Dear Colleagues,

The substantial progress in variable star astronomy is striking. In recent decades, the two major aspects of this advance are:

• The tremendous increase in the number of known variable stars;
• The unprecedented improvement in photometric accuracy.

While the first item is only partly due to the commencement of the era of photometry by space telescopes, the second one is solely the consequence of the existence of space photometry. The results of this micromagnitude revolution include the discovery of new types of variable stars, thousands of transiting exoplanets, as well as new or unusual phenomena shown by already known variables. Variable stars are important objects for astrophysics because they serve as remote “laboratories” for testing the validity of theoretical models of stellar structure and evolution. Discovering and characterizing exoplanets facilitates our understanding of the formation and evolution of our Solar System and planet Earth.

This Special Issue is a collection of papers on our latest achievements related to variable stars based on space photometry. A separate review paper will be dedicated to each of the already completed projects of MOST, CoRoT, and Kepler/K2 space telescopes, as well as the ongoing activity of BRITE and TESS projects. On the one hand, the extensive database of past space photometric projects is a treasure-house for achieving new results and discoveries, and it will be so in the near future, too. On the other hand, the ongoing projects offer a data flow to be analyzed. In addition, other past and still active space telescopes have also contributed to variable star astronomy with photometric measurements in optical and other spectral regions.

We look forward to receiving—and publishing—the most recent interesting results obtained from space photometry in this Special Issue on “Variable Stars with Photometric Space Telescopes” of the journal Universe.

Prof. Dr. Laszlo Szabados
Dr. Nikolay N. Samus
Guest Editors

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• Variable stars
• Space photometry
• Micromagnitude
• Exoplanets
• Variability of dwarf novae on various time scales
• Continuous light curve of supernovae
• Pre-main sequence variable stars (involving infrared space observations, too)
• Planetary nebulae, variability of their central stars