Sprecher/in: Serena Criscuoli (National Solar Observatory | Boulder, CO, USA)

Titel: Using Spatially Resolved Solar Observations to Improve Models of Solar and Stellar Variability

Zusammenfassung: Models of solar and stellar variability are essential for a wide range of applications, from understanding the influence of solar irradiance on Earth's atmosphere to characterizing exoplanet host stars and improving the detectability of exoplanets. Over the past decades, irradiance variability models have achieved considerable success in reproducing many observed signatures of magnetic activity. However, important discrepancies remain, highlighting limitations in our understanding of how different atmospheric structures contribute to spectral variability.
In this seminar, I will provide a brief overview of current solar and stellar variability models, discussing both their achievements and their outstanding challenges. I will then focus on one puzzling problem: the variability of the hydrogen Balmer lines. These lines, especially Hα, Hβ, Hγ, and Hδ, are among the most widely used diagnostics of stellar magnetic activity, yet recent observations have revealed complex and sometimes unexpected behavior, including weak or even anti-correlated variations with traditional chromospheric activity indicators such as the Ca II lines.
I will present recent efforts to understand the origin of this behavior through a combination of disk-integrated observations, spatially resolved measurements, and semi-empirical atmospheric modeling. I will discuss how modern high-resolution observations enable us to identify the physical origins of these discrepancies and refine existing models. Particular attention will be given to recent observations acquired with the IAG spectrograph and results from the Visible Spectro-Polarimeter (ViSP) at the Daniel K. Inouye Solar Telescope, which provide new insights into the relationship between magnetic activity and Balmer-line variability in the Sun and solar-like stars. Finally, I will present preliminary results from an analysis of synoptic ChroTel Hα and Ca II K observations, which suggest that chromospheric features, often neglected in current solar and stellar irradiance models, may play a role in shaping chromospheric variability

Anmerkung: Host: Meetu Verma

• Datum:
  18. Juni 2026, 14:30 – 15:30
  
  
• Ort:

  AIP; Kirch-Haus, Konferenzraum

  
  
• Kontakt:
  Julián Alvarado-Gómez
  julian.alvarado-gomez@aip.de