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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.
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 ...
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 ...
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.
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 ...
New 5 in Sagittarius (thus mentioned on chart 22 of Wil Tirion's Sky-Atlas 2000.0, mentioned as ESO 285-G7 on charts 411 and 412 in Uranometria 2000.0 Volume 2, 1987 edition). New 6 in Indus (chart 23 in Tirion's Sky-Atlas 2000.0, chart 413 in the 1987 edition of Uranometria 2000.0, Volume 2) (as ESO 287-G13) NGC — New General Catalogue
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.
At a distance of about eight light-minutes, the most frequently studied star is the Sun, a typical main-sequence dwarf star of stellar class G2 V, and about 4.6 billion years (Gyr) old. The Sun is not considered a variable star , but it does undergo periodic changes in activity known as the sunspot cycle .