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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for a downward mass flux in the penumbral region of a sunspot (1997)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 389 (1997), S. 47-49 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sunspots were the first extraterrestrial phenomenon found to harbour magnetic fields,. But the physical nature of sunspots and their relationship to the Sun's global magnetic field are still poorly understood. Perhaps the largest uncertainty is related to the outermost region of sunspots (the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/37933
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  • 2
    Electronic Resource
    Electronic Resource
    SIR: An Inversion Technique of Spectral Lines (1998)
    Springer
    Astrophysics and space science 263 (1998), S. 331-334 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During the last years, inversion techniques have become one of the most powerful tools to obtain, from spectropolarimetric data, the stratification of physical quantities (temperature, pressure, velocity fields, magnetic field, etc.) describing different structures in the solar atmosphere. The SIR code (Stokes Inversion based on Response functions), developed at the Instituto de Astrofísica de Canarias (IAC), is internationally acknowledged nowadays at the most sophisticated and accurate inversion method. The main results derived from its application to the study of the solar photosphere, are presented. Two recent extensions are reported as well: inversion under NLTE conditions, and the MISS code (Multiline Inversion of Stellar Spectra).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002191418914
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  • 3
    Electronic Resource
    Electronic Resource
    Stratification of the 5-min oscillation through the solar photosphere (1997)
    Springer
    Solar physics 172 (1997), S. 77-83 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The inversion of the radiative transfer equation has been applied to a time series of low spatial resolution Ki 7699 Å line spectra, allowing us to obtain a sequence of instantaneous models which are compared to the mean one to derive the 5-min oscillation stratification. The resulting models are reliable from log τ ≃ 0 to log τ ≃ -3.5. The increase of the velocity oscillation amplitude towards higher photospheric layers has been confirmed and quantified. Significant oscillation is observed in temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004991715924
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  • 4
    Electronic Resource
    Electronic Resource
    Stokes profiles inversion techniques (1996)
    Springer
    Solar physics 164 (1996), S. 169-182 
    Details
    ISSN: 1573-093X
    Keywords: Spectropolarimetry ; Magnetic field diagnostics ; Radiative Transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Inversion techniques of the radiative transfer equation for polarized light are presented as one of the best current procedures to infer the vector magnetic field, as well as other quantities governing the physical state of the atmospheric layers that photons are coming from. Several characteristics of the various available inversion procedures are pointed out. They are mostly based on the diagnostic contents of the spectral lines as well as on the main hypotheses assumed in these procedures. In particular, the role of gradients in the atmospheric quantities is emphasized as of paramount importance in any diagnostic analysis and, hence, in any interpretation of inversion results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146631
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  • 5
    Electronic Resource
    Electronic Resource
    Facular points and small-scale magnetic elements (1990)
    Springer
    Astrophysics and space science 170 (1990), S. 9-16 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present spectroscopic observations, with high spatial resolution, of Caii K bright points very near the disc centre. Magnetic concentrations have been detected in these network (facular) points by only using intensity profiles of the well-known pair of lines Fei5250.22 Å and 5247.06 Å. No brightening of these structures with respect to the quiet photosphere can be ascertained within an accuracy threshold of 1.2%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652637
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  • 6
    Electronic Resource
    Electronic Resource
    Numerical test of a newV-profile inversion technique (1990)
    Springer
    Astrophysics and space science 170 (1990), S. 113-116 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The diagnostic method proposed by Landi Degl'Innocenti and Landolfi (1982), based on the observation of circular polarization, has been generalized to derive the thermodynamic properties of unresolved magnetic elements in the solar atmosphere. The final aim is to derive the height dependence of several parameters of the flux tube atmosphere (such as temperature, magnetic field and velocity distributions, macroturbulence and filling factor). We have used a perturbation method based on the concept of response functions for the Stokes profiles introduced by Landi Degl'Innocenti and Landi Degl'Innocenti (1977). We present here the preliminary results of invertingV-profiles by an iterative standard least-squares technique, which allows to find the magnetic 1-D atmosphere consistent with simulated data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652655
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  • 7
    Electronic Resource
    Electronic Resource
    Stray-light measurements at the Observatorio del Teide (1990)
    Springer
    Solar physics 125 (1990), S. 211-218 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new procedure to separate the instrumental and atmospheric components of stray light is presented. It is based on the dependence of the aureole's atmospheric component on the air mass and is applied to measurements taken with the Vacuum Newton Telescope (VNT) at the Observatorio del Teide (Tenerife). The resulting instrumental part is independent of the air mass. The variation of both components with wavelength is also studied. The instrumental component shows no dependence on wavelength, in contrast to the atmospheric one which is greater in the blue than in the red. It is concluded that observations with air masses larger than two will probably be strongly affected by stray light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158401
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  • 8
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    Remote sensing of the solar photosphere: a tale of two methods (2018)
    Institute of Physics
    Details
    Publication Date: 2018-01-01
    Print ISSN: 1742-6588
    Electronic ISSN: 1742-6596
    Topics: Physics
    Published by Institute of Physics
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  • 9
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    Analysis of spatially deconvolved polar faculae (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-01
    Description: Polar faculae are bright features that can be detected in solar limb observations and they are related to magnetic field concentrations. Although there are a large number of works studying them, some questions about their nature as their magnetic properties at different heights are still open. Thus, we aim to improve the understanding of solar polar faculae. In that sense, we infer the vertical stratification of the temperature, gas pressure, line-of-sight velocity and magnetic field vector of polar faculae regions. We performed inversions of the Stokes profiles observed with Hinode /Spectropolarimeter after removing the stray light contamination produced by the spatial point spread function of the telescope. Moreover, after solving the azimuth ambiguity, we transform the magnetic field vector to local solar coordinates. The obtained results reveal that the polar faculae are constituted by hot plasma with low line-of-sight velocities and single polarity magnetic fields in the kilogauss range that are nearly perpendicular to the solar surface. We also found that the spatial location of these magnetic fields is slightly shifted respect to the continuum observations towards the disc centre. We believe that this is due to the hot wall effect that allows detecting photons that come from deeper layers located closer to the solar limb.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 10
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    Analysis of a spatially deconvolved solar pore (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-06
    Description: Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores present themselves as an intriguing phenomenon that is not completely understood. We examine in this work a solar pore observed with Hinode /SP using two state of the art techniques. The first one is the spatial deconvolution of the spectropolarimetric data that allows removing the stray light contamination induced by the spatial point spread function of the telescope. The second one is the inversion of the Stokes profiles assuming local thermodynamic equilibrium that let us to infer the atmospheric physical parameters. After applying these techniques, we found that the spatial deconvolution method does not introduce artefacts, even at the edges of the magnetic structure, where large horizontal gradients are detected on the atmospheric parameters. Moreover, we also describe the physical properties of the magnetic structure at different heights finding that, in the inner part of the solar pore, the temperature is lower than outside, the magnetic field strength is larger than 2 kG and unipolar, and the line-of-sight velocity is almost null. At neighbouring pixels, we found low magnetic field strengths of same polarity and strong downward motions that only occur at the low photosphere, below the continuum optical depth log  = –1. Finally, we studied the spatial relation between different atmospheric parameters at different heights corroborating the physical properties described before.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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