A main-sequence star is one that is along a curve where the majority of stars are located, when plotted in an H-R diagram. It is a star that gets its energy from fusing hydrogen-1 into helium-4.
None of those is a main sequence star.
Most stars are on the main sequence; that includes red dwarves. Specifically, in this case, the closest known star - Proxima Centauri - is also the closest main-sequence star.
Yes, the sun is a main sequence star. Main sequence stars are those, like the sun, that are fusing hydrogen into helium in their cores. This is the main stage of a star's life cycle when it is in a stable state.
Based on initial size and chemical composition a star will enter a band on the HR diagram as a mains sequence star. Stars on the main sequence are in equilibrium from thermal pressure trying to enlarge the star and gravitational pressure trying to collapse the star. Stars on the main sequence range from massive hot blue-white stars to much less massive red stars.
A neutron star is a stellar remnant
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.
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.
None of those is a main sequence star.
The defining characteristic of a main sequence star burns hydrogen to helium in its core.
Most stars are on the main sequence; that includes red dwarves. Specifically, in this case, the closest known star - Proxima Centauri - is also the closest main-sequence star.
Algol is a blue main-sequence star in the constellation Perseus
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.
Any star that it fusing hydrogen into helium is classed as a main sequence star.
main sequence star