stars

Astronoma

2022

We explain what stars are, the types that exist and their characteristics. Also, shooting stars and meteor shower.

The stars look tiny, but they are actually large spheres of plasma.

What are the stars?

When we talk about the stars, we are referring of course to those bright spots that are observed in the sky when night falls. They are actually large luminous spheres composed of plasma. Despite being in continuous combustion, retain their own shape thanks to the enormous force of gravity that generate.

The star we know best is the Sun, to which we owe the light natural. However, there are billions of stars in the observable universe, apparently scattered but in turn forming galaxies, orbiting a great common center of gravity.

Although they all emit different types of light and heat, only a small percentage can be captured by the human eye, even with the help of a telescope. Around many of them they also rotate, as in our Solar system, opaque stars like planets, meteorites or kites, hooked on its enormous gravity.

The humanity he has observed the stars since ancient times, and he has wanted to see in them forms, hidden messages or evidences of his gods. So much so that the stars in the sky have been named after the formation of mythological figures called constellations.

From the antiquity have served for the elaboration of the first calendars, as well as for the mapping and navigation. In much closer times, the observation astronomical has understood much more about them, classifying them and learning about their destinies, their constitution and their various ways of emitting Energy.

Types of stars

There are very different criteria for classifying the stars of the universe, taking into account some of its specific characteristics, such as:

  • According to its life cycle. They are classified according to the moment of their life cycles in which they are: protostars, red giants, white dwarfs, black dwarfs or stars of neutrons (or, failing that, black holes).
  • According to its luminosity and temperature. Depending on how bright and intense they are, they are classified into (from less to greater intensity and brightness): white dwarfs, sub-dwarfs, dwarf stars (like our Sun), sub-giants, giants, luminous giants, supergiants, luminous supergiants or hypergiants.
  • According to the nature of its light. According to the type of issue electromagnetic predominant, we can talk about: stars type O (violet), type B (blue), type A (blue and white), type F (yellowish-white), type G (yellow, like the Sun), type K (yellow-orange), type M (red-orange).

Characteristics of the stars

Stars are formed from high-density molecular clouds.

Stars originate from molecular clouds, that is, regions of high density from space containing mainly hydrogen, helium and other elements. Due to the forces of gravity or the collision with other similar clouds, even more dense regions are produced inside them, which start nuclear reactions of atomic fusion.

As it begins to grow in mass and density, temperature and light are produced. The magnitude of these explosions is enormous, but the star is held together due to the brutal gravitational pull it exerts on itself.

Chemically, stars are made up of hydrogen (71%) and helium (27%), with a small percentage (2%) of heavier elements, from iron and nitrogen, to chromium and rare earths, all of which they are the result of continuous fusion within it.

In other words, the simplest elements in the universe are composed. In fact, the fusion of the stars is the origin of all atoms of matter, so that we can understand the stars as great space furnaces of matter.

Examples of stars

Some of the most common stars in the sky are:

  • Sirius (Sirius). Also called Alpha Canis Maioris, is the brightest star in the terrestrial night sky, located in the constellation Canis Maior. It is actually a two-star system, Sirius A and Sirius B, and it is even assumed that there is a Sirius C.
  • Canopo (Canopus). The second brightest star in the night sky, it is located in the constellation of the keel, 309 light years from us, and has a luminosity of 13,300 times our modest Sun. That is, it is more luminous than Sirius, but it is also much further away.
  • Arthur (Arcturus). Also called Alpha Bootis, is the third brightest star in the night sky, found in the constellation of the boyero, in the northern celestial hemisphere. It is an orange giant located 36.7 light years from our Solar System.
  • Vega. Call also Alpha lyrae, since it is in the constellation of the lyre, it is relatively close to the Earth: barely 25 light years. And although it is one-tenth the age of the Sun, it is 2.1 times more massive, and quite poor in elements heavier than helium. Vega was the first star to be photographed and spectroscopically analyzed.
  • Betelgeuse. From the constellation Orion, therefore called Alpha orionis, is a red supergiant star, the ninth in brightness of the entire sky. It is an old star, which has already used up its main fuel (hydrogen), so its temperatures are relatively low (3,000 K) and it emits significant amounts of red and infrared light.
  • Aldebaran. Call also Alpha tauri, is the main star of the constellation Taurus, from color orange-red and 425 times brighter than our Sun, despite having just 1.7 times its mass. The Pionerr 10 probe is en route to Aldebaran, and it is estimated that it will reach it in about 1,690,000 years.

Shooting Stars

Contrary to what their name suggests, shooting stars are not properly stars. Rather, it is about waste and small astronomical objects that, upon entering the atmosphere terrestrial, are victims of friction and ignite, giving off light and generating a phenomenon visible from the surface.

Shooting stars are actually meteors or meteors, only they are very small (between a millimeter and several centimeters), so they do not usually reach the I usuallyrather, they fade and disintegrate as they fall.

Meteor shower

In a meteor shower we actually see fragments of a comet's coma.

In a meteor shower, no stars actually fall from the sky. On the contrary, this phenomenon is due to the fact that our planet has momentarily entered the orbit of a comet, receiving part of the gases and fragments that are detached from his coma over thousands of kilometers long.

These showers of material, which are well assimilated to meteor showers, when they are very abundant, penetrate the atmosphere where friction ignites them and generate light in their wake. Since this usually happens with some frequency (according to the period of the comets), the meteor showers can receive specific names, as it is the case of the Leonids or the Perseids.

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