Abstract
The formation channel of the tens of compact debris discs which orbit white dwarfs (WDs) at a distance of 1R⊙ remains unknown. Asteroids that survive the giant branch stellar phases beyond a few au are assumed to be dynamically thrust towards the WD and tidally disrupted within its Roche radius, generating extremely eccentric (e > 0.98) rings. Here, we establish that WD radiation compresses and circularizes the orbits of supermicron to cm-sized ring constituents to entirely within the WD's Roche radius. We derive a closed algebraic formula which well-approximates the shrinking time as a function of WD cooling age, the physical properties of the star and the physical and orbital properties of the ring particles. The shrinking time-scale increases with both particle size and cooling age, yielding age-dependent WD debris disc size distributions.
Original language | English (US) |
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Pages (from-to) | 3453-3459 |
Number of pages | 7 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 451 |
Issue number | 4 |
DOIs | |
State | Published - Apr 24 2015 |
Externally published | Yes |
Keywords
- Celestial mechanics
- Methods: numerical
- Minor planets, asteroids: general
- Planets and satellites: dynamical evolution and stability
- Protoplanetary discs
- White dwarfs
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science