Background pixels resulting from luminosity of bright-field images were removed by threshold analysis.
Digital images were elaborated using Photoshop CS3 (Adobe); the luminosity of brightest and dimmest pixel in each channel were adjusted to obtain the best visual reproduction, taking care to maintain linearity in the brightness scale.
Although Pseudotropheus species express a UV-sensitive cone opsin, examinations of photographs of these and related species taken under UV light did not reveal any UV-specific markings, simply a greater degree of luminosity of the bright blue parts of their colour, which does not vary noticeably between the populations.
The luminosity of the brightest stars at the upper end of the main sequence varies in clusters from about −8 to −2 visual magnitude.
Herschel attributed the phenomena to erupting volcanoes and perceived the luminosity of the brightest of the three as greater than the brightness of a comet that had been discovered on April 10.
Seen from a nose's length away, his broken brushwork reveals glimpses of unpainted ground, often cardboard, which help to account for its peculiarly matter-of-fact luminosity — its knitted light, with trembling contrasts of bright and dark and of warm and cool.
Because of the high luminosity of their brightest stars, some open clusters have a total luminosity as bright as that of some globular clusters (absolute magnitude of −8), which contain thousands of times as many stars.
The same study also showed that the rate of production of serotonin in the brain was reported directly related to the prevailing duration of bright sunlight and rose rapidly with increased luminosity.
It is 25 times more luminous than the Sun but has a significantly lower luminosity than other bright stars such as Canopus or Rigel.
For example, the luminosity function for the young clusters h and χ Persei, when compared with the van Rhijn function, clearly shows a large overabundance of bright stars due to the extremely young age of the cluster, which is on the order of 106 years.
The primary has an absolute magnitude of −8.5 and an unusually high luminosity of 200,000 L☉, the reason it appears so bright at such a great distance.
