The 10 Most Important Features of the Stars

The Stars have many features, Among them are: they are seen in the same relative positions throughout all years, serve as a reference system to measure the movement of planets, Moon and the Sun , And have the same life cycle.

The stars are large plasma balls formed mostly of the hydrogen element, which is transformed into helium through a thermonuclear reaction called fusion.

Characteristics of the stars The Sun, one of the million stars of the Milky Way.

For some portion of its life, a star shines because of fusion, toward the end of its life may contain degenerate matter.

Stars emit light through the universe. While there is only one star in our solar system, there are billions and billions of stars across our galaxy. Exponentially there are even many more trillions of stars in the trillions of galaxies in the universe.

Many stars are visible to the naked eye at night from Earth. The most prominent stars are grouped in constellations; The larger ones have their own names. However, many of the stars of the Universe are invisible to the human eye from Earth.

There are different types of stars: variable, binary and new stars. A star can be defined by five main characteristics: brightness, color, surface temperature, size and mass.

List of the characteristics of the stars

1- Brightness

There are two characteristics that define brightness: luminosity and magnitude. Luminosity is the amount of light radiating from a star. The size of a star and its surface temperature determine its luminosity.

The apparent magnitude of a star is its perceived brilliance, taking into account size and distance; While the absolute magnitude is the true brightness independent of its distance from Earth.

2- Color

The color of a star depends on the temperature of its surface. The colder stars tend to be more red in color, while the hottest stars have a more blue appearance.

The stars in the middle ranges are white or yellow, as is the case with the sun. Stars may also have mixed colors, such as red-orange and blue-white stars.

3- Surface temperature

Astronomers measure the temperature of a star on the Kelvin scale. Zero degrees on the Kelvin scale are theoretically absolute and equal to -273.15 degrees Celcius.

The hottest and red stars are about 2,500 K, while the hottest stars can reach 50,000 K. For example, the Earth's sun is about 5,500 K.

4- Size

Astronomers measure the size of a star in terms of the radius of the sun itself. Thus, a star that measures a solar radius would be the same size as the sun of the Earth.

The Rigel star, which is much larger than our sun, measures 78 solar radii. The size of a star, along with its ground surface, determines its luminosity.

5- Mass

The mass of a star is also measured in terms of the sun of the Earth, with 1 equivalent to the size of our sun. For example, the star Rigel which is much larger than the sun, has a mass of 3.5 solar mass.

Two stars of similar size do not necessarily have the same mass, since stars can vary greatly in density.

6- Chemical composition

Most stars are made up mostly of hydrogen. The chemical composition of most stars is about 73% hydrogen, 25% helium and 2% other elements by mass.

In fact, its chemical composition is not so different from the rest of the universe. The small other elements found, besides helium and hydrogen, are heavy elements.

7- Life cycle of a star

Stars live a large part of their lives in a phase known as the Main Sequence. After nuclear fusion occurs, stars radiate energy between space.

The star takes billions of years to compensate for the loss of heat and light energy. As this slow contraction continues, the temperature, density, and pressure of the nucleus increase.

The temperature of the star's center increases over time because the star radiates energy outward, but it also contracts slowly.

This battle between the pulling gravity and the ejecting gas pressure will continue throughout the star's life cycle.

Like humans, stars are born and also die. The stars are born in the nebulae; The matter contained here determines the mass of the star. When the gas pressure equals gravity, the star reaches a steady state.

8- Age

Stars, like the sun, derive their energy from the fusion of hydrogen into helium in their nuclei. The stars in the main sequence have a range of 40 times the mass of the sun. The most massive stars are larger, the less massive ones are smaller.

The Milky Way is about 13.6 billion years old. Stars with lower masses have not had enough time to deplete their fuel reserves. "Small"stars have formed more recently than this period.

There are some stars that are almost as old as the universe itself. Many stars are known to be very young, while others are very old; Although for astronomers it is difficult to calculate the age of the individual star.

However, it is possible to calculate the age of a group of stars.

9- Stars do not blink

Sometimes the stars seem to flicker. But the titillation is not a property of the stars, but of the turbulent atmosphere of the Earth.

As the light of a star passes through the atmosphere, it must pass through many layers of deferred density.

10- You can not see millions of stars at night

Although it is often said that you can see millions of stars on a dark night, it is not true. The stars simply are not so close or bright enough.

On an exceptional night, with no moon or any light source, you can observe up to 2,000-2,500 stars in a single moment.

References

  1. Characeteristics of a star (2017). Retrieved from sciencing.com
  2. Chemical composition of stars and the universe. Retrieved from spiff.rit.edu
  3. Characeteristics of stars. Retrieved from prezi.com
  4. How old are small starts (2015). Retrieved from askanastromer.org
  5. Top 10 cool things about stars (2016). Retrieved from earthsky.org
  6. Start. Retrieved from wikipedia.org
  7. How do scientists determine the ages of stars? Retrieved from scientificamerican.com
  8. Characteristic of stars. Retrieved from padlet.com.


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