The main sequence phase means that, if you plot an H-R (Hertzsprung-Russel) diagram, it is in the so-called "main sequence", the area in the graph where you find the majority of stars. Those are the stars that currently fuse hydrogen into helium.
When a star "goes off the main-sequence" it generally means the star has run out of hydrogen fuel and is beginning the post-main-sequence or its end of life phase. The main sequence of a star is the time where it is no longer just a proto-star but is burning hydrogen as a primary source of fuel.
When the protostar accumulates enough mass and the pressure in the core reaches 10 millions degrees Kelvin. then hydrogen fusion can start and the star starts its main sequence phase.
The sun is a main sequence star
Sirius is not a single star but a binary star system consisting of a white main sequence star and a white dwarf.
No, a white dwarf is not considered a main sequence star. A main sequence star is a star that is still fusing hydrogen in its core. A white dwarf is the remnant of a low to medium mass star in which fusion has stopped.
When a star "goes off the main-sequence" it generally means the star has run out of hydrogen fuel and is beginning the post-main-sequence or its end of life phase. The main sequence of a star is the time where it is no longer just a proto-star but is burning hydrogen as a primary source of fuel.
a red giant
When the protostar accumulates enough mass and the pressure in the core reaches 10 millions degrees Kelvin. then hydrogen fusion can start and the star starts its main sequence phase.
Main Sequence .....Have fun with the rest of Study Island Suckers :D
When a star is in the Hydrogen burning phase it said to be a Main Sequence star.
The "main sequence" is the region (on the HR diagram) for stars which burn hydrogen-1. Once stars use up most of their hydrogen-1 (and have significant amounts of helium-4), they leave the main sequence.
A Star spends most of its life on the "main sequence" of the Hertzsprung-Russell diagram (see related link below). While here it is called a "main sequence" star and its source of energy during this phase of its life is the fusion of hydrogen into helium in its core.
I actually thought that would be when the star starts fusing hydrogen into helium... But apparently there are other stages between those two.According to Wikipedia, "[The protostar phase] ends when the protostar blows back the infalling gas and is revealed as an optically visible pre-main-sequence star, which later contracts to become a main sequence star."Pre-main sequence means the star is not yet on the main sequence; and that, in turn, basically means that it is not yet fusing hydrogen into helium.
No. Red giants are not on the main sequence.
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.
The sun is a main sequence star, so 1 AU.
The sun is a main sequence star