405 research outputs found

    He-D3 Polarization observed in Prominences

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    Spectro-polarimetric measurements of the D3-HeI 5876 A line profile in 35 prominences have been performed in 2003 with the Gregory-Coud\'e Telescope in Locarno. Two different experimental techniques (ZIMPOL and Beam-exchange method) have been successfully employed to determine all four Stokes components. Both give compatible results. The preliminary results as well as the measurement techniques are reported.Comment: 4 pages, 4 figures, Latex, Proceedings "Solar Magnetic Phenomena" Summerschool & Workshop at the Kanzelhoehe Solar Observatory 200

    Evidence for the two fluid scenario in solar prominences

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    This paper presents observational evidence of the different dynamical behavior of neutral and ionized species in solar prominences. The analysis of a time-series of Sr II 4078 A and Na D spectra in a quiescent prominence yields systematically larger Doppler shifts (line-of-sight velocities) for the ions V_LOS(Sr II)= 1.22 x V_LOS (Na D). Both lines show a 30 min oscillation of good coherence. Sixteen hours later the same prominence underwent marked morphological changes (with a rising dome), and the Sr II velocity excess drops to V_LOS(Sr II)=1.11 x V_LOS(Na D). The same excess is found for the line pair Fe II 5018 A and He I 5015 A. The widths of the ionic lines, mainly non-thermally broadened, are not related to the macro velocities. The emission ratio of Na D and Sr II, a measure of the electron density, yields n_e = 4 x 10^10 1/cm, shows no relation with the V_LOS variation or with height above the limb, and seems to be reduced 16 hr later during the active phase. We apply a new wavelength reference from aureola spectra, which is independent of photospheric velocity fields

    Origin of spatial variations of scattering polarization in the wings of the Ca {\sc i} 4227 \AA line

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    Polarization that is produced by coherent scattering can be modified by magnetic fields via the Hanle effect. According to standard theory the Hanle effect should only be operating in the Doppler core of spectral lines but not in the wings. In contrast, our observations of the scattering polarization in the Ca {\sc i} 4227 \AA line reveals the existence of spatial variations of the scattering polarization throughout the far line wings. This raises the question whether the observed spatial variations in wing polarization have a magnetic or non-magnetic origin. A magnetic origin may be possible if elastic collisions are able to cause sufficient frequency redistribution to make the Hanle effect effective in the wings without causing excessive collisional depolarization, as suggested by recent theories for partial frequency redistribution with coherent scattering in magnetic fields. To model the wing polarization we apply an extended version of the technique based on the "last scattering approximation". This model is highly successful in reproducing the observed Stokes Q/IQ/I polarization (linear polarization parallel to the nearest solar limb), including the location of the wing polarization maxima and the minima around the Doppler core, but it fails to reproduce the observed spatial variations of the wing polarization in terms of magnetic field effects with frequency redistribution. This null result points in the direction of a non-magnetic origin in terms of local inhomogeneities (varying collisional depolarization, radiation-field anisotropies, and deviations from a plane-parallel atmospheric stratification).Comment: Accepted in May 2009 for publication in The Astrophysical Journa

    Helium Emissions Observed in Ground-Based Spectra of Solar Prominences

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    The only prominent line of singly ionized helium in the visible spectral range, helium-II 4686 A, is observed together with the helium-I 5015 A singlet and the helium-I 4471 A triplet line in solar prominences. The sodium emission, NaD2, is used as a tracer for helium-II emissions which are sufficiently bright to exceed the noise level near 10^-6 of the disk-center intensity. The so selected prominences are characterized by small non-thermal line broadening and almost absent velocity shifts, yielding narrow line profiles without wiggles. The reduced widths [Delta(lambda_D) / lambda] of helium-II 4686 A are 1.5 times broader than those of helium-I 4471 A triplet and 1.65 times broader than those of helium-I 5015 A singlet. This indicates that the helium lines originate in a prominence--corona transition region with outwards increasing temperature.Comment: 12 pages, 5 figure, 3 table

    Comparison of theoretical and observed Ca~{\sc ii}~8542 Stokes profiles in quiet regions at the centre of the solar disc

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    Interpreting the Stokes profiles observed in quiet regions of the solar chromosphere is a challenging task. The Stokes Q and U profiles are dominated by the scattering polarisation and the Hanle effect, and these processes can only be correctly quantified if 3D radiative transfer effects are taken into account. Forward-modelling of the intensity and polarisation of spectral lines using a 3D model atmosphere is a suitable approach in order to statistically compare the theoretical and observed line profiles. Our aim is to present novel observations of the Ca 8542 line profiles in a quiet region at the centre of the solar disc and to quantitatively compare them with the theoretical Stokes profiles. We aim at estimating the reliability of the 3D model atmosphere using not only the line intensity but the full vector of Stokes parameters. We used data obtained with the ZIMPOL instrument at the IRSOL and compared the observations with the theoretical profiles computed with the PORTA radiative transfer code, using as solar model atmosphere a 3D snapshot taken from a radiation-magnetohydrodynamics simulation. The synthetic profiles were degraded to match the instrument and observing conditions. The degraded theoretical profiles of the Ca 8542 line are qualitatively similar to the observed ones. We confirm that there is a fundamental difference in the widths of all Stokes profiles: the observed lines are wider than the theoretical lines. We find that the amplitudes of the observed profiles are larger than those of the theoretical ones, which suggests that the symmetry breaking effects in the solar chromosphere are stronger than in the model atmosphere. This means that the isosurfaces of temperature, velocity, and magnetic field strength and orientation are more corrugated in the solar chromosphere than in the currently available 3D radiation-magnetohydrodynamics simulation

    PENGARUH LOGISTICS SERVICE QUALITY TERHADAP CUSTOMER SATISFACTION CAT EMCO PT SATRIAKARYA ADIYUDHA (PT SKAY)

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    Penelitian ini dilakukan untuk mengetahui pengaruh logistics service quality terhadap customer satisfaction cat Emco PT Satriakarya Adiyudha (PT SKAY). Untuk mengukur kepuasan pelanggan maka dipergunakan logistics service quality terutama pada 7 dimensi yaitu order release quantities, information quality, ordering procedures, order accuracy, order condition, order discrepancy handling dan timeliness. Pada penelitian kausal ini digunakan pendekatan penelitian kuantitatif dengan membagikan kuesioner kepada 100 responden yang merupakan toko bahan bangunan pelanggan cat Emco di PT SKAY. Teknik analisis data yang digunakan adalah analisis regresi linear berganda. Hasil penelitian menunjukkan bahwa variabel logistics service quality berpengaruh terhadap customer satisfaction dan dimensi logistics service quality yang berpengaruh paling dominan terhadap customer satisfaction adalah ordering procedure

    Calibration of the 6302/6301 Stokes V line ratio in terms of the 5250/5247 ratio

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    Four decades ago the Stokes V line ratio in the Fe I 5247.06 and 5250.22 {\AA} lines was introduced as a powerful means of exploring the intrinsic field strengths at sub-pixel scales, which led to the discovery that most of the photospheric flux is in intermittent kG form. The "green" 5247-5250 line pair is unique because it allows the magnetic-field effects to be isolated from the thermodynamic effects. No other line pair with this property has since been identified. In recent years much of the magnetic-field diagnostics has been based on the "red" Fe I 6301.5 and 6302.5 {\AA} line pair, since it was chosen in the design of the Hinode space observatory. Although thermodynamic effects severely contaminate the magnetic-field signatures for this line ratio, it is still possible to use it to extract information on intrinsic magnetic fields, but only after it has been "renormalized", since otherwise it produces fictitious, superstrong fields everywhere. In the present work we explore the joint behavior of these two line ratios to determine how the "contaminated" red line ratio can be translated into the corresponding green line ratio, which then allows for a direct interpretation in terms of intrinsic magnetic fields. Our observations are mainly based on recordings with the ZIMPOL-3 spectro-polarimeter at IRSOL in Locarno, Switzerland, complemented by data from the STOP telescope at the Sayan solar observatory (Irkutsk, Russia). The IRSOL observations are unique by allowing both the green and red line pairs to be recorded simultaneously on the same CCD sensor. We show how the line ratios depend on both the measured flux densities and on the heliocentric distance (the \mu\ value on the solar disk), and finally derive the calibration function that enables the red line ratio to be translated to the green ratio for each \mu\ value
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