2026-09-18T20:32:28Zhttps://ecommons.cornell.edu/server/oai/requestoai:ecommons.cornell.edu:1813/107592026-05-14T13:54:44Zcom_1813_35col_1813_47
Long, Min
2008-05-02T12:22:58Z
2013-05-02T06:11:57Z
2008-05-02T12:22:58Z
https://hdl.handle.net/1813/10759
6397129
The star-disk interaction between a rotating magnetized star and a surrounding accretion disk is a fundamental process in astrophysics, and is usually difficult to investigate due to the complicated magnetohydrodynamic structures. The aim
of this work is for understanding the accretion manifestations of this interaction, especially the mechanism of the
transport of the angular momentum, and the influence of the complex magnetic geometries on the accretion behavior.
One of the complicated aspects of the disk-magnetosphere interaction is the angular momentum transport between the disk
and the star. It was proposed that the ralation between spin-up torque arising from the magnetic connection of the star
to the fast rotating inner part of the disk, and the spin-down torque arising from the connection of the star to the
slow rotating outer part of the disk determines the spin evolution of the star. It was suggested that for a particular
value of the star's rotation rate, the positive spin-up torque balances the negative spin-down torque and the star is
``locked" in the rotational equilibrium state. We improve the model of the transport of the angular moment and present
the most probable periods of rotation in the equilibrium state for different astrophysical objects, such as classical T
Tauri stars, dwarf novae and millisecond X-ray pulsars.
The magnetic geometry of a rotating star can have a strong influence on the matter in an accretion disk, which is
disrupted and channelled by the magnetic field to the star along the field lines. Theoretical and observational
approaches reveal that the actual magnetic geometries of stars may depart from the pure dipole configuration. We study
the accretion in different complex magnetic configurations including pure quadrupole, aligned dipole plus quadrupole,
misaligned dipole plus quadrupole and superposition of off-centre dipoles. The results show that they have different
features in matter flow, hot spots on the surface of the star and associated light curves, such as accretion ``belt",
extended ring-like hot spots and non-sinusoidal variations of light curves for large inclination angle, which could be
used as an indicators of a complex field.
en_US
accretion
accretion disks
magnetic fields
magnetohydrodynamics
Disk Accretion to Rotating Magnetized Stars: Magnetohydrodynamic Simulations
dissertation or thesis
application/pdf
Publication
Cornell Theses and Dissertations
Long, Min
5893a6ea-7af3-41d7-abc6-04bcd26ab5df
open.access
open.access
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="0153d2f1-9896-4b32-aca1-d24b3cca9502">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>en_US</Language>
<Title>Disk Accretion to Rotating Magnetized Stars: Magnetohydrodynamic Simulations</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2008-05-02T12:22:58Z</PublicationDate>
<Authors>
<Author>
<DisplayName>Long, Min</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<OrgUnit />
</Publisher>
</Publishers>
<Keyword>accretion</Keyword>
<Keyword>accretion disks</Keyword>
<Keyword>magnetic fields</Keyword>
<Keyword>magnetohydrodynamics</Keyword>
<Abstract>The star-disk interaction between a rotating magnetized star and a surrounding accretion disk is a fundamental process in astrophysics, and is usually difficult to investigate due to the complicated magnetohydrodynamic structures. The aim
of this work is for understanding the accretion manifestations of this interaction, especially the mechanism of the
transport of the angular momentum, and the influence of the complex magnetic geometries on the accretion behavior.
One of the complicated aspects of the disk-magnetosphere interaction is the angular momentum transport between the disk
and the star. It was proposed that the ralation between spin-up torque arising from the magnetic connection of the star
to the fast rotating inner part of the disk, and the spin-down torque arising from the connection of the star to the
slow rotating outer part of the disk determines the spin evolution of the star. It was suggested that for a particular
value of the star's rotation rate, the positive spin-up torque balances the negative spin-down torque and the star is
``locked" in the rotational equilibrium state. We improve the model of the transport of the angular moment and present
the most probable periods of rotation in the equilibrium state for different astrophysical objects, such as classical T
Tauri stars, dwarf novae and millisecond X-ray pulsars.
The magnetic geometry of a rotating star can have a strong influence on the matter in an accretion disk, which is
disrupted and channelled by the magnetic field to the star along the field lines. Theoretical and observational
approaches reveal that the actual magnetic geometries of stars may depart from the pure dipole configuration. We study
the accretion in different complex magnetic configurations including pure quadrupole, aligned dipole plus quadrupole,
misaligned dipole plus quadrupole and superposition of off-centre dipoles. The results show that they have different
features in matter flow, hot spots on the surface of the star and associated light curves, such as accretion ``belt",
extended ring-like hot spots and non-sinusoidal variations of light curves for large inclination angle, which could be
used as an indicators of a complex field.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>