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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

Soft skills

During this course you will be trained in:

  • Finding, reading and summarizing modern astronomical literature

  • Writing a structured report on simulated spectra


See Astronomy master schedules

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.


Blackboard will be used to communicate with students and to share lecture slides, homework assignments, and any extra materials. You must enroll on Blackboard before the first lecture. To have access, you need a student ULCN account.

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)


Via uSis. More information about signing up for your classes can be found here. Exchange and Study Abroad students, please see the Prospective students website for information on how to apply.

Contact information

Lecturer: Dr. J. (Jordy) Bouwman
Assistants: Dario Campisi