1+1D implicit disk computations

Ragossnig, Florian; Dorfi, E. A.; Ratschiner, Bernhard; Gehrig, Lukas; Steiner, Daniel; Stökl, Alexander; Johnstone, C. P.

doi:10.1016/j.cpc.2020.107437

“…The focus of this study is the combination of a full hydrodynamic disk simulation and a stellar spin evolution model. The disk evolution is treated with the implicit hydrodynamics TAPIR code (Ragossnig et al 2020;Steiner et al 2021) and the stellar spin model is formulated in detail in Matt et al (2010); and Gallet et al (2019). Here, we want to give a recap of the respective model's key features.…”

Section: Model Descriptionmentioning

confidence: 99%

“…We combine hydrodynamic disk and protostellar spin evolution to study the long-term effects of stellar rotation on the protoplanetary disk. The adaptive, implicit hydrodynamic (TAPIR) code for protoplanetary disks (Ragossnig et al 2020;Steiner et al 2021), which is based on Dorfi (1998) and Stoekl & Dorfi (2014), is extended with a stellar evolution model. Following Matt et al (2010), this stellar evolution model includes a simplified description of the protostellar contraction (Kelvin-Helmholtz contraction).…”

Section: Introductionmentioning

confidence: 99%

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk

Gehrig

¹

,

Steiner

²

,

Vorobyov

³

et al. 2022

A&A

Self Cite

View full text Add to dashboard Cite

Context. The spin evolution of young protostars, surrounded by an accretion disk, still poses problems for observations and theoretical models. In recent studies, the importance of the magnetic star-disk interaction for stellar spin evolution has been elaborated. The accretion disk in these studies, however, is only represented by a simplified model and important features are not considered. Aims. A more realistic representation of the accretion disk is indispensable for a better understanding of the star-disk interaction and the stellar spin evolution. The aim of this study is to investigate the influence of a hydrodynamic disk evolution on the stellar rotational period and vice versa during the accretion phase. Methods. We combined the implicit hydrodynamic TAPIR disk code with a stellar spin evolution model. The influence of stellar magnetic fields on the disk dynamics, the radial position of the inner disk radius, as well as the influence of stellar rotation on the disk were calculated self-consistently. Results. Within a defined parameter space, we can reproduce the majority of fast and slow rotating stars observed in young stellar clusters. Additionally, the back reaction of different stellar spin evolutionary tracks on the disk can be analyzed. Disks around fast rotating stars are located closer to the star. Consequently, the disk midplane temperature in the innermost disk region increases significantly compared to slow rotating stars. We can show the effects of stellar rotation on episodic accretion outbursts. The higher temperatures of disks around fast rotating stars result in more outbursts and a longer outbursting period over the disk lifetime. Conclusions. The combination of a long-term hydrodynamic disk and a stellar spin evolution model allows the inclusion of previously unconsidered effects such as the back-reaction of stellar rotation on the long-term disk evolution and the occurrence of accretion outbursts. However, a wider parameter range has to be studied to further investigate these effects. Additionally, a possible interaction between our model and a more realistic stellar evolution code (e.g., the MESA code) can improve our understanding of the stellar spin evolution and its effects on the pre-main sequence star.

show abstract

“…This includes a deviation from the Keplerian angular velocity u ϕ ∝ r −1/2 . Compared to the model presented in Ragossnig et al (2020), we added the influence of the stellar magnetic field, which is especially important in the inner part of the disk (e.g., Romanova et al 2002;Bessolaz et al 2008). The disk is assumed to be axisymmetric in angular direction and to be in hydrostatic equilibrium in vertical direction.…”

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

“…The disk is assumed to be axisymmetric in angular direction and to be in hydrostatic equilibrium in vertical direction. Our model is formulated in cylindrical coordinates with the planar components (r,ϕ), which are then discretized (for a comprehensive description regarding discretization and numerical properties, see Ragossnig et al 2020). The protoplanetary disk in our simulations is described in Eqs.…”

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk II: The importance of stellar rotation

Gehrig¹,

Steiner²,

Vorobyov³

et al. 2022

Preprint

Self Cite

0

View full text Add to dashboard Cite

Context. The spin evolution of young protostars, surrounded by an accretion disk, still poses problems for observations and theoretical models. In recent studies, the importance of the magnetic star-disk interaction for stellar spin evolution has been elaborated. The accretion disk in these studies, however, is only represented by a simplified model and important features are not considered. Aims. A more realistic representation of the accretion disk is indispensable for a better understanding of the star-disk interaction and the stellar spin evolution. The aim of this study is to investigate the influence of a hydrodynamic disk evolution on the stellar rotational period and vice versa during the accretion phase. Methods. We combined the implicit hydrodynamic TAPIR disk code with a stellar spin evolution model. The influence of stellar magnetic fields on the disk dynamics, the radial position of the inner disk radius, as well as the influence of stellar rotation on the disk were calculated self-consistently. Results. Within a defined parameter space, we can reproduce the majority of fast and slow rotating stars observed in young stellar clusters. Additionally, the back reaction of different stellar spin evolutionary tracks on the disk can be analyzed. Disks around fast rotating stars are located closer to the star. Consequently, the disk midplane temperature in the innermost disk region increases significantly compared to slow rotating stars. We can show the effects of stellar rotation on episodic accretion outbursts. The higher temperatures of disks around fast rotating stars result in more outbursts and a longer outbursting period over the disk lifetime. Conclusions. The combination of a long-term hydrodynamic disk and a stellar spin evolution model allows the inclusion of previously unconsidered effects such as the back-reaction of stellar rotation on the long-term disk evolution and the occurrence of accretion outbursts. However, a wider parameter range has to be studied to further investigate these effects. Additionally, a possible interaction between our model and a more realistic stellar evolution code (e.g., the MESA code) can improve our understanding of the stellar spin evolution and its effects on the pre-main sequence star.

show abstract

“…Recent hydrodynamic models of MRI and thermal instability bursts (Bae et al 2013;Kadam et al 2020;Vorobyov et al 2020)) have strong limitations in modeling the innermost disk regions, therefore necessitating the development of numerical codes that can realistically treat the star-disk interface in global disk simulations. Combining the requirements of (i) self-consistent treatment of both the gas dynamics in the inner disk including the effects of a stellar magnetic field and the position of the inner disk radius, (ii) the inclusion of an energy equation to investigate the effects of TI-induced episodic accretion, and (iii) maintaining the ability to resolve the very inner disk parts of a few stellar radii and carry out long-term calculations up to a few million years, we choose to use an implicit 1+1D RHD code (TAPIR, see Stoekl & Dorfi 2014;Ragossnig et al 2020) that enables us to meet all the requirements without being time-step-limited by the Courant-Friedrichs-Levy (CFL) condition (Appendix A). Until now, no comparable numerical code has combined the above requirements.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk I: The importance of stellar magnetic torques

Steiner,

Gehrig,

Ratschiner

et al. 2021

Preprint

0

View full text Add to dashboard Cite

Aims. We conduct simulations of the inner regions of protoplanetary disks (PPDs) to investigate the effects of protostellar magnetic fields on their long-term evolution. We use an inner boundary model that incorporates the influence of a stellar magnetic field. The position of the inner disk is dependent on the mass accretion rate as well as the magnetic field strength. We use this model to study the response of a magnetically truncated inner disk to an episodic accretion event. Additionally, we vary the protostellar magnetic field strength and investigate the consequences of the magnetic field on the long-term behavior of PPDs. Methods. We use the fully implicit 1+1D TAPIR code which solves the axisymmetric hydrodynamic equations self-consistently. Our model allows us to investigate disk dynamics close to the star and to conduct long-term evolution simulations simultaneously. We assume a hydrostatic vertical configuration described via an energy equation which accounts for the radiative transport in the vertical direction in the optically thick limit and the equation of state. Moreover, our model includes the radial radiation transport in the stationary diffusion limit and takes protostellar irradiation into account.Results. We include stellar magnetic torques, the influence of a pressure gradient, and a variable inner disk radius in the TAPIR code to describe the innermost disk region in a more self-consistent manner. We can show that this approach alters the disk dynamics considerably compared to a simplified diffusive evolution equation, especially during outbursts. During a single outburst, the angular velocity deviates significantly from the Keplerian velocity because of the influence of stellar magnetic torques. The disk pressure gradient switches sign several times and the inner disk radius is pushed towards the star, approaching < 1.2 R . Additionally, by varying the stellar magnetic field strength, we can demonstrate several previously unseen effects. The number, duration, and the accreted disk mass of an outburst as well as the disk mass at the end of the disk phase (after several million years) depend on the stellar field strength. Furthermore, we can define a range of stellar magnetic field strengths, in which outbursts are completely suppressed. The robustness of this result is confirmed by varying different disk parameters. Conclusions. The influences of a prescribed stellar magnetic field, local pressure gradients, and a variable inner disk radius result in a more consistent description of the gas dynamics in the innermost regions of PPDs. Combining magnetic torques acting on the innermost disk regions with the long-term evolution of PPDs yields previously unseen results, whereby the whole disk structure is affected over its entire lifetime. Additionally, we want to emphasize that a combination of our 1+1D model with more sophisticated multi-dimensional codes could improve the understanding of PPDs even further.

show abstract

1+1D implicit disk computations

Cited by 7 publications

References 25 publications

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk II: The importance of stellar rotation

Time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk I: The importance of stellar magnetic torques

Contact Info

Product

Resources

About