks observed around numerous white dwarfs elheraldo.co. Standard models attribute disk evolution to the Poynting-Robertson effect, wherein stellar radiation drag progressively saps orbital angular momentum from tiny dust particles, causing them to spiral inward elheraldo.co.

Because large fragments are largely unaffected by radiation drag compared to sub-millimeter grains, mass transfer toward the white dwarf must involve multi-stage fragmentation processes elheraldo.co. The findings indicate that circumstellar dust production occurs more gradually as these larger fragments undergo subsequent secondary collisions elheraldo.co.

Simulations show asteroids near white dwarfs break into 100-meter to 1-kilometer fragments

The Role of Cohesive Forces

Implications for Debris Disks

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