A Sub-Au outwardly truncated accretion disk around a classical T Tauri star

M. K. McClure, W. J. Forrest, B. A. Sargent, Dan M. Watson, E. Furlan, P. Manoj, K. L. Luhman, N. Calvet, C. Espaillat, P. D'Alessio, L. W. Hartmann, C. Tayrien, S. T. Harrold

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12 Scopus citations


We present the Spitzer Infrared Spectrograph (IRS) spectrum of SR 20, a 5-10 AU binary T Tauri system in the ρ Ophiuchi star-forming region. The spectrum has features consistent with the presence of a disk; however, the continuum slope is steeper than the λ-4/3 slope of an infinite geometrically thin, optically thick disk, indicating that the disk is outwardly truncated. Comparison with photometry from the literature shows a large increase in the mid-infrared flux from 1993 to 1996. We model the spectral energy distribution and IRS spectrum with a wall+optically thick irradiated disk, yielding an outer radius of 0.39+0..03 -0.01AU, much smaller than predicted by models of binary orbits. Using a two-temperature x2 minimization model to fit the dust composition of the IRS spectrum, we find that the disk has experienced significant grain growth: its spectrum is well fitted using opacities of grains larger than 1 μm. We conclude that the system experienced a significant gravitational perturbation in the 1990s.

Original languageEnglish (US)
Pages (from-to)L187-L190
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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