scholarly journals Observation of the Linear Polarization of Pulsar Integrated Pulses and Sub-Pulses at Meter Wavelengths

1992 ◽  
Vol 128 ◽  
pp. 387-390
Author(s):  
S. A. Suleymanova ◽  
V. D. Pugachev
Keyword(s):  
Measurement Technique ◽  
Linear Polarization ◽  
Statistical Distributions ◽  
Average Polarization ◽  
Polarization Profiles

AbstractA brief review of polarization observations at 103, 60, and 40 MHz is given. Our peculiar measurement technique allows us to obtain average polarization profiles as well as statistical distributions of the polarization parameters of individual pulses and subpulses. Some examples are given in this paper.

scholarly journals Polarization in Pulsar Radio Emission

1992 ◽  
Vol 128 ◽  
pp. 384-386
Author(s):  
D. M. GOULD
Keyword(s):  
Radio Emission ◽  
Circular Polarization ◽  
Linear Polarization ◽  
Large Data ◽  
Position Angle ◽  
Published Data ◽  
Data Set ◽  
Pulsar Radio ◽  
Polarization Profiles ◽  
Pulsar Radio Emission

Polarimetric observations of over 300 pulsars have been carried out between 21 December 1988 and 22 January 1990 at 606, 610, 925, and 1408 MHz using the Lovell Telescope at Jodrell Bank. Many of these pulsars have no previously published polarization profiles and will be published shortly (Gould and Lyne 1990). This large data set along with previously published data from various sources, has been used to test the correlation found by Radhakrishnan and Rankin (1990) between sense reversing circular polarization signatures and the accompanying sense of rotation of the linear polarization position angle.

Parametric Study of Molecular Line Polarization in the Solar Atmosphere

2000 ◽  
Vol 179 ◽  
pp. 269
Author(s):  
K. E. Rangarajan ◽  
D. Mohan Rao
Keyword(s):  
Solar Atmosphere ◽  
Linear Polarization ◽  
Parametric Study ◽  
Elastic Collision ◽  
The Other ◽  
Strong Line ◽  
Molecular Line ◽  
Physical Constraints ◽  
Molecular Lines ◽  
Polarization Profiles

Extended AbstractThe polarimetric observations of the quiet sun show linear polarization in molecular lines of C2, MgH, etc. The molecular lines are very faint in the intensity spectrum. Q branch transitions of MgH are considered in this study. Using radiative transfer calculations, we find that the intensity and polarization profiles of MgH lines can be matched for a range of inelastic collisional rates (ΓI) and depolarizing elastic collision rates (D(2)) of the transitions in solar atmosphere. It is shown that the physical constraints imposed on these parameters can be used to estimate them. This procedure also allows us to get the oscillator strength (f). It is found for the strong line 5156.652 Å,f= 0.12, ΓI, = 5.59 × l07sec−1andD(2)= 1.29 × 108sec−1. Most of the other lines observed are weak by a factor of 3 in intensity compared to the 5156.652 Å line but show a polarization value of the order of 0.08%. One such typical line is 5156.997 Å. This line can be fitted for the parametersf= 0.04, ΓI, = 1.22 × 107sec−1andD(2)= 2.95 × 107sec−1.

scholarly journals Master equation theory applied to the redistribution of polarized radiation in the weak radiation field limit

2020 ◽  
Vol 644 ◽  
pp. A65
Author(s):  
Véronique Bommier
Keyword(s):  
Linear Polarization ◽  
Computing Time ◽  
Solar Spectrum ◽  
Polarization Degree ◽  
Line Center ◽  
Present Calculation ◽  
Thermodynamical Equilibrium ◽  
Numerical Application ◽  
Instrumental Polarization ◽  
Polarization Profiles

Context. This paper presents a numerical application of a self-consistent theory of partial redistribution in nonlocal thermodynamical equilibrium conditions, developed in previous papers of the series. Aims. The code was described in IV of this series. However, in that previous paper, the numerical results were unrealistic. The present paper presents an approximation able to restore the reliability of the outgoing polarization profiles. Methods. The convergence of the results is also proved. It is demonstrated that the step increment decreases like 1/Nα, with α >  1. Results. Thanks to these additions, the results series behaves like a Riemann series, which is absolutely convergent. However, convergence is not fully reached in line wings within the allocated computing time. Development of efficient acceleration methods would be desirable for future work. Conclusions. Agreement between the computed and observed linear polarization profiles remains qualitative only. The discrepancy is assigned to the plane parallel atmosphere model, which is insufficient to describe the chromosphere, where these lines are formed. As all the integrals are numerical in the code, it could probably be adapted to more realistic and higher dimensional model atmospheres. However, this is time consuming for lines with a hyperfine structure, as in the Na I D lines. The net linear polarization observed in Na I D1 with the Zürich Imaging Polarimeter ZIMPOL mounted on the McMath-Pierce telescope at Kitt Peak is not confirmed by the present calculations and could be an artefact of instrumental polarization. The presence of instrumental polarization could be confirmed by the higher linear polarization degree observed by this instrument in the Na I D2 line center with respect to the present calculation result where the magnetic field is not accounted for. At this precise point, the Hanle effect acts as a depolarizing effect in the second solar spectrum. The observed linear polarization excess is found to be of the same order of magnitude in both line centers, namely 0.1%, which is also comparable to the instrumental polarization compensation level of this experiment.

scholarly journals A Decade of Low Frequency Pulsar Polarimetry at PRAO: a Review of the Main Results

2000 ◽  
Vol 177 ◽  
pp. 201-204
Author(s):  
Svetlana A. Suleymanova ◽  
V.D. Pugachev
Keyword(s):  
Linear Polarization ◽  
High Frequency ◽  
Low Frequency ◽  
Statistical Distribution ◽  
Polarization Measurements ◽  
Radio Frequencies ◽  
Polarization Profiles

AbstractThe main results of the linear polarization measurements of pulsars done at the lowest radio frequencies 40, 60 and 103 MHz are summarized in this paper. We have analyzed 35 integrated polarization profiles and 20 statistical distribution displays and compared them with published high frequency results.

scholarly journals Polarimetric Observations of 20 Weak Pulsars at 1720 Mhz

1992 ◽  
Vol 128 ◽  
pp. 165-171
Author(s):  
Kiriaki M. Xilouris ◽  
Joanna M. Rankin ◽  
John H. Seiradakis ◽  
Wolfgang Sieber
Keyword(s):  
Radio Telescope ◽  
High Frequency ◽  
Stokes Parameters ◽  
Average Polarization ◽  
On Line ◽  
Polarization Profiles ◽  
First Time

We present average polarization profiles for 20 pulsars at 1720 MHz made with the 100-m Effelsberg radio telescope. All four Stokes parameters were appropriately delayed in a linear dedisperser to correct the interstellar dispersion on-line. Our sample includes a number of complex profiles which were observed polarimetrically for the first time at a high frequency, with the aim of describing their frequency evolution. Classification of the corrected profiles is attempted according to the empirical pulsar model described earlier by Rankin(1990).

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