scholarly journals Coupling the solar surface and the corona: Coronal rotation, Alfvén wave-driven polar plumes

2013 ◽  
Author(s):  
R. F. Pinto ◽  
R. Grappin ◽  
M. Velli ◽  
A. Verdini
Keyword(s):  
Solar Surface ◽  
Coronal Rotation ◽  
Polar Plumes

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

scholarly journals Solar structure and evolution

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Solar Surface ◽  
Solar Neutrinos ◽  
Solar Interior ◽  
Stellar Structure ◽  
The Sun ◽  
Physical Processes ◽  
Solar Evolution ◽  
Internal Properties ◽  
Atmospheric Phenomena

AbstractThe Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

scholarly journals The effect of frog pressure and downward vertical load on hoof wall weight-bearing and third phalanx displacement in the horse - an in vitro study : research communication

2001 ◽  
Vol 72 (4) ◽  
Author(s):  
A. Olivier ◽  
J. Wannenburg ◽  
R.D. Gottschalk ◽  
M.J. Van der Linde ◽  
H.T. Groeneveld
Keyword(s):  
Solar Surface ◽  
Weight Bearing ◽  
Testing Machine ◽  
Vertical Component ◽  
In Vitro Study ◽  
Vitro Study ◽  
Total Weight ◽  
Strain Gauges ◽  
Tensile Testing Machine

A shoe was designed to combine the advantages of a reverse shoe and an adjustable heart bar shoe in the treatment of chronic laminitis. This reverse even frog pressure (REFP) shoe applies pressure uniformly over a large area of the frog solar surface. Pressure is applied vertically upward parallel to the solar surface of the frog and can be increased or decreased as required. Five clinically healthy horses were humanely euthanased and their dismem-bered forelimbs used in an in vitro study. Frog pressure was measured by strain gauges applied to the ground surface of the carrying tab portion of the shoe. A linear variable distance transducer (LVDT) was inserted into a hole drilled in the dorsal hoof wall. The LVDT measured movement of the third phalanx (P3) in a dorsopalmar plane relative to the dorsal hoof wall. The vertical component of hoof wall compression was measured by means of unidirectional strain gauges attached to the toe, quarter and heel of the medial hoof wall of each specimen. The entire limb was mounted vertically in a tensile testing machine and submitted to vertical downward compressive forces of 0 to 2500 Nat a rate of 5 cm/minute. The effects of increasing frog pressure on hoof wall weight-bearing and third phalanx movement within the hoof were determined. Each specimen was tested with the shoe under the following conditions: zero frog pressure; frog pressure used to treat clinical cases of chronic laminitis (7 N-cm); frog pressure clinically painful to the horse as determined prior to euthanasia; frog pressure just alleviating this pain. The specimens were also tested after shoe removal. Total weight-bearing on the hoof wall at zero frog pressure was used as the basis for comparison. Pain-causing and pain-alleviating frog pressures decreased total weight-bearing on the hoof wall (P < 0.05). Frog pressure of 7 N-cm had no statistically significant effect on hoof wall weight-bearing although there was a trend for it to decrease as load increased. Before loading, the pain-causing and pain-alleviating frog pressures resulted in a palmar movement of P3 relative to the dorsal hoof wall compared to the position of P3 at zero frog pressure (P < 0.05). This difference remained statistically significant up to 1300 Nload. At higher loads, the position of P3 did not differ significantly for the different frog pressures applied. It is concluded that increased frog pressure using the REFP shoe decreases total hoof wall weight-bearing and causes palmar movement of P3 at low weight-bearing loads. Without a shoe the toe and quarter hoof wall compression remained more constant and less in magnitude, than with a shoe.

scholarly journals Point spread function of SDO/HMI and the effects of stray light correction on the apparent properties of solar surface phenomena

2013 ◽  
Vol 561 ◽  
pp. A22 ◽  
Author(s):  
K. L. Yeo ◽  
A. Feller ◽  
S. K. Solanki ◽  
S. Couvidat ◽  
S. Danilovic ◽  
...  
Keyword(s):  
Point Spread Function ◽  
Solar Surface ◽  
Stray Light ◽  
Surface Phenomena ◽  
Point Spread ◽  
Spread Function

Realistic Solar Surface Convection Simulations

2006 ◽  
Vol 898 (1) ◽  
pp. 21-38 ◽  
Author(s):  
ROBERT F. STEIN ◽  
ÅKE NORDLUND
Keyword(s):  
Solar Surface ◽  
Surface Convection
Sign in / Sign up

Export Citation Format

Share Document