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A simple chart for classifying the main star types using Harvard classification In astronomy , stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors ...
The diagram shows the iron abundance, [Fe/H], on the x-axis and the abundance of alpha process elements, [α/Fe], on the y-axis. The data from Wallerstein (1962) is shown as red circles on top of the 2020 public data from the large scale stellar spectroscopic surveys APOGEE (DR16) and GALAH (DR3) .
An online star chart; Monthly sky maps for every location on Earth Archived 2007-09-13 at the Wayback Machine; The Evening Sky Map – Free monthly star charts and calendar for northern hemisphere, southern hemisphere, and equatorial sky watchers. Sky Map Online – Free interactive star chart (showing over 1.2 million stars up to magnitude 12)
Norton's Star Atlas is a set of 16 celestial charts, first published in 1910 and currently in its 20th edition under the editorship of Ian Ridpath. The Star Atlas covers the entire northern and southern sky, with accompanying reference information for amateur astronomers.
The equation of hydrostatic equilibrium may need to be modified by adding a radial acceleration term if the radius of the star is changing very quickly, for example if the star is radially pulsating. [9] Also, if the nuclear burning is not stable, or the star's core is rapidly collapsing, an entropy term must be added to the energy equation. [10]
A K-type main-sequence star, also referred to as a K-type dwarf, or orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ("red dwarfs") and yellow/white G-type main-sequence stars .
When a star with a mass from about 0.4 M ☉ to 12 M ☉ (8 M ☉ for low-metallicity stars) exhausts its core hydrogen, it enters a phase of hydrogen shell burning during which it becomes a red giant, larger and cooler than on the main sequence. During hydrogen shell burning, the interior of the star goes through several distinct stages which ...