Which is a type of star found on the lower end of the main sequence?
The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun () primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases. Main-sequence stars below undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.
Which is a type of star found on the lower end of the main sequence, based on its mass?
Stars below about 1.5 times the mass of the Sun
Main sequence
At a stellar core temperature of 18 million Kelvin, the PP process and CNO cycle are equally efficient, and each type generates half of the star's net luminosity. As this is the core temperature of a star with about 1.5 , the upper main sequence consists of stars above this mass. Thus, roughly speaking, stars of spectral class F or cooler belong to the lower main sequence, while A-type stars or hotter are upper main-sequence stars. The transition in primary energy production from one form to the other spans a range difference of less than a single solar mass. In the Sun, a one solar-mass star, only 1.5% of the energy is generated by the CNO cycle. By contrast, stars with 1.8 or above generate almost their entire energy output through the CNO cycle.
Which is a type of star found on the lower end of the main sequence, based on its spectral class?
stars of spectral class F or cooler F or cooler
Main sequence
Main sequence
https://en.wikipedia.org/wiki/Main%20sequence
Stars below about 1.5 times the mass of the Sun, based on mass, are types of stars found on the lower end of the main sequence. Based on spectral class, stars of spectral class F or cooler are found on the lower end of the main sequence.