had promised to publish a simple introduction to the topic of variable stars. As I already had written for many years, but was available on a page that no longer exists, I'll get it back through the blog VariaStar. I take it for good this remake if it is useful to pers onas that p irst time approaching the world of variable stars.
Variable Star: An Introduction (I)
A variable star is any star in the sky whose brightness is not constant but change with time. Although it is suspected that the Arabs already know the variability of Algol, Beta Persei, the first reference is to secure a star in the constellation of the Whale, which Fabricius observed in 1596 in the third magnitude when it was omitted from the maps, which called Mira (wonderful), and Bayer independently cataloged under the name omicron Ceti in 1603.
What appeared to be a few anomalies in the unchanging sky for astronomers of the seventeenth century were already more than three hundred by the end of last century and today are about 40000, which is why variable stars are a branch Astronomy independent today. However, and paradoxically, the importance of ee. vv. reside outside their own area, extending the full knowledge of the universe. Stellar variability responds to particular moments in the life of a star, or the interactions between the stars that make up double or multiple systems, or effects between a star and a surrounding material, or phenomena on the surface, etc, etc. Thus, in this way, variable stars are real testbeds to study the structure and evolution of stars, the fluids in the interstellar medium, exotic objects in the galaxy, or as many problems of astrophysics.
Classification of Variable Star
The variability in the brightness of a star can be caused either by:
1-fault of the star itself. In this case we Extrinsic Variables that are not ee. vv. strictly speaking, but rather specific instances of binary stars in which a hidden component of other observers. So this is also called eclipsing variables. Can be of three types: Type beta PerseiTipo beta Lyrae type W Ursae Majoris
2 - The physical structure and all kinds of processes that occur in the star. These are the stars Variables Intrinsic or Physics. This is the kind of ee.vv. to which we will pay more attention. There are two main types of ee.vv. Physical:
Pulsed . Have a brightness variation usually soft and maintains a clear schedule. May be of the following subtypes:
Cepheid (classical) (short-period Cepheids)
RV Tauri type
beta Canis Majoris type
RR Lyrae Type
Delta Scuti type
Look
Type
semiregular
alpha-2 type Venaticorum canum
Eruptive . Are sharp variations in brightness, not follow, in many cases, an appreciable frequency. They present 2 subtypes:
Eruptive Irregular
Eruptive Cataclysmic
Supernovae:
Type I
Type II
News:
Ballroom
; Glasses
; Very Slow
; Very Slow
U Geminorum type
Z Camelopardalis Type
Type Z Andromedae (symbiotic stars)
R Coronae Borealis type
Nomenclature of Variable Star
Like ordinary stars, the variables are named according to the constellation to which it belongs, identified by a Latin letter beginning with R (with so as not to be confused with Bode star catalog, which uses the alphabet from A to Q) followed by the genitive of the Latin name for the constellation within which it is.
When it comes to Z name starts with two letters, beginning a series that runs from the RR to RZ. If more variables are found in pairs series will begin with S, T, etc, to Z, combined with the R, S, T, etc to Z. Also it is possible to do sets of 2 letters from A to Q combined with the letters A through Z.
With this system 334 can be classified variable stars in a constellation when recognizing new such objects shall be named with the prefix V and the serial number (which must be from 335), accompanied by the Latin genitive of the constellation name. There are also variables that receive the traditional name or the name of Bayer to be known long before the discovery of its variability: Beta Persei (Algol), Chi Cygni, for instance.
A variable star also receives a numerical designation, the number of Harvard, which corresponds to their coordinates in the epoch 1900.0. On the other hand, different kinds of variable stars are designated by the name of a star which is usually the first such discovery and is the prototype of behavior that is classified.
When it comes to Z name starts with two letters, beginning a series that runs from the RR to RZ. If more variables are found in pairs series will begin with S, T, etc, to Z, combined with the R, S, T, etc to Z. Also it is possible to do sets of 2 letters from A to Q combined with the letters A through Z.
With this system 334 can be classified variable stars in a constellation when recognizing new such objects shall be named with the prefix V and the serial number (which must be from 335), accompanied by the Latin genitive of the constellation name. There are also variables that receive the traditional name or the name of Bayer to be known long before the discovery of its variability: Beta Persei (Algol), Chi Cygni, for instance.
A variable star also receives a numerical designation, the number of Harvard, which corresponds to their coordinates in the epoch 1900.0. On the other hand, different kinds of variable stars are designated by the name of a star which is usually the first such discovery and is the prototype of behavior that is classified.
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