Why does the size of the star remain stable while it is on the main sequence?

Why does the size of the star remain stable while it is on the main sequence?

The Sun and other main sequence stars are fusing Hydrogen into Helium in their cores. When gravity and thermal pressures balance each other out, the star is said to be in hydrostatic equilibrium. This makes stars stable for long periods of time.

Is radiation pressure significant in the stability of these stars?

Therefore, radiation pressure will not be significant in the stability of low-mass main sequence stars. This is somewhat larger than the actual luminosity of the star (L = 1.79 × 106 L⊙), and thus although the star remains below the Eddington limit, it is close to the limit — radiation pressure is important.

How does a star’s size affect its life cycle?

A star’s life cycle is determined by its mass. The larger its mass, the shorter its life cycle. When the hydrogen supply in the core begins to run out, and the star is no longer generating heat by nuclear fusion, the core becomes unstable and contracts.

How does a star maintain a stable size?

In a Star there is always gravitational force acting towards the inside of the Star. The only reason that the Star is not collapsing or even changing it’s size is because it is generating enough force to balance that gravity so it has a Stable size.

Why does the Sun’s size remain stable?

The sun’s size remains stable because it is in gravitational equilibrium – the outward pressure of hot gas balances the inward force of gravity at every point within the Sun.

What is radiation pressure in a star?

Electromagnetic radiation exerts a minute pressure on everything it encounters. In the most massive stars, the mass of the star is supported against gravity primarily by radiation pressure, a situation which ultimately sets the upper limit for how massive a star can become.

How is stability of stars maintained?

You can imagine a star as a series of layers. The inward force of gravity is balanced out by the outward force of pressure to keep the star stable. This stable balance, the outward pressure of hot gases balancing the inward pull of gravity is called the hydrostatic equilibrium.

Why do stars become much smaller and dense at the end of their life cycle?

The star can expand to 1000 times the diameter of the sun. After the star has lived through its red giant stage, the fusion essentially ends (the star runs out of fuel) allowing gravity to collapse the star. Some of the outer layers of material will be blown away and the core becomes smaller and denser.

What makes a star a stable main sequence star?

A stable main sequence star is one that has contracted until the inside is hot enough to start nuclear reactions among hydrogen atoms. At this point the interior becomes a stable heat source, radiating light and creating enough outward pressure to counterbalance the inward force of gravity.

How is the size of a star determined?

When the smaller star goes in front of the bigger one, a small amount of light from the bigger star is blocked, so there is a smaller dip in the light curve. Accurate sizes for a large number of stars come from measurements of eclipsing binary star systems, and so we must make a brief detour from our main story to examine this type of star system.

How does the force of gravity keep a star stable?

The inward force of gravity is balanced out by the outward force of pressure to keep the star stable. This stable balance, the outward pressure of hot gases balancing the inward pull of gravity is called the hydrostatic equilibrium.

How is the core of a star in equilibrium?

The star is now in equilibrium: the energy generated by nuclear fusion in the stellar core radiates outwards, balancing the force of gravity pulling the star inward. This balance is called Hydrostatic Equilibrium (or sometimes gravitational equilibrium).