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2. Stellar classification - Wikipedia

   en.wikipedia.org/wiki/Stellar_classification

   The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type).

3. Glossary of astronomy - Wikipedia

   en.wikipedia.org/wiki/Glossary_of_astronomy

   A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.

4. Hertzsprung–Russell diagram - Wikipedia

   en.wikipedia.org/wiki/Hertzsprung–Russell_diagram

   The spectral type is not a numerical quantity, but the sequence of spectral types is a monotonic series that reflects the stellar surface temperature. Modern observational versions of the chart replace spectral type by a color index (in diagrams made in the middle of the 20th Century, most often the B-V color) of the stars.

5. Henry Draper Catalogue - Wikipedia

   en.wikipedia.org/wiki/Henry_Draper_Catalogue

   The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts ...

6. Spectrum (physical sciences) - Wikipedia

   en.wikipedia.org/wiki/Spectrum_(physical_sciences)

   In the physical sciences, the spectrum of a physical quantity (such as energy) may be called continuous if it is non-zero over the whole spectrum domain (such as frequency or wavelength) or discrete if it attains non-zero values only in a discrete set over the independent variable, with band gaps between pairs of spectral bands or spectral ...

7. Semiregular variable star - Wikipedia

   en.wikipedia.org/wiki/Semiregular_variable_star

   IAU definition [1] GCVS code [2] GCVS definition [2] Standard stars SRa semi-regular variable giants of late spectral classes (M, C and S), which retain periodicity with comparative stability and possess, as a rule, small (less than 2 m.5) light-variation amplitudes. Amplitudes and forms of light curves are usually liable to strong variations ...

8. B(e) star - Wikipedia

   en.wikipedia.org/wiki/B(e)_star

   The designation results from combining the spectral class B, the lowercase e denoting emission in the spectral classification system, and the surrounding square brackets signifying forbidden lines. These stars frequently also show strong hydrogen emission lines, but this feature is present in a variety of other stars and is not sufficient to ...

9. Spectral class - Wikipedia

   en.wikipedia.org/?title=Spectral_class&redirect=no

   Spectral class. 39 languages. ... Download as PDF; Printable version; In other projects Wikimedia Commons; Wikidata item; Appearance. move to sidebar hide.