The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Trujillo J Bueno - One of the best experts on this subject based on the ideXlab platform.
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height variation of the Vector Magnetic Field in solar spicules
arXiv: Solar and Stellar Astrophysics, 2015Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Proving the Magnetic configuration of solar spicules has hitherto been difficult due to the lack of spatial resolution and image stability during off-limb ground-based observations. We report spectropolarimetric observations of spicules taken in the He I 1083 nm spectral region with the Tenerife Infrared Polarimeter II at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife; Canary Islands; Spain). The data provide the variation with geometrical height of the Stokes I, Q, U, and V profiles whose encoded information allows the determination of the Magnetic Field Vector by means of the HAZEL inversion code. The inferred results show that the average Magnetic Field strength at the base of solar spicules is about 80 gauss and then it decreases rapidly with height to about 30 gauss at a height of 3000 km above the visible solar surface. Moreover, the Magnetic Field Vector is close to vertical at the base of the chromosphere and has mid inclinations (about 50 degree) above 2 Mm height.
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height variation of the Vector Magnetic Field in solar spicules
The Astrophysical Journal, 2015Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Proving the Magnetic configuration of solar spicules has hitherto been difficult due to the lack of spatial resolution and image stability during off-limb ground-based observations. We report spectropolarimetric observations of spicules taken in the He i 1083 nm spectral region with the Tenerife Infrared Polarimeter II at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife, Canary Islands, Spain). The data provide the variation with geometrical height of the Stokes I, Q, U, and V profiles, whose encoded information allows the determination of the Magnetic Field Vector by means of the HAZEL inversion code. The inferred results show that the average Magnetic Field strength at the base of solar spicules is about 80 gauss, and then it decreases rapidly with height to about 30 gauss at a height of 3000 km above the visible solar surface. Moreover, the Magnetic Field Vector is close to vertical at the base of the chromosphere and has mid-inclinations (about 50°) above 2 Mm height.
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the Magnetic Field configuration of a solar prominence inferred from spectropolarimetric observations in the he i 10 830 a triplet
Astronomy and Astrophysics, 2014Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Context. Determining the Magnetic Field Vector in quiescent solar prominences is possible by interpreting the Hanle and Zeeman effects in spectral lines. However, observational measurements are scarce and lack high spatial resolution. Aims. We determine the Magnetic Field Vector configuration along a quiescent solar prominence by interpreting spectropolarimetric measurements in the He i 1083.0 nm triplet obtained with the Tenerife Infrared Polarimeter installed at the German Vacuum Tower Telescope of the Observatorio del Teide. Methods. The He i 1083.0 nm triplet Stokes profiles were analyzed with an inversion code that takes the physics responsible for the polarization signals in this triplet into account. The results are put into a solar context with the help of extreme ultraviolet observations taken with the Solar Dynamic Observatory and the Solar Terrestrial Relations Observatory satellites. Results. For the most probable Magnetic Field Vector configuration, the analysis depicts a mean Field strength of 7 gauss. We do not find local variations in the Field strength except that the Field is, on average, lower in the prominence body than in the prominence feet, where the Field strength reaches ∼25 gauss. The averaged Magnetic Field inclination with respect to the local vertical is ∼77 ◦ .T he acute angle of the Magnetic Field Vector with the prominence main axis is 24 ◦ for the sinistral chirality case and 58 ◦ for the dextral chirality. These inferences are in rough agreement with previous results obtained from the analysis of data acquired with lower spatial resolutions.
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advanced forward modeling and inversion of stokes profiles resulting from the joint action of the hanle and zeeman effects
The Astrophysical Journal, 2008Co-Authors: Asensio A Ramos, Trujillo J Bueno, Landi E DeglinnocentiAbstract:A big challenge in solar and stellar physics in the coming years will be to decipher the magnetism of the solar outer atmosphere (chromosphere and corona) along with its dynamic coupling with the Magnetic Fields of the underlying photosphere. To this end, it is important to develop rigorous diagnostic tools for the physical interpretation of spectropolarimetric observations in suitably chosen spectral lines. Here we present a computer program for the synthesis and inversion of Stokes profiles caused by the joint action of atomic level polarization and the Hanle and Zeeman effects in some spectral lines of diagnostic interest, such as those of the He I 10830 A and 5876 A (or D3) multiplets. It is based on the quantum theory of spectral line polarization, which takes into account in a rigorous way all the relevant physical mechanisms and ingredients (optical pumping, atomic level polarization, level crossings and repulsions, Zeeman, Paschen-Back, and Hanle effects). The influence of radiative transfer on the emergent spectral line radiation is taken into account through a suitable slab model. The user can either calculate the emergent intensity and polarization for any given Magnetic Field Vector or infer the dynamical and Magnetic properties from the observed Stokes profiles via an efficient inversion algorithm based on global optimization methods. The reliability of the forward modeling and inversion code presented here is demonstrated through several applications, which range from the inference of the Magnetic Field Vector in solar active regions to determining whether or not it is canopy-like in quiet chromospheric regions. This user-friendly diagnostic tool called HAZEL (from HAnle and ZEeman Light) is offered to the astrophysical community, with the hope that it will facilitate new advances in solar and stellar physics.
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advanced forward modeling and inversion of stokes profiles resulting from the joint action of the hanle and zeeman effects
arXiv: Astrophysics, 2008Co-Authors: Asensio A Ramos, Trujillo J Bueno, Landi E DeglinnocentiAbstract:A big challenge in solar and stellar physics in the coming years will be to decipher the magnetism of the solar outer atmosphere (chromosphere and corona) along with its dynamic coupling with the Magnetic Fields of the underlying photosphere. To this end, it is important to develop rigorous diagnostic tools for the physical interpretation of spectropolarimetric observations in suitably chosen spectral lines. Here we present a computer program for the synthesis and inversion of Stokes profiles caused by the joint action of atomic level polarization and the Hanle and Zeeman effects in some spectral lines of diagnostic interest, such as those of the He I 10830 A and D_3 multiplets. It is based on the quantum theory of spectral line polarization, which takes into account all the relevant physical mechanisms and ingredients (optical pumping, atomic level polarization, Zeeman, Paschen-Back and Hanle effects). The influence of radiative transfer on the emergent spectral line radiation is taken into account through a suitable slab model. The user can either calculate the emergent intensity and polarization for any given Magnetic Field Vector or infer the dynamical and Magnetic properties from the observed Stokes profiles via an efficient inversion algorithm based on global optimization methods. The reliability of the forward modeling and inversion code presented here is demonstrated through several applications, which range from the inference of the Magnetic Field Vector in solar active regions to determining whether or not it is canopy-like in quiet chromospheric regions. This user-friendly diagnostic tool called "HAZEL" (from HAnle and ZEeman Light) is offered to the astrophysical community, with the hope that it will facilitate new advances in solar and stellar physics.
Philippe Kobel - One of the best experts on this subject based on the ideXlab platform.
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inferring the Magnetic Field Vector in the quiet sun iii disk variation of the stokes profiles and isotropism of the Magnetic Field
Astronomy and Astrophysics, 2013Co-Authors: J. M. Borrero, Philippe KobelAbstract:Recent investigations of the Magnetic Field Vector properties in the solar internetwork have provided diverging results. While some works found that the internetwork is mostly pervaded by horizontal Magnetic Fields, other works argued in favor of an isotropic distribution of the Magnetic Field Vector. Motivated by these seemingly contradictory results and by the fact that most of these works have employed spectropolarimetric data at disk center only, we have revisited this problem employing high-quality data (noise level sigma approximate to 3 x 10(-4) in units of the quiet-Sun intensity) at different latitudes recorded with the Hinode/SP instrument. Instead of applying traditional inversion codes of the radiative transfer equation to retrieve the Magnetic Field Vector at each spatial point on the solar surface and studying the resulting distribution of the Magnetic Field Vector, we surmised a theoretical distribution function of the Magnetic Field Vector and used it to obtain the theoretical histograms of the Stokes profiles. These histograms were then compared to the observed ones. Any mismatch between them was ascribed to the theoretical distribution of the Magnetic Field Vector, which was subsequently modified to produce a better fit to the observed histograms. With this method we find that Stokes profiles with signals above 2 x 10(-3) (in units of the continuum intensity) cannot be explained by an isotropic distribution of the Magnetic Field Vector. We also find that the differences between the histograms of the Stokes profiles observed at different latitudes cannot be explained in terms of line-of-sight effects. However, they can be explained by a distribution of the Magnetic Field Vector that inherently varies with latitude. We note that these results are based on a series of assumptions that, although briefly discussed in this paper, need to be considered in more detail in the future.
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inferring the Magnetic Field Vector in the quiet sun iii disk variation of the stokes profiles and isotropism of the Magnetic Field
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:We have studied the angular distribution of the Magnetic Field Vector in the solar internetwork employing high-quality data (noise level $\sigma \approx 3\times 10^{-4}$ in units of the quiet-Sun intensity) at different latitudes recorded with the Hinode/SP instrument. Instead of applying traditional inversion codes of the radiative transfer equation to retrieve the Magnetic Field Vector at each spatial point on the solar surface and studying the resulting distribution of the Magnetic Field Vector, we surmised a theoretical distribution function of the Magnetic Field Vector and used it to obtain the theoretical histograms of the Stokes profiles. These histograms were then compared to the observed ones. Any mismatch between them was ascribed to the theoretical distribution of the Magnetic Field Vector, which was subsequently modified to produce a better fit to the observed histograms. With this method we find that Stokes profiles with signals above $2\times 10^{-3}$ (in units of the continuum intensity) cannot be explained by an isotropic distribution of the Magnetic Field Vector. We also find that the differences between the histograms of the Stokes profiles observed at different latitudes cannot be explained in terms of line-of-sight effects. However, they can be explained by a distribution of the Magnetic Field Vector that inherently varies with latitude. We note that these results are based on a series of assumptions that, although briefly discussed in this paper, need to be considered in more detail in the future.
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inferring the Magnetic Field Vector in the quiet sun ii interpreting results from the inversion of stokes profiles
Astronomy and Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:In a previous paper, we argued that the inversion of Stokes profiles applied to spectropolarimetric observations of the solar internetwork yield unrealistically large values of the inclination of the Magnetic Field Vector (γ). This is because photon noise in Stokes Q and U are interpreted by the inversion code as valid signals, that leads to an overestimation of the transverse component B⊥, thus the inclination γ. However, our study was based on the analysis of linear polarization signals that featured only uncorrelated noise. In this paper, we develop this idea further and study this effect in Stokes Q and U profiles that also show correlated noise. In addition, we extend our study to the three components of the Magnetic Field Vector, as well as the Magnetic filling factor α. With this, we confirm the tendency to overestimate γ when inverting linear polarization profiles that, although non-zero, are still below the noise level. We also establish that the overestimation occurs mainly for Magnetic Fields that are nearly vertical γ 20 ◦ . This indicates that a reliable inference of the inclination of the Magnetic Field Vector cannot be achieved by analyzing only Stokes I and V. In addition, when inverting Stokes Q and U profiles below the noise, the inversion code retrieves a randomly uniform distribution of the azimuth of the Magnetic Field Vector φ. To avoid these problems, we propose only inverting Stokes profiles for which the linear polarization signals are sufficiently above the noise level. However, this approach is also biased because, in spite of allowing for a very accurate retrieval of the Magnetic Field Vector from the selected Stokes profiles, it selects only profiles arising from highly inclined Magnetic Fields.
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inferring the Magnetic Field Vector in the quiet sun ii interpreting results from the inversion of stokes profiles
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:In a previous paper, we argued that the inversion of Stokes profiles applied to spectropolarimetric observations of the solar internetwork yield unrealistically large values of the inclination of the Magnetic Field Vector ($\gamma$). This is because photon noise in Stokes $Q$ and $U$ are interpreted by the inversion code as valid signals, that leads to an overestimation of the transverse component $B_\perp$, thus the inclination $\gamma$. However, our study was based on the analysis of linear polarization signals that featured only uncorrelated noise. In this paper, we develop this idea further and study this effect in Stokes $Q$ and $U$ profiles that also show correlated noise. In addition, we extend our study to the three components of the Magnetic Field Vector, as well as the Magnetic filling factor $\alpha$. With this, we confirm the tendency to overestimate $\gamma$ when inverting linear polarization profiles that, although non-zero, are still below the noise level. We also establish that the overestimation occurs mainly for Magnetic Fields that are nearly vertical $\gamma \lesssim 20\deg$. This indicates that a reliable inference of the inclination of the Magnetic Field Vector cannot be achieved by analyzing only Stokes $I$ and $V$. In addition, when inverting Stokes $Q$ and $U$ profiles below the noise, the inversion code retrieves a randomly uniform distribution of the azimuth of the Magnetic Field Vector $\phi$. To avoid these problems, we propose only inverting Stokes profiles for which the linear polarization signals are sufficiently above the noise level. However, this approach is also biased because, in spite of allowing for a very accurate retrieval of the Magnetic Field Vector from the selected Stokes profiles, it selects only profiles arising from highly inclined Magnetic Fields.
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inferring the Magnetic Field Vector in the quiet sun i photon noise and selection criteria
Astronomy and Astrophysics, 2011Co-Authors: J. M. Borrero, Philippe KobelAbstract:In the past, spectropolarimetric data from Hinode/SP were employed to infer the distribution of the Magnetic Field Vector in the quiet Sun. While some authors found predominantly horizontal Magnetic Fields, others favor an isotropic distribution. We investigate whether it is actually possible to accurately retrieve the Magnetic Field Vector in regions with very low polarization signals (e.g. internetwork), employing the FeI line pair at 6300 A. We first perform inversions of the Stokes Vector observed with Hinode/SP in the quiet Sun at disk center in order to confirm the distributions retrieved by other authors. We then carry out several Monte-Carlo simulations with synthetic data, with which we show that the observed distribution of the Magnetic Field Vector can be explained in terms of purely vertical (γ = 0 ◦ ) and weak Fields ( ¯ B < 20 G), which are misinterpreted by the analysis technique (Stokes inversion code) as being horizontal (γ ≈ 90 ◦ ) and stronger ( ¯ B ≈ 100 G), owing to the effect of the photon noise. This challenges the correctness of previous results, which presented the distributions for the Magnetic Field Vector peaking at γ = 90 ◦ and ¯ B = 100 G. We propose that an accurate determination of the Magnetic Field Vector can be achieved by decreasing the photon noise to a point where most of the observed profiles posses Stokes Q or U profiles that are above the noise level. Unfortunately, for noise levels as low as 2.8 × 10 −4 , only 30 % of the observed region with Hinode/SP have sufficiently strong Q or U signals, implying that the Magnetic Field Vector remains unknown in the rest of the internetwork.
J. M. Borrero - One of the best experts on this subject based on the ideXlab platform.
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inferring the Magnetic Field Vector in the quiet sun iii disk variation of the stokes profiles and isotropism of the Magnetic Field
Astronomy and Astrophysics, 2013Co-Authors: J. M. Borrero, Philippe KobelAbstract:Recent investigations of the Magnetic Field Vector properties in the solar internetwork have provided diverging results. While some works found that the internetwork is mostly pervaded by horizontal Magnetic Fields, other works argued in favor of an isotropic distribution of the Magnetic Field Vector. Motivated by these seemingly contradictory results and by the fact that most of these works have employed spectropolarimetric data at disk center only, we have revisited this problem employing high-quality data (noise level sigma approximate to 3 x 10(-4) in units of the quiet-Sun intensity) at different latitudes recorded with the Hinode/SP instrument. Instead of applying traditional inversion codes of the radiative transfer equation to retrieve the Magnetic Field Vector at each spatial point on the solar surface and studying the resulting distribution of the Magnetic Field Vector, we surmised a theoretical distribution function of the Magnetic Field Vector and used it to obtain the theoretical histograms of the Stokes profiles. These histograms were then compared to the observed ones. Any mismatch between them was ascribed to the theoretical distribution of the Magnetic Field Vector, which was subsequently modified to produce a better fit to the observed histograms. With this method we find that Stokes profiles with signals above 2 x 10(-3) (in units of the continuum intensity) cannot be explained by an isotropic distribution of the Magnetic Field Vector. We also find that the differences between the histograms of the Stokes profiles observed at different latitudes cannot be explained in terms of line-of-sight effects. However, they can be explained by a distribution of the Magnetic Field Vector that inherently varies with latitude. We note that these results are based on a series of assumptions that, although briefly discussed in this paper, need to be considered in more detail in the future.
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inferring the Magnetic Field Vector in the quiet sun iii disk variation of the stokes profiles and isotropism of the Magnetic Field
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:We have studied the angular distribution of the Magnetic Field Vector in the solar internetwork employing high-quality data (noise level $\sigma \approx 3\times 10^{-4}$ in units of the quiet-Sun intensity) at different latitudes recorded with the Hinode/SP instrument. Instead of applying traditional inversion codes of the radiative transfer equation to retrieve the Magnetic Field Vector at each spatial point on the solar surface and studying the resulting distribution of the Magnetic Field Vector, we surmised a theoretical distribution function of the Magnetic Field Vector and used it to obtain the theoretical histograms of the Stokes profiles. These histograms were then compared to the observed ones. Any mismatch between them was ascribed to the theoretical distribution of the Magnetic Field Vector, which was subsequently modified to produce a better fit to the observed histograms. With this method we find that Stokes profiles with signals above $2\times 10^{-3}$ (in units of the continuum intensity) cannot be explained by an isotropic distribution of the Magnetic Field Vector. We also find that the differences between the histograms of the Stokes profiles observed at different latitudes cannot be explained in terms of line-of-sight effects. However, they can be explained by a distribution of the Magnetic Field Vector that inherently varies with latitude. We note that these results are based on a series of assumptions that, although briefly discussed in this paper, need to be considered in more detail in the future.
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inferring the Magnetic Field Vector in the quiet sun ii interpreting results from the inversion of stokes profiles
Astronomy and Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:In a previous paper, we argued that the inversion of Stokes profiles applied to spectropolarimetric observations of the solar internetwork yield unrealistically large values of the inclination of the Magnetic Field Vector (γ). This is because photon noise in Stokes Q and U are interpreted by the inversion code as valid signals, that leads to an overestimation of the transverse component B⊥, thus the inclination γ. However, our study was based on the analysis of linear polarization signals that featured only uncorrelated noise. In this paper, we develop this idea further and study this effect in Stokes Q and U profiles that also show correlated noise. In addition, we extend our study to the three components of the Magnetic Field Vector, as well as the Magnetic filling factor α. With this, we confirm the tendency to overestimate γ when inverting linear polarization profiles that, although non-zero, are still below the noise level. We also establish that the overestimation occurs mainly for Magnetic Fields that are nearly vertical γ 20 ◦ . This indicates that a reliable inference of the inclination of the Magnetic Field Vector cannot be achieved by analyzing only Stokes I and V. In addition, when inverting Stokes Q and U profiles below the noise, the inversion code retrieves a randomly uniform distribution of the azimuth of the Magnetic Field Vector φ. To avoid these problems, we propose only inverting Stokes profiles for which the linear polarization signals are sufficiently above the noise level. However, this approach is also biased because, in spite of allowing for a very accurate retrieval of the Magnetic Field Vector from the selected Stokes profiles, it selects only profiles arising from highly inclined Magnetic Fields.
-
inferring the Magnetic Field Vector in the quiet sun ii interpreting results from the inversion of stokes profiles
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: J. M. Borrero, Philippe KobelAbstract:In a previous paper, we argued that the inversion of Stokes profiles applied to spectropolarimetric observations of the solar internetwork yield unrealistically large values of the inclination of the Magnetic Field Vector ($\gamma$). This is because photon noise in Stokes $Q$ and $U$ are interpreted by the inversion code as valid signals, that leads to an overestimation of the transverse component $B_\perp$, thus the inclination $\gamma$. However, our study was based on the analysis of linear polarization signals that featured only uncorrelated noise. In this paper, we develop this idea further and study this effect in Stokes $Q$ and $U$ profiles that also show correlated noise. In addition, we extend our study to the three components of the Magnetic Field Vector, as well as the Magnetic filling factor $\alpha$. With this, we confirm the tendency to overestimate $\gamma$ when inverting linear polarization profiles that, although non-zero, are still below the noise level. We also establish that the overestimation occurs mainly for Magnetic Fields that are nearly vertical $\gamma \lesssim 20\deg$. This indicates that a reliable inference of the inclination of the Magnetic Field Vector cannot be achieved by analyzing only Stokes $I$ and $V$. In addition, when inverting Stokes $Q$ and $U$ profiles below the noise, the inversion code retrieves a randomly uniform distribution of the azimuth of the Magnetic Field Vector $\phi$. To avoid these problems, we propose only inverting Stokes profiles for which the linear polarization signals are sufficiently above the noise level. However, this approach is also biased because, in spite of allowing for a very accurate retrieval of the Magnetic Field Vector from the selected Stokes profiles, it selects only profiles arising from highly inclined Magnetic Fields.
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inferring the Magnetic Field Vector in the quiet sun i photon noise and selection criteria
Astronomy and Astrophysics, 2011Co-Authors: J. M. Borrero, Philippe KobelAbstract:In the past, spectropolarimetric data from Hinode/SP were employed to infer the distribution of the Magnetic Field Vector in the quiet Sun. While some authors found predominantly horizontal Magnetic Fields, others favor an isotropic distribution. We investigate whether it is actually possible to accurately retrieve the Magnetic Field Vector in regions with very low polarization signals (e.g. internetwork), employing the FeI line pair at 6300 A. We first perform inversions of the Stokes Vector observed with Hinode/SP in the quiet Sun at disk center in order to confirm the distributions retrieved by other authors. We then carry out several Monte-Carlo simulations with synthetic data, with which we show that the observed distribution of the Magnetic Field Vector can be explained in terms of purely vertical (γ = 0 ◦ ) and weak Fields ( ¯ B < 20 G), which are misinterpreted by the analysis technique (Stokes inversion code) as being horizontal (γ ≈ 90 ◦ ) and stronger ( ¯ B ≈ 100 G), owing to the effect of the photon noise. This challenges the correctness of previous results, which presented the distributions for the Magnetic Field Vector peaking at γ = 90 ◦ and ¯ B = 100 G. We propose that an accurate determination of the Magnetic Field Vector can be achieved by decreasing the photon noise to a point where most of the observed profiles posses Stokes Q or U profiles that are above the noise level. Unfortunately, for noise levels as low as 2.8 × 10 −4 , only 30 % of the observed region with Hinode/SP have sufficiently strong Q or U signals, implying that the Magnetic Field Vector remains unknown in the rest of the internetwork.
Asensio A Ramos - One of the best experts on this subject based on the ideXlab platform.
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analysis of spatially deconvolved polar faculae
Monthly Notices of the Royal Astronomical Society, 2016Co-Authors: Quintero C Noda, Ruiz B Cobo, Toshifumi Shimizu, Yasuharu Suematsu, Asensio A RamosAbstract:Polar faculae are bright features that can be detected in solar limb observations and they are related to Magnetic Field concentrations. Although there is 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/SP 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.
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height variation of the Vector Magnetic Field in solar spicules
arXiv: Solar and Stellar Astrophysics, 2015Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Proving the Magnetic configuration of solar spicules has hitherto been difficult due to the lack of spatial resolution and image stability during off-limb ground-based observations. We report spectropolarimetric observations of spicules taken in the He I 1083 nm spectral region with the Tenerife Infrared Polarimeter II at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife; Canary Islands; Spain). The data provide the variation with geometrical height of the Stokes I, Q, U, and V profiles whose encoded information allows the determination of the Magnetic Field Vector by means of the HAZEL inversion code. The inferred results show that the average Magnetic Field strength at the base of solar spicules is about 80 gauss and then it decreases rapidly with height to about 30 gauss at a height of 3000 km above the visible solar surface. Moreover, the Magnetic Field Vector is close to vertical at the base of the chromosphere and has mid inclinations (about 50 degree) above 2 Mm height.
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height variation of the Vector Magnetic Field in solar spicules
The Astrophysical Journal, 2015Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Proving the Magnetic configuration of solar spicules has hitherto been difficult due to the lack of spatial resolution and image stability during off-limb ground-based observations. We report spectropolarimetric observations of spicules taken in the He i 1083 nm spectral region with the Tenerife Infrared Polarimeter II at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife, Canary Islands, Spain). The data provide the variation with geometrical height of the Stokes I, Q, U, and V profiles, whose encoded information allows the determination of the Magnetic Field Vector by means of the HAZEL inversion code. The inferred results show that the average Magnetic Field strength at the base of solar spicules is about 80 gauss, and then it decreases rapidly with height to about 30 gauss at a height of 3000 km above the visible solar surface. Moreover, the Magnetic Field Vector is close to vertical at the base of the chromosphere and has mid-inclinations (about 50°) above 2 Mm height.
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the Magnetic Field configuration of a solar prominence inferred from spectropolarimetric observations in the he i 10 830 a triplet
Astronomy and Astrophysics, 2014Co-Authors: Asensio A Ramos, Orozco D Suarez, Trujillo J BuenoAbstract:Context. Determining the Magnetic Field Vector in quiescent solar prominences is possible by interpreting the Hanle and Zeeman effects in spectral lines. However, observational measurements are scarce and lack high spatial resolution. Aims. We determine the Magnetic Field Vector configuration along a quiescent solar prominence by interpreting spectropolarimetric measurements in the He i 1083.0 nm triplet obtained with the Tenerife Infrared Polarimeter installed at the German Vacuum Tower Telescope of the Observatorio del Teide. Methods. The He i 1083.0 nm triplet Stokes profiles were analyzed with an inversion code that takes the physics responsible for the polarization signals in this triplet into account. The results are put into a solar context with the help of extreme ultraviolet observations taken with the Solar Dynamic Observatory and the Solar Terrestrial Relations Observatory satellites. Results. For the most probable Magnetic Field Vector configuration, the analysis depicts a mean Field strength of 7 gauss. We do not find local variations in the Field strength except that the Field is, on average, lower in the prominence body than in the prominence feet, where the Field strength reaches ∼25 gauss. The averaged Magnetic Field inclination with respect to the local vertical is ∼77 ◦ .T he acute angle of the Magnetic Field Vector with the prominence main axis is 24 ◦ for the sinistral chirality case and 58 ◦ for the dextral chirality. These inferences are in rough agreement with previous results obtained from the analysis of data acquired with lower spatial resolutions.
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advanced forward modeling and inversion of stokes profiles resulting from the joint action of the hanle and zeeman effects
The Astrophysical Journal, 2008Co-Authors: Asensio A Ramos, Trujillo J Bueno, Landi E DeglinnocentiAbstract:A big challenge in solar and stellar physics in the coming years will be to decipher the magnetism of the solar outer atmosphere (chromosphere and corona) along with its dynamic coupling with the Magnetic Fields of the underlying photosphere. To this end, it is important to develop rigorous diagnostic tools for the physical interpretation of spectropolarimetric observations in suitably chosen spectral lines. Here we present a computer program for the synthesis and inversion of Stokes profiles caused by the joint action of atomic level polarization and the Hanle and Zeeman effects in some spectral lines of diagnostic interest, such as those of the He I 10830 A and 5876 A (or D3) multiplets. It is based on the quantum theory of spectral line polarization, which takes into account in a rigorous way all the relevant physical mechanisms and ingredients (optical pumping, atomic level polarization, level crossings and repulsions, Zeeman, Paschen-Back, and Hanle effects). The influence of radiative transfer on the emergent spectral line radiation is taken into account through a suitable slab model. The user can either calculate the emergent intensity and polarization for any given Magnetic Field Vector or infer the dynamical and Magnetic properties from the observed Stokes profiles via an efficient inversion algorithm based on global optimization methods. The reliability of the forward modeling and inversion code presented here is demonstrated through several applications, which range from the inference of the Magnetic Field Vector in solar active regions to determining whether or not it is canopy-like in quiet chromospheric regions. This user-friendly diagnostic tool called HAZEL (from HAnle and ZEeman Light) is offered to the astrophysical community, with the hope that it will facilitate new advances in solar and stellar physics.
David D. Awschalom - One of the best experts on this subject based on the ideXlab platform.
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Vector Magnetic Field microscopy using nitrogen vacancy centers in diamond
Applied Physics Letters, 2010Co-Authors: B. J. Maertz, A. P. Wijnheijmer, M. E. Nowakowski, Gregory D. Fuchs, David D. AwschalomAbstract:The localized spin triplet ground state of a nitrogen vacancy (NV) center in diamond can be used in atomic-scale detection of local Magnetic Fields. Here we present a technique using ensembles of these defects in diamond to image Fields around Magnetic structures. We extract the local Magnetic Field Vector by probing resonant transitions of the four fixed tetrahedral NV orientations. In combination with confocal microscopy techniques, we construct a two-dimensional image of the local Magnetic Field Vectors. Measurements are done in external Fields less than 50 G and under ambient conditions.
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Vector Magnetic Field microscopy using nitrogen vacancy centers in diamond
Applied Physics Letters, 2010Co-Authors: B. J. Maertz, A. P. Wijnheijmer, M. E. Nowakowski, Gregory D. Fuchs, David D. AwschalomAbstract:The localized spin triplet ground state of a nitrogen vacancy (NV) center in diamond can be used in atomic-scale detection of local Magnetic Fields. Here we present a technique using these defects in diamond to image Fields around Magnetic structures. We extract the local Magnetic Field Vector by probing resonant transitions of the four fixed tetrahedral NV orientations. In combination with confocal microscopy techniques, we construct a 2-dimensional image of the local Magnetic Field Vectors. Measurements are done in external Fields less than 50 G and under ambient conditions.
