Understanding the idea behind the hertzsprung russell diagram or h r diagram
Cepheid variables also fall on the instability strip, at higher luminosities.
Hertzsprung russell diagram activity
Some stars are closer to the earth, while others are extremely distant. Therefore, the hotter main sequence stars are, the brighter they are. And the faint, hot stars are called white dwarfs. When we then plot luminosity or absolute brightness versus color or temperature , the stars all fall along a narrow strip in the diagram. Only neutrinos can reach to such depths. Stars of similar size, temperature, composition and other properties have similar spectra and are classified into the same spectral class. In fact, if a hot star were to get cooler without changing its radius, its luminosity would drop and its color would become more red so that it would follow the diagonal lines in the above diagram. The observational data are used to analyze variable star behavior and to develop computerized theoretical models of variable stars. They are common in globular clusters — dense groups of old stars in the halos of galaxies. Patterns in the H-R Diagram We see that the H-R diagram can help us classify different kinds of stars, according to the pattern of where the stars fall in the diagram. The momentum of the infalling material carries the contraction beyond the equilibrium point.
There are also a handful of stars which are red and very bright called red supergiants and a few stars that are hot, but very faint called white dwarfs. Let's say we try to classify stars according to their apparent brightness, also.
Theoretical calculations of stellar structure and the evolution of stars produce plots that match those from observations. Accretion disks in cataclysmic variables help us to understand larger scale disk dynamics — such as processes inside active galaxies with supermassive black holes.
Cepheids and RR Lyraes have played a major part in determining distances to galaxies and determining the age of the Universe. Inin his book The Internal Constitution of the Stars he explained the physics of how stars fit on the diagram. There are two subclasses; Mira and Semiregular.
This seems reasonable, since more luminous stars must be putting out energy at a higher rate, so they use up their hydrogen "fuel" faster.
Astronomers do this with stars.
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