The effect of finite electrical conductivity on the angular-momentum loss of the sun due to the solar wind

Solar Physics ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 470-477 ◽  
Author(s):  
E. J. Weber
Keyword(s):  
Electrical Conductivity ◽  
Solar Wind ◽  
Angular Momentum ◽  
The Sun ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Finite Electrical Conductivity

scholarly journals Lunar-forming impacts: processes and alternatives

2014 ◽  
Vol 372 (2024) ◽  
pp. 20130175 ◽  
Author(s):  
R. M. Canup
Keyword(s):  
Angular Momentum ◽  
Large Scale ◽  
Early Earth ◽  
The Sun ◽  
Initial Composition ◽  
High Angular Momentum ◽  
Giant Impact ◽  
Earth’S Mantle ◽  
Momentum Loss ◽  
Angular Momentum Loss

The formation of a protolunar disc by a giant impact with the early Earth is discussed, focusing on two classes of impacts: (i) canonical impacts, in which a Mars-sized impactor produces a planet–disc system whose angular momentum is comparable to that in the current Earth and Moon, and (ii) high-angular-momentum impacts, which produce a system whose angular momentum is approximately a factor of 2 larger than that in the current Earth and Moon. In (i), the disc originates primarily from impactor-derived material and thus is expected to have an initial composition distinct from that of the Earth's mantle. In (ii), a hotter, more compact initial disc is produced with a silicate composition that can be nearly identical to that of the silicate Earth. Both scenarios require subsequent processes for consistency with the current Earth and Moon: disc–planet compositional equilibration in the case of (i), or large-scale angular momentum loss during capture of the newly formed Moon into the evection resonance with the Sun in the case of (ii).

Plasma and magnetic field dynamics in the young solar wind

2020 ◽  
Author(s):  
Justin Kasper ◽  
Keyword(s):  
Solar Wind ◽  
Angular Momentum ◽  
Solar Wind Plasma ◽  
Distribution Functions ◽  
The Sun ◽  
Turbulent Fluctuations ◽  
Thermal Distribution ◽  
The Earth ◽  
Angular Momentum Loss ◽  
Coronal Rotation

<p>Parker Solar Probe (PSP) has completed four encounters with the Sun since launch, three with a perihelion of 35.7 solar radii and one at 27.9 solar radii in January of this year.  More than a factor of two closer to the Sun than any previous mission, observations by the spacecraft are already revealing a surprisingly dynamic and non-thermal solar wind plasma near the Sun.  An overview of initial findings related to the solar wind and coronal plasmas will be presented, including the discovery of large-amplitude velocity spikes, highly non-thermal distribution functions, and large non-radial flows of plasma near the Sun observed by the Solar Wind Electrons Alphas and Protons (SWEAP) Investigation plasma instruments and the FIELDS Investigation electromagnetic field instruments.  Once PSP dropped below a quarter of the distance from the Sun to the Earth, SWEAP began to detect a persistent and growing rotational circulation of the plasma around the Sun peaking at 40-50 km/s at perihelion as the Alfvén mach number fell to 3.  This finding may support theories for enhanced stellar angular momentum loss due to rigid coronal rotation, but the circulation is large, and angular momentum does not appear to be conserved, suggesting that torques still act on the young wind at these distances.  PSP also measured numerous intense and organized Alfvénic velocity spikes with strong propagating field reversals and large jumps in speed.  These field reversals and jets call for an overhaul in our understanding of the turbulent fluctuations that may, by energizing the solar wind, hold the key to its origin.</p>

The Aging Solar Wind: a Break in Wind Evolution at Older Ages?

2017 ◽  
Vol 13 (S335) ◽  
pp. 98-101
Author(s):  
Dúalta Ó Fionnagáin ◽  
Aline A. Vidotto
Keyword(s):  
Solar Wind ◽  
Angular Momentum ◽  
Adverse Effects ◽  
Sharp Decline ◽  
X Ray ◽  
Rotation Rates ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Steep Decay

AbstractThe current solar wind is well studied from remote observations and in situ measurements. However, we have very little information of the solar wind as it has evolved. We investigate the evolution of the solar wind by modeling the winds of solar analogues. By using X-ray temperatures as proxies for wind temperatures, we find that a break in behaviour occurs. At 2 Gyr there is a sharp decline in coronal temperatures, which results in a steep decay in mass loss rates for older stars. As the wind is responsible for stellar spin down, through angular momentum loss due to magnetised winds, our results suggest a decline in angular momentum loss for older stars. This agrees with recent observations which find anomalously high rotation rates in older stars. We also find that this evolution in the wind has adverse effects on the Earth’s magnetosphere, with an Earth aged 100 Myr having a magnetosphere 3 Earth radii in size.

scholarly journals Angular momentum loss and stellar spin-down in magnetic massive stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 423-424
Author(s):  
Asif ud-Doula ◽  
Stanley P. Owocki ◽  
Richard H.D. Townsend
Keyword(s):  
Angular Momentum ◽  
Massive Stars ◽  
Solid Angle ◽  
Magnetic Confinement ◽  
Dipole Field ◽  
Hot Stars ◽  
Momentum Loss ◽  
Dipole Magnetic Field ◽  
Angular Momentum Loss ◽  
Compare And Contrast

AbstractWe examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD simulation study that examines the interplay among wind, field, and rotation as a function of two dimensionless parameters, W(=Vrot/Vorb) and ‘wind magnetic confinement’, η∗ defined below. We compare and contrast the 2-D, time variable angular momentum loss of this dipole model of a hot-star wind with the classical 1-D steady-state analysis by Weber and Davis (WD), who used an idealized monopole field to model the angular momentum loss in the solar wind. Despite the differences, we find that the total angular momentum loss averaged over both solid angle and time follows closely the general WD scaling ~ ṀΩR2A. The key distinction is that for a dipole field Alfvèn radius RA is significantly smaller than for the monopole field WD used in their analyses. This leads to a slower stellar spin-down for the dipole field with typical spin-down times of order 1 Myr for several known magnetic massive stars.

Sign in / Sign up

Export Citation Format

Share Document