Steady State Evolution of Debris Disks around A Stars

By M. C. Wyatt, Roger M. H. Smith, K. Su, G. Rieke, J. Greaves, C. Beichman, G. Bryden. 2007

212 citations recorded by the source corpus.

This paper confronts a simple analytical model for the steady state evolution of debris disks due to collisions with Spitzer observations of dust around main-sequence A stars. It is assumed that every star has a planetesimal belt, the initial mass and radius of which are drawn from distributions. In the model disk mass is constant until the largest planetesimals reach collisional equilibrium, whereupon mass falls ∝t. We find that the detection statistics and trends seen at 24 and 70 μm can be fitted well by the model. While there is no need to invoke stochastic evolution or delayed stirring to explain the statistics, a moderate rate of stochastic events is not ruled out. Potentially anomalous systems are identified by a high dust luminosity compared with the maximum permissible in the model (HD 3003, HD 38678, HD 115892, HD 172555); their planetesimals may have unusual properties (high strength or low eccentricity), or this dust could be transient. The overall success of our model, which assumes planetesimals in all belts have the same strength, eccentricity, and maximum size, suggests the outcome of planet formation is reasonably uniform. The distribution of planetesimal belt radii, once corrected for detection bias, follows N(r) ∝ r-0.8±0.3 for 3-120 AU. Since belt boundaries may be attributed to unseen planets, this provides a unique constraint on A star planetary systems. It is also shown that P-R drag may sculpt the inner edges of A star disks close to the Spitzer detection threshold (HD 2262, HD 19356, HD 106591, HD 115892). This model can be readily applied to the interpretation of future surveys, and predictions for the upcoming SCUBA-2 survey include that 17% of A star disks should be detectable at 850 μm.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b0bc521cd6f76a70674325333ae96a4c0008fffe

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In Astronomy and Astrophysics

1. L. Hillenbrand
2. K. Luhman
3. Eric Mamajek
4. S. Kenyon
5. Philip Armitage
6. B. Bromley
7. J. Carpenter
8. S. Raymond

Citations in the corpus

• Dynamical effects of stellar mass-loss on a Kuiper-like belt (2011, methodology): “Properties of the disc were selected randomly from the main-sequence population of debris discs around A stars, and the collisionally evolved mass at the end of the main sequence determined, according to the models of Wyatt et al. (2007) and Bonsor & Wyatt (2010).”
• Variations on Debris Disks: Icy Planet Formation at 30-150 AU for 1-3 M☉ Main-Sequence Stars (2008, background): “Dominik & Decin (2003), Wyatt et al. (2007a), and Löhne et al. (2008) show that collisional evolution in a belt of high-velocity planetesimals naturally produces a dust luminosity that declines roughly inversely with time (see also Kenyon & Bromley 2002a, 2004b, 2005), which explains the observed…”
• Long-Term Collisional Evolution of Debris Disks (2007, methodology): “This discrepancy is probably a result of the particle-in-a-box assumptions made by Wyatt et al. (2007a) in derivation of Eq.”
• The Complete Census of 70 μm-Bright Debris Disks within “The Formation and Evolution of Planetary Systems” Spitzer Legacy Survey of Sun-like Stars (2007, methodology): “Another comparison that can be made is to the planetesimal formation and early debris ‘‘self-stirring’’ models of Kenyon & Bromley (2005), which predict a peak in f between 10 and 100Myr, rather than the monotonic steady decay of Dominik & Decin (2003), Wyatt et al. (2007), or Löhne et al. (2008).”
• FORMATION AND EVOLUTION OF PLANETARY SYSTEMS: PROPERTIES OF DEBRIS DUST AROUND SOLAR-TYPE STARS (2008, methodology): “6) because of additional assumptions about how physical parameters vary with radius in the latter model (see Wyatt et al. 2007a).”
• Debris disks as signposts of terrestrial planet formation (2011, methodology): “For each population of bodies (asteroidal and cometary), we calculate the collisional timescale tc, which is a function of the particle size D as well as the orbital properties of the population (Wyatt et al. 1999, 2007a).”