Stellar spectroscopy workshop (hybrid)

27-28 September 2023; Tartu observatory, Tõravere + Zoom

Spectroscopy is one of the most important observational techniques available to us for studying the vast majority of celestial objects. Stars have been among the first objects observed with spectroscopy, more than a century ago. Since then, instruments capable of delivering high-quality data have been developed, together with sophisticated computer codes for treating and analysing these data. This workshop aims at introducing the participants to the basics of stellar spectroscopy and data analysis, with a focus on intermediate-mass main-sequence stars (F-, A- and late B-type stars). The participants will obtain practical information on methods and codes that can be directly applied for the analysis of stellar spectra, therefore a significant amount of time will be devoted to hands-on sessions for learning the basic usage of some of the available tools.

The workshop is best suited for students at the master’s level and above, as well as experienced researchers. We consider that everybody will have a basic understanding of the underlying physics (e.g. radiative transfer, limb darkening, LTE vs NLTE) and be familiar with most of the basic terminology and their meaning (e.g. stellar atmospheric parameters, normalisation).


The organising committee expects participants to have their personal laptop with the necessary software installed for this workshop. If it is not possible to use a personal laptop, please let the organisers know beforehand.

  • Stellar Spectroscopy Workshop software requirements: link to document.
  • Please also go through the prerequisites document (link) to get an idea of what you should know beforehand.

Schedule (Please note some lectures have been moved around in between sessions due to time limitations on-site).

DAY 1:

  • 09:00-12:30 Session 1: Basics of stellar atmospheres and their spectra (Nikolai Piskunov; lecture slides)
  • Introduction to stellar model atmospheres
  • Linelists
  • Introduction to spectral synthesis
  • Basics of data reduction, spectral extraction, and wavelength calibration
  • 12:30-14:00 Lunch
  • 14:00-17:30 Session 2: General stellar atmospheric properties and advanced techniques
    • Non-local thermodynamic equilibrium (NLTE) effects (Anish Amarsi; lecture slides)
    • Chemically peculiar stars; magnetic fields (Oleg Kochukhov; lecture slides)
    • Spectral normalisation; line equivalent widths; projected rotational velocity (Vsini) and macroturbulence velocity (Vmac) determination (Luca Fossati; lecture slides)
    • Cross correlation, Least Squares Deconvolution (LSD), and (Zeeman) Doppler Imaging ((Z)DI) (Colin Folsom – NB! lecture will be recorded and sent to registered participants later)

DAY 2:

  • 09:00-13:00 Session 3: Stellar atmospheric parameters (Luca Fossati; lecture slides)
    • Atmospheric parameter determination via photometry and spectral energy distribution (SED)
    • Atmospheric parameter determination via lines with developed wings
    • Atmospheric parameter determination via line equivalent widths
    • Hands-on session: computation of synthetic stellar spectra with the synth3 and Zeeman codes for both hydrogen and metal lines to study the impact of changing parameters (e.g. Teff, logg, Vmic, abundances) on the different features
  • 13:00-14:00 Lunch
  • 14:00-17:30 Session 4: Atmospheric abundance analysis (Nikolai Piskunov; lecture slides)
    • Atmospheric parameters determination via spectral line fitting
    • Element abundance determination via spectral line fitting
    • Hands-on session: spectral line fitting with the SME and Zeeman codes 

All materials (lecture slides) from the workshop can be found in a joint folder here.

The workshop is financed by the EU Horizon Europe Twinning project EXOHOST (101079231) and UK Research and Innovation (10051045).

Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.

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