scholarly journals Spin evolution and saturation: new insights through 3D MHD simulations of young solar analogs

2019 ◽  
Vol 82 ◽  
pp. 233-240
Author(s):  
V. Réville ◽  
A.S. Brun
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Large Scale ◽  
Stellar Surface ◽  
Doppler Imaging ◽  
Momentum Loss ◽  
Mhd Simulations ◽  
Spin Evolution ◽  
Angular Momentum Loss ◽  
Solar Analogs

We examine how 3D MHD simulations can deliver clues on the mechanisms at the origin of angular momentum loss saturation of rapidly rotating solar-like stars. Based on a study of six targets, whose magnetic field has been observed by Zeeman Doppler Imaging (ZDI), we find that the saturation could be explained by a extremely strong coverage of the stellar surface of a large scale dipolar mode, in disagreement with recent works.

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).

scholarly journals Loss of magnetic flux and angular momentum from molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 67-74
Author(s):  
Takenori Nakano
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Flux ◽  
Molecular Clouds ◽  
Loss Rate ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
The Magnetic Field ◽  
Flux Loss

The magnetic field and the angular momentum are major obstacles against cloud contraction. I will review recent results on magnetic flux loss rate and angular momentum loss rate and will investigate a gross feature of cloud contraction.

T Tauri Angular Momentum Loss via Large Scale Eruptive Flaring Events

2009 ◽  
Author(s):  
Alicia N. Aarnio ◽  
Keivan G. Stassun ◽  
Sean P. Matt ◽  
Eric Stempels
Keyword(s):  
Angular Momentum ◽  
Large Scale ◽  
Momentum Loss ◽  
T Tauri ◽  
Angular Momentum Loss

scholarly journals Loss of magnetic flux and angular momentum from molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 67-74
Author(s):  
Takenori Nakano
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Flux ◽  
Molecular Clouds ◽  
Loss Rate ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
The Magnetic Field ◽  
Flux Loss

The magnetic field and the angular momentum are major obstacles against cloud contraction. I will review recent results on magnetic flux loss rate and angular momentum loss rate and will investigate a gross feature of cloud contraction.

scholarly journals Rotation and Macroturbulence in Supergiant Stars

1970 ◽  
Vol 4 ◽  
pp. 122-129
Author(s):  
Jeffrey D. Rosendhal
Keyword(s):  
Angular Momentum ◽  
Strong Evidence ◽  
Large Scale ◽  
Statistical Investigation ◽  
Mass Motion ◽  
Early Type ◽  
Line Broadening ◽  
B Stars ◽  
Momentum Loss ◽  
Angular Momentum Loss

AbstractA statistical investigation has been made of rotation and macroturbulence in early type la and lab supergiants. The principal results are: (1) At all spectral types in the range B0-A5 both rotation and macroturbulence contribute to the observed line broadening. In the early B stars rotation is as important a broadening agent as large-scale mass motion. In the middle B and A stars turbulence dominates but there still is an appreciable contribution from rotation. (2) In spite of the fact that the stars observed seem to be losing mass, there is no strong evidence for significant angular momentum loss.

scholarly journals Circumstellar environment of 55 Cancri

2020 ◽  
Vol 633 ◽  
pp. A48 ◽  
Author(s):  
C. P. Folsom ◽  
D. Ó Fionnagáin ◽  
L. Fossati ◽  
A. A. Vidotto ◽  
C. Moutou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Stellar Wind ◽  
Large Scale ◽  
Rotation Axis ◽  
Doppler Imaging ◽  
Magnetic Pole ◽  
Average Strength ◽  
Detailed Understanding ◽  
The Magnetic Field ◽  
Circumstellar Environment

Context. 55 Cancri hosts five known exoplanets, most notably the hot super-Earth 55 Cnc e, which is one of the hottest known transiting super-Earths. Aims. Because of the short orbital separation and host star brightness, 55 Cnc e provides one of the best opportunities for studying star-planet interactions (SPIs). We aim to understand possible SPIs in this system, which requires a detailed understanding of the stellar magnetic field and wind impinging on the planet. Methods. Using spectropolarimetric observations and Zeeman Doppler Imaging, we derived a map of the large-scale stellar magnetic field. We then simulated the stellar wind starting from the magnetic field map, using a 3D magneto-hydrodynamic model. Results. The map of the large-scale stellar magnetic field we derive has an average strength of 3.4 G. The field has a mostly dipolar geometry; the dipole is tilted by 90° with respect to the rotation axis and the dipolar strength is 5.8 G at the magnetic pole. The wind simulations based on this magnetic geometry lead us to conclude that 55 Cnc e orbits inside the Alfvén surface of the stellar wind, implying that effects from the planet on the wind can propagate back to the stellar surface and result in SPI.

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