Universe

The Stars, their types and their evolution

The Stars, their types and their evolution

Those bright spots in the night sky ... Although most of the space we can see is empty, it is inevitable that we look at the brightness of each star.

It is not that empty space lacks interest, that it has it. Simply, these stars attract our attention. Few shows thrill as much as contemplating a starry night sky, far from the light pollution of cities, on a clear and serene night.

Ancient cultures were privileged in the vision of the stars live. They hallucinated a lot! And granted them all kinds of powers. They thought they saw drawings, imagined the constellations and they invented astrology. But in AstroMía we try to learn astronomy. That is why we have prepared this chapter: to study the sky from an astronomical point of view.

There are stars so colorful that they have their own names since ancient times. Others have been named after the invention of the telescope and are grouped into catalogs. However, most are invisible, even with telescopes. We only see some, few, of our own galaxy.

What are the stars? How do they work?

A star (of the Universe) is a plasma sphere. We can investigate one from near, the Sun. This has served to obtain much information about the stars. For example, we know that because of gravitational attraction, the matter of a star tends to fall towards the center and concentrate there. That increases its temperature and pressure.

From certain limits, this increase causes nuclear reactions that release energy, generating an outward impulse that balances the force of gravity, so that the size of the star remains more or less stable for a while. Meanwhile, it emits large amounts of radiation into space, including light. It was made - and made - light.

What really determines the life and evolution of each star is its mass. Those that have little remain for a long time in the main sequence. Those of intermediate mass last less, and usually evolve towards red giants, which give off a planetary nebula and remain like white dwarfs. Supermassive stars have a shorter and more violent life, and many end up exploding as supernovae.

Depending on the amount of matter that manages to gather a star and the moment of the cycle in which it is, we can find very diverse phenomena and behaviors. There are dwarf stars, giants, binaries, variables, quasars, pulsars, holes or black holes ...

In the following pages we will give an overview about the stars, their types, their behaviors and their evolution. We take off

In this chapter:

Stars of the Universe: The stars are masses of gases, mainly hydrogen and helium, that emit light ... Read pageClassification of the Stars: The photographic study of the star spectra was started in 1885 by astronomer Edward Pickering ... Read pageVisible stars AL: Alcor: Star little bright belonging to the Big Dipper, which forms, together with Mizar, a double system… Read page Visible stars MZ: Markab: Star of the constellation of Perseus, belonging to the spectral type A and whose magnitude has a… Read page Double stars: One double star is a pair of stars that are held together by the force of gravitation and rotate in ... Read page Variable stars: The concept of variable stars encompasses any star whose brightness, seen from Earth, is not constant ... Read pageNovas and supernovae: Novas and supernovas are stars that explode releasing part of their material in space ... Read pageCasars: L The Quasars are distant objects that emit large amounts of energy, with radiations similar to those of the stars ... Read page Pulsars: Pulsars are sources of radio waves that vibrate with regular periods. They are detected by radio telescopes ... Read pageBlack holes: The so-called black holes are places with a very large, huge gravitational field. Can't escape any… Read page