HAO Colloquium - Ana Belén Griñón Marín, Instituto de Astrofísica de Canarias

Long-term Evolution of Active Regions

In this talk I would like to present the research done along my PhD degree that I am finishing. The project is done under the supervision of Dr. Héctor Socas Navarro and Dr. Rebecca Centeno. My thesis is focused on the study of the long-term evolution of the photospheric magnetic field in sunspots. To that aim, I have deepened into the study of the oscillations and dynamic phenomena of the magnetic field in sunspots by means of full spectropolarimetric data from HMI on board SDO and data from the GRIS (GRegor Infrared Spectrograph) instrument installed at the GREGOR solar telescope. SDO data enable the long-term evolution study of the magnetic field of the penumbra of sunspots during their passage across the visible disk. GRIS data allow us to study the magnetic field evolution in the umbra of a sunspot when a light bridge (LB) is forming.

To that aim, the research project has focused on the study of:

• Torsional oscillations: We have used long time series of continuum intensity and magnetic field vector maps from the HMI/SDO data. We have analyzed the long-term evolution of the magnetic field azimuth to seek evidence for global torsional oscillations in the penumbra of alpha sunspots (Griñón-Marín et al. 2017).

• Penumbral dynamic phenomena oriented towards nearby opposite polarity areas: During the previous work, we found that the magnetic field inclination of the penumbra of alpha sunspots presents some events at particular places of the penumbra and during intervals of the whole time series. The analysis of the long-term evolution of the magnetic field inclination, we discovered a new type of dynamical phenomena that evolve and propagate in timescales of several hours. 

• Light Bridge long-term evolution: We acquire full spectropolarimetric data with the GRIS instrument at GREGOR of the leading sunspot of AR 12049 spanning from the 29th April to the 5th May, 2014. These data were used to analyze the temporal evolution of different atmospheric parameters, magnetic field included, of 3 LBs in the same sunspot, which were formed by different mechanisms. 

Date and time: 
Tuesday, January 23, 2018 - 11:00am to 12:00pm