Search results
Results From The WOW.Com Content Network
Resolution B2 defines an absolute bolometric magnitude scale where M bol = 0 corresponds to luminosity L 0 = 3.0128 × 10 28 W, with the zero point luminosity L 0 set such that the Sun (with nominal luminosity 3.828 × 10 26 W) corresponds to absolute bolometric magnitude M bol,⊙ = 4.74.
The apparent magnitude is the observed visible brightness from Earth which depends on the distance of the object. The absolute magnitude is the apparent magnitude at a distance of 10 pc (3.1 × 10 17 m), therefore the bolometric absolute magnitude is a logarithmic measure of the bolometric luminosity.
Absolute magnitude, which measures the luminosity of an object (or reflected light for non-luminous objects like asteroids); it is the object's apparent magnitude as seen from a specific distance, conventionally 10 parsecs (32.6 light years). The difference between these concepts can be seen by comparing two stars.
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 object's actual luminosity is determined using the inverse-square law and the proportions of the object's apparent distance and luminosity distance. Another way to express the luminosity distance is through the flux-luminosity relationship, = where F is flux (W·m −2), and L is luminosity (W). From this the luminosity distance (in meters ...
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. The phase curve is useful for characterizing an object's regolith (soil) and atmosphere. It is also the basis for computing the geometrical albedo and the Bond albedo of the body.
Because the magnitude is logarithmic, calculating surface brightness cannot be done by simple division of magnitude by area. Instead, for a source with a total or integrated magnitude m extending over a visual area of A square arcseconds, the surface brightness S is given by S = m + 2.5 ⋅ log 10 A . {\displaystyle S=m+2.5\cdot \log _{10}A.}
Absolute darkness 10 −4: 100 microlux 100 microlux: Starlight overcast moonless night sky [1] 140 microlux: Venus at brightest [1] 200 microlux: Starlight clear moonless night sky excluding airglow [1] 10 −3: 1 millilux: 2 millilux: Starlight clear moonless night sky including airglow [1] 10 −2: 1 centilux: 1 centilux: Quarter Moon 10 − ...