scholarly journals The Application of High Angular Resolution Stellar Interferometry to the Study of Single Objects in the Visual Region of the Spectrum

1979 ◽  
Vol 50 ◽  
pp. 1-1-1-27 ◽  
Author(s):  
John Davis
Keyword(s):  
Angular Resolution ◽  
Angular Diameter ◽  
High Angular Resolution ◽  
Visual Region ◽  
Stellar Interferometry ◽  
Minimum Requirements

AbstractA brief review of existing angular diameter measurements of single objects is given. Potential astronomical programmes for high angular resolution stellar interferometry in the visual region of the spectrum are discussed with particular regard to the sensitivity, resolution, and accuracy required for significant astrophysical results to be obtained. This discussion is used as a basis for suggesting the minimum requirements for future high angular resolution stellar interferometers.

High Angular Resolution Stellar Interferometry

1976 ◽  
Vol 3 (1) ◽  
pp. 26-32 ◽  
Author(s):  
John Davis
Keyword(s):  
Angular Resolution ◽  
Angular Diameter ◽  
High Angular Resolution ◽  
Present Discussion ◽  
Stellar Interferometry

The history and achievements of interferometric angular diameter measurements have been reviewed recently by Hanbury Brown (1974) and only a brief outline will be given here. As the title is intended to imply, the present discussion will be limited to interferometry involving baselines in excess of telescope aperture diameters.

scholarly journals Simulation and Analysis of Telescopic Photonic Beam Combiner for Stellar Interferometry in Labview

2019 ◽  
Vol 8 (9S) ◽  
pp. 230-236
Keyword(s):  
Angular Resolution ◽  
Mechanical Stability ◽  
Optical Interferometry ◽  
Physical Contact ◽  
Optical Methods ◽  
High Angular Resolution ◽  
Multiple Observations ◽  
Beam Combiner ◽  
Stellar Interferometry ◽  
The Universe

The optical methods are the sensitive and subtle techniques of conducting optical investigations without any physical contact. They are both accurate and fast at the same time which provides an ease of having multiple observations. The need of optical interferometry has been increased at a very quick pace due to its high range of applications, from surface testing to locating of extra-solar planets in the universe. Optical Interferometry is a process or technique of combining light from various telescopes for calculating the angular resolution. The technique of optical interferometry helps astronomers for achieving a high angular resolution, that is not possible with the conventional telescopes. Optical approaches are the best approaches for non-contact evaluations, and these are accurate and fast. Due to optical nature of the interferometry, this process is used in various fields, and today it has become one of the important areas of research. Integrated Optics (IO) beam combiners are an efficient and compact technology to combine light interferometrically collected by multiple telescopes. IO beam combiner is based on the modal filtering properties of waveguides or fibers, and it improves thermo-mechanical stability, because of the characteristic rigidity of IO component substrate. Other advantages of this technology are miniaturization and non-existence of alignment needs. Several IO beam combiners are being proposed and tested nowadays. The purpose of this paper is to investigate different techniques used to develop interferometric instrument from previous researches and to simulate the technique suggested by Ermann in Labview.

scholarly journals Dusty Blue Supergiants: News from High-Angular Resolution Observations

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
W. J. de Wit ◽  
R. D. Oudmaijer ◽  
J. S. Vink
Keyword(s):  
Angular Resolution ◽  
High Angular Resolution ◽  
Dust Production ◽  
Circumstellar Material ◽  
Long Baseline ◽  
Recent Advances ◽  
Stellar Interferometry ◽  
Evolutionary Phase

An overview is presented of the recent advances in understanding the B[e] phenomenon among blue supergiant stars in light of high-angular resolution observations and with an emphasis on the results obtained by means of long baseline optical stellar interferometry. The focus of the review is on the circumstellar material and evolutionary phase of B[e] supergiants, but recent results on dust production in regular blue supergiants are also highlighted.

scholarly journals Angular Diameters of O- and B-type Stars

2014 ◽  
Vol 9 (S307) ◽  
pp. 293-294
Author(s):  
Kathryn Gordon ◽  
Douglas Gies ◽  
Gail Schaefer
Keyword(s):  
Stellar Evolution ◽  
Effective Temperature ◽  
Angular Resolution ◽  
Rotational Velocity ◽  
Angular Diameter ◽  
High Angular Resolution ◽  
Long Baseline ◽  
Evolutionary State ◽  
The World ◽  
Angular Diameters

AbstractWe are observing a sample of 10 O-type stars and 60 B-type stars to determine angular diameters using the Center for High Angular Resolution Astronomy (CHARA) Array, the foremost optical long baseline interferometer in the world. Our goal is to establish accurate stellar parameters to test modern theories of stellar evolution that include rotation. We will combine our stellar angular diameter measurements with flux and line measurements from spectroscopy, projected rotational velocities, and distances to determine radius, effective temperature, luminosity, equatorial rotational velocity, and evolutionary mass. Knowing these properties will allow us to place the stars in a Hertzsprung-Russell diagram and obtain estimates for the age and evolutionary state.

Small-Angle Electron Scattering (SAES) of Polymers

1985 ◽  
Vol 43 ◽  
pp. 78-79
Author(s):  
Ralph Oralor ◽  
Pamela Lloyd ◽  
Satish Kumar ◽  
W. W. Adams
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Angular Resolution ◽  
Structural Features ◽  
Objective Lens ◽  
High Angular Resolution ◽  
Push Button ◽  
First Case ◽  
Diffraction Mode ◽  
Very High

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ø meters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.

Large-angle convergent-beam electron-diffraction study of coherent precipitates and decorated dislocations

1996 ◽  
Vol 54 ◽  
pp. 1002-1004
Author(s):  
J.M.K. Wiezorek ◽  
H.L. Fraser
Keyword(s):  
Electron Diffraction ◽  
Angular Resolution ◽  
Large Angle ◽  
Electron Diffraction Study ◽  
Convergent Beam Electron Diffraction ◽  
Crystal Defects ◽  
High Angular Resolution ◽  
Beam Electron ◽  
Diffraction Plane ◽  
Convergent Beam

Conventional methods of convergent beam electron diffraction (CBED) use a fully converged probe focused on the specimen in the object plane resulting in the formation of a CBED pattern in the diffraction plane. Large angle CBED (LACBED) uses a converged but defocused probe resulting in the formation of ‘shadow images’ of the illuminated sample area in the diffraction plane. Hence, low-spatial resolution image information and high-angular resolution diffraction information are superimposed in LACBED patterns which enables the simultaneous observation of crystal defects and their effect on the diffraction pattern. In recent years LACBED has been used successfully for the investigation of a variety of crystal defects, such as stacking faults, interfaces and dislocations. In this paper the contrast from coherent precipitates and decorated dislocations in LACBED patterns has been investigated. Computer simulated LACBED contrast from decorated dislocations and coherent precipitates is compared with experimental observations.

Binary Cepheids From High-Angular Resolution

2015 ◽  
Vol 71-72 ◽  
pp. 187-188
Author(s):  
A. Gallenne ◽  
A. Mérand ◽  
P. Kervella
Keyword(s):  
Angular Resolution ◽  
High Angular Resolution
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