Archive for November, 2016

Our most recent work comes as a proceedings paper for the conference “Stars: from collapse to collapse” (Special Astrophysical Observatory, Nizhnij Arkhyz, Karachai-Cherkessian Republic, Russia, 3-7 October 2016):

The yellow hypergiant – B[e] supergiant connection

A. Aret, M. Kraus, I. Kolka, G. Maravelias

B[e] supergiants and yellow hypergiants share a number of common properties regarding their circumstellar environments. Using the forbidden [O I] and [Ca II] lines as disk tracers, we suggest the presence of a Keplerian disk or ring around the yellow hypergiant V509 Cas and confirm the pole-on inner disk around V1302 Aql. These findings indicate a change in mass-loss behavior from spherical in cooler yellow hypergiants to axisymmetric in the hotter ones during the passage through the Yellow Void. The accumulation of material in the equatorial plane reminds of the disks of B[e] supergiants, supporting the suggestion that yellow hypergiants might appear as B[e] supergiants after they reach the blue edge of the yellow instability domain.

arXiv: 1611.06044

The New DUSTER !

Posted November 21, 2016 By grigoris



Workshop on Python and IRAF/PyRAF

Posted November 16, 2016 By grigoris

Between 12 to 19 of September 2016, we organized the Ondřejov Summer School 2016, which was held at the Stellar Stellar Department of the Astronomical Institute (Czech Academy of Sciences), in Ondřejov. The main aim of the school was to provide students hands-on experience with real observational data, i.e. to understand observations, reduce them, and discuss their results. This project-oriented activity was supplemented with lectures on various techniques and one of them was a workshop on Python and IRAF/PyRAF.

As a workshop the main focus was given to show examples that the students could repeat at the own computers. Its structure was based on a very small introductory talk and then examples of how to use Python and IRAF in real problems. With this post I make public all of this material both as a reference and as a (hopeful) help to others.


  • Introductory talk [ .pdf / .odp ]
  • Talk images [ .tar.gz ]
  • Videos – (I need to work on this !)
  • IRAF files (will be added later)

    All of this work is licensed under CC-BY-SA – which means that you can work on it and expand!
    If you like it and want to refer to this work, please cite it as:
    G. Maravelias 2016, “Workshop on Python and IRAF/PyRAF”, Ondřejov Summer School 2016, Ondřejov, Czechia
    online at: