What occurs inside a main sequence star quizlet?
After exhausting its hydrogen fuel, a main-sequence star will become a very large, low-density star. The cores of main-sequence stars begin to collapse when they exhaust their hydrogen. More massive stars will fuse the helium in their cores into heavier elements. Variable stars are expanding and contracting.
What is the HR diagram what are its axes?
These diagrams, called the Hertzsprung-Russell or HR diagrams, plot luminosity in solar units on the Y axis and stellar temperature on the X axis, as shown below. Hot stars inhabit the left hand side of the diagram, cool stars the right hand side. Bright stars at the top, faint stars at the bottom.
What is the HR diagram Why is it important quizlet?
Astronomers generally use the HR diagram to either summarise the evolution of stars, or to investigate the properties of a collection of stars.
Why was the HR diagram so important for Stellar Astrophysics quizlet?
An H-R diagram plots the stellar luminosity of stars versus surface temperature (or color or spectral type). —A star’s mass determines its position along the main sequence (high mass: luminous and blue; low mass: faint and red).
What does an HR diagram describe?
The Hertzsprung-Russell Diagram is a graphical tool that astronomers use to classify stars according to their luminosity, spectral type, color, temperature and evolutionary stage. Stars in the stable phase of hydrogen burning lie along the Main Sequence according to their mass.
When stars have no fuel left?
A star like our Sun will become a white dwarf when it has exhausted its nuclear fuel. Near the end of its nuclear burning stage, such a star expels most of its outer material (creating a planetary nebula) until only the hot (T > 100,000 K) core remains, which then settles down to become a young white dwarf.
What star that has used up its fuel?
The same is true with stars; no more fuel in the stellar core will end the stellar fusion process. When the core hydrogen is used up and no more nuclear fusion occurs, the star’s outer stellar layers expand and the core shrinks. At this point, the star becomes a Subgiant Star .