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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).
The spectral signature of an object is a function of the incidental EM wavelength and material interaction with that section of the electromagnetic spectrum. The measurements can be made with various instruments, including a task specific spectrometer , although the most common method is separation of the red, green, blue and near infrared ...
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.
It is an ageing A-type star of spectral class A0 III [7] located 280 ± 20 light-years away [8] from the Solar System. At the age of 385 million years, [9] it is exhausting hydrogen at its core and leaving the main sequence. γ Sextantis is the second brightest star in the constellation with an apparent magnitude of 5.05.
The vast majority of known shell stars are of spectral class B. However, partly because of this many cooler shell stars have remained undetected. [ 1 ] The Be phenomenon, and hence the term Be star itself, is now widely applied to similar stars not only of spectral class B, but also A and sometimes O and F.
The Star-Spectroscope of the Lick Observatory in 1898. Designed by James Keeler and constructed by John Brashear.. Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects.
The spectral flux density is used to represent the spectrum of a light-source, such as a star. In radiometry and colorimetry (or color science more generally), the spectral power distribution (SPD) of a light source is a measure of the power contributed by each frequency or
The original definition of an S star was that the ZrO bands should be easily detectable on low dispersion photographic spectral plates, but more modern spectra allow identification of many stars with much weaker ZrO. MS stars, intermediate with normal class M stars, have barely detectable ZrO but otherwise normal class M spectra.