GAS INSIDE THE 97 AU CAVITY AROUND THE TRANSITION DISK Sz 91

Cánovas, H.; Schreiber, M. R.; Cáceres, C.; Ménard, F.; Pinte, C.; Mathews, Geoffrey S.; Cieza, Lucas A.; Casassus, S.; Hales, Antonio; Williams, Jonathan P.; Román, Pablo E.; Hardy, Adam

doi:10.1088/0004-637x/805/1/21

Cited by 58 publications

(48 citation statements)

References 60 publications

(92 reference statements)

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“…To prove this we build a simple but realistic model of a transition disk using the 3D radiative transfer code MCFOST (Pinte et al 2006(Pinte et al , 2009. The radial structure of the model is similar to that found in the well-studied disks RX J1633.9-2442 and Sz 91 (Cieza et al 2012;Canovas et al 2015b): the innermost region is completely devoid of dust, followed by a dust-depleted region extending up to the cavity radius ("Region 1"), and the outer disk ("Region 2"). A&A 582, L7 (2015) 2.1.…”

Section: Modelingmentioning

confidence: 86%

Nonazimuthal linear polarization in protoplanetary disks

Cánovas

Ménard

Boer

et al. 2015

A&A

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102

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Several studies discussing imaging polarimetry observations of protoplanetary disks use the so-called radial Stokes parameters Q φ and U φ to discuss the results. This approach has the advantage of providing a direct measure of the noise in the polarized images under the assumption that the polarization is only azimuthal, i.e., perpendicular to the direction toward the illuminating source. However, a detailed study of the validity of this assumption is currently missing. We aim to test whether departures from azimuthal polarization can naturally be produced by scattering processes in optically thick protoplanetary disks at near infrared wavelengths. We use the radiative transfer code MCFOST to create a generic model of a transition disk using different grain size distributions and dust masses. From these models we generate synthetic polarized images at 2.2 µm. We find that even for moderate inclinations (e.g., i = 40 • ), multiple scattering alone can produce significant (up to ∼4.5% of the Q φ image, peak-to-peak) nonazimuthal polarization reflected in the U φ images. We also find that different grain populations can naturally produce radial polarization (i.e., negative values in the Q φ images). Despite the simplifications of the models, our results suggest that caution is recommended when interpreting polarized images by only analyzing the Q φ and U φ images. We find that there can be astrophysical signal in the U φ images and negative values in the Q φ images, which indicate departures from azimuthal polarization. If significant signal is detected in the U φ images, we recommend checking the standard Q and U images to look for departures from azimuthal polarization. On the positive side, signal in the U φ images once all instrumental and data-reduction artifacts have been corrected for means that there is more information to be extracted regarding the dust population and particle density.

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Section: Modelingmentioning

confidence: 86%

Nonazimuthal linear polarization in protoplanetary disks

Cánovas

Ménard

Boer

et al. 2015

A&A

Self Cite

102

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“…Most TDs show significantly reduced fluxes at short wavelengths ( 10 µm), while still showing average emission at longer wavelengths. This observation is indicative of a dust cavity in the innermost region of the disk, and indeed sub-mm images of TDs have proved this to be the case (Piétu et al 2006;Hughes et al 2007;Brown et al 2009;Canovas et al 2015). This kind of geometry requires a mechanism that can clear the dust from the inside out, which is not consistent with the previously dominant mechanism of Article published by EDP Sciences viscous accretion (Hartmann et al 1998;Armitage et al 1999).…”

Section: Introductionmentioning

confidence: 86%

Probing the final stages of protoplanetary disk evolution with ALMA

Hardy

Cáceres

Schreiber

et al. 2015

A&A

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Context. The evolution of a circumstellar disk from its gas-rich protoplanetary stage to its gas-poor debris stage is not understood well. It is apparent that disk clearing progresses from the inside-out on a short time scale and models of photoevaporation are frequently used to explain this. However, the photoevaporation rates predicted by recent models differ by up to two orders of magnitude, resulting in uncertain time scales for the final stages of disk clearing. Aims. Photoevaporation theories predict that the final stages of disk-clearing progress in objects that have ceased accretion but still posses considerable material at radii far from the star. Weak-line T Tauri stars (WTTS) with infrared emission in excess of what is expected from the stellar photosphere are likely in this configuration. We aim to provide observational constraints on theories of disk-clearing by measuring the dust masses and CO content of a sample of young (1.8−26.3 Myr) WTTS. Methods. We used ALMA Band 6 to obtain continuum and 12 CO(2−1) line fluxes for a sample of 24 WTTS stars with known infrared excess. For these WTTS, we inferred the dust mass from the continuum observations and derived disk luminosities and ages to allow comparison with previously detected WTTS. Results. We detect continuum emission in only four of 24 WTTS, and no 12 CO(2−1) emission in any of them. For those WTTS where no continuum was detected, their ages and derived upper limits suggest they are debris disks, which makes them some of the youngest debris disks known. Of those where continuum was detected, three are possible photoevaporating disks, although the lack of CO detection suggests a severely reduced gas-to-dust ratio. Conclusions. The low fraction of continuum detections implies that, once accretion onto the star stops, the clearing of the majority of dust progresses very rapidly. Most WTTS with infrared excess are likely not in transition but are instead young debris disks, whose dust is either primordial and has survived disk-clearing, or is of second-generation origin. In the latter case, the presence of giant planets within these WTTS might be the cause.

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“…They mark a crucial phase in disk evolution, intermediate between fully gas-rich and gas-depleted systems. Their existence was first suggested by the distinctive near-tomid-infrared (NIR-MIR) dips in their spectral energy distributions (SEDs; e.g., Strom et al 1989;Skrutskie et al 1990;Calvet et al 2005;Espaillat et al 2007Espaillat et al , 2008, and later confirmed by resolved images in NIR scattered light (e.g., Thalmann et al 2010;Hashimoto et al 2012;Mayama et al 2012;Garufi et al 2013;Quanz et al 2013;Avenhaus et al 2014aAvenhaus et al , 2014bTsukagoshi et al 2014) and by resolved mm wave maps of dust continuum and gas line emission (e.g., Andrews et al 2011;Mathews et al 2012;Tang et al 2012;Fukagawa et al 2013;Isella et al 2013;van der Marel et al 2013van der Marel et al , 2014van der Marel et al , 2015aPérez et al 2014;Zhang et al 2014;Canovas et al 2015;Hashimoto et al 2015).…”

Section: Introductionmentioning

confidence: 94%

The Sizes and Depletions of the Dust and Gas Cavities in the Transitional Disk J160421.7-213028

Dong

Marel

Hashimoto

et al. 2017

ApJ

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We report ALMA Cycle 2 observations of 230 GHz (1.3 mm) dust continuum emission, and 12 CO, 13 CO, and C 18 O J=2-1 line emission, from the Upper Scorpius transitional disk [PZ99] J160421.7-213028, with an angular resolution of ∼  0. 25 (35 au). Armed with these data and existing H-band scattered light observations, we measure the size and depth of the disk's central cavity, and the sharpness of its outer edge, in three components: sub-μm-sized "small" dust traced by scattered light, millimeter-sized "big" dust traced by the millimeter continuum, and gas traced by line emission. Both dust populations feature a cavity of radius ∼70 au that is depleted by factors of at least 1000 relative to the dust density just outside. The millimeter continuum data are well explained by a cavity with a sharp edge. Scattered light observations can be fitted with a cavity in small dust that has either a sharp edge at 60 au, or an edge that transitions smoothly over an annular width of 10 au near 60 au. In gas, the data are consistent with a cavity that is smaller, about 15 au in radius, and whose surface density at 15 au is  10 3 1 times smaller than the surface density at 70 au; the gas density grades smoothly between these two radii. The CO isotopologue observations rule out a sharp drop in gas surface density at 30 au or a double-drop model, as found by previous modeling. Future observations are needed to assess the nature of these gas and dust cavities (e.g., whether they are opened by multiple as-yet-unseen planets or photoevaporation).

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GAS INSIDE THE 97 AU CAVITY AROUND THE TRANSITION DISK Sz 91

Cited by 58 publications

References 60 publications

Nonazimuthal linear polarization in protoplanetary disks

Nonazimuthal linear polarization in protoplanetary disks

Probing the final stages of protoplanetary disk evolution with ALMA

The Sizes and Depletions of the Dust and Gas Cavities in the Transitional Disk J160421.7-213028

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