Variations of the 10 μm silicate features in the actively accreting T Tauri stars: DG Tau and XZ Tau

Jeffrey S. Bary, Jarron M. Leisenring, Michael F. Skrutskie

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Using the Infrared Spectrograph aboard the Spitzer Space Telescope, we observed multiple epochs of 11 actively accreting T Tauri stars in the nearby Taurus-Auriga star-forming region. In total, 88 low-resolution mid-infrared spectra were collected over 1.5 years in Cycles 2 and 3. The results of this multi-epoch survey show that the 10 μm silicate complex in the spectra of two sources - DG Tau and XZ Tau - undergoes significant variations with the silicate feature growing both weaker and stronger over month- and year-long timescales. Shorter timescale variations on day- to week-long timescales were not detected within the measured flux errors. The time resolution coverage of this data set is inadequate for determining if the variations are periodic. Pure emission compositional models of the silicate complex in each epoch of the DG Tau and XZ Tau spectra provide poor fits to the observed silicate features. These results agree with those of previous groups that attempted to fit only single-epoch observations of these sources. Simple two-temperature, two-slab models with similar compositions successfully reproduce the observed variations in the silicate features. These models hint at a self-absorption origin of the diminution of the silicate complex instead of a compositional change in the population of emitting dust grains. We discuss several scenarios for producing such variability including disk shadowing, vertical mixing, variations in disk heating, and disk wind events associated with accretion outbursts.

Original languageEnglish (US)
Pages (from-to)L168-L172
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - 2009
Externally publishedYes


  • Circumstellar matter
  • Infrared: stars
  • Solar system: formation
  • Stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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