In Memory Of A Friend Wedding Program

COURSE Introduction to Astronomy (45)

Variable stars

A large number of stars will not shine steadily, but will vary periodically, or whatever it is, do not retain the same apparent magnitude and in a shorter or longer period and more or less regular, their magnitudes reach different values, such stars are called variables.
For example, the star Mira Ceti (constellation of the whale), which historically was the first known variable star in a period of 332 days passed from 2 nd to 9 th magnitude.
With the use of photography in astronomy, he discovered so much better the variability of the stars, so it was photographed the same region of sky in two different dates with the same instrument and in identical positions, comparing the two pictures can be seen if the stellar image varies or not.
Variable stars are classified as:
1) Intrinsic: those in which their magnitude variations due to changes in the star's internal structure, and that changes color, temperature and range, along with these changes of light .
2) Extrinsic: not regarded as real variables, since variability of sun light is produced by external physical causes unrelated to the star itself. According
cuva variability of the stars, they are divided into:
1) Periodic or regular: the light curve is periodic, ie, after an interval of time, called period, plays unalterably.
2) semiregular: ligeramnete period is variable and the curve is reproduced with low accuracy in each period.
3) Irregular: in these there is only one small indication of periodicity.
Observing variable stars is one of the most interesting work programs for the amateur astronomer. NO requeire costososy use of instruments made, and often most suitable for visual observation using binoculars or a 60 mm refractor. The work of variability is to define the range of variation of brightness and the period of the variable in question. For those observers who want to delve into this area to get in touch with major international organizations variable stars, and that through their newsletters, online via email or we can read the latest news that most interest us. These organizations also distribute some star charts to find the variable to consider, among other important features