PHY305: Stellar Atmospheres

Limb darkening Solar spectrum M1-67 WR Ejecta Nebula


Stellar atmospheres (PHY305) is a compulsory first-semester half-module course for third year undergraduates taking dual-honours Astronomy with Physics or Mathematics. PHY305 has been running since 2003-04 with extra elements on the Solar atmosphere added in 2007-08 once the level 2 `Sun & Moon' module was laid to rest. For each past paper, you'll need a formulae sheet (in nasty S.I. units). There will be a revision lecture to go through specific examples from last year's paper on Tue 26 Jan in LT-D at noon.

Aims and Objectives

This course aims to describe how astronomers obtain information about the properties of stars from their atmospheres. On completion of this half-module you should be able to understand how the interaction of radiation with matter affects the appearance of a stellar atmosphere, including the major sources of opacity. You will have a knowledge of the formation of spectral lines, line broadening mechanisms, plus an appreciation of the use of stellar continua and lines as atmospheric diagnostics. Details of course objectives are given here (pdf), while an outline syllabus is provided here (pdf).


Two continuous assessment problem sheets each contribute 7.5% of the course ( HW1 due Mon 16 Nov 2015 at 4pm, ( HW2, due Mon 14 Dec 2015 at 4pm) while a final 2 hour exam contributes the remaining 85%.

Text Books

Introduction to Stellar Astrophysics, Vol 2, E. Bohm-Vitense, 1989 (CUP)

Observation and Analysis of Stellar Photospheres (3rd Ed)., D. Gray, 2005 (CUP)

Theory of Stellar Atmospheres, I. Hubeny and D. Mihalas, 2015 (Princeton)

For further reading on spectral classification, you are referred to:

Stars and their spectra, J.B. Kaler, 1997 (CUP)

For further reading on spectral winds, you are referred to:

Introduction to Stellar Winds, H. Lamers and J. Cassinelli, 1999 (CUP)

Week Mon (11:00 LT-B) Thu (10:00 LT-D) Thu (13:00 E36)
wk1. Sep 28 PHY305-1 Outline PDF PHY305-2 Stars & spectra PDF
wk2. Oct 05 - -
wk3. Oct 12 PHY305-3 Magnitudes, fluxes PDF PHY305-4 Saha-Boltzmann PDF -
wk4. Oct 19PHY305-5 Saha Eqn, Rad. terms PDF PHY305-6 Rad. Transfer PDF PHY305-7 Rad. Transfer PDF
wk5. Oct 26 - PHY305-8 Limb Darkening PDF PHY305-9 Radiative Equil. PDF
wk6. Nov 2 PHY305-10 Opacity PDF PHY305-11 More Opacity PDF PHY305-12 Temperature PDF
wk7. Nov 9 Reading Week Reading Week Reading Week
wk8. Nov 16 PHY305-13 Pressure PDF PHY305-14 Pressure Broad. PDF -
wk9. Nov 23 PHY305-15 Thermal Broad. CoG PDF PHY305-16 Abundances/non-LTE PDF -
wk10. Nov 30 PHY305-17 Solar corona PDF PHY305-18 Cool star winds PDF -
wk11. Dec 7 PHY305-19 Hot star winds PDF PHY305-20 Dense Outflows/BDs PDF -

Students unfamiliar with the notation used in atomic spectroscopy may wish to consult the National Institute of Standards and Technology (NIST) document Atomic Spectroscopy which summarises basic ideas of notation and allowed/forbidden selection rules.

For background details on interferometry, see handouts on CHARA array. Videos focused on the solar chromosphere and corona include: Solar granulation (Big Bear Solar Observatory), Solar Prominence (Solar Dynamics Observatory), CMEs (SOHO), The Solar cycle (NASA).