Turbulence in the Convection-Radiation Transition Layer of Solar-Type Stars: Effects on Oscillation Frequencies

2007 ◽  
Vol 26 ◽  
pp. 145-152
Author(s):  
C.W. Straka
Keyword(s):  
Transition Layer ◽  
Solar Type ◽  
Oscillation Frequencies ◽  
Radiation Transition

scholarly journals MEASUREMENT OF ACOUSTIC GLITCHES IN SOLAR-TYPE STARS FROM OSCILLATION FREQUENCIES OBSERVED BYKEPLER

2014 ◽  
Vol 782 (1) ◽  
pp. 18 ◽  
Author(s):  
A. Mazumdar ◽  
M. J. P. F. G. Monteiro ◽  
J. Ballot ◽  
H. M. Antia ◽  
S. Basu ◽  
...  
Keyword(s):  
Solar Type ◽  
Oscillation Frequencies

scholarly journals Probing turbulence with seismic observations of α Centauri

2006 ◽  
Vol 2 (S239) ◽  
pp. 388-390
Author(s):  
C. W. Straka ◽  
P. Demarque ◽  
F. J. Robinson
Keyword(s):  
Binary System ◽  
Transition Layer ◽  
Large Eddy Simulations ◽  
Observational Constraints ◽  
Evolutionary Models ◽  
Large Eddy ◽  
Radiation Transition

AbstractWe present two 3D Large Eddy Simulations (LES) of the convection-radiation transition layer for both the A and the B component of the α Centauri binary system. Theoretical oscillation spectra are then calculated from stellar evolutionary models that include the effects of turbulence based on the LES simulations. By taking both non-seismic and seismic observational constraints into account we discuss the possibility to probe turbulence beyond standard 5mixing-length-theory in a star other than Sun.

scholarly journals Theoretical oscillation frequencies for solar-type dwarfs from stellar models with 〈3D〉-atmospheres

2017 ◽  
Vol 472 (3) ◽  
pp. 3264-3276 ◽  
Author(s):  
Andreas Christ Sølvsten Jørgensen ◽  
Achim Weiss ◽  
Jakob Rørsted Mosumgaard ◽  
Victor Silva Aguirre ◽  
Christian Lundsgaard Sahlholdt
Keyword(s):  
Solar Type ◽  
Stellar Models ◽  
Oscillation Frequencies

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

1997 ◽  
Vol 161 ◽  
pp. 707-709 ◽  
Author(s):  
Jun Jugaku ◽  
Shiro Nishimura
Keyword(s):  
Solar Neighborhood ◽  
The Sun ◽  
Late Type ◽  
Solar Type

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

1997 ◽  
Vol 161 ◽  
pp. 267-282 ◽  
Author(s):  
Thierry Montmerle
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Necessary Condition ◽  
Sequence Evolution ◽  
T Tauri ◽  
Solar Type ◽  
Optical Domain ◽  
The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

Improving the wear resistance of hoe blades by modifying of restoration coatings

2019 ◽  
Vol 24 (94/4) ◽  
pp. 27-32
Author(s):  
T.S. Skoblo ◽  
I.N. Rybalko ◽  
A.V. Tihonov ◽  
T.V. Maltsev
Keyword(s):  
Wear Resistance ◽  
Transition Layer ◽  
Surface Coating ◽  
Dry Friction ◽  
Raw Materials ◽  
Bentonite Clay ◽  
Magnetic Fraction ◽  
Cutting Surface ◽  
Agricultural Machines ◽  
Modifying Additive

The possibility of using a non-magnetic fraction of a detonation charge with a diamond fraction from the disposal of ammunition to modify the restoration coatings of a natural product – clay and secondary raw materials — was studied. Four different coating variants were investigated. For this, a T-620 electrode was used with its additional modification by coating with bentonite clay, as well as with a non-magnetic fraction of the detonation charge and applying it in the form of a slip coating on the cutting surface of the cultivator. It is shown that the use of such additives allows to increase the resistance of the working tool of agricultural machines, reduces its tendency to damage due to the minimum penetration of the thin-walled product of the hoe blade and a decrease in the cross section of the transition layer and the level of stress. Each modifier makes changes to increase the microhardness to varying degrees. An increase in microhardness is observed on the surface of the coating and its gradual decrease to the transition layer. The surface coating with the additional introduction of bentonite clay in a liquid bath has the highest microhardness. Its microhardness varies from HV-50-1009.7 to HV-50-615.2. Similarly, the effect of the modifying additive of the detonation charge, the microhardness varies from HV-50-969.6 to HV-50-633.26. When clay or a mixture is introduced into the restoration coating, the wear resistance increases by 1.3 - 2 times with respect to the deposited surfacing only by the electrode and by 2 - 3 times to the initial material of the cultivator. It was found that the lowest coefficient is characteristic for dry friction, as well as for hydroabrasive, for samples with additional modification with clay or a detonation charge

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