What governs the spin distribution of very young &lt; 1 Myr low-mass stars

Gehrig, L.; Vorobyov, E. I.

doi:10.1051/0004-6361/202345916

Cited by 3 publications

(1 citation statement)

References 114 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the observed rotation rates are typically an order of magnitude or more below break-up velocity (Mestel 1965;Bodenheimer 1995). Understanding the mechanisms that regulate the angular momentum of a CTTS remains one of the greatest challenges related to understanding the early stages of stellar evolution (Bouvier 2014;Gehrig & Vorobyov 2023).…”

Section: Introductionmentioning

confidence: 99%

Tests of Disk-locking in T Tauri Stars of the Orion Nebula Cluster

Mueller,

Johns-Krull,

Stassun

et al. 2024

ApJ

View full text Add to dashboard Cite

We look for specific correlations predicted by magnetospheric accretion models for young stars that assume disk-locking using stellar and accretion parameters derived from low-resolution HST-STIS spectra of 33 T Tauri stars in the Orion Nebula Cluster. Our results provide strong support for the correlation predicted by a model that does not constrain the stellar magnetic field to a specific geometry, while little support is found for the correlation that assumes a dipolar stellar field geometry. These results support the conclusions from similar studies of older T Tauri stars in Taurus and NGC 2264 and underscore the role that trapped flux plays in regulating a young star’s angular momentum as detailed by Ostriker & Shu. While our targets were all selected to be accreting young stars based on photometric indices, approximately half of the observed stars show no significant signs of accretion in our spectra, illustrating the difficulty in using photometric indices to find accreting stars and the possible role that variability has in the appearance of spectra in young stars. Although values of accretion luminosity derived from our models agree well with those derived from Hβ luminosity for strongly accreting stars, we find that accretion luminosity derived from Hβ luminosity is not a reliable parameter for discriminating between weakly accreting and nonaccreting T Tauri stars due to chromospheric emission that is likely present in all T Tauri stars.

show abstract

Section: Introductionmentioning

confidence: 99%

Tests of Disk-locking in T Tauri Stars of the Orion Nebula Cluster

Mueller,

Johns-Krull,

Stassun

et al. 2024

ApJ

View full text Add to dashboard Cite

show abstract

Effects of accretion on the structure and rotation of forming stars

Amard,

Matt

2023

A&A

View full text Add to dashboard Cite

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.

show abstract

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

Cecil,

Gehrig,

Steiner

2024

A&A

View full text Add to dashboard Cite

The final stages of a protoplanetary disk are essential for our understanding of the formation and evolution of planets. Photoevaporation is an important mechanism that contributes to the dispersal of an accretion disk and has significant consequences for the disk's lifetime. However, the combined effects of photoevaporation and star-disk interaction have not been investigated in previous studies. A photoevaporative disk evolution model including a detailed formulation of the inner star-disk interaction region will improve the understanding of the final stages of disk evolution. We combined an implicit disk evolution model with a photoevaporative mass-loss profile. By including the innermost disk regions down to 0.01 AU, we could calculate the star-disk interaction, the stellar spin evolution, and the transition from an accreting disk to the propeller regime self-consistently. Starting from an early Class II star-disk system (with an age of 1 Myr), we calculated the long-term evolution of the system until the disk becomes almost completely dissolved. Photoevaporation has a significant effect on disk structure and evolution. The radial extent of the dead zone decreases, and the number of episodic accretion events (outbursts) is reduced by high stellar X-ray luminosities. Reasonable accretion rates ($> 10^ M_ / yr $) in combination with photoevaporative gaps are possible for a dead zone that is still massive enough to develop episodic accretion events. Furthermore, the stellar spin evolution during the Class II evolution is less affected by the star-disk interaction in the case of high X-ray luminosities. Our results suggest that the formation of planets, especially habitable planets, in the dead zone is strongly impaired in the case of strong X-ray luminosities. Additionally, the importance of the star-disk interaction during the Class II phase with respect to the stellar spin evolution is reduced.

show abstract

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

Cited by 3 publications

References 114 publications

Tests of Disk-locking in T Tauri Stars of the Orion Nebula Cluster

Tests of Disk-locking in T Tauri Stars of the Orion Nebula Cluster

Effects of accretion on the structure and rotation of forming stars

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

Contact Info

Product

Resources

About