15.02.2021

Studies about Stars since Ancient Times

Every atom in your body originates in an exploding star. This is the most poetic thing I know about physics: you are all stardust (Laurence Maxwell Krauss).

The ancient people loved to watch the movement of luminaries across the starry sky. And since in their views on wisdom itself there was never a consensus among them, astronomical knowledge received both mystical - the prediction of fate - and a purely utilitarian application - to clarify the calendar and navigation. But knowledge has remained extremely limited for millennia. People only knew about the stars that they were. Now we know much more about the types of stars . The first known characteristic of stars was luminosity. Stargazers began to sort celestial bodies by size by eye.

What Steps Were Taken to Study Stars?

Realizing that the apparent brightness depends on the distance, the ancient Greeks tried to determine the distance to the stars by the annual parallax, that is, the change in the background of an object depending on which side of the Sun the observer is looking at. But this succeeded only in 1837 by the Dane Friedrich Struve. After that, a distance correction was made to the estimate of the luminosity of the stars.

The next step was taken at the beginning of the last century, when spectral analysis made it possible to transform the color of a star, which had been estimated subjectively up to this point, into an accurate numerical characteristic. And in 1910, the famous diagram of the relationship between spectrum and luminosity appeared, compiled by the Dane Einar Hertzsprung and the American Henry Russell. Summarizing the accumulated data , scientists found that 80% of the luminaries line up in a line stretching from the lower right to the upper left corner.

The discovery had two consequences.

  • First, the diagram made it possible, knowing only the apparent luminosity and spectrum, to roughly estimate the distance to stars that are too distant for the application of the annual parallax method.
  • Secondly, in addition to the main sequence, the branch was visible on the diagram. And if you look closely, there is more than one. Some luminaries did not want to obey the general rule of increasing brightness with temperature.

Since then, astronomy and astrophysics have been enthusiastically seeking an explanation for the picture visible on the diagram. And now we can already say that the main sequence is formed by "correct" stars synthesizing helium. Such an object is characterized by a solid core of "metallic" hydrogen, divided into an inner core, in which thermonuclear reactions take place, and a radiant transfer zone, through which the released energy with great difficulty (black hydrogen is opaque and hardly conducts heat) reaches the convection zone. Now, you can name a star by yourself or by the name of your loved one. For this, you can contact Cosmonova online and choose the best star gift. You are the lucky one living in the 21st century when people have studied much about stars and their unique features.

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