asterism


Also found in: Dictionary, Thesaurus, Wikipedia.

asterism

A prominent grouping of stars forming a distinctive shape but not a complete or recognized constellation. The Plough is an asterism within the constellation Ursa Major. Other examples of asterisms are the Sickle in Leo, the False Cross and the Summer Triangle.

asterism

[′as·tə‚riz·əm]
(astronomy)
A constellation or small group of stars.
(optics)
A starlike optical phenomenon seen in gemstones called star stones; due to reflection of light by lustrous inclusions reduced to sharp lines of light by a domed cabochon style of cutting.
(spectroscopy)
A star-shaped pattern sometimes seen in x-ray spectrophotographs.
References in periodicals archive ?
Wide-field scopes can trace the delightful "kite" asterism that captures NGC 6939.
In China the oldest date could be about 1300 B.C.E., when oracle bone inscriptions mention asterisms later marking the quadrants of the year, such as the "Bird star" identified with the later "Red Bird."
We concluded that this was a natural sapphire that had been diffused-treated to induce its colour and asterism. Although some previously documented diffusion-induced star sapphires were synthetic in origin ('AIGS finds more stars', 1994; Kammerling and Fritsch, 1995; Singbamroong et al., 2015), gemmologists should remember that natural as well as synthetic starting materials may be used for this type of treatment.
About 2.5[degrees] further south-west, among a multitude of galaxies, another asterism can be found.
The very center of the Purple Tenuity Enclosure is said to be the North Pole asterism. The fifth star of the North Pole asterism is called 'Celestial Pivot' [TEXT NOT REPRODUCIBLE IN ASCII] and the place nearby which lacks stars is called the Vermilion Pole [TEXT NOT REPRODUCIBLE IN ASCII].
Microscopic observation of the colourless dome revealed small colourless inclusions and/or negative crystals, primary fluid inclusions and tiny, very fine, oriented needles (which caused the asterism).
Object Type RA (J2000.0) Dec RT Capricorni Carbon Star 20h17m2 -21[degrees]20 NGC 6908 Nebulosity 20 25 1 -24 48 NGC 6907 Galaxy 20 25 6 -24 49 Asterism Star Group 20 26 7 -24 57 NGC 7099, M 30 Globular Cluster 21 40 4 -23 11 Palomar 12 Globular Cluster 21 46 6 -21 15 NGC 7158 Unknown 21 57 4 -11 36 Object Type Mag Size RT Capricorni Carbon Star 7-11 * NGC 6908 Nebulosity 14 0.5' x 0.3' NGC 6907 Galaxy 11 3.2' x 2.3' Asterism Star Group 8 10' NGC 7099, M 30 Globular Cluster 6.9 9' Palomar 12 Globular Cluster 11.7 2.9' NGC 7158 Unknown 9.5 ' x 6'
The less-well known area of Corona Borealis just above the crown asterism lays claim to three superb double stars that look great in small scopes powered up to around 50x.
A very fascinating asterism called Jaws accompanies M104 only 25' towards the west.
As you might suspect from its appearance, NGC 358 is most likely an asterism rather a cluster.
The lovely double star chi 1&2 Hydrae, quite bright with magnitudes 4.8 and 5.7, point the way 4.5 degrees south to the asterism Alessi J11046-3157--five magnitude 12 to 13 stars in a short string from north to south, with two fainter ones topping the scale to the west (see sketch).