c2d Spitzer IRS Spectra of Disks around T Tauri Stars. I. Silicate Emission and Grain Growth

By J. Kessler-Silacci, Jean Augereau, C. Dullemond, V. Geers, F. Lahuis, N. Evans II, E. V. van Dishoeck, G. Blake, A. Boogert, Joanna M. Brown and 3 more. 2005

216 citations recorded by the source corpus.

Infrared ~5-35 μm spectra for 40 solar mass T Tauri stars and 7 intermediate-mass Herbig Ae stars with circumstellar disks were obtained using the Spitzer Space Telescope as part of the c2d IRS survey. This work complements prior spectroscopic studies of silicate infrared emission from disks, which were focused on intermediate-mass stars, with observations of solar mass stars limited primarily to the 10 μm region. The observed 10 and 20 μm silicate feature strengths/shapes are consistent with source-to-source variations in grain size. A large fraction of the features are weak and flat, consistent with micron-sized grains indicating fast grain growth (from 0.1 to 1.0 μm in radius). In addition, approximately half of the T Tauri star spectra show crystalline silicate features near 28 and 33 μm, indicating significant processing when compared to interstellar grains. A few sources show large 10-to-20 μm ratios and require even larger grains emitting at 20 μm than at 10 μm. This size difference may arise from the difference in the depth into the disk probed by the two silicate emission bands in disks where dust settling has occurred. The 10 μm feature strength versus shape trend is not correlated with age or Hα equivalent width, suggesting that some amount of turbulent mixing and regeneration of small grains is occurring. The strength versus shape trend is related to spectral type, however, with M stars showing significantly flatter 10 μm features (larger grain sizes) than A/B stars. The connection between spectral type and grain size is interpreted in terms of the variation in the silicate emission radius as a function of stellar luminosity, but could also be indicative of other spectral-type-dependent factors (e.g., X-rays, UV radiation, and stellar/disk winds).

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/2c069361ecfec8a6d7adfc2a4d7acbd852a6ea4a

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In Astronomy and Astrophysics

1. S. Andrews
2. C. Dullemond
3. Jonathan P. Williams
4. D. Wilner
5. L. Hartmann
6. L. Cieza
7. L. Testi
8. T. Birnstiel

In Spectroscopy

1. C. Dullemond
2. Jonathan P. Williams
3. L. Hartmann
4. L. Cieza
5. N. Evans II
6. N. Calvet
7. S. Andrews
8. L. Testi

Citations in the corpus

• Cold Disks: Spitzer Spectroscopy of Disks around Young Stars with Large Gaps (2007, background): “There is general evidence for grain growth in disks from both mid-IR and millimeter data (Kessler-Silacci et al. 2006; Rodmann et al. 2006).”
• CRYSTALLINE SILICATES AND DUST PROCESSING IN THE PROTOPLANETARY DISKS OF THE TAURUS YOUNG CLUSTER (2007, methodology): “This alternative has been fruitful before in the analysis of Class II YSO spectra (e.g., Kessler-Silacci et al. 2005, 2006) and Herbig Ae/Be stars (e.g., Bouwman et al. 2001; van Boekel et al. 2003).”
• Protoplanetary Disks and Their Evolution (2011, background): “…studies have searched for a correlation between the large scale properties of the disk (e.g., mass, accretion rates) and grain characteristics (sizes, degree of crystallization), no conclusive evidence has yet been found (e.g., Furlan et al. 2009, Kessler-Silacci et al. 2006, Oliveira et al. 2010).”
• Size-sorting dust grains in the surface layers of protoplanetary disks (2008, unknown): “…have been studied in great detail with the Infrared Space Observatory (ISO; e.g. Meeus et al. 2001; Bouwman 2001), with ground-based instruments (van Boekel et al. 2003; Honda et al. 2003) and with the Spitzer Space Telescope (e.g. Apai et al. 2005; Kessler-Silacci et al. 2006; Furlan et al. 2006).”
• A SPITZER SURVEY OF MID-INFRARED MOLECULAR EMISSION FROM PROTOPLANETARY DISKS. I. DETECTION RATES (2010, background): “Why have these complex infrared emission spectra not previously been seen (e.g., Meeus et al. 2001; Kessler-Silacci et al. 2006)?”
• Spitzer IRS Spectroscopy of IRAS-discovered Debris Disks (2006, background): “Non-zero vacuum volume fractions shift the peak positions of silicate features to longer wavelengths and broaden the features (Kessler-Silacci et al. 2006).”
• Dust grain growth in ρ-Ophiuchi protoplanetary disks (2010, methodology): “8, are interpreted in terms of grain growth to micron sizes (Bouwman et al. 2001; Kessler-Silacci et al. 2006).”
• ALMA SURVEY OF LUPUS PROTOPLANETARY DISKS. I. DUST AND GAS MASSES (2016, background): “Although RY Lup was not previously identified as a TD by its SED (Manset et al. 2009), this is likely because its strong 10 µm silicate emission feature, seen in its IRS spectrum (Kessler-Silacci et al. 2006), washes out the mid-IR dip in its broadband fluxes.”
• Probing dust grain evolution in IM Lupi's circumstellar disc. Multi-wavelength observations and mo (2008, methodology): “We measured the shape and strength of the IM Lupi 10µm feature following the approach described in Kessler-Silacci et al. (2006).”
• H2O and OH Gas in the Terrestrial Planet-forming Zones of Protoplanetary Disks (2008, methodology): “The Spitzer IRS Short-High (SH) module spectrum of AS 205A was taken as part of the “cores to disks” (c2d) Legacy program (Evans et al. 2003; Kessler-Silacci et al. 2006), while the spectrum of DR Tau, observed as part of the guaranteed time observations (Houck et al. 2004), was obtained from the…”
• A Perspective from Extinct Radionuclides on a Young Stellar Object: The Sun and Its Accretion Disk (2011, background): “Infrared observations of pre–main sequence stars less than 1.5 Myr old show that dust particles grow rapidly to micrometer-sized agglomerates (Kessler-Silacci et al. 2006).”
• C2D Spitzer-IRS spectra of disks around T Tauri stars. II. PAH emission features (2006, methodology): “These include the 40 T Tauri stars and 7 HAeBe stars in Kessler-Silacci et al. (2006), although we label 4 of their T Tauri sources here as “unclassified” for lack of spectral type (RNO 15, IRAS 03446+3254, VSSG1, CK 4) and we label 1 of their HAeBe stars here as a T Tauri star since it has…”