High Angular Resolution Determination of Extinction in the Orion Nebula

2000 ◽  
Vol 120 (1) ◽  
pp. 382-392 ◽  
Author(s):  
C. R. O’Dell ◽  
F. Yusef-Zadeh
Keyword(s):  
Angular Resolution ◽  
High Angular Resolution ◽  
Orion Nebula

scholarly journals Classification of Wolf-Rayet stars in NGC 595 in M 33 through high-spatial resolution observations

2003 ◽  
Vol 212 ◽  
pp. 572-573 ◽  
Author(s):  
Pierre Royer ◽  
Ingemar Lundström ◽  
Jean-Marie Vreux
Keyword(s):  
Stellar Population ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Photometric Technique ◽  
H Ii Region ◽  
The One ◽  
First Time ◽  
Rayet Star

NGC 595 is, after NGC 604, the second most luminous H ii region in the Milky Way's neighbouring spiral galaxy M 33. Its Wolf-Rayet star content has mainly been unveiled by two different channels. On the one hand, the stellar population of NGC 595 has been resolved and its WR stars identified through online/off-line H ii λ4686 observations realised with the HST. Nevertheless, due to the limited number of filters used, this did not give any information on the WR spectral subtypes. On the other hand, spectroscopic observations of NGC 595, realised at optical and ultraviolet wavelengths, have enabled the determination of some spectral subtypes, but this time, the lack of angular resolution did not allow to resolve the whole population. Thanks to our photometric technique, based on five dedicated narrow-band filters, we present here a determination of the spectral subtypes of NGC 595 WR stars which for the first time combines high-angular resolution and high-‘spectroscopic’ discrimination capabilities.

scholarly journals Low Frequency Radio Astronomy from the Moon

1998 ◽  
Vol 11 (2) ◽  
pp. 988-989
Author(s):  
D.L. Jones ◽  
K.W. Weiler
Keyword(s):  
High Frequency ◽  
Angular Resolution ◽  
Low Frequency ◽  
High Angular Resolution ◽  
Radio Sources ◽  
The Moon ◽  
Interstellar Scintillation ◽  
Wide Range ◽  
Lunar Farside

AbstractThe radio sky at frequencies of several MHz and below is essentially unexplored with high angular resolution due to refraction and opacity in the Earth’s ionosphere. An interferometer array in space providing arcminute resolution images would allow a wide range of problems in solar, planetary, galactic, and extragalactic astronomy to be attacked. These include the evolution of solar and planetary radio bursts, interplanetary and interstellar scintillation, the distribution of low energy cosmic rays and diffuse ionized hydrogen in our galaxy, the determination of spectral turnover frequencies and magnetic field strengths in galactic and extragalactic radio sources, searches for “fossil” radio galaxies which are no longer detectable by high frequency surveys, and searches for new sources of coherent radio emission. In addition, it is likely that unexpected objects and emission processes will be discovered by such an instrument, as has often happened when high resolution observations first become possible in a new spectral region. The Moon can provide shielding from terrestrial interference (and from the Sun half of the time) and consequently the lunar farside surface offers an ideal site of a low frequency radio array.

scholarly journals Measuring Stars with High Angular Resolution: Current Status and Future Prospects

1985 ◽  
Vol 111 ◽  
pp. 193-208
Author(s):  
John Davis
Keyword(s):  
Angular Resolution ◽  
Modern Technology ◽  
Surface Fluxes ◽  
Current Status ◽  
High Angular Resolution ◽  
Long Baseline ◽  
Stellar Interferometer ◽  
Current State ◽  
The University

The current state of knowledge of angular diameters of stars is reviewed and, based on this review and the requirements for the determination of surface fluxes, effective temperatures, radii and masses, targets of sensitivity, angular resolution and accuracy for future programs of stellar angular diameter measurements are established. Long baseline interferometry is the only technique with the potential to meet all the targets. The necessary improvements in sensitivity, angular resolution and accuracy are promised by the approach adopted in the modern Michelson stellar interferometer under development at the University of Sydney and the prototype instrument, which is currently nearing completion, is briefly described to illustrate how the atmospheric and mechanical problems which have inhibited the development of amplitude interferometry may be overcome using modern technology. This program together with the developments taking place at CERGA lead to the conclusion that the prospects for contributions by high angular resolution measurements to the determination of fundamental stellar quantities during the next decade are excellent.

High angular resolution observations of CS in the Orion nebula

1980 ◽  
Vol 240 ◽  
pp. 524 ◽  
Author(s):  
P. F. Goldsmith ◽  
W. D. Langer ◽  
F. P. Schloerb ◽  
N. Z. Scoville
Keyword(s):  
Angular Resolution ◽  
High Angular Resolution ◽  
Orion Nebula

scholarly journals High Angular Resolution Binary Star Interferometry

1979 ◽  
Vol 50 ◽  
pp. 3-1-3-16
Author(s):  
Harold A. McAlister
Keyword(s):  
Binary Stars ◽  
Angular Resolution ◽  
Binary Star ◽  
Star Clusters ◽  
Direct Determination ◽  
Complete Analysis ◽  
High Angular Resolution ◽  
Effective Temperatures ◽  
Absolute Magnitudes

AbstractThe benefits and limitations of the application of high angular resolution interferometry to the study of binary stars are considered. The principle advantage of such observations is that they provide data complementary to parameters determined by other techniques and permit the direct determination of masses, angular diameters and distances to systems which would otherwise be inaccessible to such complete analysis. These values then directly lead to linear diameters, absolute magnitudes, absolute emergent fluxes and effective temperatures. The prospects for significantly increasing our knowledge of these fundamental astrophysical parameters are extremely promising. The applications of interferometry to surveys for new binary stars, to star clusters, and to wider visual binaries with the goal of detecting planetary perturbations are also briefly considered.

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.

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