C2d Spitzer IRS spectra of disks around T Tauri stars. I. Silicate emission and grain growth
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C2d Spitzer IRS spectra of disks around T Tauri stars. I. Silicate emission and grain growth. / Kessler-Silacci, Jacqueline; Augereau, Jean Charles; Dullemond, Cornelis P.; Geers, Vincent; Lahuis, Fred; Evans, Neal J.; Van Dishoeck, Ewine F.; Blake, Geoffrey A.; Adwin Boogert, A. C.; Brown, Joanna; Jørgensen, Jes K.; Knez, Claudia; Pontoppidan, Klaus M.
In: Astrophysical Journal, Vol. 639, No. 1 I, 01.03.2006, p. 275-291.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - C2d Spitzer IRS spectra of disks around T Tauri stars. I. Silicate emission and grain growth
AU - Kessler-Silacci, Jacqueline
AU - Augereau, Jean Charles
AU - Dullemond, Cornelis P.
AU - Geers, Vincent
AU - Lahuis, Fred
AU - Evans, Neal J.
AU - Van Dishoeck, Ewine F.
AU - Blake, Geoffrey A.
AU - Adwin Boogert, A. C.
AU - Brown, Joanna
AU - Jørgensen, Jes K.
AU - Knez, Claudia
AU - Pontoppidan, Klaus M.
PY - 2006/3/1
Y1 - 2006/3/1
N2 - 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 Ha 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).
AB - 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 Ha 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).
KW - Circumstellar matter
KW - Infrared: ISM
KW - ISM: lines and bands
KW - Solar system: formation
KW - Stars: formation
KW - Stars: pre-main-sequence
UR - http://www.scopus.com/inward/record.url?scp=33645008193&partnerID=8YFLogxK
U2 - 10.1086/499330
DO - 10.1086/499330
M3 - Journal article
AN - SCOPUS:33645008193
VL - 639
SP - 275
EP - 291
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 I
ER -
ID: 234019820