Astrophysical: Sunspots

  • Publication
    Sunspot populations and their relation with the solar cycle
    The joint consideration of theoretical and observational arguments is used to conclude that two different spot populations co-exist in the Sun.
  • Publication
    Supersonic Continuation of the Evershed Flow Outside a Sunspot as Observed with Hinode
    We report on the discovery of mostly horizontal field channels just outside sunspot penumbrae (in the so-called "moat" region) that are seen to sustain...
  • Publication
    Temporal and center-to-limb variations of the K I 769.9 NM line profiles in quiet and active solar regions
    The temporal and spatial behaviour of the K I 769.9 nm solar line are investigated using several series of high spectral resolution low-noise photoelectric...
  • Publication
    Temporal Evolution of Fine Structures in and around Solar Pores
    Time series of high-resolution white-light images of six solar pores, observed in 1993 and 1995 at the Swedish Vacuum Solar Telescope (La Palma), are analyzed...
  • Publication
    Temporal evolution of the Evershed flow in sunspots. I. Observational characterization of Evershed clouds
    Context: The magnetic and kinematic properties of the photospheric Evershed flow are relatively well known, but not completely understood. The evolution of the...
  • Talk
    Testing new ideas of sunspot formation: the negative effective magnetic pressure instability
    The formation of active regions and its most visible outcome-sunspots-are still a matter of research. Magnetic flux tubes theory tends to explain the formation...
  • Publication
    The 2024 May event in the context of auroral activity over the past 375 yr
    We survey 223 916 auroral records from the Northern hemisphere observed between 1650 January and 2024 July, making full allowance for the secular change in the...
  • Publication
    The Canopy Structure above Light Bridges
    An analysis of high-resolution Stokes observations of two light bridges in the active region NOAA 8990 is presented. The observations were recorded with the La...
  • Publication
    The continuum intensity-magnetic field relation in sunspot umbrae
    We describe the work carried out to obtain observational evidence of a local relation between the temperature and the magnetic field in different regions of...