Importance of radiative effects in gap opening by planets in protoplanetary disks

Abstract

Recent ALMA observations revealed concentric annular structures in several young class-II objects. In an attempt to produce the rings and gaps in some of these systems, they have been modeled numerically with a single embedded planet assuming a locally isothermal equation of state. This is often justified by observations targeting the irradiation-dominated outer regions of disks (approximately 100 au). We test this assumption by conducting hydrodynamics simulations of embedded planets in thin locally isothermal and radiative disks that mimic the systems HD 163296 and AS 209 in order to examine the effect of including the energy equation in a seemingly locally isothermal environment as far as planet-disk interaction is concerned. We find that modeling such disks with an ideal equation of state makes a difference in terms of the number of produced rings and the spiral arm contrast in the disk. Locally isothermal disks produce sharper annular or azimuthal features and overestimate a single planet's gap-opening capabilities by producing multiple gaps. In contrast, planets in radiative disks carve a single gap for typical disk parameters. Consequently, for accurate modeling of planets with semimajor axes up to about 100 au, radiative effects should be taken into account even in seemingly locally isothermal disks. In addition, for the case of AS 209, we find that the primary gap is significantly different between locally isothermal and radiative models. Our results suggest that multiple planets are required to explain the ring-rich structures in such systems.

Migration of gap-opening planets in 3D stellar-irradiated accretion disks

“…6 reveals azimuthal asymmetries in the temperature variations from which we calculated the maximum temperature contrast reached in the planetary spiral wake with A219, page 9 of 17 respect to the disk background as 17%. The obtained value is in a good agreement with Ziampras et al (2020; their contrast from 2D simulations was 15%). Figure 7 then shows that in our radiative simulation, the spiral arms have a decreased density contrast (again as in Ziampras et al 2020) and their winding is less tight in the outer disk.…”

“…The obtained value is in a good agreement with Ziampras et al (2020; their contrast from 2D simulations was 15%). Figure 7 then shows that in our radiative simulation, the spiral arms have a decreased density contrast (again as in Ziampras et al 2020) and their winding is less tight in the outer disk. The latter can be explained by the dependence of the pitch angle tan β h/|1 − (r/r p ) 3/2 | (Zhu et al 2015), which grows as h becomes puffed up in the outer disk in the presence of gap irradiation.…”

Annular substructures in the transition disks around LkCa 15 and J1610

“…Recent numerical simulations of planet-disk interaction have shown that the propagation and dissipation of planet-driven spiral waves and the number and depth of associated gaps strongly depend on the thermal properties of the disk gas, in particular, the cooling timescale of the disk gas (Miranda & Rafikov 2020;Zhang & Zhu 2020;Weber et al 2019;Ziampras et al 2020). Inspired by these studies, we run three hydrodynamical simulations: (1) a locally isothermal simulation, adopting an isothermal equation of state (hereafter isothermal model); (2) an adiabatic simulation, adopting an adiabatic equation of state with an adiabatic index γ = 1.4 and β = 1 (hereafter β = 1 model), where β is defined as the multiplication of the cooling time t cool and local orbital frequency Ω, β ≡ t cool Ω; and (3) an adiabatic simulation with γ = 1.4 and β = 100 (hereafter β = 100 model).…”

The birth environment of planetary systems

“…One of the first images to come from ALMA was the now famous HL Tau disc, a disc surrounding a young, nearby star in the Taurus star-forming region [67]. Further observational studies, in particular, the Disc Substructures at High Angular Resolution Project (DSHARP) [68], have shown that discs around young stars display features than can be attributed to a change in disc composition [69][70][71][72] as a function of radius, or the presence of fledgling planets within those discs [73][74][75][76][77] (although the latter scenario is still hotly debated [78,79]).…”