9 lines
823 B
Markdown
9 lines
823 B
Markdown
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name: Alfirk (β Cep)
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constellation: Cep
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created_by: editor.cs
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created_date: 2023-11-05 16:36:17.355201
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updated_by: editor.cs
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updated_date: 2023-11-05 16:36:17.355204
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---
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A double star distinguishable by a small telescope with a 6 cm diameter objective, consisting of two components with magnitudes 3.2 (bright white) and 7.9 (blue - appearing emerald green in a large telescope) at a mutual distance of 13.3". The primary star is also a spectroscopic binary, with an orbital period of only 4 and 3/4 hours. In the same period, it exhibits a slight change in brightness between magnitudes 3.3 and 3.4. It is even a prototype of a group of variable stars called beta Cepheids, whose brightness fluctuations are so small that they can hardly be observed with the naked eye. It is located at a distance of 690 light-years. |