scholarly journals Observational tests of the bow shock theory of Herbig-Haro objects

1987 ◽  
Vol 122 ◽  
pp. 187-188
Author(s):  
K.-H. Böhm ◽  
A. C. Raga ◽  
J. Solf
Keyword(s):  
Double Layer ◽  
Bow Shock ◽  
Emission Lines ◽  
Low Velocity ◽  
Layer Structures

We discuss four different tests of the bow-shock theory of Herbig-Haro objects, emphasizing especially tests based on position-velocity diagrams and on the appearance of “double layer” structures in the spatial maxima of the high- and low-velocity components of the emission lines. Though this latter effect is surprising, it is a fundamental consequence of the bow shock theory.

Restricted Rotational Motion of InterlayerWaterMolecules in Vanadium Pentoxide Hydrate, V2O5·n D2O, as Studied by Deuterium NMR

2002 ◽  
Vol 57 (6-7) ◽  
pp. 419-424 ◽  
Author(s):  
Sadamu Takeda ◽  
Yuko Gotoh ◽  
Goro Maruta ◽  
Shuichi Takahara ◽  
Shigeharu Kittaka
Keyword(s):  
Double Layer ◽  
Vanadium Pentoxide ◽  
Rotational Motion ◽  
Interlayer Space ◽  
Layer Structure ◽  
Bond Distance ◽  
Adsorbed Water ◽  
Deuterium Nmr ◽  
Water Molecules ◽  
Layer Structures

The rotational behavior of the interlayer water molecules of deuterated vanadium pentoxide hydrate, V2O5.nD2O, was studied by solid-state deuterium NMR for the mono- and double-layer structures of the adsorbed water molecules. The rotational motion was anisotropic even at 355 K for both the mono- and double-layer structures. The 180° flipping motion about the C2-symmetry axis of the water molecule and the rotation around the figure axis, which makes an angle Ɵ with the C2-axis, occurred with the activation energy of (34±4) and (49±6) kJmol-1, respectively. The activation energies were almost independent of the mono- and double-layer structures of the water molecules, but the angle Ɵ made by the two axes varied from 33° for the monolayer to 25° for the double-layer at 230 K. The angle started to decrease above 250 K (e. g. the angle was 17 at 355 K for the double-layer structure). The results indicate that the average orientation of the water molecules in the two dimensional interlayer space depends on the layer structure and on the temperature. From the deuterium NMR spectrum at 130 K, the quadrupole coupling constant e2Qq/h = 240 kHz and the asymmetry parameter η= 0.12 were deduced. These values indicate the average hydrogen bond distance R(O H) = 2.0 Å for the D2O molecules in the 2D-interlayer space

Electrical properties of silicon oxide/polyimide double layer structures

2002 ◽  
Author(s):  
A. Lian ◽  
L. Martinu ◽  
J.E. Klemberg-Sapieha ◽  
M.R. Wertheimer
Keyword(s):  
Electrical Properties ◽  
Double Layer ◽  
Silicon Oxide ◽  
Layer Structures

Magnetic properties of two double-layer structures built from hydroxynaphthoic acids and manganese

2005 ◽  
Vol 61 (7) ◽  
pp. m361-m364 ◽  
Author(s):  
Martin U. Schmidt ◽  
Edith Alig ◽  
Lothar Fink ◽  
Michael Bolte ◽  
Robin Panisch ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Double Layer ◽  
Layer Structures

scholarly journals Type Ia Supernova Models and Progenitor Scenarios

2011 ◽  
Vol 7 (S281) ◽  
pp. 253-260
Author(s):  
Ken'ichi Nomoto ◽  
Yasuomi Kamiya ◽  
Naohito Nakasato
Keyword(s):  
White Dwarf ◽  
Emission Lines ◽  
Type Ia Supernovae ◽  
Theoretical Studies ◽  
Low Velocity ◽  
Dynamical Phase ◽  
Type Ia ◽  
Recent Developments ◽  
Ia Supernovae ◽  
Interesting Constraint

AbstractWe review some recent developments in theoretical studies on the connection between the progenitor systems of Type Ia supernovae (SNe Ia) and the explosion mechanisms. (1) DD-subCh: In the merging of double C+O white dwarfs (DD scenario), if the carbon detonation is induced near the white dwarf (WD) surface in the early dynamical phase, it could result in the (effectively) sub-Chandrasekhar mass explosion. (2) DD-Ch: If no surface C-detonation is ignited, the WD could grow until the Chandrasekhar mass is reached, but the outcome depends on whether the quiescent carbon shell burning is ignited and burns C+O into O+Ne+Mg. (3) SD-subCh: In the single degenerate (SD) scenario, if the He shell-flashes grow strong to induce a He detonation, it leads to the sub-Chandra explosion. (4) SD-Ch: If the He-shell flashes are not strong enough, they still produce interesting amounts of Si and S near the surface of the C+O WD before the explosion. In the Chandra mass explosion, the central density is high enough to produce electron capture elements, e.g., stable 58Ni. Observations of the emission lines of Ni in the nebular spectra provides useful diagnostics of the sub-Chandra vs. Chandra issue. The recent observations of relatively low velocity carbon near the surface of SNe Ia provide also an interesting constraint on the explosion models.

Sign in / Sign up

Export Citation Format

Share Document