Trends in torques acting on the star during a star-disk magnetospheric interaction

@article{77251,
   author = {Čemeljić, Miljenko and Brun, A. S.},
   article_location = {LES ULIS CEDEX A},
   article_number = {Nov 2023},
   doi = {http://dx.doi.org/10.1051/0004-6361/202243517},
   keywords = {stars: formation;stars: pre-main sequence;stars: magnetic field;magnetohydrodynamics (MHD)},
   language = {eng},
   issn = {0004-6361},
   journal = {ASTRONOMY & ASTROPHYSICS},
   title = {Trends in torques acting on the star during a star-disk magnetospheric interaction},
   url = {https://www.aanda.org/articles/aa/full_html/2023/11/aa43517-22/aa43517-22.html},
   volume = {679},
   year = {2023}
}

TY  - JOUR
ID  - 77251
AU  - Čemeljić, Miljenko - Brun, A. S.
PY  - 2023
TI  - Trends in torques acting on the star during a star-disk magnetospheric interaction
JF  - ASTRONOMY & ASTROPHYSICS
VL  - 679
IS  - Nov 2023
SP  - "A16-1"-"A16-14"
EP  - "A16-1"-"A16-14"
PB  - EDP SCIENCES S A
SN  - 00046361
KW  - stars: formation;stars: pre-main sequence;stars: magnetic field;magnetohydrodynamics (MHD)
UR  - https://www.aanda.org/articles/aa/full_html/2023/11/aa43517-22/aa43517-22.html
N2  - Aims. We assess the modification of angular momentum transport in various configurations of star-disk accreting systems based on numerical simulations with different parameters. In particular, we quantify the torques exerted on a star by the various components of the flow and field in our simulations of a star-disk magnetospheric interaction. Methods. In a suite of resistive and viscous numerical simulations, we obtained results using different stellar rotation rates, dipole magnetic field strengths, and resistivities. We probed a part of the parameter space with slowly rotating central objects, up to 20% of the Keplerian rotation rate at the equator. Different components of the flow in star-disk magnetospheric interaction were considered in the study: a magnetospheric wind (i.e., the "stellar wind") ejected outwards from the stellar vicinity, matter infalling onto the star through the accretion column, and a magnetospheric ejection launched from the magnetosphere. We also took account of trends in the total torque in the system and in each component individually. Results. We find that for all the stellar magnetic field strengths, B-star, the anchoring radius of the stellar magnetic field in the disk is extended with increasing disk resistivity. The torque exerted on the star is independent of the stellar rotation rate, Omega(star), in all the cases without magnetospheric ejections. In cases where such ejections are present, there is a weak dependence of the anchoring radius on the stellar rotation rate, with both the total torque in the system and torque on the star from the ejection and infall from the disk onto the star proportional to Omega B-star(3). The torque from a magnetospheric ejection is proportional to Omega(4)(star). Without the magnetospheric ejection, the spin-up of the star switches to spin-down in cases involving a larger stellar field and faster stellar rotation. The critical value for this switch is about 10% of the Keplerian rotation rate.
ER  - 

ČEMELJI$\backslash$'C, Miljenko a A. S. BRUN. Trends in torques acting on the star during a star-disk magnetospheric interaction. \textit{ASTRONOMY \&{}amp; ASTROPHYSICS}. LES ULIS CEDEX A: EDP SCIENCES S A, 2023, roč.~679, Nov 2023, s.~''A16-1''-''A16-14'', 14 s. ISSN~0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/202243517.