Cold Disks:
                    <i>Spitzer</i>
                    Spectroscopy of Disks around Young Stars with Large Gaps

Brown, J. M.; Blake, Geoffrey A.; Dullemond, C. P.; Merın, Bruno; Augereau, J.-C.; Boogert, A. C. A.; Evans, Neal J.; Geers, V. C.; Lahuis, F.; Kessler-Silacci, J. E.; Pontoppidan, K. M.; Dishoeck, E. F. van

doi:10.1086/520808

Cited by 182 publications

(288 citation statements)

References 36 publications

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“…The near-infrared-excess in the SED of HD 135344B is an indicator for dust at small orbital radii (Brown et al 2007;Carmona et al 2014). A dust belt at sub-au distance from the star was confirmed by mid-and near-infrared interferometric observations (Carmona et al 2014;Menu et al 2015) with possibly a misalignment of the inner and outer disk (Fedele et al 2008).…”

Section: Introductionmentioning

confidence: 82%

“…Analysis of the SED by Brown et al (2007) suggested that a large dust cavity with a radius of 45 au is present in the disk. Dust continuum (sub-)millimeter observations have confirmed the presence of the dust cavity and show a crescent-shaped asymmetry with a factor of two emission contrast due to an azimuthal asymmetry in the thermal disk structure and/or the distribution of the large dust grains (Brown et al 2009;Lyo et al 2011;Andrews et al 2011;Pérez et al 2014;Pinilla et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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Shadows cast on the transition disk of HD 135344B

Stolker

Dominik

Avenhaus

et al. 2016

A&A

157

124

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Context. The protoplanetary disk around the F-type star HD 135344B (SAO 206462) is in a transition stage and shows many intriguing structures both in scattered light and thermal (sub-)millimeter emission which are possibly related to planet formation processes. Aims. We aim to study the morphology and surface brightness of the disk in scattered light to gain insight into the innermost disk regions, the formation of protoplanets, planet-disk interactions traced in the surface and midplane layers, and the dust grain properties of the disk surface. Methods. We have carried out high-contrast polarimetric differential imaging (PDI) observations with VLT/SPHERE and obtained polarized scattered light images with ZIMPOL in the R and I-bands and with IRDIS in the Y and J-bands. The scattered light images and surface brightness profiles are used to study in detail structures in the disk surface and brightness variations. We have constructed a 3D radiative transfer model to support the interpretation of several detected shadow features. Results. The scattered light images reveal with unprecedented angular resolution and sensitivity the spiral arms as well as the 25 au cavity of the disk. Multiple shadow features are discovered on the outer disk with one shadow only being present during the second observation epoch. A positive surface brightness gradient is observed in the stellar irradiation corrected (r 2 -scaled) images in southwest direction possibly due to an azimuthally asymmetric perturbation of the temperature and/or surface density by the passing spiral arms. The disk integrated polarized flux, normalized to the stellar flux, shows a positive trend towards longer wavelengths which we attribute to large (2πa λ) aggregate dust grains in the disk surface. Part of the non-azimuthal polarization signal in the U φ image of the J-band observation can be attributed to multiple scattering in the disk. Conclusions. The detected shadow features and their possible variability have the potential to provide insight into the structure of and processes occurring in the innermost disk regions. Possible explanations for the presence of the shadows include a 22 • misaligned inner disk, a warped disk region that connects the inner disk with the outer disk, and variable or transient phenomena such as a perturbation of the inner disk or an asymmetric accretion flow. The spiral arms are best explained by one or multiple protoplanets in the exterior of the disk although no gap is detected beyond the spiral arms up to 1. 0.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Shadows cast on the transition disk of HD 135344B

Stolker

Dominik

Avenhaus

et al. 2016

A&A

157

124

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“…The disk around HD 135344B has been the subject of numerous studies carried out over a large wavelength range using imaging, spectroscopy, and interferometry (e.g., Thi et al 2001;Dent et al 2005;Doucet et al 2006;Brown et al 2007;Fedele et al 2008;Pontoppidan et al 2008;Grady et al 2009;Verhoeff et al 2010) that have identified a complex structure. An outer radius of 200 AU for the dusty disk was derived by Doucet et al (2006) at 20.5 μm.…”

Section: Astrophysical Parameters Of Hd 135344bmentioning

confidence: 99%

“…The detection of polycyclic aromatic hydrocarbon (PAH) features (e.g. Coulson & Walther 1995;Brown et al 2007;Fedele et al 2008) implies that there is rich chemistry in the vicinity of the star. From J = 3-2 12 CO measurements, Dent et al (2005) derived an inner radius of ≤10 AU and 75 ± 5 AU for the outer radius where emitting gas is present.…”

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confidence: 99%

HD 135344B: a young star has reached its rotational limit

Müller

Ancker

Launhardt

et al. 2011

A&A

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Aims. We search for periodic variations in the radial velocity of the young Herbig star HD 135344B to determine a rotation period. Methods. We analyze 44 high-resolution optical spectra taken over a time period of 151 days. The spectra were acquired with FEROS at the 2.2 m MPG/ESO telescope in La Silla. The stellar parameters of HD 135344B are determined by fitting synthetic spectra to the stellar spectrum. To obtain radial velocity measurements, the stellar spectra are cross-correlated with a theoretical template computed from determined stellar parameters. Results. We report the first direct measurement of the rotation period of a Herbig star from radial velocity measurements. The rotation period is found to be 0.16 d (3.9 h), which makes HD 135344B a rapid rotator at or close to its break-up velocity. The rapid rotation could explain some of the properties of the circumstellar environment of HD 135344B such as an inner disk with properties (composition, inclination) that differ significantly from the outer disk.

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“…Transition disks are commonly identified through their SEDs showing a strong excess over the stellar photosphere at wavelengths 20 μm, but little excess at shorter wavelengths. The deficit of near infrared excess arises from the absence of hot small dust close to the star, suggesting the presence of an inner dust cavity (Strom et al 1989;Calvet et al 2002;Brown et al 2007). Several of these dust holes have been imaged directly in (sub)millimeter interferometric imaging (Piétu et al 2006;Brown et al 2009;Andrews et al 2011;Isella et al 2012Isella et al , 2013.…”

Section: Introductionmentioning

confidence: 99%

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

Bruderer

Marel

Dishoeck

et al. 2014

A&A

134

196

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Context. Transition disks are recognized by the absence of emission of small dust grains inside a radius of up to several 10s of AUs. Owing to the lack of angular resolution and sensitivity, the gas content of these dust holes has not yet been determined, but is of importance for constraining the mechanism leading to the dust holes. It is thought that transition disks are currently undergoing the process of dispersal, setting an end to the giant planet formation process. Aims. We present new high-resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of gas lines towards the transition disk Oph IRS 48 previously shown to host a large dust trap. The ALMA telescope has detected the J = 6−5 line of 12 CO and C 17 O around 690 GHz (434 μm) at a resolution of ∼0.25 corresponding to ∼30 AU (FWHM). The observed gas lines are used to set constraints on the gas surface density profile. Methods. New models of the physical-chemical structure of gas and dust in Oph IRS 48 are developed to reproduce the CO line emission together with the spectral energy distribution and the VLT-VISIR 18.7 μm dust continuum images. Integrated intensity cuts and the total spectrum from models having different trial gas surface density profiles are compared to observations. The main parameters varied are the drop in gas surface density inside the dust-free cavity with a radius of 60 AU and inside the gas-depleted innermost 20 AU. Using the derived surface density profiles, predictions for other CO isotopologues are made, which can be tested by future ALMA observations of the object. Results. From the ALMA data we find a total gas mass of the disk of 1.4 × 10 −4 M . This gas mass yields a gas-to-dust ratio of ∼10, but with considerable uncertainty. Inside 60 AU, the gas surface density drops by a factor of ∼12 for an assumed surface density slope of γ = 1 (Σ ∝ r −γ ). Inside 20 AU, the gas surface density drops by a factor of at least 110. The drops are measured relative to the extrapolation to small radii of the surface density law at radii >60 AU. The inner radius of the gas disk at 20 AU can be constrained to better than ±5 AU. Conclusions. The derived gas surface density profile points to the clearing of the cavity by one or more massive planets/companions rather than just photoevaporation or grain-growth.

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Cold Disks: Spitzer Spectroscopy of Disks around Young Stars with Large Gaps

Cited by 182 publications

References 36 publications

Shadows cast on the transition disk of HD 135344B

Shadows cast on the transition disk of HD 135344B

HD 135344B: a young star has reached its rotational limit

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

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