It is a large celestial matter composed of plasma, with a circular shape and its own light splendor. Some stars can be seen with the naked eye during the hour of the night from the Earth, manifesting as a variety of luminous fixed points in the sky, being appreciated in this way because of the great distance at which they are. Certainly, the most voluminous stars were grouped into asterisms and constellations, the brighter ones receiving proper names.
What are the stars
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They are large plasma spheres, whose shape is defined by their gravity, having their own light and energy due to the internal processes of nuclear fusion. They are far apart from each other by great distances. That is why they can be seen as tiny points in the sky despite their large size. Its etymology comes from the Latin term stella and its name in English translates as star.
Of all those that exist, the closest to planet Earth is the Sun, being the center of the solar system, and around it eight planets revolve with their satellites. It can be observed with the naked eye, as well as a large number of these stars in the sky on a starry night, but for the most complete observation of the rest of stars that are not easily observable from Earth, a telescope is necessary. Although the exact number of these stars in the universe is not known, it is believed that there could be about 100,000 million of these in each of the 100,000 million galaxies.
It should be noted that those that can be observed on a starry night from our planet, are contained in a very small part of the Milky Way, our galaxy. There is a certain proximity and alignment of groups of these, presenting certain invariable formations and which are called constellations and asterisms. The difference between the two terms is that a constellation is a formally recognized grouping, while asterisms are the simplest of the brightest associations.
Characteristics of the stars
Composition
These are mainly composed of plasma and gases. Its chemical composition is determined by 71% hydrogen, 27% helium and the remaining 2% is made up of other heavy elements such as iron. These elements could determine if a star is accompanied by one or more orbiting planets.
Exclusively the fraction of heavy matter is calculated in terms of the volume of iron in the atmosphere, since iron is a common matter and its absorption rate is more or less easy to measure. The fraction of the heaviest elements may be an indication of the possibility that the star has a planetary system.
The plasma in these bodies is the state of extreme heating of very small particles contained in them. Other elements present in them are nitrogen and carbon. There are neutron stars, which are those resulting from the collapse of a super giant as a result of the depletion of its nuclear fuel, which will result in a smaller one but with higher densities. On the other hand, quark stars are those whose matter is quark-gluon plasma (high-density phase and temperature).
Brightness
To measure it, a scale of stellar dimensions has been established. A very bright one, like the one called Antares, is of the first dimension; on the other hand, one that can barely be seen with the naked eye is in the sixth dimension level.
Their apparent brightness or luminosity from Earth will depend on their characteristics and how distant they are, so their presence in the celestial vault will become more or less noticeable. However, the fact that one stands out more in luminosity than another does not mean that it is of a greater size than another whose brightness is barely visible, but that its distance is perhaps considerably less than another whose size is hundreds of times greater.
Size
These have huge differences in their magnitudes and size. The red giant of Antares is approximately 290 times bigger than the Sun. On the other hand, the smallest that can be observed has magnitudes lower than those of the Earth, although its densities are greater than those of a larger one.
Astronomy in this way believes that these are like an accumulation of matter in a plasma condition that is in a constant process of collapse. In this march different forces interact that are balanced in a hydrostatic state. These gas agglomerations scatter stellar winds, electromagnetic radiation, neutrinos, which allow them to be visible in the sky as bright spots that flash due to their proximity to the earth, on the other hand, the sun is estimated as the prototype star. Because of this, the characteristics of stars are usually determined in solar units in terms of their dimensions.
Age
From their birth, they begin to burn hydrogen, a stage in which it is very stable. Then, when it is exhausted, processes of fusion of carbon, helium and other elements are started that may vary according to the mass of each one. As its life passes, it loses its mass, which is violently thrown out of it, thereby losing density, producing a nova explosion.
The speed of these events will be determined by the mass of each one, and astronomers believe that those with the greatest amount of mass become black holes. In the most massive the processes occur more quickly. For example, those with the least amount of mass can be more than ten billion years old; while those with the greatest mass barely reach a few million years of life.
That is why although two stars are observed in the same life stage, they may not be the same age, it will depend on their mass.
Types of stars
The cosmographers have gathered an extensive catalog, supplying standardized star designations.
According to its luminosity
These can be classified according to their luminosity or spectrum. It is known that these are cataloged by their spectral lines and the incidence of mass and gravity in their luminosity. The classification of these according to their luminosity are the following:
- Hypergiants (0): these have a colossal size, in addition to a large amount of mass, about 100 times greater than that of the Sun. It is accepted that stars with masses greater than 120 solar masses cannot exist; However, in 2010 British astronomers discovered in the R136 cluster one with about 300 solar masses of weight at the time of its birth and 8,700,000 times brighter than the Sun.
- Luminous supergiants (Ia): their composition is between 10 and 50 solar masses, whose size can be about a thousand times larger than the Sun. You can find red supergiants and blue supergiants, the latter being smaller than red ones.
- Supergiants (Ib): their masses and sizes are similar to the previous ones, but they are of lower luminosity than those of classification Ia.
- Luminous giants (II): they are characterized by being of lower brightness and mass than supergiants, but their luminosity is high. The giant red star can have a mass less than 9 solar masses.
- Giants (III): in these you get the blue giants and the orange giants, with a luminosity between 60 and 300 times greater than that of the Sun.
- Subgigants (IV): these will be less luminous due to cooling and evident color change, having a larger diameter.
- Dwarf stars (V), sub-dwarfs (VI) and white dwarfs (VII): their spectra are unique, which due to having fewer metals, their luminosity is lower, so they are last in this category.
You can get in this classification some white, red, blue and yellow star.
According to its life cycle
The life cycle of these stars is divided into twelve phases according to the Hertzprung-Russell diagram (which takes into account the relationship of their luminosity and their temperature), and will depend on their amount of mass.
- PSP Main Presequence: it is the phase prior to the main sequence, having as an energy source the collapse of gravity. Protostars, which are the transformation of stars from their formation to their main sequence, are part of this phase.
- SP Main sequence: in this phase are most of these stars. In this sequence, low-mass and lower-temperature red dwarfs can be found, as well as super-massive blue giants. In this phase, hydrogen is burned at its core.
- SubG Subgiant: at the beginning of the phase, both its size and brightness will increase, but its temperature will decrease and its color will vary. Towards the end of this, they will grow in size and the temperature will be lower than their mass equivalents.
- GR Giant red: in this phase, they have about 9 solar masses, and they reach this state when their atmospheric temperature cannot be lower, so they must increase their volume and brightness, with a constant temperature, taking on a reddish color. In this stage, hydrogen is incinerated surrounding helium in the core.
- AR Red crowding: the radii of these are greater than in their main sequence and the helium in the nucleus of them is burned.
- RH Horizontal branch: in this phase, the hottest ones are closer to the main sequence and the cooler ones towards the red giants. Its luminosity is greater than that of the Sun approximately 50 times.
- RAG Giant asymptotic branch: the RAG-T (early) and RAG-PT (with thermal pulses) sub-phases are distinguished. In the first, the stars obtain their energy from the fusion of the helium that surrounds the carbon and oxygen in the nucleus, and they are colder and grow enormously, so they could absorb the planets that are around them. In the second, the energy comes when hydrogen is fused into helium more externally.
- SGAz Blue supergiant: in this stage, hydrogen is consumed in a vertiginous way in large quantities, so the dynamics of nuclear fusion is very active, so the temperature is high and its color is hot (blue).
- SGAm Yellow supergiant: this is presented by those with large amounts of mass, which will quickly gain size due to the activity of their nuclei. However, it is a fast phase.
- SGR Red supergiant: this phase is reached by those with high mass, obtaining the largest size of the stars that exist. They are the product of the depletion of hydrogen in their nucleus and begin to fuse helium. Despite their size, they are cooler than blue ones and have lower density.
- WR Star Wolf-Rayet: in this stage, the ones of great mass lose it due to the stellar winds. They are very bright and bluish in color.
- VLA Blue luminous variable: this is one of the last in the life of these stars, which can give rise to what is known as a supernova, which is a stellar explosion caused by the end of the life of a star with a lot of mass.
According to gravitational criteria
These can be in different gravitational systems. Four criteria are known according to the International Astronomical Union, which were established by the organization since 2006.
- By gravitational grouping: this consists of differentiating if a star is independent or cumular. The independent ones are not united to others forming stellar clusters, although the exceptions are those that are orbiting others (they are part of that system) or they are the center and others orbit them (they are the center). The cumulars are part of a stellar cluster, and can be spherical, in which they attract each other; or open, so they are attracted to a center of gravity in the cluster that keeps them grouped.
- Systemic by position: in this classification, those that are part of a stellar system are located, being able to be central or satellite. The centrals will have other stars trapped in their gravitational center, so they will orbit it; while satellites are those that surround a central.
- By planetary system: they are the center of a planetary system that can be made up of planets, satellites, comets, among others; although it contemplates those that are not orbited by any body, which are called unique.
- By stellar gravitational center: this classification distinguishes those that are part of a stellar system, where there is a gravitational center; and those that do not are called solitary.
Star formation
These originate in the dust nebulae, which will be attracted by gravity, shrinking and fragmenting. Then, the fragments heat up and gain density, exceeding 10 million degrees Celsius, giving rise to a new star.
During a part of its life, a star glows because of the thermonuclear fusion of hydrogen in its center; releasing energy that passes through the interior of the star and is subsequently reflected into outer space. When the center of a star has almost depleted hydrogen, practically all matter heavier than helium, formed naturally, are produced by stellar nucleosynthesis throughout the life of the star and in some stars, by supernova nucleosynthesis when explode. At the end of its life cycle, the star can also store degenerate matter.
Other meanings of the term
Shooting Star
These are known by this name, although in reality it is not a star. They are defined as small particles of dust or remains of other bodies that enter the Earth's atmosphere and that, due to friction and the change in temperature, ignite the particle, so it can be observed as a beam of light that quickly crosses the firmament, being visualized with the naked eye in the night sky, and when it is in large quantities, they are called meteor showers.
These are actually known to astronomers by other designations. The smallest are called meteoroids (very small asteroids), which measure between a few microns to a meter and when they enter the atmosphere and produce light, they are called meteors, which will be disintegrated before touching the earth's surface. If they manage to touch the earth's surface, they are classified as meteorites, which can weigh up to several tons, as the cause of mass extinction in the age of dinosaurs.
According to their luminosity, these can be fireballs, whose brightness exceeds the appearance of Venus; and superbolides, when its brightness is greater than that of the Moon due to its explosion in the atmosphere. At certain times of the year several of these can be observed, having a meteor shower.
Polar Star
It is the one that has the brightest brightness in the sky and that is closest to the axis of rotation of the Earth, although it is also known as the one closest to the North Pole or the South Pole, as the case may be. Due to the variation and displacement of the celestial poles and the location of the stars, each pole star can vary over time, with Cinosura being that of today in the northern hemisphere and Sigma Octantis that of the southern hemisphere.
This "title" or position can be kept for periods of approximately three thousand years. These have served as a guide for navigators, since thanks to their visibility in the sky, they can locate their latitude more easily.
David's star
This is a symbol that consists of a star with six points, which belong to two triangles superimposed one on the other (one to the right and the other inverted). This, called in the past "Seal of Solomon", became one of the most representative of Judaism since medieval times, representing the connection between God and man, and the covenant between God and Abraham, when he promised that his descendants would be as abundant as the stars in the sky.
Before Christ, this symbol in the form of a regular hexagram was used in Israel, Palestine and their surroundings, although it was also used by ancient civilizations such as Hindu and Chinese culture and in secular, Buddhist and Islamic religions.
Starfish
Whose scientific name is asteroid, it is a marine animal belonging to the class of echinoderms, which are invertebrate animals with a pentameric symmetry, that is, it has symmetry in which its body is divided equally into five parts around its mouth. The asteroid has five pointed arms. There are about 1,900 species of this animal, present in the oceans of the entire planet, both at the littoral and abyssal levels.
Although there are males and females in this species, there are also hermaphrodites, and their reproduction may be asexual. Some of these start their life as males and end it by becoming females, or vice versa. In others, its reproduction is by division, generating a new specimen of a severed member; or by fertilization.
Star of fame
It is a recognition granted by the Hollywood Chamber of Commerce to personalities in different categories of entertainment such as film, television, music, radio and theater. This consists of a kind of terrazzo embedded in the sidewalk of the Hollywood Walk of Fame in Hollywood, California, United States, which has the name of the award-winning artist and a symbol of the category for which it is recognized.
These are salmon-colored, where the names are inscribed in bronze and the respective insignia, surrounded by a black base.
Star rating
These are used to evaluate the quality of certain products, pages, establishments, services, among others. For example, there is an international convention in the valuation of hotels or restaurants that is carried out in stars, and the best ones obtain the five-star rating when they exceed all the evaluated standards in quality.
These allow travelers to know the quality of the accommodation establishments and make a more informed decision for their stay or to know the quality of the gastronomy. It should be noted that in the same way, guests and diners may give them a user assessment, which will also serve as a recommendation or warning to other people who have not visited the facility.
Stars in popular culture
The term is used in show business to refer to a person who enjoys immense popularity among the public, and its origin is because the MGM production company "had more stars than the sky." On the other hand, Canal de las Estrellas is a Mexican television station that belongs to the Televisa group. The first official broadcast was made on March 21, 1952 and is broadcast in an open signal throughout the Mexican nation through a network of 128 retransmitters. The first broadcast of the Canal de las Estrellas was a baseball game from Delta Park.
Titles can be found in literature, film and television, such as John Green's book "Under the Same Star", which was adapted for the cinema, or the game show "A Star Is Born". In the cinema, the "Death Star" is also very famous, which is a space station in the world famous fictional saga Star Wars. There is also the character Patrick Star, who belongs to the SpongeBob cartoons. Patrick Estrella is Bob's best friend, being an asteroid, hence his name.
T lso his name has been used for brands and companies, such as the Grupo Estrella Blanca, which is a company that has to its credit several brands in the area of transportation in Mexico. Likewise, there is a so-called Red Star Bus and another Gold Star.
The graphic representation of this figure consists of a star polygon, which can have five or more points and can be found by searching for stars to color online.
