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In astronomy, surface brightness (SB) quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background. An object's surface brightness depends on its surface luminosity density, i.e., its luminosity emitted per unit surface area.
An image of NGC 45, a low surface brightness spiral galaxy, by GALEX. UGC 477 is located over 110 million light-years away in the constellation of Pisces. [1]A low-surface-brightness galaxy, or LSB galaxy, is a diffuse galaxy with a surface brightness that, when viewed from Earth, is at least one magnitude lower than the ambient night sky.
UGC 6614 is classified as a low surface brightness (LSB) galaxy. [3] [4] [5] The galaxy is nearly face-on and has a ring-like feature around its bulge, [6] with distinctive extended spiral arms. [7] The bulge of UGC 6614 is found to be red, similar to those of S0 and other elliptical galaxies, hinting at the existence of an old star population. [8]
An object's surface brightness is its brightness per unit solid angle as seen in projection on the sky, and measurement of surface brightness is known as surface photometry. [9] A common application would be measurement of a galaxy's surface brightness profile, meaning its surface brightness as a function of distance from the galaxy's center.
Modified Newtonian dynamics (MOND) is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies.Modifying Newton's law of gravity results in modified gravity, while modifying Newton's second law results in modified inertia.
The intensity of the gegenschein is relatively enhanced because each dust particle is seen at full phase, [3] having a difficult to measure apparent magnitude of +5 to +6, with a very low surface brightness in the +10 to +12 magnitude range.
In some applications, the brightness temperature of a surface is determined by an optical measurement, for example using a pyrometer, with the intention of determining the real temperature. As detailed below, the real temperature of a surface can in some cases be calculated by dividing the brightness temperature by the emissivity of the surface ...
Sometimes there is an observed truncation in the surface brightness profiles of lenticular galaxies at ~ 4 disk scalelengths. [7] These features are consistent with the general structure of spiral galaxies. However, the bulge component of lenticulars is more closely related to elliptical galaxies in terms of morphological classification.