Main sequence
The sequence of stars listed in order of increasing luminosity typically includes red dwarfs, main-sequence stars (like our Sun), giant stars, and supergiant stars. Red dwarfs are the least luminous, followed by main-sequence stars, then giant stars, and finally supergiants, which are the most luminous. This order reflects the increasing energy output and size of the stars as they evolve.
Main sequence stars best obey the mass-luminosity relation. This empirical relation states that there is a direct relationship between a star's mass and its luminosity. In general, the more massive a main sequence star is, the more luminous it will be.
The next sequence of letters following OBAFGKM in the spectral classification system are L, T, Y. These letters are used to classify cooler and less luminous stars outside the main sequence, such as brown dwarfs.
The main sequence stars on the Hertzsprung-Russell diagram that are least massive are the red dwarfs. These stars have low masses compared to other main sequence stars like our sun. They are cooler and fainter, making them difficult to observe compared to more massive stars.
Main sequence
The sequence of stars listed in order of increasing luminosity typically includes red dwarfs, main-sequence stars (like our Sun), giant stars, and supergiant stars. Red dwarfs are the least luminous, followed by main-sequence stars, then giant stars, and finally supergiants, which are the most luminous. This order reflects the increasing energy output and size of the stars as they evolve.
Blue stars are more luminous than other main sequence stars but not necessarily brighter than giant and supergiant stars.
Most stars are plotted along the main sequence in the Hertzsprung-Russell (HR) diagram, which extends diagonally from the upper left (hot and luminous stars) to the lower right (cool and less luminous stars). This is because the majority of stars, including our Sun, spend the majority of their lives in the main sequence phase where they are fusing hydrogen into helium.
O, because O stars are the hottest, so they use their energy faster than the lower stars.
red
Two types of stars that can form from a nebula are main sequence stars, like our sun, and giant stars, which are larger and more luminous than main sequence stars.
The location of a main sequence star on the H-R diagram depends on its temperature and its luminosity (or brightness). Main sequence stars follow a diagonal band on the diagram, with hotter and more luminous stars located towards the top left and cooler and less luminous stars towards the bottom right.
Main sequence stars best obey the mass-luminosity relation. This empirical relation states that there is a direct relationship between a star's mass and its luminosity. In general, the more massive a main sequence star is, the more luminous it will be.
Neither, the sun is on the small side of the middle range of main sequence stars.
The cooler a star is, the less luminous it is. That's assuming the star stays about the same size. "Red giant" stars for example are relatively cool, but very luminous because of their size. However, red giants are not main sequence stars. For a main sequence star, a lower temperature means it is LESS bright. That means it has a higher number on the "magnitude" scale. So the answer is: "the magnitude increases" Our Sun is putting out more energy than it did a billion years ago. It is expected to get even hotter before it leaves the main sequence and becomes a red giant.
Red