How is it possible that life cycles of stars are so well understood and tested?

Just as the Sun has an 11 year sunspot cycle, stars also have activity cycles; they have many "star-spots" sometimes, and a few at other times. These cycles are detectable by looking for the spectral features that active surface regions emit, such as the emission lines of the common element calcium.

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How do astronomers know what stage a star is in?

The length of time a star spends in the main sequence phase depends on its mass. "Constructing a plot, called the HR diagram, of the stars in the cluster, scientists can determine the mass of the stars that are just ending this phase and moving on to the next phase of their life, the red giant phase. What determines the life cycle of a star quizlet? Mass impacts the life cycle of a star by determining what life cycle it takes. Also by determining the end of its life cycle. What is a star? A star is an extremely hot ball of gas with hydrogen fusing into helium.

Correspondingly, will stars with negative magnitudes be brighter than stars with positive magnitudes?

A higher positive number means a fainter celestial object; whereas a higher negative number means a brighter celestial object. One may also ask where do supernovas take place? Astronomers believe that about two or three supernovas occur each century in galaxies like our own Milky Way. Because the universe contains so many galaxies, astronomers observe a few hundred supernovas per year outside our galaxy. Space dust blocks our view of most of the supernovas within the Milky Way.

And another question, can a star turn into a planet?

Yes, a star can turn into a planet, but this transformation only happens for a very particular type of star known as a brown dwarf. Some scientists do not consider brown dwarfs to be true stars because they do not have enough mass to ignite the nuclear fusion of ordinary hydrogen.