Lab 4-Life Cycle of Stars PDF

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Life cycle of stars filling in the blanks...

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Part 3: Lab Report – Star Cycle: Stages Based on the information presented in the “Background – Star Cycle”, fill in the blanks to complete the statements of each stage in the Star Cycle: Stage 1: Collapse of Interstellar Cloud 1. The life of a star starts out as a cold and dense interstellar cloud or interstellar nebula 2. As the initial nebula collapses, gravitational energy is converted into thermal energy. 3. Due to conservation of angular momentum the nebula will also begin to spin faster as it collapses.

Stage 2: Protostar 1. When an interstellar nebula becomes dense enough so that light has to scatter its way outwards (rather than escaping in a straight line), it becomes a protostar. 2. A spinning disk of gas and dust will be formed around the protostar. 3. What may be formed around the protostar from the material in the spinning disk? A spinning disk of gas and dust.

Stage 3B: Brown Dwarf 1. Why do some protostars become brown dwarfs?

If a protostar does not have sufficient mass to generate high enough temperatures to initiate nuclear fusion and is less than 0.08 MSun it becomes a brown dwarf. 2. In a brown dwarf, gravitational equilibrium is achieved by the balance between gravity and electron degeneracy pressure.

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Stage 3LH: Main Sequence Star 1. When does the protostar becomes a star?

When the core of a protostar becomes hot enough to initiate nuclear fusion of hydrogen to helium. 2. How much mass must a protostar have to become a star?

have a mass greater than about 0.08MSun. 3. If a protostar has a mass greater than about 150 MSun, the energy production will be so great that it will literally blow itself apart. 4. A main sequences star achieves gravitational equilibrium by balancing gravity and pressure generated by the nuclear fusion at the star’s core. 5. When does a star leave the main sequence stage?

Once a main sequence star has consumed all its hydrogen fuel in its core.

6. A star with larger mass will remain in the main sequence a (longer/shorter) shorter time than a star with a smaller mass.

Stage 4L: Red Giant 1. In this stage nuclear fusion is not occurring in the low-mass star’s core, where does it occur in? in a hydrogen shell around the helium core. 2. In this stage the luminosity of the star (decreases/increases) increases even though the surface temperature (decreases/increases) decreases.

Stage 5L: Helium Burning 1. A low-mass star enters this stage when its core becomes hot enough to burn helium. 2. During this stage, in its core, the low-mass star is burning helium into carbon.

Stage 6L: Double Burning Shell 1. Why is this stage called the double burning shell stage?

a hydrogen burning shell continues around the helium burning shell. 2. Using the information from the background section, label the layers of the image below:

1.Hydrogen-burning shell 2. Helium-burning shell 3. Carbon ash

Stage 7L: Planetary Nebulae 1. In this stage the outer layers of the low-mass star are ejected away, in time these outer layers will become part of the interstellar medium.

Stage 8L: White Dwarf 1. Gravitational equilibrium in a white dwarf is obtained through the balance of gravity and Electron degeneracy pressure.

Stage 4H: Supergiant 1. What happens to the temperature of the star’s core as the core of the star shrinks in this stage? It becomes higher 2. On the other hand, in this stage the photosphere of the star is expanding, causing the surface temperature of the star to (decrease/increase) decrease.

Stage 5H: Multiple Burning Shell 1. Towards the end of this stage, the last element to be produced in the star’s core is iron. 2. Using the information from the background section, label the layers of the image bellow:

1. Hydrogen Fusion 2. Helium Fusion 3. Carbon Fusion

Stage 6H: Supernova (Type II) 1. The ejected layers than remain visible after the titanic explosion (supernova) is called “supernova remnant.”

Stage 7Hn: Neutron Star 1. How is the gravitational equilibrium sustained in this stage? With neutron degeneracy pressure. 2. How are most neutron stars detected? They are detected as pulsars. Stage 7Hb: Black Hole 1. If the mass of the leftover core is so large that not even neutron degeneracy pressure can stop gravitational collapse, the leftover core will become a black hole. 2. Compare a star’s life cycle pattern to a life cycle we see on the Earth. In the main sequence and supernova, they both have stages where they are born and die, whereas humans are born in wombs and die at old age. Stars have a stage in where they spend most of their time, which is the main sequence, while it would be the childhood stage for humans....