The accretion of matter due to gravity.
planetary
On a Hertzsprung-Russell diagram, a main sequence star that is cooler and dimmer than the Sun would appear to the right and below the Sun's position. The Sun is located approximately in the middle of the main sequence, so a cooler and dimmer star would have a lower temperature and luminosity compared to the Sun, indicating it would be plotted in the lower left section of the main sequence.
The sun's life cycle includes the stages of formation, main-sequence, red giant, and white dwarf. It is currently in the main-sequence stage, where it fuses hydrogen into helium in its core. Eventually, it will expand into a red giant before shedding its outer layers and becoming a white dwarf.
Depending on how "low" on the chart it will either be a red dwarf or a PMS (Pre-main sequence) star.
Main sequence stars are bigger.
Protostar formation - The Birth of a starMain sequence - When it converts hydrogen into energyPost main Sequence - When they die.
planetary
A red main sequence star would be a red dwarf or a branch red giant. To be on the main sequence, you have to have hydrogen nuclear fusion.
A Planetary Nebula. See related question.
On a Hertzsprung-Russell diagram, a main sequence star that is cooler and dimmer than the Sun would appear to the right and below the Sun's position. The Sun is located approximately in the middle of the main sequence, so a cooler and dimmer star would have a lower temperature and luminosity compared to the Sun, indicating it would be plotted in the lower left section of the main sequence.
Main Sequence
its to the right of the middle of the main sequence.
There are billions of stars that are not on the main sequence.
No. They have the lowest temperatures on the main sequence. The hottest main sequence stars are blue.
The sun's life cycle includes the stages of formation, main-sequence, red giant, and white dwarf. It is currently in the main-sequence stage, where it fuses hydrogen into helium in its core. Eventually, it will expand into a red giant before shedding its outer layers and becoming a white dwarf.
Stage 4 of star formation is characterized by the formation of a protostar, where the collapsing gas and dust from a molecular cloud begin to accumulate in a dense core. As the core contracts, it heats up, leading to the onset of nuclear fusion in the core when temperatures rise sufficiently. This stage marks the transition from a protostar to a main-sequence star, with the surrounding material forming a protoplanetary disk that may lead to planet formation. Eventually, the protostar stabilizes, and the star begins its life on the main sequence.
Unfortunately, it is impossible to tell accurately where a star is on the main sequence.