“A search for Rieger-type periodicities in solar-type stars”

I search for the short term periodicities in the magnetic activity of solar-type stars. The short term variation, known as Rieger-type periodicity was first found on the sun. This phenomenon is very interesting to me because of its enigmatic character: Previous studies revealed that the Rieger-type periodicity does not have regular character: it appears/disappears in different solar cycles and is different in various activity indices. They correlate with solar cycle strength: stronger cycles show shorter periods. It depends on solar activity level because of its possible connection with solar interior. The observed periods can be used to probe the magnetic field strength in the solar interior using the dispersion relation of magnetic Rossby waves. Recent space satellite observations showed evidence of shorter periodicity in several solar-like stars, which is similar to the periods observed on the Sun. Using these data, it is possible to find Rieger-type cycles in the activity of solar-type stars, which will be used to estimate the magnetic field strength in stellar dynamo layers. This is a novel research and will have tremendous consequences to understand solar and stellar activity and related phenomena.

Scientific Articles/Papers:

• Rieger-type Periodicity during Solar Cycles 14-24: Estimation of Dynamo Magnetic Field Strength in the Solar Interior. Authors: Gurgenashvili, Eka; Zaqarashvili, Teimuraz V.; Kukhianidze, Vasil; Oliver, Ramon; Ballester, Jose Luis; Ramishvili, Giorgi; Shergelashvili, Bidzina; Hanslmeier, Arnold; Poedts, Stefan. The Astrophysical Journal, Volume 826, Issue 1, article id. 55, 10 pp. (2016). DOI: 10.3847/0004-637X/826/1/55
• North-South Asymmetry in Rieger-type Periodicity during Solar Cycles 19-23. Authors: Gurgenashvili, Eka; Zaqarashvili, Teimuraz V.; Kukhianidze, Vasil; Oliver, Ramon; Ballester, Jose Luis; Dikpati, Mausumi; McIntosh, Scott W. The Astrophysical Journal, Volume 845, Issue 2, article id. 137, 11 pp. (2017). DOI: 10.3847/1538-4357/aa830a
• Long-period oscillations of active region patterns: least-squares mapping on second-order curves. Authors: Dumbadze, G.; Shergelashvili, B. M.; Kukhianidze, V.; Ramishvili, G.; Zaqarashvili, T. V.; Khodachenko, M.; Gurgenashvili, E.; Poedts, S.; De Causmaecker, P. Astronomy & Astrophysics, Volume 597, id.A93, 10 pp (2017). DOI: 10.1051/0004-6361/201628213
• Magneto-Rossby waves and seismology of solar interior. Authors: Zaqarashvili, Teimuraz V.; Gurgenashvili, Eka. Frontiers in astronomy and Space sciences, 26 February (2018) https://doi.org/10.3389/fspas.2018.00007
• Magneto-Rossby Waves in the Solar Tachocline and the Annual Variations in Solar Activity. Authors: Gachechiladze, T., Zaqarashvili, T. V., Gurgenashvili, E., Ramishvili, G., Carbonell, M., Oliver, R., Ballester, J. L., The Astrophysical Journal, Volume 874, Issue 2, article id. 162, 13 pp. (2019). DOI: 10.3847/1538-4357/ab0955

• 2016: IBUKS 2016, Leuven, Belgium, “Rieger-type periodicity during solar cycles 14-24: estimation of dynamo magnetic field strength in the solar interior” (Poster)
• 2016: The SOLARNET 5 summer school and workshop, Belfast, United Kingdom, “Rieger-type periodicity in solar activity and estimation of dynamo magnetic field” (Talk)
• 2017: ISSI workshop – Rossby waves in astrophysics, Bern, Switzerland, “Rieger periodicity and seismology of solar interior” and “Rieger periodicity and north-south asymmetry on the Sun” (Talk)
• 2017: ESPM-15: 15th European Solar Physics Meeting, Budapest, Hungary, “North-South asymmetry in Rieger-type periodicity during solar cycles 19-23” (Poster)
• 2017: Our mysterious sun: magnetic coupling between solar interior and atmosphere, Tbilisi, Georgia, “North-South asymmetry in Rieger-type periodicity during solar cycles 19-23” (Talk)
• 2018: ISSI workshop – Rossby waves in astrophysics, Bern, Switzerland, “N-S asymmetry and Rieger type periodicity in solar cycle 24” (Talk)
• 2019: Stars and their Variability, Observed from Space – Celebrating the 5^th Anniversary of BRITE constellation, Vienna, Austria, “Rieger-type periodicity in activity of solar-type stars” (Poster)

• 2012-2016: Researcher, Space and Solar Weather Network of Excellence, SOLSPANET
• 2016-2017: PhD Scholarship 2016, “Rieger-type periodicity in solar activity and estimation of dynamo magnetic field strength”, Shota Rustaveli National Science Foundation
• 2016 -2019: Key Personnel, Basic research 2016, “Rieger-type periodicity in solar activity and seismology of solar interior”, Shota Rustaveli National Science Foundation
• 2017: Coordinator, Conference grants 2017, “Our mysterious sun: magnetic coupling between solar interior and atmosphere”, Shota Rustaveli National Science Foundation
• 2017 -2018: Key Personnel, Basic research 2017, “Solar flare velocity field: observation and modelling”, Shota Rustaveli National Science Foundation

” I appreciate the chance to broaden my knowledge and experience by attending different courses and seminars in Göttingen, led by experts in this research field. The Lehmann-Haupt International Doctoral Program will thus greatly help me in formulating my ideas into research, which is invaluable for me and for my future endeavors. It is an excellent opportunity to meet well-known experts and to improve the quality of my future work. This experience will help me derive outstanding new skills and competences. It is my belief that the double degree from one of the most recognized European university and one of the most prestigious university in Georgia is my chance to make an important progress in my personal career and development. “