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This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a V-band filter in the UBV photometric system.
maximum brightness; largest moon of Saturn; [59] [60] mean opposition magnitude 8.4 [61] +8.29 star UY Scuti: seen from Earth Maximum brightness; one of largest known stars by radius +8.94: asteroid 10 Hygiea: seen from Earth maximum brightness [62] +9.50: Faintest objects visible using common 7×50 binoculars under typical conditions [63] +10
The first list shows a few of the known stars with an estimated luminosity of 1 million L ☉ or greater, including the stars in open cluster, OB association and H II region. The majority of stars thought to be more than 1 million L ☉ are shown, but the list is incomplete. The second list gives some notable stars for the purpose of comparison.
Blue and white supergiants are high luminosity stars somewhat cooler than the most luminous main sequence stars. A star like Deneb, for example, has a luminosity around 200,000 L ⊙, a spectral type of A2, and an effective temperature around 8,500 K, meaning it has a radius around 203 R ☉ (1.41 × 10 11 m).
[5] [6] By the time of William Herschel astronomers recognized that the telescopic disks of stars were spurious and a function of the telescope as well as the brightness of the stars, but still spoke in terms of a star's size more than its brightness. [5]
The Greek astronomer Hipparchus established a numerical scale to describe the brightness of each star appearing in the sky. The brightest stars in the sky were assigned an apparent magnitude m = 1, and the dimmest stars visible to the naked eye are assigned m = 6. [7] The difference between them corresponds to a factor of 100 in brightness.
This is based on the width of certain absorption lines in the star's spectrum, which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class 0 or Ia+ is used for hypergiants, class I for supergiants, class II for bright giants, class III for regular giants, class IV for subgiants, class V for main ...
This plot shows 22,000 stars from the Hipparcos Catalog together with 1,000 low-luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. In astronomy , the main sequence is a classification of stars which appear on plots of stellar color versus brightness as a continuous and distinctive band.