Starshine
Al Nahda National Schools (Boys) Class: 12G, H & I Teacher: Nidal Al Halabi life cycle of a star
Physics The life cycle of a star
The Life of a small Star, a star of mass up to eight times that of the sun(< 8M o) or has a core remnant of mass up to one and a half times that of the sun(< 1.5M o), can be summarized in the following stages: Stage 1- Stars are born in a region of high density Nebula. Stage 2 – Under its own gravitational force, interstellar clouds of dust and gases condenses into a huge globule of gas and dust to form a glowing Protostar. If there is not enough material in the protostar, one possible outcome is a large, notvery-luminous celestial body called brown dwarf. Stage 3–If a protostar contains enough matter the central temperature reaches 15 million ˚C. At this temperature, Hydrogen nuclei start to fuse together to form Helium and the star begins to release energy. This energy radiation production prevents further contraction of the star. It is now Main Sequence Star so it settles to an almost constant luminosity and temperature. The nearest main sequence star to Earth is the Sun. A star of one solar mass remains in main sequence for about 10 billion years, until all of the hydrogen has fused to form helium. Large main sequence stars have large gravitational forces acting on them. They therefore have a large inwards pull. They have higher temperatures so they burn hydrogen very quickly resulting in shorter stay as a main sequence star. Stage 4 - When the Hydrogen in the core runs out, the fusing of helium to form carbon starts in the core. This releases a huge amount of energy which causes the outer layers of star to expand and become a Red giant. Stage 5 - When the Helium in the core runs out, the core will collapse to form a white dwarf and the outer layers drift of away from the core as a gaseous shell; this gas that surrounds the core is called a Planetary Nebula. Stage 6 - As time continues, a white dwarf will eventually cool and
Physics The life cycle of a star
The Life of a small Star, a star of mass up to eight times that of the sun(< 8M o) or has a core remnant of mass up to one and a half times that of the sun(< 1.5M o), can be summarized in the following stages: Stage 1- Stars are born in a region of high density Nebula. Stage 2 – Under its own gravitational force, interstellar clouds of dust and gases condenses into a huge globule of gas and dust to form a glowing Protostar. If there is not enough material in the protostar, one possible outcome is a large, notvery-luminous celestial body called brown dwarf. Stage 3–If a protostar contains enough matter the central temperature reaches 15 million ˚C. At this temperature, Hydrogen nuclei start to fuse together to form Helium and the star begins to release energy. This energy radiation production prevents further contraction of the star. It is now Main Sequence Star so it settles to an almost constant luminosity and temperature. The nearest main sequence star to Earth is the Sun. A star of one solar mass remains in main sequence for about 10 billion years, until all of the hydrogen has fused to form helium. Large main sequence stars have large gravitational forces acting on them. They therefore have a large inwards pull. They have higher temperatures so they burn hydrogen very quickly resulting in shorter stay as a main sequence star. Stage 4 - When the Hydrogen in the core runs out, the fusing of helium to form carbon starts in the core. This releases a huge amount of energy which causes the outer layers of star to expand and become a Red giant. Stage 5 - When the Helium in the core runs out, the core will collapse to form a white dwarf and the outer layers drift of away from the core as a gaseous shell; this gas that surrounds the core is called a Planetary Nebula. Stage 6 - As time continues, a white dwarf will eventually cool and