Formation of narrow dust rings in circumstellar debris disks

Gurtina Besla, Yanqin Wu

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Narrow dust rings observed around some young stars (e.g., HR 4796A) need to be confined. We present a possible explanation for the formation and confinement of such rings in optically thin circumstellar disks, without invoking shepherding planets. If an enhancement of dust grains (e.g., due to a catastrophic collision) occurs somewhere in the disk, photoelectric emission from the grains can heat the gas to temperatures well above that of the dust. The gas orbits with super (sub)-Keplerian speeds inward (outward) of the associated pressure maximum. This tends to concentrate the grains into a narrow region. The rise in dust density leads to further heating and a stronger concentration of grains. A narrow dust ring forms as a result of this instability. We show that this mechanism not only operates around early-type stars that have high UV flukes, but also around stars with spectral types as late as K. This implies that this process is generic and may have occurred during the lifetime of each circumstellar disk. We examine the stringent upper limit on the H2 column density in the HR 4796A disk and find it to be compatible with the presence of a significant amount of hydrogen gas in the disk. We also compute the O I and C II infrared line fluxes expected from various debris disks and show that these will be easily detectable by the upcoming Herschel mission. Herschel will be instrumental in detecting and characterizing gas in these disks.

Original languageEnglish (US)
Pages (from-to)528-540
Number of pages13
JournalAstrophysical Journal
Volume655
Issue number1 I
DOIs
StatePublished - Jan 20 2007
Externally publishedYes

Fingerprint

debris
dust
rings
gas
gases
stars
planet
collision
hydrogen
heating
planets
photoelectric emission
orbits
heat
life (durability)
collisions
augmentation
temperature

Keywords

  • Circumstellar matter
  • Hydrodynamics
  • Infrared: stars
  • Instabilities

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Formation of narrow dust rings in circumstellar debris disks. / Besla, Gurtina; Wu, Yanqin.

In: Astrophysical Journal, Vol. 655, No. 1 I, 20.01.2007, p. 528-540.

Research output: Contribution to journalArticle

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