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For comparison, Sirius has an absolute magnitude of only 1.4, which is still brighter than the Sun, whose absolute visual magnitude is 4.83. The Sun's absolute bolometric magnitude is set arbitrarily, usually at 4.75. [4] [5] Absolute magnitudes of stars generally range from approximately −10 to +20. The absolute magnitudes of galaxies can be ...
The absolute magnitude M, of a star or astronomical object is defined as the apparent magnitude it would have as seen from a distance of 10 parsecs (33 ly). The absolute magnitude of the Sun is 4.83 in the V band (visual), 4.68 in the Gaia satellite's G band (green) and 5.48 in the B band (blue). [20] [21] [22]
Betelgeuse (apparent magnitude 0.5, absolute magnitude −5.8) appears slightly dimmer in the sky than Alpha Centauri A (apparent magnitude 0.0, absolute magnitude 4.4) even though it emits thousands of times more light, because Betelgeuse is much farther away.
For example, 3C 273 has an average apparent magnitude of 12.8 (when observing with a telescope), but an absolute magnitude of −26.7. If this object were 10 parsecs away from Earth it would appear nearly as bright in the sky as the Sun (apparent magnitude −26.744).
The bolometric correction scale is set by the absolute magnitude of the Sun and an adopted (arbitrary) absolute bolometric magnitude for the Sun.Hence, while the absolute magnitude of the Sun in different filters is a physical and not arbitrary quantity, the absolute bolometric magnitude of the Sun is arbitrary, and so the zero-point of the bolometric correction scale that follows from it.
The typical visual absolute magnitude of Type Ia supernovae is M v = −19.3 (about 5 billion times brighter than the Sun), with little variation. [13] The Type Ia supernova leaves no compact remnant, but the whole mass of the former white dwarf dissipates through space.
Prior to photographic methods to determine magnitude, the brightness of celestial objects was determined by visual photometric methods.This was simply achieved with the human eye by compared the brightness of an astronomical object with other nearby objects of known or fixed magnitude: especially regarding stars, planets and other planetary objects in the Solar System, variable stars [1] and ...
For example, apparent magnitude in the UBV system for the solar-like star 51 Pegasi [18] is 5.46V, 6.16B or 6.39U, [19] corresponding to magnitudes observed through each of the visual 'V', blue 'B' or ultraviolet 'U' filters. Magnitude differences between filters indicate colour differences and are related to temperature. [20]