Dust in discs around T Tauri stars: grain growth?

Mannings, V.; Emerson, J. P.

doi:10.1093/mnras/267.2.361

Cited by 99 publications

(94 citation statements)

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“…As grains grow and the opacity law flattens, the spectral index of the millimeter continuum thermal emission is also expected to flatten. Beckwith et al (1990), Beckwith & Sargent (1991), and Mannings & Emerson (1994) found that the spectral index from a sample of disks was shallower than would be expected for ISM dust and interpreted this as evidence for an enhanced population of large grains in disks around T Tauri stars.…”

Section: Introductionmentioning

confidence: 94%

“…Furthermore, grain growth is probably the first step in the process of planet formation. For this reason, there has been intense interest in finding evidence for grain growth in circumstellar disks, with many observational claims for its discovery (Beckwith et al 1990;Beckwith & Sargent 1991;Mannings & Emerson 1994;Throop et al 2001;Cotera et al 2001;D'Alessio, Calvet, & Hartmann 2001;Calvet et al 2002;Wood et al 2002;Wolf, Padgett, & Stapelfeldt 2003) but also indications that in some disks the dust is not too different from ISM dust (Silber et al 2000;Stapelfeldt et al 2003;Wolf et al 2003).…”

Section: Introductionmentioning

confidence: 99%

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The Visible and Near‐Infrared Dust Opacity Law in the HH 30 Circumstellar Disk

Watson

Stapelfeldt

2004

ApJ

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We present new images of the scattered-light disk around HH 30 at 0.44 and 0.81 m. We model these images and an existing 2.04 m image by using a multiple-scattering code, varying and fitting for the disk parameters and the dust opacity ratios at these wavelengths. A wide range of different disk geometries provide adequate fits to the data; there is no single best-fit geometry. In particular, the fits cannot resolve the ambiguity between the power-law indices in surface density and scale height. On the other hand, the inclination, opacity-mass product, scale height, and to a lesser degree the extinction to the star are relatively tightly constrained. Despite the ambiguity in geometry, we conclude that the dust opacity in the scattering layers of the outer parts of the HH 30 circumstellar disk drops from 0.44 to 2.04 m, but by less than in the low-density ISM. The median fit shows a drop by a factor of less than 2. This result is robust to reasonable changes in the disk density distribution. It suggests that moderate grain growth has occurred but that small grains still dominate the visible and near-infrared opacity.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

The Visible and Near‐Infrared Dust Opacity Law in the HH 30 Circumstellar Disk

Watson

Stapelfeldt

2004

ApJ

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“…An exponent β ≈ 0 would point to grains radiating almost as blackbodies, while largely unprocessed interstellar dust grains have been shown to have β ≈ 2 (Hildebrand 1983). A β of 0.5−1 has been found in protoplanetary (T Tauri) disks, indicating amorphous or fractal dust grains, or perhaps just grains significantly larger than those in the interstellar medium (Mannings & Emerson 1994). We made χ 2 -minimisation fits to available photometry data (weighted with the accuracy of the flux density measurement) of our three detected objects with the total SED function, F SED (ν) = F star (ν)C star + F disk (ν)(C disk /C), where the stellar photosphere F star is simply approximated by a blackbody function, and C star and C disk are scale factors depending on distance and radiating surface area.…”

Section: Spectral Energy Distribution and Disk Propertiesmentioning

confidence: 99%

A submillimetre search for cold extended debris disks in the $\mathsf{\beta}$ Pictoris moving group

Nilsson

Liseau

Brandeker

et al. 2009

A&A

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Context. Previous observations with the Infrared Astronomical Satellite and the Infrared Space Observatory, and ongoing observations with Spitzer and AKARI, have led to the discovery of over 200 debris disks, based on detected mid-and far infrared excess emission, indicating warm circumstellar dust. To constrain the properties of these systems, e.g., to more accurately determine the dust mass, temperature and radial extent, follow-up observations in the submillimetre wavelength region are needed. Aims. The β Pictoris moving group is a nearby stellar association of young (∼12 Myr) co-moving stars including the classical debris disk star β Pictoris. Due to their proximity and youth, they are excellent targets when searching for submillimetre emission from cold, extended, dust components produced by collisions in Kuiper-Belt-like disks. They also allow an age independent study of debris disk properties as a function of other stellar parameters. Methods. We observed 7 infrared-excess stars in the β Pictoris moving group with the LABOCA bolometer array, operating at a central wavelength of 870 μm at the 12-m submillimetre telescope APEX. The main emission at these wavelengths comes from large, cold dust grains, which constitute the main part of the total dust mass, and hence, for an optically thin case, make better estimates on the total dust mass than earlier infrared observations. Fitting the spectral energy distribution with combined optical and infrared photometry gives information on the temperature and radial extent of the disk. Results. From our sample, β Pic, HD 181327, and HD 172555 were detected with at least 3σ certainty, while all others are below 2σ and considered non-detections. The image of β Pic shows an offset flux density peak located near the south-west extension of the disk, similar to the one previously found by SCUBA at the JCMT. We present SED fits for detected sources and give an upper limit on the dust mass for undetected ones. Conclusions. We find a mean fractional dust luminosityf dust = 1.1 × 10 −3 at t ≈ 12 Myr, which together with recent data at 100 Myr suggests an f dust ∝ t −α decline of the emitting dust, with α > 0.8.

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“…Interestingly, this decrease of β could be due to larger grains (e.g. Mannings & Emerson 1994), hence suggesting grain growth in the denser inner regions. Grain shape evolution or chemical evolution are also possible (see, e.g.…”

Section: Spectral Index Mapmentioning

confidence: 99%

L1157: Interaction of the molecular outflow with the Class 0 environment

Beltrán

Gueth

Guilloteau

et al. 2004

A&A

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Abstract. We present high angular resolution interferometric observations [ ] of the dust continuum at 2.7 and 1.3 mm, and of the HC 3 N (J = 12 → 11) and C 18 O (J = 2 → 1) emission around L1157-mm, a Class 0 object that drives a spectacular molecular outflow. The millimeter dust emission is clearly resolved into two components, a flattened compact source of ∼450 × 250 AU at 1.3 mm, and mass ∼0.1 M , plus an extended envelope of ∼3000 AU at 1.3 mm, and mass ∼1.1 M . The millimeter spectral index varies throughout the region, with the lower value found toward the compact protostar, possibly indicating grain growth in the denser regions. A strong interaction between the molecular outflow and the close protostellar environment is taking place and affects the structure of the innermost parts of the envelope. This is shown by the spatial coincidence between the molecular outflow and the dust (1.3 mm continuum) and HC 3 N emission: both tracers show structures associated to the edges of the outflow lobes. Basically, the global picture sketched for the Class 0 object L1157-mm by Gueth et al. (1997) is supported. We find possible evidence of infall, but we do not detect any velocity gradient indicative of a rotating circumstellar disk.

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Dust in discs around T Tauri stars: grain growth?

Cited by 99 publications

References 0 publications

The Visible and Near‐Infrared Dust Opacity Law in the HH 30 Circumstellar Disk

The Visible and Near‐Infrared Dust Opacity Law in the HH 30 Circumstellar Disk

A submillimetre search for cold extended debris disks in the $\mathsf{\beta}$ Pictoris moving group

L1157: Interaction of the molecular outflow with the Class 0 environment

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