DUST PROPERTIES AND DISK STRUCTURE OF EVOLVED PROTOPLANETARY DISKS IN Cep OB2: GRAIN GROWTH, SETTLING, GAS AND DUST MASS, AND INSIDE-OUT EVOLUTION

Journal Article · Sun Nov 20 00:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/742/1/39; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612612

Sicilia-Aguilar, Aurora; Henning, Thomas; Dullemond, Cornelis P; Bouwman, Jeroen; Sturm, Bernhard ^[1]; Patel, Nimesh ^[2]; Juhasz, Attila ^[3]

---

1. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)
2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
3. Leiden Observatory, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands)

We present Spitzer/Infrared Spectrograph spectra of 31 T Tauri stars (TTS) and IRAM/1.3 mm observations for 34 low- and intermediate-mass stars in the Cep OB2 region. Including our previously published data, we analyze 56 TTS and 3 intermediate-mass stars with silicate features in Tr 37 ({approx}4 Myr) and NGC 7160 ({approx}12 Myr). The silicate emission features are well reproduced with a mixture of amorphous (with olivine, forsterite, and silica stoichiometry) and crystalline grains (forsterite, enstatite). We explore grain size and disk structure using radiative transfer disk models, finding that most objects have suffered substantial evolution (grain growth, settling). About half of the disks show inside-out evolution, with either dust-cleared inner holes or a radially dependent dust distribution, typically with larger grains and more settling in the innermost disk. The typical strong silicate features nevertheless require the presence of small dust grains, and could be explained by differential settling according to grain size, anomalous dust distributions, and/or optically thin dust populations within disk gaps. M-type stars tend to have weaker silicate emission and steeper spectral energy distributions than K-type objects. The inferred low dust masses are in a strong contrast with the relatively high gas accretion rates, suggesting global grain growth and/or an anomalous gas-to-dust ratio. Transition disks in the Cep OB2 region display strongly processed grains, suggesting that they are dominated by dust evolution and settling. Finally, the presence of rare but remarkable disks with strong accretion at old ages reveals that some very massive disks may still survive to grain growth, gravitational instabilities, and planet formation.

• OSTI ID: 21612612
• Journal Information: Astrophysical Journal, Vol. 742, Issue 1; Other Information: DOI: 10.1088/0004-637X/742/1/39; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
DUSTS
ENERGY SPECTRA
ENSTATITE
GRAIN GROWTH
GRAIN SIZE
GRAVITATIONAL INSTABILITY
OLIVINE
PLANETS
PROTOPLANETS
SILICA
SILICATES
STAR EVOLUTION
STOICHIOMETRY
T TAURI STARS
BINARY STARS
ERUPTIVE VARIABLE STARS
EVOLUTION
INSTABILITY
MICROSTRUCTURE
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
PHYSICS
PLASMA INSTABILITY
SILICATE MINERALS
SILICON COMPOUNDS
SIZE
SPECTRA
STARS
VARIABLE STARS