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Below there are lists the nearest stars separated by spectral type.The scope of the list is still restricted to the main sequence spectral types: M, K, F, G, A, B and O.It may be later expanded to other types, such as S, D or C.
In this 5th edition the Milky Way was included for the first time, and he incorporated the official constellation boundaries that had been laid down by the International Astronomical Union in 1930. Norton redrew his charts yet again for the 9th edition published in 1943, extending the magnitude limit of the stars from 6.2 to 6.35.
The scale ranges from Class 1, the darkest skies available on Earth, through to Class 9, inner-city skies. It gives several criteria for each level beyond naked-eye limiting magnitude (NELM). [1] The accuracy and utility of the scale have been questioned in 2014 research. [2] [why?] The table summarizes Bortle's descriptions of the classes. For ...
Class II objects have circumstellar disks and correspond roughly to classical T Tauri stars, while Class III stars have lost their disks and correspond approximately to weak-line T Tauri stars. An intermediate stage where disks can only be detected at longer wavelengths (e.g., at 24 μ m {\displaystyle 24{\mu }m} ) are known as transition-disk ...
9th-century diagram of the positions of the seven planets on 18 March 816, from the Leiden Aratea (from History of astronomy) Image 33 Segment of the astronomical ceiling of Senenmut's Tomb (circa 1479–1458 BC), depicting constellations, protective deities, and twenty-four segmented wheels for the hours of the day and the months of the year ...
Note that the brighter the star, the smaller the magnitude: Bright "first magnitude" stars are "1st-class" stars, while stars barely visible to the naked eye are "sixth magnitude" or "6th-class". The system was a simple delineation of stellar brightness into six distinct groups but made no allowance for the variations in brightness within a group.
Gamma Cephei (γ Cephei, abbreviated Gamma Cep, γ Cep) is a binary star system approximately 45 light-years away in the northern constellation of Cepheus.The primary (designated Gamma Cephei A, officially named Errai / ɛ ˈ r eɪ. iː /, the traditional name of the system) [11] [12] is a stellar class K1 orange giant or subgiant star; it has a red dwarf companion (Gamma Cephei B).
HD 141569 is an isolated [5] Herbig Ae/Be star [6] of spectral class A2Ve [7] approximately 364 light-years away in the constellation of Libra. The primary star has two red dwarf companions (orbiting each other) at about nine arcseconds. In 1999, a protoplanetary disk was discovered around the star.