How Do Low Mass Stars Die?
- There are three mass categories for stars: low mass stars are those stars consisting of .5 solar mass or less; medium stars, such as our sun, are classified as holding a mass of .5 to 3 solar mass; and massive stars, such as Betelgeuse, possess 3 solar mass or more. The more mass a star holds, generally the shorter its life span. Eventually, the hydrogen a star uses to convert into helium begins to grow scarce. Without hydrogen, the star begins the death process. However, a low mass star may live for a total of approximately 15 billion years.
- When a low mass star uses up all of the hydrogen in its core, the core starts to collapse and produces greater heat. As the interior of the star grows hotter, the exterior layers of the star begin to push outward. The exterior layers cool due to the outward expansion. The star now transforms into one of its final forms as a red giant star. All stars, regardless of mass, first become red giants when hydrogen stores deplete in the core.
- After transforming into a red giant, a low mass star's superwind, or stellar wind, moves across the red giant's surface and removes the outer layers of the star. The star uses up the last of its fuel and, unlike the red giant's expansion, it transforms into a white dwarf that contracts. The surface of the white dwarf is hot. The white dwarf continues to cool over several billion years as it prepares to turn into a black dwarf.
- The existence of a black dwarf star remains a subject of theory only; the universe itself numbers less than 14 billion years, and it may take that long before a low mass star transitions into a red giant. Estimates suggest that it can take a trillion years for a star to go from birth to black dwarf status. A star dies when it reaches black dwarf status; it no longer contains any fuel, light or heat. It is a dark, cold mass.