Subgiant star is a class of stars that are brighter than normal main sequence (dwarf) stars of the same spectral class, but not as bright as true giant stars. The Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram or HRD, also known as a colour-magnitude diagram, or CMD In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics Brown dwarfs are sub- stellar objects with a mass below that necessary to maintain Hydrogen -burning Nuclear fusion reactions in their cores as do stars A white dwarf, also called a degenerate dwarf, is a small Star composed mostly of Electron-degenerate matter. According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool Star, of the Main sequence, either late K A subdwarf star, sometimes denoted by "sd" is Luminosity class VI under the Yerkes spectral classification system The main sequence is the name for a continuous and distinctive band of stars that appear on a plot of stellar color versus brightness The main sequence is the name for a continuous and distinctive band of stars that appear on a plot of stellar color versus brightness A giant star is a Star with substantially larger Radius and Luminosity than a Main sequence star of the same surface temperature. The luminosity class II in the Yerkes spectral classification is given to bright giants. Supergiants are among the most massive Stars In the Hertzsprung-Russell diagram they occupy the top region of the diagram A hypergiant ( luminosity class 0) is a Star with a tremendous Mass and Luminosity, showing signs of a very high rate of mass loss In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth The main sequence is the name for a continuous and distinctive band of stars that appear on a plot of stellar color versus brightness A giant star is a Star with substantially larger Radius and Luminosity than a Main sequence star of the same surface temperature. They are believed to be stars that are ceasing or already ceased fusing hydrogen in their cores. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In stars of roughly a solar mass, this causes the core to contract, which increases the star's central temperature enough to move hydrogen fusion into a shell surrounding the core. The solar mass is a standard way to express Mass in Astronomy, used to describe the masses of other Stars and galaxies. This swells the star on the way to becoming a true giant. At the start of the subgiant phase (such as a star like Procyon A) the diameter and brightness have increased, but the star has yet to cool down or change color significantly. This article is about the star Procyon is also the mammalian genus to which raccoons belong Later subgiants that are closer to becoming true giants have larger diameters and lower temperature than stars of similar mass in the main sequence. A giant star is a Star with substantially larger Radius and Luminosity than a Main sequence star of the same surface temperature. Overall luminosity changes little during the subgiant stage, a feature prominent in Hertzsprung-Russell diagrams of globular clusters. The Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram or HRD, also known as a colour-magnitude diagram, or CMD A globular cluster is a spherical collection of Stars that orbits a galactic core as a Satellite. [1] In Yerkes spectral classification their luminosity class is IV. In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics