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Astronomical Spectroscopy


Admission requirements

Knowledge of calculus and linear algebra at the bachelor level is required. In terms of the Leiden curriculum, the Astronomy bachelor's courses Quantum Mechanics 1 and Quantum Mechanics 2 are a prerequisite for enrolling in the course and the bachelor's course Radiative processes is strongly recommended.


In this course you will learn to understand and apply atomic and molecular spectroscopy in an astronomical context. The course covers the basics of absorption spectroscopy and the history of astronomical spectroscopy. It summarizes the general principles of quantum mechanics, and from these derives the principles behind atomic and molecular spectroscopy of molecules commonly found in the interstellar medium. You will learn how to interpret spectra and how to simulate spectra. From spectroscopic information you will learn to deduce astrophysical and astrochemical processes occurring in the gas phase and the solid state. Throughout, the course highlights the synergy between observational and laboratory spectroscopy in astronomical research.

The following topics are covered:

  • Atomic spectroscopy and Grotrian diagrams

  • Molecular spectroscopy (electronic, vibrational, rotational)

  • Spectroscopy as a probe of physical conditions

  • Interpreting and simulating spectra

  • Transition strengths and life times of states

  • Excitation mechanisms

  • Lineshapes

  • Optical thickness

  • Boltzmann level population

  • Fine and hyper fine structure

  • Labeling of electronic states

  • Born-Oppenheimer approximation

  • Frank-Condon factors

  • Linking spectroscopy to chemistry

  • Laboratory spectroscopy for assigning interstellar species

Course objectives

Upon completion of this course you will be able to:

  • Read spectroscopic notation, and interpret and simulate (interstellar) spectra

  • Explain the origin of atomic and molecular spectra

  • Reproduce and simulate the typical shape of molecular spectra

  • Calculate physical parameters from spectra

  • Explain which physical quantities are probed using spectroscopy

  • Read and summarize literature on spectroscopy with astronomical applications

  • Read and explain Grotrian diagrams and potential energy wells in relation to spectra

  • Explain what determines the strength of absorption

  • Explain the excitation and emission mechanism of atoms and molecules

  • Explain solid state and gas phase spectra in relation to astrochemistry


See Astronomy master schedules

You will find the timetables for all courses and degree programmes of Leiden University in the tool MyTimetable (login). Any teaching activities that you have sucessfully registered for in MyStudyMap will automatically be displayed in MyTimeTable. Any timetables that you add manually, will be saved and automatically displayed the next time you sign in.

MyTimetable allows you to integrate your timetable with your calendar apps such as Outlook, Google Calendar, Apple Calendar and other calendar apps on your smartphone. Any timetable changes will be automatically synced with your calendar. If you wish, you can also receive an email notification of the change. You can turn notifications on in ‘Settings’ (after login).

For more information, watch the video or go the the 'help-page' in MyTimetable. Pleas note: Joint Degree students Leiden/Delft have to merge their two different timetables into one. This video explains how to do this.

Mode of instruction

  • Lectures

  • Exercise class

Assessment method

  • Written exam (80% of final grade)

  • Written report about a recent paper and simulations performed in the exercise class (20% of final grade)

Please note that the written report does not count for the retake exam.

Reading list

  • Astronomical spectroscopy: An Introduction to the Atomic and Molecular Physics of Astronomical Spectra (J. Tennyson), ISBN 1860945139 (optional)

  • Modern Spectroscopy (J. Michael Hollas), ISBN 0470844159 (optional)


From the academic year 2022-2023 on every student has to register for courses with the new enrollment tool MyStudyMap. There are two registration periods per year: registration for the fall semester opens in July and registration for the spring semester opens in December. Please see this page for more information.

Please note that it is compulsory to both preregister and confirm your participation for every exam and retake. Not being registered for a course means that you are not allowed to participate in the final exam of the course. Confirming your exam participation is possible until ten days before the exam.

Extensive FAQ's on MyStudymap can be found here.


Lecturer: Dr. K. Chuang
Assistants: Katie Slavicinska


Soft skills
During this course you will be trained in:

  • Finding, reading and summarizing modern astronomical literature

  • Writing a structured report on simulated spectra