Evolution of stars
Author: Róża Chojnacka
„Everything on earth
has its own time
and its own season.
There is a time
for birth and death.
(Ec 3, 1-2)”
The conception of stars evolution and H-R diagram
An evolution is an ambiguous notion and many spheres of life have observed similar processes of changing. That’s why the "evolution" is connected with among other things in biology to biology evolution, in philosophy to evolutionism, in astronomy to stars evolution etc. What’s more, evolution can mean manoeuvre of ships team used to alley from one battle array, course or also aerobatics.
In this article I’ll busy myself stars evolution. This notion relates to changes, which take place in stars during their "getting old" in whole period of their life. Because evolution takes milliard years, we can’t observe the changes directly. The astronomers first construct evolution theories to being true to physics laws and after that they check up this by observing real stars.
To verify conformability a theory with observing, the astronomers use Hertzsprunga-Russella diagrams. Every spot on the H-R diagram represents one star, which temperature (or its spectral type) can be read on horizontal axis, and radian strength (or absolute star size) on vertical axis. If we mark a few thousands of chosen by chance stars on H-R diagram, they will lay down in some definite areas. This schedule of stars suggests exist dependence between star’s radian strength and its temperature - in other way spots would be thrown by chance in all diagram’s area. About 90% of stars lay in narrow piece called main pathway, which takes place from upper left piece of diagram (hot, very light, blue giant stars) to lower right (cold, poor light, red starlets). Most of left 10% of stars lay or in upper right piece of diagram (cold, light, red giant stars and supergiants stars),or in lower left corner (hot, white starlets).
A birth
Stars are created by matter from cosmic space. Interstellar clouds (include gassy and dust matter) are probably place of stars’ birth. The closest area, where right now are creating new stars is Nebula in Orion (M42), which lays 1500 light years from us, in Orion Constellation. (this place is worth to remember, because in our quiz there is a question about place of stars’ birth). The Nebula in Orion you can see in included picture like a dusty spot. It’s also visible with the naked eye under the stripe of Orion.
A time of life
A protoplanet is a star in the moment of birth. Protoplanets are created by chance in condensation inside turbulent gassy and dusty clouds in cosmic space and they are hold by gravity. Clouds, in which protoplanets are created, differentiate considering a mass and schedule of chemical elements; cycle of star’s life (time, in which star submits followed stages of evolution) depends of that fact. From stars with similar schedule of chemical elements, stars with enormous mass evaluates faster; stars with quite a little mass need the longest period of time to evaluate.
An old age
A star from main pathway emits light evenly until the time, when all approachable hydrogen in its core will be changed into helium. Then star starts dying. Our Sun is average star with medium size. For about five milliards years it has emitted light stably, as star from main pathway should and then, it will be shine in next five milliards years.
The lightest stars with enormous mass and high temperature die at the fastest, because they use their hydrogen at the fastest. Massive, blue giantstars like Rigel Orion Constellation only in a few millions years shine as stars from main pathway. Darkly shined, cold stars with the littlest masses live the longest, because they consume their hydrogenous fuel slower than others. The oldest and plenty fullest stars of main pathway are red starlets with little mass. They live many milliards years.
A death
All stars, but in different speed, evaluate in the same way until the moment, when their cores include mainly carbon. The last stage of evolution, so the way of star’s death depends mainly of its mass.
Little stars with mass to 1.4 of Sun’s mass, die calmly, silently die down in cosmic black. The stars with enormous mass finish with rapid explosion shining until they lost their life. Supernova is giant star explosion.
Translated by Monika Rap