FY3451: Astrophysics II

H 2024
The course aims to provide a more advanced discussion of selected topics in astrophysics, in particular fusion and nuclear reaction, final stages of stars, high-energy processes plus some extragalactic astrophysics. The course is taught regularly in the autumn semester starting from 2021; the selection of topics is still adaptable.
FY2450 Astrophysics (or an equivalent course) is not a prerequisite for this course - but is a useful preparation for "astrophysical" thinking.

Lecturer, time and place:

Michael Kachelrieß, email; office: D5-123
Lectures: Monday 14.15-16.00, Realfag C4-118.
Lectures + Exercises: Thursday 14.15-16.00, Realfag C4-118.

Plan of the lectures:

Week 34: Overview, radiation
Week 35: Equations of stellar structure
Week 36: Stellar structure, stellar models
Week 37: Stellar models, nuclear reactions
Week 38: interstellar medium, (minimal) fluid dynamics, turbulence
Week 39: turbulence, accretion,
Week 40: home exam
Week 41: supernovae, pulsars, Thursday: guest lectures PWN
Week 42: supernova remnants, GRBs Thursday: guest lectures binaries; slides on binaries;
Week 43: Cosmic rays and acceleration; CR sources
Week 44: High-energy processes; guest lectures TDE; slides on TDE's
Week 45: High-energy processes, active galaxies
Week 46: Active galaxies; dark matter
Week 47: dark matter

Pensum

The pensum is defined by the content of the lectures. We will follow roughly my lecture notes (which are still pretty rough and will be updated during the course), see the link below. The number of excellent text-books on astrophysics is large: Check out the library to find book(s) suitable for you. Some recommend ones are
  • A.R. Choudhuri: Astrophysics for Physicists, Cambridge University Press 2006 [similar level as this course].
  • D. Prialnik: Theory of Stellar Structure and Evolution, Cambridge University Press, 2.nd edition 2010 [similar level as this course, but much more detailed and concentrated on stellar physics].
  • M.S. Longair: High Energy Astrophysics, Cambridge University Press 2011 [covers in addition to high-energy astrophysics also the basics of stellar physics].
The starred sections in the updated version (1.Nov.) of the script are not part of the pensum.

Lectures notes

You can find a 2023 draft of the notes here, an updated version (1.Nov.) is here, If you find errors, let me know. You can obtain a maximal bonus of 5% for finding errors in the lecture notes: 5% for the student finding most errors, 4% for second most, etc. Email errors to me.

Corrections:

Language corrections are welcome, but not listed below
  • p. 6: \( 1pc= \) should be \( 1pc=1/1296000.. \) (BD)
  • p. 16/17: the classical electron radius should be \(\alpha \lambda_e\), the Bohr radius \(\lambda_e/\alpha \) where \( \lambda_e=\hbar/m_e c\) (NM)
  • p. 20, above (2.50): delete 2 or g in \((n_\gamma=...) \) (SS)
  • p. 23, (2.67): \( 2x^2/3-1 \) should be \( 2x^2-3 \) (MK)
  • p. 23, after (2.36): ultra-relativistic limit \( x\ll 1 \) should be ultra-relativistic limit \( x\gg 1 \) (MPV)
  • p. 29, top: \( K=\rho T_0/\mu \) should be \( K= RT_0/\mu \) (BD)
  • p. 85, in Eq. (8.8): \(+2/r\) should be \(-2/r \) (BD)
  • p. 85, in Eq. (8.11): \(-GM/r\) should be \(+GM/r \) (BD)
  • p. 114, in Eq. (10.15): \(z\) should be \(y \) (OKB)
  • p. 126, in Eq. (11.12): value of \(L_{iso} \) wrong (BD)
  • p. 131, in Eq. (11.25): on RHS \(t_{em,2} \) and \(t_{em,1} \) should be interchanged (MK)
  • p. 143, in Eq. (13.4): change \(1/\gamma^2\) to \(1/2\gamma^2 \), same below in the text. (LSPC)
  • p. 144, in Eq. (13.5): add \(1/3\) to RHS (BD)
  • p. 144, in Eq. (13.6): change \(3/2\) to \(2/3\) (BD)
  • p. 144, in Eq. (13.7): delete time on RHS (BD)
  • ======= errors above should be corrected in the updated script (11.01); starred sections according to pensum 2024 ==========
  • p. 118, first sentence in the section "Generalities of compact stars": increase should be decrease (IMH)
  • p. 148, in Eq. (13.22): change \(1/\ln(.)\) to \( 1-1/\ln(.)\) (LSPC)
  • p. 150, in Eq. (13.27): change \(\pm\) to \(\mp\) in denominator (BD)
  • p. 150, in Eq. (13.29): add \(\beta\) to denominator (BD,LSPC)
  • p. 152, in paragraph charged pion decay: last should be muon neutrino (LMD)
  • p. 178, below Eq. (16.1): \(x=T/m\) should be \(x=m/T\) (IMH)
  • p. 180, first phrase in 16.1.3: \( \ll 3\) should be \( \gg 3\) (IMH)
Final ranking for the bonus:
  • BD: 5
  • IMH: 4
  • LSPC: 4

Exercises

Week 36: exercises 1 and solutions.
Week 37: exercises 2 and solutions.
Week 38: exercises 3 and solutions.
Week 39: exercises 4 and solutions.
Week 42: exercises 5 and solutions.
Week 43: exercises 6 and solutions.
Week 44: exercises 7 and solutions.
Week 46: exercises 8 and solutions.
Week 47: exercises 9

Home Exam

The one-week home exam in the middle of semester will count 33% of the final mark. The exercises will be available Thursday, 26.09. after the lectures. Or you can download the exam here after 16.15. Solutions should be handed in before Monday, 07.10, latest 14.15, via inspera. If it is not working, in the lectures, my mailbox (D5-166), or by email.
For (concise) solutions see here.

Exam and Marks

The mark for this course will be based on a home exam counting 33% and a final exam counting 67% to the mark. The final exam takes place 26.11. in Sluppen. The exam with solutions from 2021 can be found here, from 2022 here, from 2023 here.

Marks and solution

For a sketch of the solutions see here. The distributions of marks was
  • A:
  • B:
  • C:
  • D:
  • E:
  • F: 0