DP Physics Questionbank
D.2 – Stellar characteristics and stellar evolution
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Description
Nature of science:
Evidence: The simple light spectra of a gas on Earth can be compared to the light spectra of distant stars. This has allowed us to determine the velocity, composition and structure of stars and confirmed hypotheses about the expansion of the universe. (1.11)
Understandings:
- Stellar spectra
- Hertzsprung–Russell (HR) diagram
- Mass–luminosity relation for main sequence stars
- Cepheid variables
- Stellar evolution on HR diagrams
- Red giants, white dwarfs, neutron stars and black holes
- Chandrasekhar and Oppenheimer–Volkoff limits
Applications and skills:
- Explaining how surface temperature may be obtained from a star’s spectrum
- Explaining how the chemical composition of a star may be determined from the star’s spectrum
- Sketching and interpreting HR diagrams
- Identifying the main regions of the HR diagram and describing the main properties of stars in these regions
- Applying the mass–luminosity relation
- Describing the reason for the variation of Cepheid variables
- Determining distance using data on Cepheid variables
- Sketching and interpreting evolutionary paths of stars on an HR diagram
- Describing the evolution of stars off the main sequence
- Describing the role of mass in stellar evolution
Guidance:
- Regions of the HR diagram are restricted to the main sequence, white dwarfs, red giants, super giants and the instability strip (variable stars), as well as lines of constant radius
- HR diagrams will be labelled with luminosity on the vertical axis and temperature on the horizontal axis
- Only one specific exponent (3.5) will be used in the mass–luminosity relation
- References to electron and neutron degeneracy pressures need to be made
Data booklet reference:
Theory of knowledge:
- The information revealed through spectra needs a trained mind to be interpreted. What is the role of interpretation in gaining knowledge in the natural sciences? How does this differ from the role of interpretation in other areas of knowledge?
Utilization:
- An understanding of how similar stars to our Sun have aged and evolved assists in our predictions of our fate on Earth
Aims:
- Aim 4: analysis of star spectra provides many opportunities for evaluation and synthesis
- Aim 6: software-based analysis is available for students to participate in astrophysics research
Directly related questions
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16N.3.SL.TZ0.15e:
A standard Hertzsprung–Russell (HR) diagram is shown.
Using the HR diagram, draw the present position of Alpha Centauri A and its expected evolutionary path.
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16N.3.SL.TZ0.16a:
Determine the distance from Earth to the Cepheid star in parsecs. The luminosity of the Sun is 3.8 × 1026 W. The average apparent brightness of the Cepheid star is 1.1 × 10–9 W m–2.
- 16N.3.SL.TZ0.15d: Alpha Centauri A is in equilibrium at constant radius. Explain how this equilibrium is maintained.
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16N.3.SL.TZ0.15c:
Show, without calculation, that the radius of Alpha Centauri B is smaller than the radius of Alpha Centauri A.
- 16N.3.SL.TZ0.16b: Explain why Cephids are used as standard candles.
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17M.3.SL.TZ1.10a.ii:
The present temperature of the CMB is 2.8 K. Calculate the peak wavelength of the CMB.
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17M.3.SL.TZ1.9a.ii:
Show that the mass of Theta 1 Orionis is about 40 solar masses.
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17M.3.SL.TZ1.9c:
The Sun and Theta 1 Orionis will eventually leave the main sequence. Compare and contrast the different stages in the evolution of the two stars.
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17M.3.SL.TZ2.11b:
The Hertzsprung–Russell (HR) diagram shows two main sequence stars X and Y and includes lines of constant radius. R is the radius of the Sun.
Using the mass–luminosity relation and information from the graph, determine the ratio .
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17M.3.SL.TZ2.11c.iv:
Determine the region of the electromagnetic spectrum in which the neutron star in (c)(iii) emits most of its energy.
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17M.3.SL.TZ2.11c.ii:
Outline why the neutron star that is left after the supernova stage does not collapse under the action of gravitation.
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17M.3.SL.TZ2.11c.i:
On the HR diagram in (b), draw a line to indicate the evolutionary path of star X.
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17M.3.SL.TZ2.12c.ii:
Describe how type Ia supernovae could be used to measure the distance to this galaxy.
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20N.3.SL.TZ0.17a:
Show by calculation that Eta Aquilae A is not on the main sequence.
- 20N.3.SL.TZ0.17d: Eta Aquilae A is a Cepheid variable. Explain why the brightness of Eta Aquilae A varies.
- 20N.3.HL.TZ0.22d: Eta Aquilae A is a Cepheid variable. Explain why the brightness of Eta Aquilae A varies.
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20N.3.HL.TZ0.22a:
Show by calculation that Eta Aquilae A is not on the main sequence.
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17N.3.SL.TZ0.12d.i:
Determine the radius of Sirius B in terms of the radius of the Sun.
- 17N.3.SL.TZ0.12d.ii: Identify the star type of Sirius B.
- 17N.3.SL.TZ0.12e.i: draw the approximate positions of Sirius A, labelled A and Sirius B, labelled B.
- 17N.3.SL.TZ0.12e.ii: sketch the expected evolutionary path for Sirius A.
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18M.3.SL.TZ2.11d.ii:
plot the position, using the letter P, of the main sequence star P you calculated in (b).
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18M.3.SL.TZ2.11d.iii:
plot the position, using the letter G, of Gacrux.
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18M.3.SL.TZ2.11e:
Discuss, with reference to its change in mass, the evolution of star P from the main sequence until its final stable phase.
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18M.3.SL.TZ2.11d.i:
draw the main sequence.
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18M.3.SL.TZ1.11a.i:
Suggest, using the graphs, why star X is most likely to be a main sequence star.
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18M.3.SL.TZ1.11a.ii:
Show that the temperature of star X is approximately 10 000 K.
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18M.3.SL.TZ1.11b.i:
Write down the luminosity of star X (LX) in terms of the luminosity of the Sun (Ls).
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18M.3.SL.TZ1.11b.ii:
Determine the radius of star X (RX) in terms of the radius of the Sun (Rs).
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18M.3.SL.TZ1.11b.iii:
Estimate the mass of star X (MX) in terms of the mass of the Sun (Ms).
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18M.3.SL.TZ1.11c:
Star X is likely to evolve into a stable white dwarf star.
Outline why the radius of a white dwarf star reaches a stable value.
- 21N.1.SL.TZ0.30: Which is correct for a black-body radiator? A. The power it emits from a unit surface area...
- 18N.3.SL.TZ0.12d: Describe the stages in the evolution of Epsilon Indi from the point when it leaves the main...
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18N.3.SL.TZ0.12b:
Epsilon Indi is a main sequence star. Show that the mass of Epsilon Indi is 0.64 .
- 18N.3.SL.TZ0.12a.ii: Using the axis, draw the variation with wavelength of the intensity of the radiation emitted by...
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18N.3.HL.TZ0.18a.i:
Determine the peak wavelength of the radiation emitted by Epsilon Indi.
- 18N.3.SL.TZ0.12c: Describe how the chemical composition of a star may be determined.
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18N.3.SL.TZ0.12a.i:
Determine the peak wavelength of the radiation emitted by Epsilon Indi.
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18N.3.HL.TZ0.18b:
Epsilon Indi is a main sequence star. Show that the mass of Epsilon Indi is 0.64 .
- 18N.3.HL.TZ0.18a.ii: Using the axis, draw the variation with wavelength of the intensity of the radiation emitted by...
- 18N.3.HL.TZ0.18d: Describe the stages in the evolution of Epsilon Indi from the point when it leaves the main...
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18N.3.HL.TZ0.18c:
The Sun will spend about nine billion years on the main sequence. Calculate how long Epsilon Indi will spend on the main sequence.
- 19M.3.SL.TZ2.13aii: Explain how Cepheid variables are used to determine distances.
- 19M.3.SL.TZ2.15a: Identify, on the HR diagram, the position of the Sun. Label the position S.
- 19M.3.SL.TZ2.15b: Suggest the conditions that will cause the Sun to become a red giant.
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19M.3.SL.TZ2.13bii:
Calculate the peak surface temperature of δ-Cephei.
- 19M.3.SL.TZ2.13ai: Outline the processes that produce the change of luminosity with time of Cepheid variables.
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19M.3.SL.TZ2.15c:
Outline why the Sun will maintain a constant radius after it becomes a white dwarf.
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17N.3.SL.TZ0.12c:
The mass of Sirius B is about the same mass as the Sun. The luminosity of Sirius B is 2.5 % of the luminosity of the Sun. Show, with a calculation, that Sirius B is not a main sequence star.
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17N.3.SL.TZ0.12b:
The peak spectral line of Sirius B has a measured wavelength of 115 nm. Show that the surface temperature of Sirius B is about 25 000 K.
- 17N.3.SL.TZ0.12a: State what is meant by a binary star.
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19N.3.SL.TZ0.10c(iii):
Calculate the ratio .
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19N.3.SL.TZ0.10b(i):
The peak wavelength of radiation from Eta Cassiopeiae A is 490 nm. Show that the surface temperature of Eta Cassiopeiae A is about 6000 K.
- 19N.3.SL.TZ0.10c(i): On the HR diagram, draw the present position of Eta Cassiopeiae A.
- 19N.3.SL.TZ0.10c(ii): State the star type of Eta Cassiopeiae A.
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19N.3.SL.TZ0.10c(iv):
Deduce the final evolutionary state of Eta Cassiopeiae A.
