Diagnostic potential of the Ca II 8542 Ångstrom line for solar filaments

• Aims. In this study we explore the diagnostic potential of the chromospheric Ca II line at 8542 angstrom for studying the magnetic and dynamic properties of solar filaments. We have acquired high spatial resolution spectropolarimetric observations in the Ca II 8542 angstrom line using the CRISP instrument at the Swedish 1 m Solar Telescope. Methods. We used the NICOLE inversion code to infer physical properties from observations of a solar filament. We discuss the validity of the results due to the assumption of hydrostatic equilibrium. We have used observations from other telescopes such as CHROTEL and SDO, in order to study large scale dynamics and the long term evolution of the filament. Results. We show that the Ca II 8542 angstrom line encodes information of the temperature, line-of-sight velocity and magnetic field vector from the region where the filament is located. The current noise levels only allow us to estimate an upper limit of 260 G for the total magnetic field of the filament. Our study also reveals that if we consider information from the aforementioned spectral line alone, the geometric height, the temperature and the density could be degenerated parameters outside the hydrostatic equilibrium approach.

Subject headings

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Keyword

Sun: filaments

prominences

Sun: chromosphere

Sun: magnetic fields

Sun: oscillations

Sun: evolution

Publication and Content Type

ref (subject category)

art (subject category)