TRANSITIONAL AND PRE-TRANSITIONAL DISKS: GAP OPENING BY MULTIPLE PLANETS?

By Zhaohuan Zhu, R. Nelson, L. Hartmann, Catherine C. Espaillat, N. Calvet. 2010

225 citations recorded by the source corpus.

We use two-dimensional hydrodynamic simulations of viscous disks to examine whether dynamically interacting multiple giant planets can explain the large gaps (spanning over one order of magnitude in radius) inferred for the transitional and pre-transitional disks around T Tauri stars. In the absence of inner disk dust depletion, we find that it requires three to four giant planets to open up large enough gaps to be consistent with inferences from spectral energy distributions, because the gap width is limited by the tendency of the planets to be driven together into 2:1 resonances. With very strong tidal torques and/or rapid planetary accretion, fewer planets can also generate a large cavity interior to the locally formed gap(s) by preventing outer disk material from moving in. In these cases, however, the reduction of surface density produces a corresponding reduction in the inner disk accretion rate onto the star; this makes it difficult to explain the observed accretion rates of the pre-transitional/transitional disks. We find that even with four planets in disks, additional substantial dust depletion is required to explain observed disk gaps/holes. Substantial dust settling and growth, with consequent significant reductions in optical depths, is inferred for typical T Tauri disks in any case, and an earlier history of dust growth is consistent with the hypothesis that pre-transitional/transitional disks are explained by the presence of giant planets. We conclude that the depths and widths of gaps and disk accretion rates in pre-transitional/transitional disks cannot be reproduced by a planet-induced gap opening scenario alone. Significant dust depletion is also required within the gaps/holes. Order-of-magnitude estimates suggest that the mass of small dust particles (≲1 μm) relative to the gas must be depleted to 10−5 to 10−2 of the interstellar medium value, implying a very efficient mechanism of small dust removal or dust growth.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/296dbf23debb4cb01aa5e7162605168ded39cb9b

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Citations in the corpus

Planet-Disk Interaction and Orbital Evolution (2012, background): “This possibility has been studied by Quillen et al. (2004), Varnière et al. (2006), Dodson-Robinson & Salyk (2011), and Zhu et al. (2011).”
DUST FILTRATION BY PLANET-INDUCED GAP EDGES: IMPLICATIONS FOR TRANSITIONAL DISKS (2012, background): “Zhu et al. (2011) concluded that dust depletion/growth is still required in the inner disk to be consistent with observations.”
TRANSITIONAL DISKS AS SIGNPOSTS OF YOUNG, MULTIPLANET SYSTEMS (2011, methodology): “The apparent contradiction between optically thin holes and high stellar accretion rates comes from the assumption that gas and grains are evenly and axisymmetrically distributed within the hole (Espaillat et al. 2008, Espaillat et al. 2010, Zhu et al. 2011).”
Survival of molecular gas in cavities of transition disks - I. CO (2013, background): “Low gas masses in the gap (δgas < 3× 10−5) on the other hand are hard to achieve with planet clearing, even in the case of multiple systems (Dodson-Robinson & Salyk 2011; Zhu et al. 2011).”
Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA (2015, background): “The decrease in gas density due to companion clearing depends on the mass of the companion and other parameters such as the viscosity (Zhu et al. 2011; Dodson-Robinson & Salyk 2011; Pinilla et al. 2012; Mulders et al. 2013; Fung et al. 2014).”
LkCa 15: A YOUNG EXOPLANET CAUGHT AT FORMATION? (2011, unknown): “This discrepancy could indicate that there are other, less luminous planets in the system and we simply can not detect them yet, a possibility that has been suggested to explain the wide cleared gaps for many transitional disks (e.g., Zhu et al. 2011; Dodson-Robinson & Salyk 2011).”
HOW EMPTY ARE DISK GAPS OPENED BY GIANT PLANETS (2013, background): “…underestimates insofar as we have neglected accretion onto the planet; but arguably the disk accretion rate cannot be reduced by more than a factor of order unity, lest the planet starve the host star and violate observed stellar accretionrates (Zhu et al. 2011; see also Lubow and D’Angelo 2006).”
Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA (2015, background): “…cavities are only an indirect consequence of planet clearing: a planet will lower the gas surface density along its orbit, creating a gas gap with a pressure bump at its outer edge where the millimeter-sized dust is trapped (e.g., Zhu et al. 2011; Dodson-Robinson & Salyk 2011; Pinilla et al. 2012).”
RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, background): “Zhu et al. (2011) have suggested that multi-planet systems can dynamically clear large cavities while also rapidly transporting gas across the large distances between the remnant outer disk and the star.”
Radial Migration of Gap-opening Planets in Protoplanetary Disks. I. The Case of a Single Planet (2018, background): “…strong disk–planet interaction (e.g., Lin & Papaloizou 1993; Ward 1997; Lubow et al. 1999; Nelson et al. 2000; Crida & Morbidelli 2007; Edgar 2007; Zhu et al. 2011; Baruteau & Papaloizou 2013; Duffell et al. 2014; Dürmann & Kley 2015; Kanagawa et al. 2015b; Dong & Dawson 2016; Dong & Fung 2017).”
The Disk Substructures at High Angular Resolution Project (DSHARP). VII. The Planet–Disk Interactions Interpretation (2018, background): “…recently efforts have been dedicated to studying observable disk features induced by planets (Wolf & D’Angelo 2005; Dodson-Robinson & Salyk 2011; Zhu et al. 2011; Gonzalez et al. 2012; Pinilla et al. 2012; Ataiee et al. 2013; Bae et al. 2016; Kanagawa et al. 2016; Rosotti et al. 2016; Isella &…”
Accretion onto Pre-Main-Sequence Stars (2016, background): “In any event, it seems clear that the depletion of small dust in the inner cavity is generally much greater than the gas depletion, posing challenges to theories (e.g., Zhu et al. 2011).”
Dust Evolution and the Formation of Planetesimals (2016, background): “Casassus et al. (2013) also detected faint stream-like features in HCO+ and dust continuum at 345 GHz in the transition disk, HD 142527, which could be explained as funnel flows into the inner disk through planets (Zhu et al. 2011).”
Observational Signatures of Planets in Protoplanetary Disks I: Gaps Opened by Single and Multiple Young Planets in Disks (2014, background): “The more efficient accretion is, the cleaner the gap is (Zhu et al. 2011).”
Ring shaped dust accumulation in transition disks (2012, methodology): “However, studies based on hydrodynamical simulation of gap opening in a gaseous disk have shown that a single planet could not open the large gap inferred from spatially resolved millimeter observations (e.g. Dodson-Robinson & Salyk 2011; Zhu et al. 2011).”