The Photometric Properties of the Ap Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100080684 ◽

1976 ◽

Vol 32 ◽

pp. 365-377 ◽

Cited By ~ 2

Author(s):

B. Hauck

Keyword(s):

Physical Properties ◽

Ap Stars

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).

Download Full-text

Variation of Heavy Element Lines in the Ap Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100080623 ◽

1976 ◽

Vol 32 ◽

pp. 311-320 ◽

Cited By ~ 1

Author(s):

I.A. Aslanov ◽

Yu. S. Rustamov ◽

M. Kowalski

Keyword(s):

Heavy Element ◽

Ap Stars

SummaryLines of U II were found in the spectrograms of the Ap stars HR 465, 17 Com A and HD 224801. Pm II lines were found in HR 465. These lines vary in intensity in HR 465 with a period of 6h41m, in 17 Com A of 71m, and in HD 224801 of 6h.

Download Full-text

Peculiarity Parameters

International Astronomical Union Colloquium ◽

10.1017/s0252921100080581 ◽

1976 ◽

Vol 32 ◽

pp. 233-254

Author(s):

H. M. Maitzen

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Theoretical Work ◽

Observational Evidence ◽

Rotator Model ◽

Peculiar Behaviour ◽

Field Spectrum ◽

Oblique Rotator ◽

Ap Stars ◽

The Way

Ap stars are peculiar in many aspects. During this century astronomers have been trying to collect data about these and have found a confusing variety of peculiar behaviour even from star to star that Struve stated in 1942 that at least we know that these phenomena are not supernatural. A real push to start deeper theoretical work on Ap stars was given by an additional observational evidence, namely the discovery of magnetic fields on these stars by Babcock (1947). This originated the concept that magnetic fields are the cause for spectroscopic and photometric peculiarities. Great leaps for the astronomical mankind were the Oblique Rotator model by Stibbs (1950) and Deutsch (1954), which by the way provided mathematical tools for the later handling pulsar geometries, anti the discovery of phase coincidence of the extrema of magnetic field, spectrum and photometric variations (e.g. Jarzebowski, 1960).

Download Full-text

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

International Astronomical Union Colloquium ◽

10.1017/s0252921100080520 ◽

1976 ◽

Vol 32 ◽

pp. 169-182

Author(s):

B. Kuchowicz

Keyword(s):

Nuclear Physics ◽

Nuclear Reactions ◽

Chemical Elements ◽

Fission Products ◽

Abundance Pattern ◽

Isotopic Shifts ◽

Processed Material ◽

R Process ◽

Ap Stars ◽

Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Download Full-text

On The Radii of Ap Stars

International Astronomical Union Colloquium ◽

10.1017/s025292110008043x ◽

1976 ◽

Vol 32 ◽

pp. 49-55 ◽

Cited By ~ 1

Author(s):

F.A. Catalano ◽

G. Strazzulla

Keyword(s):

Observational Data ◽

Line Width ◽

Main Sequence ◽

Main Sequence Stars ◽

Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

Download Full-text

The Infection of Cells by Bullet-Shaped Viruses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063779 ◽

1969 ◽

Vol 27 ◽

pp. 372-373

Author(s):

Frederick A. Murphy ◽

Alyne K. Harrison ◽

Sylvia G. Whitfield

Keyword(s):

Electron Microscopy ◽

Physical Properties ◽

Host Cell ◽

Thin Section ◽

Cultured Cells ◽

Cell Infection ◽

Thin Section Electron Microscopy ◽

Section Electron ◽

Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Download Full-text

Transmission electron microscopy of composite materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107125 ◽

1988 ◽

Vol 46 ◽

pp. 1012-1015

Author(s):

K.P.D. Lagerlof

Keyword(s):

Composite Materials ◽

Physical Properties ◽

Structural Defects ◽

Structural Composites ◽

Multiphase Materials ◽

Structural Reinforcement ◽

Transmission Electron ◽

Reinforced Fiber ◽

Particulate Reinforced Composites ◽

Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

Download Full-text