# Absolute magnitude

Hbolometric magnitudeabsolute magnitude (H)absolute visual magnitudebrightnessabsoluteabsolute bolometric magnitudebolometricMmagnitude
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.wikipedia
2,062 Related Articles

### Luminosity

luminousbolometric luminosityluminosities
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale. Hertzsprung–Russell diagram – relates absolute magnitude or luminosity versus spectral color or surface temperature.
Values for luminosity are often given in the terms of the luminosity of the Sun, L ⊙ . Luminosity can also be given in terms of the astronomical magnitude system: the absolute bolometric magnitude (M bol ) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or filter band.

### Magnitude (astronomy)

magnitudemagnitudesmag
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.
Astronomers use two different definitions of magnitude: apparent magnitude and absolute magnitude.

### Sun

solarSolThe Sun
The Sun has absolute magnitude M V =+4.83. For comparison, Sirius has an absolute magnitude of 1.4, which is brighter than the Sun, whose absolute visual magnitude is 4.83 (it actually serves as a reference point).
The Sun has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in the Milky Way, most of which are red dwarfs.

### Sirius

SothisDog StarSirius B
For comparison, Sirius has an absolute magnitude of 1.4, which is brighter than the Sun, whose absolute visual magnitude is 4.83 (it actually serves as a reference point).
Sirius A is about twice as massive as the Sun and has an absolute visual magnitude of +1.42.

### Bolometric correction

bolometric
To convert from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction is applied.
In astronomy, the bolometric correction is the correction made to the absolute magnitude of an object in order to convert its visible magnitude to its bolometric magnitude.

### Betelgeuse

α OriBetelg'''euseBetelgeuse mass loss
Examples include Rigel (−7.0), Deneb (−7.2), Naos (−6.0), and Betelgeuse (−5.6).
It is calculated to be 640 light-years away, yielding an absolute magnitude of about −6. Less than 10 million years old, Betelgeuse has evolved rapidly because of its high mass. Having been ejected from its birthplace in the Orion OB1 Association—which includes the stars in Orion's Belt—this runaway star has been observed moving through the interstellar medium at a speed of 30 km/s, creating a bow shock over four light-years wide.

### Milky Way

galaxyMilky Way Galaxyour galaxy
Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8.
The integrated absolute visual magnitude of the Milky Way is estimated to be around −20.9.

### Parsec

Mpcpckpc
An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), with no extinction (or dimming) of its light due to absorption by interstellar dust particles.
In August 2015, the IAU passed Resolution B2, which as part of the definition of a standardized absolute and apparent bolometric magnitude scale, mentioned an existing explicit definition of the parsec as exactly 1⁄648000 astronomical units, or approximately 3.08567758149137 metres (based on the IAU 2012 exact SI definition of the astronomical unit).

### Deneb

Alpha Cygniα CygAlpha Cygni (Deneb)
Examples include Rigel (−7.0), Deneb (−7.2), Naos (−6.0), and Betelgeuse (−5.6).
Deneb's absolute magnitude is currently estimated as −8.4, placing it among the most luminous stars known, with an estimated luminosity nearly 200,000 times that of the Sun.

### Phase curve (astronomy)

phase curvephase curvesphase function
This relationship is referred to as the phase curve.
The brightness usually refers the object's absolute magnitude, which, in turn, is its apparent magnitude at a distance of one astronomical unit from the Earth and Sun.

### Effective temperature

surface temperatureeffective (surface) temperaturetemperature
In the case of stars with few observations, it must be computed assuming an effective temperature.
. Notice that the total (bolometric) luminosity of a star is then

### Alpha Centauri

α CentauriAlphaα Centauri A
Alpha Centauri A has a parallax of 0.742″ and an apparent magnitude
Alpha Centauri A and B have absolute magnitudes of +4.38 and +5.71, respectively.

### Distance modulus

or using apparent magnitude and distance modulus :
The distance modulus \mu=m-M is the difference between the apparent magnitude m (ideally, corrected from the effects of interstellar absorption) and the absolute magnitude M of an astronomical object.

### Asteroid

asteroidsminor bodyMinor Planet
For planets and asteroids a definition of absolute magnitude that is more meaningful for non-stellar objects is used.
The smallest asteroids discovered (based on absolute magnitude H) are with H = 33.2 and with H = 32.1 both with an estimated size of about 1 meter.

### K correction

To compare the magnitudes of very distant objects with those of local objects, a K correction might have to be applied to the magnitudes of the distant objects.
I.E. the adjustment to the standard relationship between absolute and apparent magnitude required to correct for the redshift effect.

### Hertzsprung–Russell diagram

color-magnitude diagramHR diagramcolor magnitude diagram
Hertzsprung–Russell diagram – relates absolute magnitude or luminosity versus spectral color or surface temperature.
The Hertzsprung–Russell diagram, abbreviated as H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.

### List of most luminous stars

most luminousmost luminous starsmost luminous stars known
List of most luminous stars
Below is a list of stars arranged in order of decreasing luminosity (increasing bolometric magnitude).

### Meteoroid

meteormeteorsfireball
For a meteor, the standard distance for measurement of magnitudes is at an altitude of 100 km at the observer's zenith.
Some of the smallest asteroids discovered (based on absolute magnitude H) are with H = 33.2 and with H = 32.1 both with an estimated size of.

### Albedo

albedosgeometrical albedosolar reflectance
*Earth's albedo varies by a factor of 6, from 0.12 in the cloud-free case to 0.76 in the case of altostratus cloud.
The correlation between astronomical (geometric) albedo, absolute magnitude and diameter is:

### Surface brightness

integrated magnitudeintegrated visual magnitudemag/squ arc sec
Surface brightness – the magnitude for extended objects
where M_{\odot} and L_{\odot} are the absolute magnitude and the luminosity of the Sun in chosen color-band respectively.

### Photographic magnitude

Photographic magnitude
Absolute magnitude

### Astronomical object

celestial bodiescelestial bodycelestial object
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.

### Logarithmic scale

logarithmiclogarithmic unitlog
Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale.

### Light-year

light yearlight yearsly
An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), with no extinction (or dimming) of its light due to absorption by interstellar dust particles.

### Extinction (astronomy)

extinctionextinction factorinterstellar extinction
An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), with no extinction (or dimming) of its light due to absorption by interstellar dust particles.