0000000000307266

AUTHOR

J. Sánchez Almeida

showing 3 related works from this author

Center-to-limb variation of the area covered by magnetic bright points in the quiet Sun

2011

CONTEXT: The quiet Sun magnetic fields produce ubiquitous bright points (BPs) that cover a significant fraction of the solar surface. Their contribution to the total solar irradiance (TSI) is so-far unknown. AIMS: To measure the center-to-limb variation (CLV) of the fraction of solar surface covered by quiet Sun magnetic bright points. The fraction is referred to as 'fraction of covered surface', or FCS. METHODS: Counting of the area covered by BPs in G-band images obtained at various heliocentric angles with the 1-m Swedish Solar Telescope on La Palma. Through restoration, the images are close to the diffraction limit of the instrument (~0.1 arcsec). RESULTS: The FCS is largest at disk cen…

DiffractionPhysicsPhotosphereFOS: Physical sciencesAstronomy and AstrophysicsContext (language use)AstrophysicsSolar irradianceMagnetic fieldSolar telescopeAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceQUIETPhysics::Space PhysicsAstrophysics::Solar and Stellar AstrophysicsAstrophysics::Earth and Planetary AstrophysicsVariation (astronomy)Solar and Stellar Astrophysics (astro-ph.SR)Astronomy & Astrophysics
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Convectively driven vortex flows in the Sun

2008

We have discovered small whirlpools in the Sun, with a size similar to the terrestrial hurricanes (<~0.5 Mm). The theory of solar convection predicts them, but they had remained elusive so far. The vortex flows are created at the downdrafts where the plasma returns to the solar interior after cooling down, and we detect them because some magnetic bright points (BPs) follow a logarithmic spiral in their way to be engulfed by a downdraft. Our disk center observations show 0.009 vortexes per Mm^2, with a lifetime of the order of 5 min, and with no preferred sense of rotation. They are not evenly spread out over the surface, but they seem to trace the supergranulation and the mesogranulation. T…

ConvectionPhysicsAstrophysics (astro-ph)FOS: Physical sciencesAstronomy and AstrophysicsPlasmaAstrophysicsAstrophysicsRotationVortexSpace and Planetary ScienceAstrophysics::Solar and Stellar AstrophysicsSupergranulationAstrophysics::Earth and Planetary AstrophysicsLogarithmic spiralCooling down
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SUNRISE/IMaX observations of convectively driven vortex flows in the Sun

2010

We characterize the observational properties of the convectively driven vortex flows recently discovered on the quiet Sun, using magnetograms, Dopplergrams and images obtained with the 1-m balloon-borne Sunrise telescope. By visual inspection of time series, we find some 3.1e-3 vortices/(Mm^2 min), which is a factor of 1.7 larger than previous estimates. The mean duration of the individual events turns out to be 7.9 min, with a standard deviation of 3.2 min. In addition, we find several events appearing at the same locations along the duration of the time series (31.6 min). Such recurrent vortices show up in the proper motion flow field map averaged over the time series. The typical vertica…

Rotation periodPhysicsProper motionFOS: Physical sciencesAstronomy and AstrophysicsAstrophysicsVorticityRotationVortexPhysics::Fluid DynamicsAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceSunriseDifferential rotationAstrophysics::Solar and Stellar AstrophysicsClockwiseSolar and Stellar Astrophysics (astro-ph.SR)
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