Astrophysical: Sunspots

  • Publication
    Are the small active regions related to the decay of the larger ones?
    To investigate the location of the actual limit for the different behavior, the active regions with fluxes greater than 10 to the 20 Mx are investigated. After...
  • Publication
    Automatic log spectrum restoration of atmospheric seeing
    This paper presents an automatic method for (1) digital estimation of the width of the atmospherical seeing in astronomical images of extended objects and (2)...
  • Publication
    Chromospheric polarity reversals on sunspots. Are they consistent with weak line emission?
    Photospheric and chromospheric solar magnetograms sometimes show opposite polarity. This intriguing phenomenon is associated with the emergence of magnetic flux...
  • Publication
    Chromospheric Resonances above Sunspots and Potential Seismological Applications
    Oscillations in sunspot umbrae exhibit remarkable differences between the photosphere and chromosphere. We evaluate two competing scenarios proposed for...
  • Publication
    Circular polarization of the CA II H and K lines in solar quiet and active regions
    A representative set of profiles is presented for the Ca II H resonace line in Stokes V and I, for the quiet sun, plages, sunspot umbrae, and a flare, as well...
  • Publication
    Cold, Supersonic Evershed Downflows in a Sunspot
    We report here on the discovery of supersonic Evershed downflows in the penumbra of a sunspot. These flows are shown to occur along spatially unresolved, very...
  • Publication
    Combining magneto-hydrostatic constraints with Stokes profile inversions. IV. Imposing ∇⋅B = 0 condition
    Context. Inferences of the magnetic field in the solar atmosphere by means of spectropolarimetric inversions (i.e., Stokes inversion codes) yield magnetic...
  • Publication
    Combining magneto-hydrostatic constraints with Stokes profiles inversions. II. Application to Hinode/SP observations
    Context. Inversion techniques applied to the radiative transfer equation for polarized light are capable of inferring the physical parameters in the solar...
  • Publication
    Combining magnetohydrostatic constraints with Stokes profiles inversions. I. Role of boundary conditions
    Context. Inversion codes for the polarized radiative transfer equation, when applied to spectropolarimetric observations (i.e., Stokes vector) in spectral lines...