Observational Properties of Protoplanetary Disk Gaps

Bjorkman, J. E.; Frank, Adam; Quillen, Alice C.; Carciofi, A. C.; Whitney, B. A.; Wood, Kenneth

doi:10.1086/500584

Cited by 36 publications

(41 citation statements)

References 26 publications

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“…For example, if the gap is cleared by the planet to a fraction of the surrounding density, the disk is not directly irradiated, but is shadowed by the inner wall of the gap (Varnière et al 2006). This mild heating causes a temperature drop at the inner gap wall, which results in a depressed CO flux.…”

Section: Discussionmentioning

confidence: 99%

Detectability of giant planets in protoplanetary disks by CO emission lines

Regály

Sándor

Dullemond

et al. 2010

A&A

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Context. Planets are thought to form in protoplanetary accretion disks around young stars. Detecting a giant planet still embedded in a protoplanetary disk would be very important and give observational constraints on the planet-formation process. However, detecting these planets with the radial velocity technique is problematic owing to the strong stellar activity of these young objects. Aims. We intend to provide an indirect method to detect Jovian planets by studying near infrared emission spectra originating in the protoplanetary disks around T Tauri stars. Our idea is to investigate whether a massive planet could induce any observable effect on the spectral lines emerging in the disks atmosphere. As a tracer molecule we propose CO, which is excited in the ro-vibrational fundamental band in the disk atmosphere to a distance of ∼2−3 AU (depending on the stellar mass) where terrestrial planets are thought to form. Methods. We developed a semi-analytical model to calculate synthetic molecular spectral line profiles in a protoplanetary disk using a double layer disk model heated on the outside by irradiation by the central star and in the midplane by viscous dissipation due to accretion. 2D gas dynamics were incorporated in the calculation of synthetic spectral lines. The motions of gas parcels were calculated by the publicly available hydrodynamical code FARGO which was developed to study planet-disk interactions. Results. We demonstrate that a massive planet embedded in a protoplanetary disk strongly influences the originally circular Keplerian gas dynamics. The perturbed motion of the gas can be detected by comparing the CO line profiles in emission, which emerge from planet-bearing to those of planet-free disk models. The planet signal has two major characteristics: a permanent line profile asymmetry, and short timescale variability correlated with the orbital phase of the giant planet. We have found that the strength of the asymmetry depends on the physical parameters of the star-planet-disk system, such as the disk inclination angle, the planetary and stellar masses, the orbital distance, and the size of the disk inner cavity. The permanent line profile asymmetry is caused by a disk in an eccentric state in the gap opened by the giant planet. However, the variable component is a consequence of the local dynamical perturbation by the orbiting giant planet. We show that a forming giant planet, still embedded in the protoplanetary disk, can be detected using contemporary or future high-resolution near-IR spectrographs like VLT/CRIRES and ELT/METIS.

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Section: Discussionmentioning

confidence: 99%

Detectability of giant planets in protoplanetary disks by CO emission lines

Regály

Sándor

Dullemond

et al. 2010

A&A

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“…Lin & Papaloizou 1979, 1986. A gap carved by a single planet has very little impact on the spectral energy distribution (SED), but could be identified by imaging of the disk (Steinacker & Henning 2003;Varnière et al 2006;Wolf et al 2007). Nonetheless, a class of so-called transitional disks have been identified on the basis of their low near-infrared excess, which is apparently caused by depleted inner regions (Strom et al 1989;Muzerolle et al 2004;Calvet et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Planet or brown dwarf? Inferring the companion mass in HD 100546 from the wall shape using mid-infrared interferometry

Mulders

Paardekooper

Panić

et al. 2013

A&A

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Context. Giant planets form in protoplanetary disks while these disks are still gas-rich, and can reveal their presence through the annular gaps they carve out. HD 100546 is a gas-rich disk with a wide gap between a radius of ∼1 and 13 AU, possibly cleared out by a planetary companion or planetary system. Aims. We aim to identify the nature of the unseen companion near the far end of the disk gap. Methods. We used mid-infrared interferometry at multiple baselines to constrain the curvature of the disk wall at the far end of the gap. We used 2D hydrodynamical simulations of embedded planets and brown dwarfs to estimate the viscosity of the disk and the mass of a companion close to the disk wall. Results. We find that the disk wall at the far end of the gap is not vertical, but rounded-off by a gradient in the surface density. This gradient can be reproduced in hydrodynamical simulations with a single, heavy companion ( 30 . . . 80 M Jup ) while the disk has a viscosity of at least α 5 × 10 −3 . Taking into account the changes in the temperature structure after gap opening reduces the lower limit on the planet mass and disk viscosity to 20 M Jup and α = 2 × 10 −3 . Conclusions. The object in the disk gap of HD 100546 that shapes the disk wall is most likely a 60 +20 −40 M Jup brown dwarf, while the disk viscosity is estimated to be at least α = 2 × 10 −3 . The disk viscosity is an important factor in estimating planetary masses from disk morphologies: more viscous disks need heavier planets to open an equally deep gap.

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“…Vorobyov et al (2013) and Zakhozhay et al (2013) show that a presence of hot and massive (32 -64 M J ) fragments -proto-brown dwarfs during the first few 10,000 years -initiate an additional peak in SEDs at 5 -10 µm. Varnière et al (2006), considered the example of a 2 Jupiter mass planet on a very close orbit to the star, and found that SEDs from discs with gaps may not only have a reduced emission at λ ∼ 5 − 20 µm due to the removal of the emission from the gap, but also may have a measurable excess emission at longer wavelengths (∼ 10 − 100 µm), that rises from the heat-2 O.V. Zakhozhay ing of the vertical disc wall at the outer edge of the gap.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Forming Companions on the Spectral Energy Distributions of Stars with Circumstellar Discs

Zakhozhay

2017

Publ. Astron. Soc. Aust.

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We study a possibility to detect signatures of brown dwarf companions in a circumstellar disc based on spectral energy distributions (SED). We present the results of SED simulations for a system with a 0.8 M⊙ central object and a companion with a mass of 30 MJ embedded in a typical protoplanetary disc. We use a solution to the one-dimensional radiative transfer equation to calculate the protoplanetary disc flux density and assume, that the companion moves along a circular orbit and clears a gap. The width of the gap is assumed to be the diameter of the brown dwarf Hill sphere. Our modelling shows that the presence of such a gap can initiate an additional minimum in the SED profile of a protoplanetary disc at λ = 10 − 100 µm. We show that the depth of this minimum and the wavelength of the maximum difference between the SEDs of the system with and without a companion are related to the companion mass and its proximity to the star. We found that it is possible to detect signatures of the companion when it is located within 10 AU, even when it is as small as 3 MJ . We also analyse how the disc parameters (the inner radius and the temperature profile) change the maximum difference between the SEDs for the same systems with and without a companion. The SED of a protostellar disc with a massive fragment might have a similar double peaked profile to the SED of a more evolved disc that contains a gap. However, in this case, it will be caused by the presence of an additional maximum at shorter wavelengths and will be similar only when the massive fragment is relatively cold (∼400 K).

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Observational Properties of Protoplanetary Disk Gaps

Cited by 36 publications

References 26 publications

Detectability of giant planets in protoplanetary disks by CO emission lines

Detectability of giant planets in protoplanetary disks by CO emission lines

Planet or brown dwarf? Inferring the companion mass in HD 100546 from the wall shape using mid-infrared interferometry

The Influence of Forming Companions on the Spectral Energy Distributions of Stars with Circumstellar Discs

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