Transience of hot dust around Sun-like stars

M. C. Wyatt, R. Smith, J. S. Greaves, C. A. Beichman, G. Bryden, C. M. Lisse

Research output: Contribution to journalArticlepeer-review

247 Citations (Scopus)

Abstract

In this paper a simple model for the steady state evolution of debris disks due to collisions is developed and confronted with the properties of the emerging population of seven Sun-like stars that have hot dust at < 10 AU. The model shows that there is a maximum possible disk mass at a given age, since more massive primordial disks process their mass faster. The corresponding maximum dust luminosity is f(max) = 0.16; 10(-3)r(7/3)t(age)(-1) age, where r is disk radius in AU and t(age) is system age in Myr. The majority (4/7) of the hot disks exceed this limit by >> 1000 and so cannot be the products of massive asteroid belts; rather, the following systems must be undergoing transient events characterized by an unusually high dust content near the star: eta Corvi, HD 69830, HD 72905, and BD + 20 307. It is also shown that the hot dust cannot originate in a recent collision in an asteroid belt, since there is also a maximum rate at which collisions of sufficient magnitude to reproduce a given dust luminosity can occur. The planetesimal belt feeding the dust in these systems must be located farther from the star than the dust, typically at >> 2 AU. Other notable properties of the four hot dust systems are as follows: two also have a planetesimal belt at > 10 AU (eta Corvi and HD 72905); one has three Neptune mass planets at < 1 AU (HD 69830); all exhibit strong mid-IR silicate features. We consider the most likely origin for this transient dust to be a dynamical instability that scattered planetesimals inward from a more distant planetesimal belt in an event akin to the late heavy bombardment in our own system, the dust being released from such planetesimals in collisions and sublimation.

Original languageEnglish
Pages (from-to)569-583
Number of pages15
JournalAstrophysical Journal Letters
Volume658
DOIs
Publication statusPublished - 20 Mar 2007

Keywords

  • circumstellar matter
  • planetary systems : formation
  • TERRESTRIAL PLANET FORMATION
  • EDGEWORTH-KUIPER BELT
  • MAIN-SEQUENCE STARS
  • OUTER SOLAR-SYSTEM
  • SIZE DISTRIBUTION
  • ASTEROID BELT
  • DEBRIS DISKS
  • VEGA PHENOMENON
  • AGE-DEPENDENCE
  • BETA-PICTORIS

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