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Abell Catalog Of Planetary Nebulae
The Abell Catalog of Planetary Nebulae was created in 1966 by George O. Abell and was composed of 86 entries thought to be planetary nebulae that were collected from discoveries, about half by Albert George Wilson and the rest by Abell, Robert George Harrington, and Rudolph Minkowski. All were discovered before August 1955 as part of the National Geographic Society – Palomar Observatory Sky Survey on photographic plates created with the Samuel Oschin telescope at Mount Palomar. Four are better known from previous catalogs: Abell 50 is NGC 6742, Abell 75 is NGC 7076, Abell 37 is IC 972, and Abell 81 is IC 1454. Another four were later rejected as not being planetaries: Abell 11 (reflection nebula), Abell 32 (red plate flaw), Abell 76 (ring galaxy PGC 85185), and Abell 85 (supernova remnant CTB 1 and noted as possibly such in Abell's 1966 paper). Another three were also not included in the St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Ogden Abell
George Ogden Abell (March 1, 1927 – October 7, 1983) was an American educator. Teaching at UCLA, priorly he worked as a research astronomer, administrator, as a popularizer of science and of education, and as a skeptic. He earned his B.S. in 1951, his M.S. in 1952 and his Ph.D. in 1957, all from the California Institute of Technology. He was a Ph.D. student under Donald Osterbrock. His astronomical career began as a tour guide at the Griffith Observatory in Los Angeles. Abell made great contributions to astronomical knowledge which resulted from his work during and after the National Geographic Society - Palomar Observatory Sky Survey, especially concerning clusters of galaxies and planetary nebulae. A galaxy, an asteroid, a periodic comet, and an observatory are all named in his honor. His teaching career extended beyond the campus of UCLA to the high school student oriented Summer Science Program, and educational television. He not only taught about science but also about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Catalogues
An astronomical catalog or catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. The oldest and largest are star catalogues. Hundreds have been published, including general ones and special ones for such items as infrared stars, variable stars, giant stars, multiple star systems, star clusters, and so forth. General catalogs for deep space objects or for objects other than stars are also large. Again, there are specialized ones for nebulas, galaxies, X-ray sources, radio sources, quasars and other classes. The same is true for asteroids, comets and other solar system bodies. Astronomical catalogs such as those for asteroids may be compiled from multiple sources, but most modern catalogs are the result of a particular astronomical survey of some kind. Since the late 20th century catalogs are increasingly often compiled by computers from an au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 39
Abell 39 (PN A66 39) is a low surface brightness planetary nebula in the constellation of Hercules. It is the 39th entry in George Abell's 1966 Abell Catalog of Planetary Nebulae (and 27th in his 1955 catalog) of 86 old planetary nebulae which either Abell or Albert George Wilson discovered before August 1955 as part of the National Geographic Society - Palomar Observatory Sky Survey. It is estimated to be about 3,800 light-years from earth and thus 2,600 light-years above the Galactic plane. It is almost perfectly spherical and also one of the largest known spheres with a radius of about 1.4 light-years. Central star Its central star is slightly west of center by about 2 or 0.1 light-years. This offset does not appear to be due to interaction with the interstellar medium, but instead, it is hypothesized that a small asymmetric mass ejection has accelerated the central star. The mass of the central star is estimated to be about with the material in the planetary nebula compri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 33
Abell 33 (Also called A33 or the Diamond ring nebula) is a planetary nebula located 2700 light years away in the constellation of Hydra. It lies just behind the star HD 83535. The star HD 83535 is also responsible for the " diamond ring" effect seen in the photograph. The nebula gets its coloration from the Olll emissions (doubly ionized oxygen). The nebula is faint making it difficult to be seen using a telescope. The spherical shape of Abell 33 is mainly caused by its central star not having much of a spin. The nebula shares similar morphology to another nebula with the same spherical shape, the Owl Nebula The Owl Nebula (also known as Messier 97, M97 or NGC 3587) is a starburst planetary nebula, ("planetary") nebula approximately 2,030 light years away in the celestial hemisphere, northern constellation Ursa Major. The estimated age of the Owl Nebu ... ( M 97) but is much darker than the owl nebula. References *http://www.caelumobservatory.com/gallery/abell33.shtml * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 21
The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. Until the early 1970s, the nebula was thought to be a supernova remnant. With the computation of expansion velocities and the thermal character of the radio emission, Soviet astronomers in 1971 concluded that it was most likely a planetary nebula. As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported. The central star of the planetary nebula is an PG 1159 star. See also * Abell Catalog of Planetary Nebulae * Geminga, Gemini gamma-ray source * Gemini in Chinese astronomy * IC 444, reflection nebula * Messier 35 open cluster * Cancer Minor (constellation) - Obsolete constellation inside modern Gemini Refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichroic Filter
A dichroic filter, thin-film filter, or interference filter is a color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the colors of light that they reflect, rather than the colors they pass. Dichroic filters can filter light from a white light source to produce light that is perceived by humans to be highly saturated in color. Such filters are popular in architectural and theatrical applications. Dichroic reflectors known as cold mirrors are commonly used behind a light source to reflect visible light forward while allowing the invisible infrared light to pass out of the rear of the fixture. Such an arrangement allows intense illumination with less heating of the illuminated object. Many quartz-halogen lamps have an integrated dichroic reflector for this purpose, being originally designed for use in slide projectors to avoid melting the slides, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doubly Ionized Oxygen
In astronomy and atomic physics, doubly ionized oxygen is the ion O2+ (O III in spectroscopic notation). Its emission forbidden lines in the visible spectrum fall primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm. Before spectra of oxygen ions became known, these lines once led to a spurious identification of the substance as a new chemical element. Concentrated levels of O III are found in diffuse and planetary nebulae. Consequently, narrow band-pass filters that isolate the 500.7 nm and 495.9 nm wavelengths of light, that correspond to green-turquoise-cyan spectral colors, are useful in observing these objects, causing them to appear at higher contrast against the filtered and consequently blacker background of space (and possibly light-polluted terrestrial atmosphere) where the frequencies of IIIare much less pronounced. These emission lines were first discovered in the spectra of planetary nebulae in the 1860s. At that time, they were th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
