A Major Asymmetric Dust Trap in a Transition Disk

Marel, Nienke van der; Dishoeck, E. F. van; Bruderer, S.; Birnstiel, T.; Pinilla, P.; Dullemond, C. P.; Kempen, T. A. van; Schmalzl, M.; Brown, J. M.; Herczeg, Gregory J.; Mathews, Geoffrey S.; Geers, V. C.

doi:10.1126/science.1236770

Cited by 560 publications

(379 citation statements)

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“…This indicates a temperature enhancement of at least 20 K compared to the surrounding optically thick CO gas. The feature is clearly dominated by the gas emission, unlike the recent detection of a dusty vortex-like structure, or dust trap, in the circumstellar disc associated with Oph IRS 48 41 . In the high angular resolution continuum maps at 0.45 mm and 1.3 mm, there is no dust counterpart to this bright CO peak.…”

mentioning

confidence: 55%

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Dutrey

Folco

Guilloteau

et al. 2014

Nature

105

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Forming planets around binary stars may be more difficult than around single stars [1][2][3] . In a close binary star (< 100 au separation), theory predicts the presence of circumstellar discs around each star, and an outer circumbinary disc surrounding a gravitationally cleared inner cavity 4,5 . As the inner discs are depleted by accretion onto the stars on timescales of few 10 3 yr, replenishing material must be transferred from the outer reservoir in order to fuel 1 planet formation (which occurs on timescales of ∼1 Myr). Gas flowing through disc cavities has been detected in single star systems 6 . A circumbinary disc was discovered around the young low-mass binary system GGTau-A 7 , which has recently been proven to be a hierarchical triple system 8 . It has one large inner disc 9 around the southern single star and shows small amounts of shocked H 2 gas residing within the central cavity 10 , but other than a weak detection 11 , hitherto the distribution of cold gas in this cavity or in any other binary or multiple star system has never been determined. Here we report imaging of massive CO-emitting gas fragments within the GG Tau-A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disc beyond the accretion lifetime, leaving time for planet formation to occur.The 1-5 Million year old 12, 13 triple stellar system GGTau-A is located at 140 pc in a hole of the Taurus molecular cloud. Its molecular emission is free of contamination 14 and there is no known outflow neither jet associated to the source. The main binary GGTau-A (Aa-Ab) and the close-binary GGTau-Ab (Ab1-Ab2) have an apparent separation of 35 au and 4.5 au, respectively 8 .The outer circumbinary Keplerian disc of gas and dust surrounding GGTau-A consists of a ring extending from radius r ∼ 190 to 280 au and an outer disc extending up to 800 au from the central stars with a total mass ∼ 0.15 M ⊙ 14 .Using the Atacama Large Millimetre Array (ALMA), we observed GGTau-A in the dust thermal emission at 0.45 mm and in CO J=6-5 line ( Fig.1: panels a,b,c) with an angular resolution θ ≃ 0.25 ′′ or ∼35 au. The continuum image shows cold dust emission from only one circumstellar 2 disc-like structure associated with GGTau-Aa 9, 15 . We estimate the minimum dust disc size to be ∼ 7 au while the minimum mass of gas and dust is roughly 10 −3 M ⊙ about Jupiter's mass. The complex CO J=6-5 spectral line shape at the location of GGTau-Aa also reveals the existence of a CO circumstellar disc of outer radius ∼ 20 au (Methods and Extended Data: Fig.2). We do not detect cold dust emission around GGTau-Ab even though the existence of inner dust disc(s) was reported from unresolved Infrared emission 16 . Our 0.45 mm upper limits (Methods) are compatible with tidal truncation which prevents any circumstellar disc to extend beyond about 2 au 8 .The ALMA CO J=6-5 image ( Fig.1 panels a,b,c and Extended Data: Fig.1 and Fig.2) also clearly resolves CO gas within the central cavity with a structure indicative of the streamer-like f...

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mentioning

confidence: 55%

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Dutrey

Folco

Guilloteau

et al. 2014

Nature

105

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“…These vortices can survive for several orbits, which can be shortened depending on several complicated effects such as, for instance, the amount of turbulence or dust feedback effects (Fu et al 2014). One such vortex was plausibly observed by ALMA ( Van der Marel et al 2013). These vortices can be, as a first approximation, modelled as we have done for dust clouds.…”

Section: -Inhomogeneties In Protoplanetary Discmentioning

confidence: 79%

Effects of disc asymmetries on astrometric measurements

Kral

Kennedy

Souami

2016

A&A

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Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement of the photo-centre owing to inhomogeneities in a dust disc around the parent star. Indeed, theory and observations show that circumstellar discs can present strong asymmetries. We model the pseudo-astrometric signal caused by these inhomogeneities, asking whether a dust clump in a disc can mimic the astrometric signal of an Earth-like planet. We show that these inhomogeneities cannot be neglected when using astrometry to find terrestrial planets. We provide the parameter space for which these inhomogeneities can affect the astrometric signals but still not be detected by mid-IR observations. We find that a small cross section of dust corresponding to a cometary mass object is enough to mimic the astrometric signal of an Earth-like planet. Astrometric observations of protoplanetary discs to search for planets can also be affected by the presence of inhomogeneities. Some further tests are given to confirm whether an observation is a real astrometric signal from a planet or an impostor. Eventually, we also study the case where the cross-section of dust is high enough to provide a detectable IR-excess and to have a measurable photometric displacement by actual instruments such as Gaia, IRAC, or GRAVITY. We suggest a new method, which consists of using astrometry to quantify asymmetries (clumpiness) in inner debris discs that cannot be otherwise resolved.

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“…The VLT-CRIRES spectra of the 4.7 μm CO line reveal a gas ring with a radius of ∼25−35 AU (Brown et al 2012). The submillimeter continuum (685 GHz or 0.43 mm) of our ALMA observations was presented in van der Marel et al (2013a). In contrast to the gas and small dust grains, the millimeter dust is concentrated on one side of the disk, with a high azimuthal contrast of >130 compared to the other side.…”

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

Self Cite

136

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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A Major Asymmetric Dust Trap in a Transition Disk

Cited by 560 publications

References 51 publications

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Effects of disc asymmetries on astrometric measurements

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

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