Formation of planetary debris discs around white dwarfs - II: Shrinking extremely eccentric collisionless rings

Dimitri Veras, Zoe M. Leinhardt, Siegfried Eggl, Boris T. Gaensicke

Research output: Contribution to journalArticle (Academic Journal)peer-review

65 Citations (Scopus)
256 Downloads (Pure)

Abstract

The formation channel of the tens of compact debris discs which orbit white dwarfs (WDs) at a distance of one Solar radius 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 super-micron 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 timescale increases with both particle size and cooling age, yielding age-dependent WD debris disc size distributions.
Original languageEnglish
Pages (from-to)3453-3459
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume451
Issue number4
Early online date25 Jun 2015
DOIs
Publication statusPublished - 21 Aug 2015

Keywords

  • methods: numerical
  • celestial mechanics
  • minor planets, asteroids: general
  • planets and satellites: dynamical evolution and stability
  • protoplanetary discs
  • white dwarfs

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