High-resolution spectra of solar magnetic features. I - Analysis of penumbral fine structure

Abstract

view Abstract Citations (88) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Resolution Spectra of Solar Magnetic Features. I. Analysis of Penumbral Fine Structure Lites, B. W. ; Scharmer, G. B. ; Skumanich, A. Abstract The Swedish Vacuum Telescope on La Palma was used to obtain spectra of the magnetic-sensitive Fe I 630.25 nm line under conditions of exceptional angular resolution (0.32 arcsec) and high spectral resolution (FWHM 2.5 pm). Simultaneous 0.02 s CCD exposures of both the spectrum and the slit-jaw image effectively 'freeze' the atmospheric seeing motions and permit unambiguous identification of the spectra of the various penumbral structures. These spectra reveal the magnetic field strength in penumbral filaments through an intensity fit of the Zeeman splitting of this line. The observations show that: (1) the field strength varies from about 2100 G near the umbra-penumbra boundary to about 900 G at the outer edge of the penumbra, (2) the observed fluctuation of penumbral magnetic field is much less dramatic than the fluctuation in intensity, (3) there is a suggestion of a rapid change in field inclination between some light and dark filaments near the edge of the penumbra, and (4) there is no obvious correlation between Doppler shift (in part due to the Evershed flow) and filament intensity. Publication: The Astrophysical Journal Pub Date: May 1990 DOI: 10.1086/168767 Bibcode: 1990ApJ...355..329L Keywords: Fine Structure; Solar Magnetic Field; Solar Spectra; Sunspots; Iron; Penumbras; Solar Granulation; Solar Observatories; Solar Physics; SUN: MAGNETIC FIELDS; SUN: SUNSPOTS full text sources ADS | Related Materials (1) Part 2: 1991ApJ...373..683L