MAGNETIC AND GRAVITATIONAL DISK-STAR INTERACTIONS: AN INTERDEPENDENCE OF PMS STELLAR ROTATION RATES AND SPIN-ORBIT MISALIGNMENTS

Here, we analyze the primordial excitation of spin-orbit misalignment of Sun-like stars in light of disk-star angular momentum transfer. We begin by calculating the stellar pre-main-sequence rotational evolution, accounting for spin-up due to gravitational connection and accretion as well as spin-do...

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Bibliographic Details
Published inThe Astrophysical journal Vol. 778; no. 2; pp. 1 - 17
Main Authors BATYGIN, KONSTANTIN, Adams, Fred C
Format Journal Article
LanguageEnglish
Published United States 01.12.2013
Subjects
ACCRETION DISKS
Angular momentum
ANGULAR MOMENTUM TRANSFER
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CONTRACTION
DIPOLES
Dynamical systems
Dynamics
EXCITATION
Gravitation
INTERACTIONS
JUPITER PLANET
MAGNETIC FIELDS
MAGNETIC STARS
Misalignment
NEBULAE
PROTOPLANETS
ROTATION
SATELLITES
SPIN
Stars
Stellar rotation
SUN
SURFACES
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Summary:Here, we analyze the primordial excitation of spin-orbit misalignment of Sun-like stars in light of disk-star angular momentum transfer. We begin by calculating the stellar pre-main-sequence rotational evolution, accounting for spin-up due to gravitational connection and accretion as well as spin-down due to magnetic star-disk coupling. We devote particular attention to angular momentum transfer by accretion, and show that while generally subdominant to gravitational contraction, this process is largely controlled by the morphology of the stellar magnetic field (that is, specific angular momentum accreted by stars with octupole-dominated surface fields is smaller than that accreted by dipole-dominated stars by an order of magnitude). Subsequently, we examine the secular spin-axis dynamics of disk-bearing stars, accounting for the time-evolution of stellar and disk properties, and demonstrate that misalignments are preferentially excited in systems where stellar rotation is not overwhelmingly rapid. Cumulatively, the model developed herein opens up a previously unexplored avenue toward understanding star-disk evolution and its consequences in a unified manner.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/778/2/169