scholarly journals Two Types of Pulsars

1987 ◽  
Vol 125 ◽  
pp. 425-437
Author(s):  
J.H. Huang
Keyword(s):  
Neutron Stars ◽  
Supernova Explosion ◽  
Type I ◽  
Type Ii ◽  
Emission Mechanism ◽  
X Ray ◽  
Origin And Evolution ◽  
Binary Pulsars ◽  
Self Consistent ◽  
Evolutionary Mode

To sort out the whole sample of pulsars with measured P and P into two types has much something to do with the origin and evolution of neutron stars. Under the configuration of two types of pulsars with different spindown mechanism, we have discussed a variety of their properties, including their radio emission mechanism, space velocities, interior structures and evolutionary modes. The fact that different type of pulsars does have quite different properties indicates that the processes to create neutron stars may have two distinct types, say, Type II supernova explosion and the collapse of accreting white dwarfs. The evolutionary mode for our Type I pulsars provides such a key link between binary pulsars and X-ray binary pulsars that we may propose a self-consistent scenario for binary pulsars, X-ray binary pulsars, fast pulsars as well as Type I pulsars.

scholarly journals Observations of X-ray Burst Sources

1987 ◽  
Vol 125 ◽  
pp. 161-172
Author(s):  
Y. Tanaka
Keyword(s):  
Neutron Stars ◽  
Type I ◽  
Type Ii ◽  
X Ray ◽  
Type Ii Bursts

Recent observational results on X-ray bursts and burst sources are reviewed. Two distinct types of bursts, Type I and Type II bursts, are discussed in relation to the mass and radius of neutron stars and to the problems of unusual mass accretion in some burst sources.

DO YOUNG NEUTRON STARS WHICH SHOW THEMSELVES AS AXPs AND SGRs ACCRETE?

2003 ◽  
Vol 12 (05) ◽  
pp. 825-831 ◽  
Author(s):  
S. O. TAGIEVA ◽  
E. YAZGAN ◽  
A. ANKAY
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Explosion ◽  
X Ray ◽  
X Ray Binaries

We examined the fall-back disk models, and in general accretion, proposed to explain the properties of AXPs and SGRs. We checked the possibility of some gas remaining around the neutron star after a supernova explosion. We also compared AXPs and SGRs with the X-ray pulsars in X-ray binaries. We conclude that the existing models of accretion from a fall-back disk are insufficient to explain the nature of AXPs and SGRs.

Pyrophosphates of Tetravalent Elements and a Mössbauer Study of SnP2O7

1975 ◽  
Vol 53 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Chung-Hsi Huang ◽  
Osvald Knop ◽  
David A. Othen ◽  
Frank W. D. Woodhams ◽  
R. Allan Howie
Keyword(s):  
Chemical Shift ◽  
Electric Field ◽  
Electric Field Gradient ◽  
The Other ◽  
Type I ◽  
Type Ii ◽  
Transition Elements ◽  
Mössbauer Study ◽  
X Ray ◽  
Ionic Compounds

Cubic M4+P2O7 pyrophosphates of Ti, Zr, Hf, Sn, and Pb have been examined by X-ray powder diffractometry and by infrared, Raman, and Mössbauer 119Sn spectroscopy. The tin compound appeared to be of Chaunac's type I (with P2O7 groups oriented at random) and could be converted to type II (with ordered P2O7 groups) by heating to high temperatures. All the other preparations were of Chaunac's type II. Evidence from lattice parameters and intensity features of the Raman spectra suggests that the cubic MP2O7 pyrophosphates fall in two groups, one containing the compounds of the typical elements (Ge, Sn, Pb) and the other, the compounds of the transition elements. No support has been found for the view that the P—O—P groupings of the pyrophosphate anion in these compounds are linear. The 119Sn chemical shift in SnP2O7 is only slightly less negative than the shift in CuSnF6.4H2O, which makes SnP2O7 one of the most ionic compounds of tetravalent tin known. The observed quadrupole splitting in the Mössbauer spectrum of SnP2O7 arises largely from the contribution of the valence term to the electric field gradient at the Sn atom.

X-ray structure determination of the monoclinic (121 K) and orthorhombic (85 K) phases of langbeinite-type dithallium dicadmium sulfate

2000 ◽  
Vol 56 (6) ◽  
pp. 921-935 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
W. Morgenroth ◽  
M. I. Aroyo ◽  
T. Breczewski ◽  
...  
Keyword(s):  
Orthorhombic Symmetry ◽  
Type I ◽  
Type Ii ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distortion Analysis ◽  
Precise Analysis ◽  
Monoclinic Distortion

The structures of the monoclinic and the orthorhombic phases of type I langbeinite Tl2Cd2(SO4)3 have been determined at 121 and 85 K, respectively, by X-ray diffraction. A precise analysis of these structures shows the existence of some differences compared to langbeinites of type II. The monoclinic structure differs very little from the high-temperature cubic structure and the distortion relating the monoclinic structure to the cubic one is very small. SO4 tetrahedra seem to rotate under orthorhombic symmetry in the monoclinic phase. A symmetry distortion analysis of the ferroelectric monoclinic distortion discloses the importance of the secondary modes with orthorhombic symmetry, especially for the O atoms of the SO4 groups.

scholarly journals A Two‐Zone Model for Type I X‐Ray Bursts on Accreting Neutron Stars

2006 ◽  
Vol 652 (1) ◽  
pp. 584-596 ◽  
Author(s):  
Randall L. Cooper ◽  
Ramesh Narayan
Keyword(s):  
Neutron Stars ◽  
Zone Model ◽  
Type I ◽  
X Ray

scholarly journals Acemetacin cocrystal structures by powder X-ray diffraction

IUCrJ ◽  
2017 ◽  
Vol 4 (3) ◽  
pp. 206-214 ◽  
Author(s):  
Geetha Bolla ◽  
Vladimir Chernyshev ◽  
Ashwini Nangia
Keyword(s):  
Crystal Structures ◽  
Molecular Electrostatic Potential ◽  
Acid Group ◽  
Mutual Orientation ◽  
Type I ◽  
Type Ii ◽  
Melt Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bond Interactions

Cocrystals of acemetacin drug (ACM) with nicotinamide (NAM),p-aminobenzoic acid (PABA), valerolactam (VLM) and 2-pyridone (2HP) were prepared by melt crystallization and their X-ray crystal structures determined by high-resolution powder X-ray diffraction. The powerful technique of structure determination from powder data (SDPD) provided details of molecular packing and hydrogen bonding in pharmaceutical cocrystals of acemetacin. ACM–NAM occurs in anhydrate and hydrate forms, whereas the other structures crystallized in a single crystalline form. The carboxylic acid group of ACM forms theacid–amide dimer three-point synthonR32(9)R22(8)R32(9) with three differentsynamides (VLM, 2HP and caprolactam). The conformations of the ACM molecule observed in the crystal structures differ mainly in the mutual orientation of chlorobenzene fragment and the neighboring methyl group, beinganti(type I) orsyn(type II). ACM hydrate, ACM—NAM, ACM–NAM-hydrate and the piperazine salt of ACM exhibit the type I conformation, whereas ACM polymorphs and other cocrystals adopt the ACM type II conformation. Hydrogen-bond interactions in all the crystal structures were quantified by calculating their molecular electrostatic potential (MEP) surfaces. Hirshfeld surface analysis of the cocrystal surfaces shows that about 50% of the contribution is due to a combination of strong and weak O...H, N...H, Cl...H and C...H interactions. The physicochemical properties of these cocrystals are under study.

Notizen: The Crystal Structure of N3P3C15(NPPh3) — a Novel Conformation in Phosphazenylcyclophosphazene Chemistry

1976 ◽  
Vol 31 (7) ◽  
pp. 999-1000 ◽  
Author(s):  
Y. Sudhakara Babu ◽  
T. Stanley Cameron ◽  
S. S. Krishnamurthy ◽  
H. Manohar ◽  
Robert A. Shaw
Keyword(s):  
Crystal Structure ◽  
Crystallographic Structure ◽  
Type I ◽  
Type Ii ◽  
Structure Investigation ◽  
X Ray ◽  
Ring Segment

An X-ray crystallographic structure investigation of pentachloro(triphenylphosphazenyl)cyclotriphosphazatriene, N3P3C15(NPPh3), reveals a novel conformation (type I) of the triphenylphosphazenyl group with respect to the adjacent ring segment. This is contrasted with the structure of gem. –N3P3CI4Ph(NPPh3), where a type II conformation is observed.

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