Oxford Index Search Results

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field-names

Overview page. Subjects: History.

Collecting all the field‐names of a parish from every available source, from earliest times to the present day, is a worthwhile task for a local historian or a group project. Unlike the...

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Erfle eyepiece

Overview page. Subjects: Astronomy and Astrophysics.

A design of wide-field eyepiece consisting of three lenses, two or three of which may be doublets, that gives a field of view of 65–70°. Although the field of view is slightly curved and...

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Galilean telescope

Overview page. Subjects: Astronomy and Astrophysics.

A refracting telescope with a converging lens as the objective and a diverging lens as the eyepiece. It is named after Galileo, who used a telescope of this type. It has the advantage of an...

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Hanle effect

Overview page. Subjects: Astronomy and Astrophysics.

The rotation of the plane of polarization of spectral lines due to a magnetic field. The Hanle effect has been used to measure the weak magnetic fields of solar prominences, which are found...

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Alfvén surface

Overview page. Subjects: Astronomy and Astrophysics.

The surface of the region surrounding a neutron star within which ionized gas is pulled around by the star's magnetic field as it spins. It is named after H. O. G. Alfvén.

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Couder telescope

Overview page. Subjects: Astronomy and Astrophysics.

A Ritchey–Chrétien reflecting telescope with an aspheric concave primary mirror and a concave ellipsoidal secondary. It has a short focal ratio and wide field of view free from coma,...

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Goddard Trophy

Overview page. Subjects: Astronomy and Astrophysics.

A US trophy awarded annually by the National Space Club for significant contributions in the fields of rocketry and astronautics. Established in 1958, the trophy is named after the rocket...

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cyclotron radiation

Overview page. Subjects: Astronomy and Astrophysics.

Electromagnetic radiation emitted by a charged particle circling in a magnetic field substantially below the speed of light. It is named after the type of particle accelerator in which it...

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coma, optical

Overview page. Subjects: Astronomy and Astrophysics.

A defect of an optical component or system in which star images become increasingly fan-shaped away from the optical axis; the shape resembles the coma of a comet, hence the name. In positi...

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schiefspiegler telescope

Overview page. Subjects: Astronomy and Astrophysics.

A reflecting telescope that incorporates two spheroidal concave mirrors. The secondary mirror is offset from the primary, and brings light to a focus adjacent to the primary. This gives an...

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Stark broadening

Overview page. Subjects: Astronomy and Astrophysics.

The broadening or splitting of lines in a spectrum by the electric field of electrons and ionized atoms. The effect is much more pronounced in main-sequence stars, which have higher...

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