Residual Gas and Dust around Transition Objects and Weak T Tauri Stars*

Doppmann, Greg; Najita, J.; Carr, John S.

doi:10.3847/1538-4357/aa5c3c

Cited by 10 publications

(9 citation statements)

References 109 publications

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“…Even for an angular resolution of 0.3 , the molecular intensity profile never shows an actual cavity, indicating that some additional mechanism not included needs to reduce the CO emission from the very inner regions to reproduce the observations. Moreover, as discussed in Section 1, the low CO column densities in the inner disks of some transition disks are also probed by the modeling of CO vibrationally excited IR lines (Pontoppidan et al 2008;Carmona et al 2014Carmona et al , 2017van der Plas et al 2015;Banzatti & Pontoppidan 2015;Doppmann et al 2017); this thus corroborates the evidence of depletion of CO in the inner disk regions, which is not compatible with the gap scenario. If accretion onto the planet were included in the hydrodynamical simulations, the gas surface density in the inner regions would have been lower by a factor of a few at the most (e.g., Owen 2016, see their fig.…”

Section: Co Gap Versus Co Cavity: a Resolution Effect?mentioning

confidence: 76%

Inferring giant planets from ALMA millimeter continuum and line observations in (transition) disks

Facchini

Pinilla

Dishoeck

et al. 2018

A&A

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Context. Radial gaps or cavities in the continuum emission in the IR-mm wavelength range are potential signatures of protoplanets embedded in their natal protoplanetary disk are . Hitherto, models have relied on the combination of mm continuum observations and near-infrared (NIR) scattered light images to put constraints on the properties of embedded planets. Atacama Large Millimeter/submillimeter Array (ALMA) observations are now probing spatially resolved rotational line emission of CO and other chemical species. These observations can provide complementary information on the mechanism carving the gaps in dust and additional constraints on the purported planet mass. Aims. We investigate whether the combination of ALMA continuum and CO line observations can constrain the presence and mass of planets embedded in protoplanetary disks. Methods. We post-processed azimuthally averaged 2D hydrodynamical simulations of planet-disk models, in which the dust densities and grain size distributions are computed with a dust evolution code that considers radial drift, fragmentation, and growth. The simulations explored various planet masses (1 M J ≤ M p ≤ 15 M J ) and turbulent parameters (10 −4 ≤ α ≤ 10 −3 ). The outputs were then post-processed with the thermochemical code DALI, accounting for the radially and vertically varying dust properties. We obtained the gas and dust temperature structures, chemical abundances, and synthetic emission maps of both thermal continuum and CO rotational lines. This is the first study combining hydrodynamical simulations, dust evolution, full radiative transfer, and chemistry to predict gas emission of disks hosting massive planets. Results. All radial intensity profiles of 12 CO, 13 CO, and C 18 O show a gap at the planet location. The ratio between the location of the gap as seen in CO and the peak in the mm continuum at the pressure maximum outside the orbit of the planet shows a clear dependence on planet mass and is independent of disk viscosity for the parameters explored in this paper. Because of the low dust density in the gaps, the dust and gas components can become thermally decoupled and the gas becomes colder than the dust. The gaps seen in CO are due to a combination of gas temperature dropping at the location of the planet and of the underlying surface density profile. Both effects need to be taken into account and disentangled when inferring gas surface densities from observed CO intensity profiles; otherwise, the gas surface density drop at the planet location can easily be overestimated. CO line ratios across the gap are able to quantify the gas temperature drop in the gaps in observed systems. Finally, a CO cavity not observed in any of the models, only CO gaps, indicating that one single massive planet is not able to explain the CO cavities observed in transition disks, at least without additional physical or chemical mechanisms.Key words. astrochemistry -planetary systems: protoplanetary disks -planetary systems: planet-disk interactions -submillimeter: planetary syste...

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Section: Co Gap Versus Co Cavity: a Resolution Effect?mentioning

confidence: 76%

Inferring giant planets from ALMA millimeter continuum and line observations in (transition) disks

Facchini

Pinilla

Dishoeck

et al. 2018

A&A

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“…For instance, a stellar mass is necessary to calculate the photoionization impacting the disk (Ercolano et al 2017). More significantly, Doppmann et al (2017) input effective temperatures and surface gravities to identify Moog models for M-band spectra to search for CO v=1-0 emission (and thus gas in the disk). The presence of residual gas would have implications for the disk dispersal timescales and the role of the gas in planet formation.…”

Section: Discussionmentioning

confidence: 99%

Characterizing TW Hydra

Sokal

Deen

Mace

et al. 2018

ApJ

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At 60 pc, TW Hydra (TW Hya) is the closest example of a star with a gas-rich protoplanetary disk, though TW Hya may be relatively old (3-15 Myr). As such, TW Hya is especially appealing to test our understanding of the interplay between stellar and disk evolution. We present a high-resolution near-infrared spectrum of TW Hya obtained with the Immersion GRating INfrared Spectrometer (IGRINS) to re-evaluate the stellar parameters of TW Hya. We compare these data to synthetic spectra of magnetic stars produced by MoogStokes, and use sensitive spectral line profiles to probe the effective temperature, surface gravity, and magnetic field. A model with T eff = 3800 K, log g = 4.2, and B= 3.0 kG best fits the near-infrared spectrum of TW Hya. These results correspond to a spectral type of M0.5 and an age of 8 Myr, which is well past the median life of gaseous disks.

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“…They postulated that instead of an extended disk or a grain size distribution, the disk consists of two spatially separated dust belts, one at ∼38 au and another at ∼75 au. They did not detect the [O I] emission in the PACS spectroscopic observations, and regarding CO, Doppmann et al (2017) did not detect any emission lines in highresolution 4.7 µm spectroscopic NIRSPEC observations. More recently, Holland et al (2017) also modeled the SED of TWA 7, with additional unresolved SCUBA-2 observations, and the best fit model suggests that there are two dust rings around the central star, one at 2.5 au and the other one at ∼49 au.…”

Section: Introductionmentioning

confidence: 89%

Resolving faint structures in the debris disk around TWA 7

Olofsson

Holstein

Boccaletti

et al. 2018

A&A

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Context. Debris disks are the intrinsic by-products of the star and planet formation processes. Most likely due to instrumental limitations and their natural faintness, little is known about debris disks around low mass stars, especially when it comes to spatially resolved observations. Aims. We present new VLT/SPHERE IRDIS dual-polarization imaging (DPI) observations in which we detect the dust ring around the M2 spectral type star TWA 7. Combined with additional angular differential imaging observations we aim at a fine characterization of the debris disk and setting constraints on the presence of low-mass planets. Methods. We modeled the SPHERE DPI observations and constrain the location of the small dust grains, as well as the spectral energy distribution of the debris disk, using the results inferred from the observations, and performed simple N-body simulations. Results. We find that the dust density distribution peaks at ~0.72′′ (25 au), with a very shallow outer power-law slope, and that the disk has an inclination of ~13° with a position angle of ~91° east of north. We also report low signal-to-noise ratio detections of an outer belt at a distance of ~1.5′′ (~52 au) from the star, of a spiral arm in the southern side of the star, and of a possible dusty clump at 0.11′′. These findings seem to persist over timescales of at least a year. Using the intensity images, we do not detect any planets in the close vicinity of the star, but the sensitivity reaches Jovian planet mass upper limits. We find that the SED is best reproduced with an inner disk at ~0.2′′ (~7 au) and another belt at 0.72′′ (25 au). Conclusions. We report the detections of several unexpected features in the disk around TWA 7. A yet undetected 100M⊕ planet with a semi-major axis at 20−30 au could possibly explain the outer belt as well as the spiral arm. We conclude that stellar winds are unlikely to be responsible for the spiral arm.

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Residual Gas and Dust around Transition Objects and Weak T Tauri Stars*

Cited by 10 publications

References 109 publications

Inferring giant planets from ALMA millimeter continuum and line observations in (transition) disks

Inferring giant planets from ALMA millimeter continuum and line observations in (transition) disks

Characterizing TW Hydra

Resolving faint structures in the debris disk around TWA 7

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