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Physical Sciences and Mathematics Commons™
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- Keyword
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- BL Lacertae objects: individual (Markarian 421) — galaxies: active — galaxies: jets — radio continuum: galaxies (1)
- Binaries: eclipsing - stars: variables: other - open cluster and associations: individual: NGC 6819 (1)
- Methods: data analysis – binaries: eclipsing – Hertzsprung–Russell (HR) diagram – planetary systems – open clusters and associations: general – open clusters and associations: individual: NGC 7789 (1)
- Methods: data analysis – planetary systems – stars: variables: other – open clusters and associations: individual: NGC 6940 (1)
Articles 31 - 34 of 34
Full-Text Articles in Physical Sciences and Mathematics
Variable Stars In The Field Of Open Cluster Ngc 6819 – Ii, R. A. Street, Keith Horne, T. A. Lister, A. Penny, Y. Tsapras, A. Quirrenbach, N. Safizadeh, J. Cooke, David Mitchell, A. Collier Cameron
Variable Stars In The Field Of Open Cluster Ngc 6819 – Ii, R. A. Street, Keith Horne, T. A. Lister, A. Penny, Y. Tsapras, A. Quirrenbach, N. Safizadeh, J. Cooke, David Mitchell, A. Collier Cameron
Physics
We report on the discovery of 141 further variable stars found in the field of the open cluster NGC 6819. The stars were identified from time-series photometric data obtained on the Isaac Newton Telescope, La Palma, during two observing runs covering the 19 nights between 1999 June 22–30 and 1999 July 22–31. The variables found include 53 eclipsing binaries, of which eight stars appear to be RS CVns, in addition to 70 stars showing spot activity, 13 showing long-period variability and five variables of other types.
Vector Diffraction Theory Of Light Propagation Through Nanostructures, Glen D. Gillen, Shekhar Guha
Vector Diffraction Theory Of Light Propagation Through Nanostructures, Glen D. Gillen, Shekhar Guha
Physics
It is well known that “vector” diffraction theory needs to be invoked to describe the propagation of light through apertures having dimensions on the order of the wavelength of light. For regions close to the aperture, use of Kirchhoff boundary conditions in the aperture plane is invalid. The Hertz vector formalism provides a way to describe the diffraction of light beams through apertures having sizes ranging from half the wavelength of light to larger values. Here we will present a summary of the method used to calculate the distribution of all of the electromagnetic field components and a Poynting vector …
Description Of Light Propagation Through A Circular Aperture Using Nonparaxial Vector Diffraction Theory, Glen D. Gillen, Shekhar Guha
Description Of Light Propagation Through A Circular Aperture Using Nonparaxial Vector Diffraction Theory, Glen D. Gillen, Shekhar Guha
Physics
Using nonparaxial vector diffraction theory derived using the Hertz vector formalism, integral expressions for the electric and magnetic field components of light within and beyond an apertured plane are obtained for an incident plane wave. For linearly polarized light incident on a circular aperture, the integrals for the field components and for the Poynting vector are numerically evaluated. By further two-dimensional integration of a Poynting vector component, the total transmission of a circular aperture is determined as a function of the aperture radius to wavelength ratio. The validity of using Kirchhoff boundary conditions in the aperture plane is also examined …
Vlba Polarization Observations Of Markarian 421 After A Gamma-Ray High State, B. Glenn Piner, Philip G. Edwards
Vlba Polarization Observations Of Markarian 421 After A Gamma-Ray High State, B. Glenn Piner, Philip G. Edwards
Physics
We present four high dynamic range, dual-circular polarization, Very Long Baseline Array (VLBA) observations at 22 GHz of Mrk 421, taken throughout the year following the source's unprecedented gamma-ray high state in early 2001. Previous VLBI observations of this source had shown only subluminal apparent motions in the parsec-scale jet and no apparent connection between jet components and gamma-ray flares, so we examined whether the larger gamma-ray flares of 2001 had produced a component that could be followed on the parsec-scale VLBA images. These four new VLBA observations are combined with data from our earlier 1999 paper and archival VLBA …