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

Gehrig, Lukas; Steiner, Daniel; Vorobyov, Eduard I.; Güdel, M.

doi:10.1051/0004-6361/202243549

Cited by 8 publications

(11 citation statements)

References 95 publications

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“…Differential rotation between the stellar magnetic field lines, which are assumed to be in rigid rotation with the star, and the disk's material generates an angular magnetic field component B ϕ (e.g. Rappaport et al 2004;Kluźniak & Rappaport 2007;Steiner et al 2021;Gehrig, L. et al 2022).…”

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

“…Finally, Ėrad and Q depict the net heating/cooling rate per unit surface area and the viscous stress tensor, respectively (e.g. Steiner et al 2021;Gehrig, L. et al 2022). The kinematic viscosity is formulated according to Shakura & Sunyaev (1973) ν = αc S H P ; with the viscous α parameters, the isothermal sound speed c S and the pressure scale height H P .…”

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

“…The stellar spin model used in our simulations is based on Matt et al (2010) and Gallet et al (2019) and summarized in detail in Gehrig, L. et al (2022). In this study, we assume solid body rotation for the star.…”

Section: Stellar Spin Modelmentioning

confidence: 99%

“…Similar to Rappaport et al (2004) and Kluźniak & Rappaport (2007), we ignore the radial magnetic field component B r = 0. Differential rotation between the stellar magnetic field lines, which are assumed to be in rigid rotation with the star, and the disk's material generates an angular magnetic field component B φ (e.g., Rappaport et al 2004;Kluźniak & Rappaport 2007;Steiner et al 2021;Gehrig, L. et al 2022). The radial radiative transport (depicted by (J − S )) is modeled in a radiative diffusion approximation with an Eddington factor of 1/3.…”

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

“…During the disk phase, the stellar rotation period can also influence the evolution of the accretion rate. Fast-rotating stars tend to experience more outbursts compared to slow-rotating stars (e.g., Gehrig, L. et al 2022). According to recent spin evolution models (e.g., Matt et al 2010;Matt et al 2012;Gallet et al 2019;Ireland et al 2021), the stellar accretion rate is an important factor for determining the stellar rotation rate.…”

Section: Introductionmentioning

confidence: 99%

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The influence of metallicity on a combined stellar and disk evolution

Gehrig

Steindl

Vorobyov

et al. 2023

A&A

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Context. The effects of an accretion disk are crucial to understanding the evolution of young stars. During the combined evolution, stellar and disk parameters influence each other, motivating a combined stellar and disk model. This makes a combined numerical model, evolving the disk alongside the star, the next logical step in the progress of studying early stellar evolution. Aims. We aim to understand the effects of metallicity on the accretion disk and the stellar spin evolution during the T Tauri phase. Methods. We combine the numerical treatment of a hydrodynamic disk with stellar evolution, including a stellar spin model, allowing a self-consistent calculation of the back-reactions between the individual components. Results. We present the self-consistent theoretical evolution of T-Tauri stars coupled to a stellar disk. We find that disks in low metallicity environments are heated differently and have shorter lifetimes, compared to their solar metallicity counterparts. Differences in stellar radii, the contraction rate of the stellar radius, and the shorter disk lifetimes result in faster rotation of low metallicity stars. Conclusions. We present an additional explanation for the observed short disk lifetimes in low metallicity clusters. A combination of our model with previous studies (e.g., a metallicity-based photo-evaporation) could help to understand disk evolution and dispersal at different metallicities. Furthermore, the stellar spin evolution model includes several important effects, previously ignored (e.g., the stellar magnetic field strength and a realistic calculation of the disk lifetime) and we motivate to include our results as initial or input parameters for further spin evolution models, covering the stellar evolution towards and during the main sequence.

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Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

Section: Stellar Spin Modelmentioning

confidence: 99%

Section: Hydrodynamic Disk Evolution With the Tapir Codementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The influence of metallicity on a combined stellar and disk evolution

Gehrig

Steindl

Vorobyov

et al. 2023

A&A

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What governs the spin distribution of very young < 1 Myr low-mass stars

Gehrig¹,

Vorobyov²

2023

A&A

Self Cite

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Context. The origin of the stellar spin distribution at young ages is still unclear. Even in very young clusters (∼ 1 Myr), a significant spread is observed in rotational periods ranging from 1 to ∼ 10 days. Aims. We aim to study the parameters that might govern the spin distribution of low mass ( 1.0 M ) stars during the first million years of their evolution. Methods. We compute the evolution and rotational periods of young stars, using the MESA code, starting from a stellar seed, and take protostellar accretion, stellar winds, and the magnetic star-disk interaction into account. Furthermore, we add a certain fraction of the energy of accreted material into the stellar interior as additional heat and combine the resulting effects on stellar evolution with the stellar spin model. Results. For different combinations of parameters, stellar periods at an age of 1 Myr range between 0.6 days and 12.9 days. Thus, during the relatively short time period of 1 Myr, a significant amount of stellar angular momentum can already be removed by the interaction between the star and its accretion disk. The amount of additional heat added into the stellar interior, the accretion history, and the presence of disk and stellar winds have the strongest impact on the stellar spin evolution during the first million years. The slowest stellar rotations result from a combination of strong magnetic fields, a large amount of additional heat, and effective winds. The fastest rotators combine weak magnetic fields and ineffective winds or result from a small amount of additional heat added to the star. Scenarios that could lead to such configurations are discussed. Different initial rotation periods of the stellar seed, on the other hand, quickly converges and do not affect the stellar period at all. Conclusions. Our model matches up to 90% of the observed rotation periods in six young ( 3 Myr) clusters. Based on these intriguing results, we motivate to combine our model with a hydrodynamic disk evolution code to self-consistently include several important aspects such as episodic accretion events, magnetic disk winds, internal, and external photo-evaporation. Such a combined model could replace the widely-used disk-locking model during the lifetime of the accretion disk and provide valuable insights into the origin of the rotational period distribution of young clusters.

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Effects of accretion on the structure and rotation of forming stars

Amard,

Matt

2023

A&A

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Context. Rotation period measurements of low-mass stars show that the spin distributions in young clusters do not exhibit the spin-up expected due to contraction in the phase when a large fraction of stars is still surrounded by accretion discs. Many physical models have been developed to explain this feature based on different types of star-disc interactions alone. In this phase, the stars accrete mass and angular momentum and may experience accretion-enhanced magnetised winds. The stellar structure and angular momentum content thus strongly depend on the properties of the accretion mechanism. At the same time, the accretion of mass and energy has a significant impact on the evolution of the stellar structure and the moment of inertia. Our understanding of the spin rates of young stars therefore requires a description of how accretion affects the stellar structure and angular momentum simultaneously. Aims. We aim to understand the role of accretion to explain the observed rotation-rate distributions of forming stars. Methods. We computed evolution models of accreting very young stars and determined in a self-consistent way the effect of accretion on stellar structure and the angular momentum exchanges between the stars and their disc. We then varied the deuterium content, the accretion history, the entropy content of the accreted material, and the magnetic field as well as the efficiency of the accretion-enhanced winds. Results. The models are driven alternatively both by the evolution of the momentum of inertia and by the star-disc interaction torques. Of all the parameters we tested, the magnetic field strength, the accretion history, and the deuterium content have the largest impact. The injection of heat plays a major role only early in the evolution. Conclusions. This work demonstrates the importance of the moment of inertia evolution under the influence of accretion for explaining the constant rotation-rate distributions that are observed during the star-disc interactions. When we account for rotation, the models computed with the recently calculated torque along with a consistent structural evolution of the accreting star are able to explain the almost constant spin evolution for the whole range of parameters we investigated, but it only reproduces a narrow range around the median of the observed spin rate distributions. Further development, including for example more realistic accretion histories based on dedicated disc simulations, are likely needed to reproduce the extremes of the spin rate distributions.

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

Cited by 8 publications

References 95 publications

The influence of metallicity on a combined stellar and disk evolution

The influence of metallicity on a combined stellar and disk evolution

What governs the spin distribution of very young < 1 Myr low-mass stars

Effects of accretion on the structure and rotation of forming stars

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