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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.
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. The absolute magnitude M can also be written in terms of the apparent magnitude m and stellar parallax p : M = m + 5 ( log 10 p + 1 ) , {\displaystyle M=m+5\left(\log _{10}p+1\right ...
The evolving star may eject some portion of its atmosphere to form a nebula, either steadily to form a planetary nebula or in a supernova explosion that leaves a remnant. Depending on the initial mass of the star and the presence or absence of a companion, a star may spend the last part of its life as a compact object ; either a white dwarf ...
The absolute magnitude (M) describes the intrinsic luminosity emitted by an object and is defined to be equal to the apparent magnitude that the object would have if it were placed at a certain distance, 10 parsecs for stars. A more complex definition of absolute magnitude is used for planets and small Solar System bodies, based on its ...
where is the luminosity produced in the form of neutrinos (which usually escape the star without interacting with ordinary matter) per unit mass. Outside the core of the star, where nuclear reactions occur, no energy is generated, so the luminosity is constant.
Luminosity functions are used to study the properties of large groups or classes of objects, such as the stars in clusters or the galaxies in the Local Group. Note that the term "function" is slightly misleading, and the luminosity function might better be described as a luminosity distribution .
Stars can form orbital systems with other astronomical objects, as in planetary systems and star systems with two or more stars. When two such stars orbit closely, their gravitational interaction can significantly impact their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.
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).