Question

How are AGB stars formed?

Answer 1

We know that the night sky is filled with stars of different ages and distance when compared with that of the earth. Also every day, and every second a new star is either formed or decayed in the form of disturbances, these disturbances are the signals which we call as the gravitational waves.

Complete answer:
The night sky is a very interesting and evolving discipline of study. There are numerous stars and planets which decorate the night sky. One of such stars is the asymptotic giant branch star.
These are observed to appear as red bright giants with brightness greater that thousand times the sun. These ABG stars are made up of carbon and oxygen core with helium shells on the outer surface.
The phase of the ABG stars is as follows, early AGB and the thermally pulsing AGB. In the early AGB the energy of the star is due to the helium fusion which occurs around the core in the shells. Here the star swells to become the red bright giant. When this ends the thermally pulsing AGB stars, here the energy of the star is due to the fusion of hydrogen to form helium shells. This is a very long process taking around 10,000 to 100,000 years. After the constant formation of helium shells, the giants are now massive and ignite explosively to form the helium shell flash. During this process the mass of the star is reduced drastically. These flash signals are studied using the Hertzsprung-Russell diagram.

Note:
This asymptotic giant branch star is a region, where it is densely populated which consists of evolved cool luminous stars. This region is found in the Hertzsprung-Russell diagram. These are stars, whose stellar evolution period is between low-intermediate star mass, that is around, 0.6-10 solar masses, in lives.