Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin Evolution of Accreting Young Stars. II. Effect of Accretion-Powered
  Stellar Winds   We present a model for the rotational evolution of a young, solar-mass star
interacting magnetically with an accretion disk. As in a previous paper (Paper
I), the model includes changes in the star's mass and radius as it descends the
Hayashi track, a decreasing accretion rate, and a prescription for the angular
momentum transfer between the star and disk. Paper I concluded that, for the
relatively strong magnetic coupling expected in real systems, additional
processes are necessary to explain the existence of slowly rotating
pre-main-sequence stars. In the present paper, we extend the stellar spin model
to include the effect of a spin-down torque that arises from an
accretion-powered stellar wind. For a range of magnetic field strengths,
accretion rates, initial spin rates, and mass outflow rates, the modeled stars
exhibit rotation periods within the range of 1--10 days in the age range of
1--3 Myr. This range coincides with the bulk of the observed rotation periods,
with the slow rotators corresponding to stars with the lowest accretion rates,
strongest magnetic fields, and/or highest stellar wind mass outflow rates. We
also make a direct, quantitative comparison between the accretion-powered
stellar wind scenario and the two types of disk-locking models (namely the
X-wind and Ghosh & Lamb type models) and identify some remaining theoretical
issues for understanding young star spins.

1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th