A star cluster is a group of stars that form at the same time. Hertzsprung-Russell diagrams for three star clusters,
Which row of the table correctly shows the three star clusters from youngest to oldest?
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A star cluster is a group of stars that form at the same time. Hertzsprung-Russell diagrams for three star clusters,
Which row of the table correctly shows the three star clusters from youngest to oldest?
→ Most stars begin on the main sequence when they begin to fuse hydrogen to helium in their core. As the stars get older and run out of hydrogen to fuse they will begin to fuse heavier elements and move off the main sequence. When stars stop fusing elements they become white dwarf stars and move to the bottom left side of the Hertzsprung-Russell diagram.
→ Hotter stars with a higher luminosity will move off the main sequence before cooler and less luminous stars.
→ All stars in cluster
→ Cluster
A Hertzsprung–Russell diagram is shown.
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a. The luminosity of a star can be determined by its size and temperature.
Other variables could include:
→ Mass, colour and the power output of a star.
b. Differences:
→ Star A is a main sequence star and is therefore fusing hydrogen to helium in its core via both the proton-proton chain and CNO cycle whereas Star B is a white dwarf star and therefore has no fusion taking place in its core.
→ Star A has a greater luminosity compared to Star B.
→ Star A is a younger star then Star B which is at the end of its lifecycle.
Other differences could include:
→ Mass
→ Radius or size
a. The luminosity of a star can be determined by its size and temperature.
Other variables could include:
→ Mass, colour and the power output of a star.
b. Differences between stars:
→ Star A is a main sequence star and is therefore fusing hydrogen to helium in its core via both the proton-proton chain and CNO cycle whereas Star B is a white dwarf star and therefore has no fusion taking place in its core.
→ Star A has a greater luminosity compared to Star B.
→ Star A is a younger star then Star B which is at the end of its lifecycle.
Other differences could include:
→ Mass
→ Radius or size
The Hertzsprung-Russell diagram shown is used to classify stars.
Stars in region
What property of the stars in region
By elimination:
→ All stars in the same spectral class have similar temperatures (eliminate A).
→ Stars become white dwarves when they no longer are able to fuse elements to generate energy. The outer gaseous layers are expelled and only the hot, dense core is left. In this way, white dwarves do not have significantly lower masses compared to other stars (eliminate B).
→ Luminosity refers to the total energy radiated by a star per second and is independent on a star’s distance from Earth (eliminate D).
A Hertzsprung-Russell diagram is shown.
In which region would a star have the same surface temperature as a star on the main sequence?
→ Using the
The position of the Sun, star
The curves
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i. → Curve A represents star
→
ii. Differences displayed in H-R graph:
→ Star
→ Star
→ Since star
Other possible answers could include:
→ Differences in fuel source, size and temperature of the stars.
i. → Curve A represents star
→
ii. Differences displayed in H-R graph:
→ Star
→ Star
→ Since star
Other possible answers could include:
→ Differences in fuel source, size and temperature of the stars.
Describe how the distribution of stars on a Hertzsprung-Russell diagram relates to the processes that occur during their evolution. (6 marks)
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→ An H-R diagram distributes stars into different groupings that relate to the processes that occurred during their evolution.
→ Hydrogen fusion is the primary source of energy of stars on the main sequence.
→ Hydrogen fusion is replaced by helium fusion as the main source of energy in the star’s next evolutionary phase. This grouping of stars is also known as red giants.
→ After helium fusion, the next evolutionary stage for most stars involves gravitational collapse. At this stage, the surface of the star recedes and gravitational potential energy is converted to radiant energy. This grouping is known as white dwarfs.
→ A star’s transition between evolutionary phases occurs quickly relative to time spent in each group.
→ This transition speed results in fewer stars being distributed in areas outside of these groups on the H-R diagram.
Other possible answers could include:
→ Reference to other groups such as protostars, supergiants
→ Sketch of H-R diagram
→ Reference to properties of stars related to their distribution within particular groups
→ Globular and open clusters.
→ An H-R diagram distributes stars into different groupings that relate to the processes that occurred during their evolution.
→ Hydrogen fusion is the primary source of energy of stars on the main sequence.
→ Hydrogen fusion is replaced by helium fusion as the main source of energy in the star’s next evolutionary phase. This grouping of stars is also known as red giants.
→ After helium fusion, the next evolutionary stage for most stars involves gravitational collapse. At this stage, the surface of the star recedes and gravitational potential energy is converted to radiant energy. This grouping is known as white dwarfs.
→ A star’s transition between evolutionary phases occurs quickly relative to time spent in each group.
→ This transition speed results in fewer stars being distributed in areas outside of these groups on the H-R diagram.
Other possible answers could include:
→ Reference to other groups such as protostars, supergiants
→ Sketch of H-R diagram
→ Reference to properties of stars related to their distribution within particular groups
→ Globular and open clusters.
The diagram shows the positions of stars
Outline the differences in the spectra of stars
→ Star
→ Star
→ Star
→ Star
A H–R diagram is shown. Star
Describe how star
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→ Star
→ Its next evolutionary stage will be a red supergiant where its size will increase dramatically although its luminosity would stay the same.
→ At this next stage, Helium burning starts in the core and changes to fusion between helium and carbon to form oxygen.
→ As the temperature rises carbon fuses to form heavier elements such as iron. This eventually causes the core to collapse forming a supernova explosion.
→ The explosion results in an increase in its luminosity and eventually to a gravitational collapse into a black hole.
→ Star
→ Its next evolutionary stage will be a red supergiant where its size will increase dramatically although its luminosity would stay the same.
→ At this next stage, Helium burning starts in the core and changes to fusion between helium and carbon to form oxygen.
→ As the temperature rises carbon fuses to form heavier elements such as iron. This eventually causes the core to collapse forming a supernova explosion.
→ The explosion results in an increase in its luminosity and eventually to a gravitational collapse into a black hole.
The positions of two stars,
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a. Surface Temperature: The surface temperature of
Luminosity: The luminosity of
b. →
→
a. Surface Temperature:
→ The surface temperature of
Luminosity:
→ The luminosity of
b. →
→
Four stars,
Which statement is correct?
Stars further to the left of the Hertzsprung-Russell diagram have greater surface temperatures.
The Hertzsprung-Russell diagram shows characteristics of stars in a globular cluster 100 light years in diameter and 27 000 light years from Earth.
The stars plotted on this Hertzsprung-Russell diagram have approximately the same
The
The
The fact that the stars are found in a cluster suggests they are of a similar age.