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For example, all observations seem to indicate that Type Ia supernovae that are of known distance have the same brightness, corrected by the shape of the light curve. The basis for this closeness in brightness is discussed below; however, the possibility exists that the distant Type Ia supernovae have different properties than nearby Type Ia ...
Note that the brighter the star, the smaller the magnitude: Bright "first magnitude" stars are "1st-class" stars, while stars barely visible to the naked eye are "sixth magnitude" or "6th-class". The system was a simple delineation of stellar brightness into six distinct groups but made no allowance for the variations in brightness within a group.
minimum brightness [42] +1.33: star Alpha Centauri B: seen from Earth +1.86: planet Mars: seen from Earth minimum brightness [42] +1.98: star Polaris: seen from Earth mean brightness [49] +3.03: supernova SN 1987A: seen from Earth in the Large Magellanic Cloud (160,000 light-years away) +3 to +4: Faintest stars visible in an urban neighborhood ...
Galaxy color–magnitude diagram – Chart depicting the relationship between brightness and mass of large star systems Hayashi track – Luminosity–temperature relationship in stars Henyey track – path taken by pre-main-sequence stars in the Hertzsprung–Russell diagram Pages displaying wikidata descriptions as a fallback
So far, 131 such objects have been found. Only 22 are bright enough to be visible without a telescope, for which the star's visible light needs to reach or exceed the dimmest brightness visible to the naked eye from Earth, 6.5 apparent magnitude. [1] The known 131 objects are bound in 94 stellar systems.
With the period-luminosity relation providing a way to accurately measure distances on an inter-galactic scale, a new era in modern astronomy unfolded with an understanding of the structure and scale of the universe. [27] The discovery of the expanding universe by Georges Lemaître and Hubble were made possible by Leavitt's groundbreaking research.
The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution .
This section lists examples of luminances, measured in candelas per square metre and grouped by order of magnitude. Factor (cd/m 2) Multiple Value Item 10 −6: