The length of time that a star stays in the main sequence varies by a huge amount depending on its mass. The whole reason is much too long and complicated to be placed here. (You need to read an encyclopedia article on the different classes of the starts.)
However, the simple summary is that the largest (and hottest) stars stay in the main sequence for the shorter lengths of time (like 10 million years), but the smaller and cooler stars (smaller than our Sun) stay in the main sequence for the longest lengths of time - billions and billions of years, really long, like 50 billion years.
Our Sun is in between, and it has an estimated lifetime of about five billion years on the main sequence.
Theoretically, in 5 billion years, the Sun will still be in the main sequence. 5.4 billion years (estimated) marks the end of main sequence, where it will be in the intermediary point between a main-sequence star and a post-main-sequence red giant, where it will slowly reach over 200 times it's current mass over the course of about a billion more years, at which point it would be classified as an official red giant and be fully burning helium-4 as a main source of fuel as well as burning a hydrogen shell it built up during the main-sequence. After that point it will eject most of its mass into a planetary nebula and slowly cool as a stellar remnant over the course of a few quadrillion years until it reaches 3K.
Most stars are classified as main sequence stars, including our Sun. Main sequence stars are in a stable stage of nuclear fusion, converting hydrogen into helium in their cores. This is the longest stage in a star's life cycle, lasting for billions of years.
Approximately 90% of stars are considered to be part of the main sequence. These are stars that are fusing hydrogen into helium in their cores, like our Sun. The main sequence is a stable period in a star's life cycle that can last for billions of years.
The Main Sequence stage.
Main sequence stars are bigger.
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.
No, main sequence stars last more then a few hundred years. Depending on their mass main sequence stars may last anywhere from several million to several trillion years. Our sun is a main sequence star that is about halfway through its 10 billion year duration.
The star 61 Cygni B is estimated to have a main sequence lifetime of approximately 10 billion years.
An O star will stay on the main sequence for millions of years whereas a M star can stay on the main sequence for billions and billions of years.
Yes, Proxima Centauri is a main-sequence star and will remain so for about another four trillion years.
Percentage wise - all of them.There are a number that have progressed off of the main sequence:-Betelgeuse. CNO cycle.Rigel: Shell burning.
Percentage wise - all of them.There are a number that have progressed off of the main sequence:-Betelgeuse. CNO cycle.Rigel: Shell burning.
About another 4.5 to 5 billion years
About midway (4.5 billion years) through the main sequence.
A protostar takes about 100,000 years to reach the main sequence.
Main Sequence
Most stars are classified as main sequence stars, including our Sun. Main sequence stars are in a stable stage of nuclear fusion, converting hydrogen into helium in their cores. This is the longest stage in a star's life cycle, lasting for billions of years.