The Theory of Magnitude in-Astrophysics - Physics-Astronomy.org

The Theory of Magnitude in-Astrophysics

In Astrophysics, frequently the terms like clear magnitude, Absolute magnitude and Bolometric magnitude are encountered. Ever wonder what are these terms and how a great deal are they significant in Astronomy? Well, a lot.The concept of magnitude is extremely important to understand for an part-time astronomer or a science enthusiast.
Magnitude is on the whole the” brightness” of an astronomical thing. There are numerous substance visible in the night sky. These objects differ in distance from earth and hence they also differ in their brightness. We shall first discuss the concept of obvious magnitude.The apparent scale is the brightness of an object as noticeable through the naked eye. In 2nd Century BC, Hipparchus 1st classified the stars according to their obvious brightness of apparent scale and cataloged some 1000 stars into 6 groups. The collection 1 stars were the brightest, collection two stars were fainter than the group 1 and so on. The 6th group stars were the faintest. In 2nd Century AD, Ptolemy as well used the same move toward and secret the stars into his own catalog.
in 1830, British Astronomer William Herschel exposed that the stars of collection 1 were 100 times brighter than stars of group 6. Later in 1856, N.R. Pogson urbanized a scale in which he unspecified that the ratio of the brightness of substance in two successive group is same.
This led to the conclusion that a 1st magnitude star is 2.5 times brighter than the next magnitude star and so on for the next ratios.Mathematically, if B(m) and B(n) are the brightnesses of 2  stars with magnitudes m and n ( n>m ), then
B(m)/B(n) = (2.5)^ n-m
This equation has amazing very significant to tell. According to this equation, the brighter the thing, lesser is its magnitude. This means that an thing with magnitude -4 is brighter than the object with scale, say +2.
Example: The obvious magnitude of Sun is -26.74 and that of the brightest star in the nighttime sky is -1.74 So according to the on top of equation, Sun turns out to be more than 10 billion times brighter than Sirius. The picture below illustrates the concept briefly.All the magnitudes defined so are plaster only limited regions of stellar spectrum. The stellar scale based on the radiations measured over the entire range of electromagnetic spectrum is recognized as the Bolometric magnitude. Except since no single detector is responsive to all the wavelengths of the stellar spectrum, to change any other other scale into bolometric magnitude, some corrections need to be practical. In particular, the dissimilarity flanked by the bolometric magnitude and photovisual magnitude is term as Bolometric correction ( BC).
The BC for sun is -0.11 The BC is forever a negative quantity. The significance of this magnitude can be understood from a simple instance. There is an orange giant star Arcturus, in the group of Bootes. It is about 110 times brighter than the Sun. But in the infrared spectrum, the star is 180 the celebrity is 180 times more powerful than the Sun. So the totality ( bolometric ) output of Arcturus is far additional greater than its obvious output.
The Theory of Magnitude in-Astrophysics


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