We welcome our STCE visitor Sneha Pandit from Inter University Center for Astronomy & Astrophysics (IUCAA), Pune, India. She will present her research on the solar chromosphere and magnetic field switchbacks, a zigzag configuration.
Title: Long Term Solar Activity Using mm Indicators + Investigating the Origin of Switchbacks in the Solar Corona using Statistical Approach
Abstract: The Sun, our nearest star, serves as an invaluable reference for the study of solar-like stars, due to the availability of many spatiotemporally resolved solar spectra. Amongst several spectral lines, some of the strongest chromospheric diagnostics are the H alpha line and Ca II H K lines which can be used to gauge the magnetic structures and temperature stratification of the atmosphere as the line core and wings are formed at different heights of the solar atmosphere. Complementing these diagnostics are brightness temperatures derived from observations made by the Atacama Large Millimeter (mm)/ submillimeter (sub-mm) Array (ALMA). These data open up fresh perspectives on stellar atmospheric activity and thermal structures. We compare synthetic Ca II and H alpha spectra with millimetre continuum maps for deeper stellar structure insights, using radiative transfer codes and a Bifrost-based network atmosphere model. The resulting activity indices reveal crucial details about temperature stratification, magnetic structures, and mass density distribution in stellar atmospheres. Notably, we find strong correlations between the H alpha linewidth and ALMA Band~7 data, the Ca~II s index and the lower chromosphere, and the Ca~II Infrared triplet (IRT) index and an even lower atmospheric layer near the upper photosphere. Additionally, we compare long-term ALMA observations with UV-EUV and microwave data, marking the first solar activity variation using ALMA TP data. Short-term variations are also observed. In summary, the major part of the talk revolves around a comparative exploration of solar and stellar activity among Sun-like stars. The investigations are based on observations from ALMA, in conjunction with other solar and stellar observational and synthetic data. Lastly, we discuss the solar wind-coronal connection, focusing on switchbacks observed by the Parker Solar Probe. We analyse small-scale jets and transient events in the solar corona, comparing them with switchback events to explore their solar connectivity.
September 17, 14:30
ROB director’s house 1+2
Zoom: https://us06web.zoom.us/j/81512296087?pwd=72gGZarPgsa3JSL18tsvr5GJq7Bau6.1
Welcome!
Elke and Petra, on behalf of Ketaki Deshpande
