Silicate dust in evolved protoplanetary disks: Growth, sedimentation, and accretion

Aurora Sicilia-Aguilar (Lead / Corresponding author), Lee W. Hartmann, Dan Watson, Chris Bohac, Thomas Henning, Jeroen Bouwman

Research output: Contribution to journalArticle

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Abstract

We present the Spitzer IRS spectra for 33 young stars in Tr 37 and NGC 7160. The sample includes the high- and intermediate-mass stars with MIPS 24 mu m excess, the only known active accretor in the 12 Myr old cluster NGC 7160, and 19 low-mass stars with disks in the 4 Myr old cluster Tr 37. We examine the 10 mu m silicate feature, present in the whole sample of low-mass stars and in three of the high- and intermediate-mass targets, and we find that PAH emission is detectable only in the Herbig Be star. We analyze the composition and size of the warm photospheric silicate grains by fitting the 10 mu m silicate feature and study the possible correlations between the silicate characteristics and the stellar and disk properties (age, SED slope, accretion rate, and spectral type). We find indications of dust settling with age and of the effect of turbulent enrichment of the disk atmosphere with large grains. Crystalline grains are only small contributors to the total silicate mass in all disks and do not seem to correlate with any other property, except maybe binarity. We also observe that spectra with very weak silicate emission are at least 3 times more frequent among M stars than among earlier spectral types, which may be evidence of inner disk evolution. Finally, we find that five of the high- and intermediate-mass stars have SEDs and IRS spectra consistent with debris disk models involving planet formation, which could indicate debris disk formation at ages as early as 4 Myr.
Original languageEnglish
Pages (from-to)1637-1660
Number of pages24
JournalAstrophysical Journal
Volume659
Issue number2
DOIs
Publication statusPublished - 20 Apr 2007

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protoplanetary disks
silicates
silicate
dust
accretion
sedimentation
stars
Indian spacecraft
debris
M stars
settling
polycyclic aromatic hydrocarbons
PAH
planet
planets
indication
slopes
atmosphere
atmospheres

Keywords

  • accretion, accretion disks planetary systems : protoplanetary disks stars : pre-main-sequence T-TAURI STARS INTERMEDIATE-MASS STARS MAIN-SEQUENCE STARS HERBIG AE/BE STARS SPECTRAL ENERGY-DISTRIBUTIONS SPITZER-SPACE-TELESCOPE CIRCUMSTELLAR DISKS GRAIN-GROWTH CRYSTALLINE SILICATES OPTICAL-PROPERTIES

Cite this

Sicilia-Aguilar, Aurora ; Hartmann, Lee W. ; Watson, Dan ; Bohac, Chris ; Henning, Thomas ; Bouwman, Jeroen. / Silicate dust in evolved protoplanetary disks : Growth, sedimentation, and accretion. In: Astrophysical Journal. 2007 ; Vol. 659, No. 2. pp. 1637-1660.
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Sicilia-Aguilar, A, Hartmann, LW, Watson, D, Bohac, C, Henning, T & Bouwman, J 2007, 'Silicate dust in evolved protoplanetary disks: Growth, sedimentation, and accretion', Astrophysical Journal, vol. 659, no. 2, pp. 1637-1660. https://doi.org/10.1086/512121

Silicate dust in evolved protoplanetary disks : Growth, sedimentation, and accretion. / Sicilia-Aguilar, Aurora (Lead / Corresponding author); Hartmann, Lee W.; Watson, Dan; Bohac, Chris; Henning, Thomas; Bouwman, Jeroen.

In: Astrophysical Journal, Vol. 659, No. 2, 20.04.2007, p. 1637-1660.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Silicate dust in evolved protoplanetary disks

T2 - Growth, sedimentation, and accretion

AU - Sicilia-Aguilar, Aurora

AU - Hartmann, Lee W.

AU - Watson, Dan

AU - Bohac, Chris

AU - Henning, Thomas

AU - Bouwman, Jeroen

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N2 - We present the Spitzer IRS spectra for 33 young stars in Tr 37 and NGC 7160. The sample includes the high- and intermediate-mass stars with MIPS 24 mu m excess, the only known active accretor in the 12 Myr old cluster NGC 7160, and 19 low-mass stars with disks in the 4 Myr old cluster Tr 37. We examine the 10 mu m silicate feature, present in the whole sample of low-mass stars and in three of the high- and intermediate-mass targets, and we find that PAH emission is detectable only in the Herbig Be star. We analyze the composition and size of the warm photospheric silicate grains by fitting the 10 mu m silicate feature and study the possible correlations between the silicate characteristics and the stellar and disk properties (age, SED slope, accretion rate, and spectral type). We find indications of dust settling with age and of the effect of turbulent enrichment of the disk atmosphere with large grains. Crystalline grains are only small contributors to the total silicate mass in all disks and do not seem to correlate with any other property, except maybe binarity. We also observe that spectra with very weak silicate emission are at least 3 times more frequent among M stars than among earlier spectral types, which may be evidence of inner disk evolution. Finally, we find that five of the high- and intermediate-mass stars have SEDs and IRS spectra consistent with debris disk models involving planet formation, which could indicate debris disk formation at ages as early as 4 Myr.

AB - We present the Spitzer IRS spectra for 33 young stars in Tr 37 and NGC 7160. The sample includes the high- and intermediate-mass stars with MIPS 24 mu m excess, the only known active accretor in the 12 Myr old cluster NGC 7160, and 19 low-mass stars with disks in the 4 Myr old cluster Tr 37. We examine the 10 mu m silicate feature, present in the whole sample of low-mass stars and in three of the high- and intermediate-mass targets, and we find that PAH emission is detectable only in the Herbig Be star. We analyze the composition and size of the warm photospheric silicate grains by fitting the 10 mu m silicate feature and study the possible correlations between the silicate characteristics and the stellar and disk properties (age, SED slope, accretion rate, and spectral type). We find indications of dust settling with age and of the effect of turbulent enrichment of the disk atmosphere with large grains. Crystalline grains are only small contributors to the total silicate mass in all disks and do not seem to correlate with any other property, except maybe binarity. We also observe that spectra with very weak silicate emission are at least 3 times more frequent among M stars than among earlier spectral types, which may be evidence of inner disk evolution. Finally, we find that five of the high- and intermediate-mass stars have SEDs and IRS spectra consistent with debris disk models involving planet formation, which could indicate debris disk formation at ages as early as 4 Myr.

KW - accretion, accretion disks planetary systems : protoplanetary disks stars : pre-main-sequence T-TAURI STARS INTERMEDIATE-MASS STARS MAIN-SEQUENCE STARS HERBIG AE/BE STARS SPECTRAL ENERGY-DISTRIBUTIONS SPITZER-SPACE-TELESCOPE CIRCUMSTELLAR DISKS GRAIN-GROW

U2 - 10.1086/512121

DO - 10.1086/512121

M3 - Article

VL - 659

SP - 1637

EP - 1660

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

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