Linear Polarization Parameters Research Articles

Novel schiff base-azide metal complexes: Synthesis, spectral, nonlinear optics, and DFT studies

In order to enhance nonlinear optics (NLO)-based technologies, current research focuses on the design and synthesis of coordination materials. In this context, to investigate spectral and theoretical linear optical (LO)/nonlinear optical (NLO) behaviors, novel metal complexes including azide {[Mn (L1)2(N3)2], (9), [Ni(L1)2(N3)], (10), [Co2(L1)2(N3)2]⋅2H2O, (11); L1: N-(pyridin-2-ylmethylene)methanamine} were synthesized. The vibrational and electronic spectral features of complexes 9–11 were investigated by UV–Vis and FT–IR spectra. Depending on the central metal ion and coordination geometries of complexes, the microscopic static nonlinear behaviors were examined by using the CAM-B3LYP/and ωB97XD/6–311 + G (d,p)//LanL2DZ levels of density functional theory (DFT). Furthermore, the vibrational and electronic properties of complexes 9–11 based on the same levels of time-dependent/density functional theory (TD-DFT/DFT) were surveyed. Additionally, the theoretical χ(1), χ(2), and χ(3) parameters, known as linear optical, second-, and third-order nonlinear optical susceptibility tensors, as well as linear, second-, and third-order polarization parameters (P(1), P(2), and P(3)) for complexes 9–11 were examined. The greatest <β(0; 0,0)> value for complex 10 found to be 262.55 × 10−30 esu using CAM-B3LYP level is 820.5 and 2019.6 times higher than the urea findings (0.32 × 10−30 esu and 0.130 × 10−30 esu). The <γ(0; 0,0,0)> results indicate that complex 9 having the highest value obtained at 2216.40 × 10−36 esu using CAM-B3LYP level is 47.76 and 316.63 times greater than those of pNA (15 × 10−36 esu) and urea (7 × 10−36 esu), respectively. Complexes 10 and 9 demonstrated promising microscopic second-order and third-order NLO features, respectively. Our research is anticipated to provide insight into NLO materials that may have applications in optoelectronics and telecommunication field.

The Analysis and Experiment of Pixel-Matching Method for Space-Dimensional Dual-Coded Spectropolarimeter

In order to meet the high accuracy pixel-matching requirements of space-dimensional dual-coded spectropolarimeter, a dual-coded image pixel-matching method based on dispersion modulation is proposed. The mathematics of the dispersion power and the pixel matching is modeled. The relationship between different pixel-matching coefficients and the peak signal-to-noise ratio (PSNR) and structure similarity index measure (SSIM) of reconstructed images is analyzed. An imaging system experiment consisting of a digital micromirror device (DMD), a micro-polarizer array detector (MPA), and a prism–grating–prism (PGP) is built to reconstruct a spectral linear polarization data cube with 50 spectral channels and linear polarization parameters. The contrast ratio of the reconstructed spectropolarimeter image was raised 68 times against the ground truth. It can be seen from the reconstruction evaluation analysis that the spectral data and polarization data can be matched effectively by optimizing the dispersion coefficient of the PGP. The system can effectively reconstruct when the noise SNR is greater than 15 dB. The PSNR and SSIM of the reconstruction images can be improved by increasing the pixel-matching spacing. The optimal choice of the dual-coded pixel-matching spacing is one super-polarized pixel. The spectral resolution and quality of the spectropolarimeter are improved using the pixel-matching method.

Probing axions via light circular polarization and event horizon telescope

The impact of axion-like particles on the light polarization around the horizon of supermassive black hole (SMBH) is discussed in the light of the latest polarization measurement of the Event Horizon Telescope (EHT). We investigate different sources of the polarization due to axion interaction with photons and the magnetic field of SMBH. These can modify the linear and circular polarization parameters of the emitted light. We have shown that a significant circular polarization can be produced via the photon scattering from the background magnetic field with axions as off-shell particles. This can further constrain the parameter space of ultralight axion-like particles and their couplings with photons. The future precise measurements of circular polarization can probe the features of ultralight axions in the near vicinity of SMBH.

Investigation of backbone dynamics and local geometry of bio-molecules using calculated NMR chemical shifts and anisotropies.

Prerequisite for chemical shift (CS) and CS tensor calculations are highly refined structures defining the molecular surroundings of the nuclei under study. Here, we present geometry optimizations with 13C and 15N CS constraints for large bio-molecules like peptides and proteins. The method discussed here provides both, refined structures and chemical shift tensors. Furthermore, since the experimental resonances of aligned systems are related to CS tensors, they strongly depend on the orientation and motion of molecules, their fragments, functional groups and moieties. For efficient CS calculations we apply a semi-empirical approach-the bond polarization theory (BPT). The BPT relies on linear bond polarization parameters and we present a new set of parameters based on ab initio second-order Møller-Plesset perturbation theory calculations. The new parametrization extends the applicability of the BPT approach to a wide range of organic molecules and bio-polymers. Here, the method has been applied to the protein ubiquitin and the membrane-active peptide gramicidin A (dimer) in oriented bilayers. The calculated 13C and 15N CS values of best-refined structures published until now gave a large scatter with respect to the experiment. It will be shown that BPT CS optimizations can reduce these errors to values near the experimental uncertainty. In combination with molecular dynamics with orientational constraints it is possible to study motional dynamics and BPT calculations can provide residual chemical shift anisotropies.

Wind Speed Retrieval from Simulated RADARSAT Constellation Mission Compact Polarimetry SAR Data for Marine Application

RADARSAT Constellation Mission (RCM) compact polarimetry (CP) data were simulated using 504 RADARSAT-2 quad-pol SAR images. These images were used to samples CP data in three RCM modes to build a data set with co-located ocean wind vector observations from in situ buoys on the West and East coasts of Canada. Wind speeds up to 18 m/s were included. CP and linear polarization parameters were related to the C-band model (CMOD) geophysical model functions CMOD-IFR2 and CMOD5n. These were evaluated for their wind retrieval potential in each RCM mode. The CP parameter Conformity was investigated to establish a data-quality threshold (&gt;0.2), to ensure high-quality data for model validation. An accuracy analysis shows that the first Stokes vector (SV0) and the right-transmit vertical-receive backscatter (RV) parameters were as good as the VV backscatter with CMOD inversion. SV0 produced wind speed retrieval accuracies between 2.13 m/s and 2.22 m/s, depending on the RCM mode. The RCM Medium Resolution 50 m mode produced the best results. The Low Resolution 100 m and Low Noise modes provided similar results. The efficacy of SV0 and RV imparts confidence in the continuity of robust wind speed retrieval with RCM CP data. Three image-based case studies illustrate the potential for the application of CP parameters and RCM modes in operational wind retrieval systems. The results of this study provide guidance to direct research objectives once RCM is launched. The results also provide guidance for operational RCM data implementation in Canada’s National SAR winds system, which provides near-real-time wind speed estimates to operational marine forecasters and meteorologists within Environment and Climate Change Canada.

Influence of the Disk Wind on the Intrinsic Polarization of Young Stars

The behavior of the linear polarization parameters of UX Ori stars during their eclipses by circumstellar dust clouds is studied. A circumstellar disk with a disk wind creating a puffing in the dust sublimation zone is considered. We show that the disk puffing can strongly affect the degree of polarization and color index of the star during its eclipse. A strong wind can change the orientation of the plane of linear polarization. The scattered radiation from a thin disk is polarized perpendicularly to its plane, but the radiation from a disk with a strong wind can be polarized along the disk plane. A situation where the disk-scattered radiation is not polarized in a certain spectral band is possible owing to the disk puffing. There can be different orientations of the linear polarization of the disk radiation in different spectral bands.

High cadence, linear, and circular polarization monitoring of OJ 287

Aims. We present a multifrequency, dense radio monitoring program of the blazar OJ 287 using the 100-m Effelsberg radio telescope. The program aims to test different binary supermassive black hole (SMBH) scenarios and studying the physical conditions in the central region of this bright blazar. Here, we analyze the evolution in total flux density, linear and circular polarization as a means to study the OJ 287 jet structure and its magnetic field geometry. Methods. We used a recently developed, high-precision data analysis methodology to recover all four Stokes parameters. We measured the total flux density of OJ 287 at nine bands from 2.64 GHz to 43 GHz, the linear polarization parameters at four bands between 2.64 GHz and 10.45 GHz, and the circular polarization at two bands, 4.85 GHz and 8.35 GHz. The mean cadence of our measurements is ten days. Results. Between December 2015 and January 2017 (MJD 57370–57785), OJ 287 showed flaring activity and complex linear and circular polarization behavior. The radio electric vector position angle (EVPA) showed a large clockwise (CW) rotation by ∼340° with a mean rate of −1.04°/day. Based on concurrent very long baseline interferometric (VLBI) polarization data at 15 GHz and 43 GHz, the rotation seems to originate within the jet core at 43 GHz (projected angular size ≤0.15 mas or 0.67 pc at the redshift of the source). Moreover, optical polarization data show a similar monotonic CW rotation with a rate of about −1.1°/day which is superposed with shorter and faster rotations that exhibit rates of about 7.8°/day, mainly in the CW sense. Conclusions. The flux density and polarization variability of the single dish, VLBI and optical data is consistent with a polarized emission component propagating on a helical trajectory within a bent jet. We constrained the helix arc length to 0.26 pc and radius to ≤0.04 pc as well as the jet bending arc length projected on the plane of the sky to ≤1.9–7.6 pc. A similar bending has been observed also in high angular resolution VLBI images of the OJ 287 jet at its innermost regions. The helical trajectory covers only a part of the jet width, possibly its spine. In addition, our results indicate the presence of a stable polarized emission component. Its EVPA (−10°) is oriented perpendicular to the large scale jet, suggesting dominance of the poloidal magnetic field component. Finally, the EVPA rotation begins simultaneously with an optical flare and hence the two might be physically connected. That optical flare has been suggested to be linked to the interaction of a secondary SMBH with the inner accretion disk or originating in the jet of the primary.

Ocean Wind Study Using Simulated RCM Compact-Polarimetry SAR

. The incidence angle, wind speed, and wind direction dependence of compact polarimetry (CP) synthetic aperture radar (SAR) parameters are presented for open water. Selected CP parameters are related to C-band geophysical model function (CMOD) output. Wind speeds range between 0 and 24 m/s, and incidence angles range between 18 and 50°. SAR data are coincident with meteorological buoy data. CP parameters are simulated from polarimetric RADARSAT-2 data and emulate data available on the pending RADARSAT Constellation Mission (RCM). Analysis is performed for 20 CP parameters, based on RADARSAT-2 images. Five linear-polarization SAR parameters are included for comparison. Results show robust relationships for CP parameters related to CMOD. For CP parameters unrelated to CMOD, results provide first-, second-, or third-order linear regression models, as functions of incidence angle, wind speed, wind direction, or combinations thereof. These models provide a set of values for comparison with sea ice or other features on, or adjacent to, open water. The results of this study are of value to the Canadian Ice Service of the Meteorological Service of Canada, as well as other government of Canada departments, for implementing CP SAR data in their operational workflows once RCM is launched.Résumé. La dépendance à l’angle d’incidence, à la vitesse et à la direction du vent des paramètres mesurés en polarimétrie compacte (CP) est présentée pour l’eau libre. Les paramètres de CP sélectionnés sont liés aux sorties de la fonction du modèle géophysique en bande C (CMOD). Les vitesses du vent varient entre 0 et 24 m/s, et les angles d’incidence varient entre 18 et 50 degrés. Les données SAR coïncident avec les données des bouées météorologiques. Les paramètres en CP sont simulés à partir des données polarimétriques de RADARSAT-2, et ils simulent les données qui seront disponibles à partir de la mission de la Constellation RADARSAT prévue (MCR). L’analyse est effectuée pour 20 paramètres en CP, sur la base des images RADARSAT-2. Cinq paramètres SAR en polarisation linéaire sont inclus pour comparaison. Les résultats montrent des relations robustes pour les paramètres en CP liés à CMOD. Pour les paramètres en CP non liés à la CMOD, les résultats fournissent des modèles de régression linéaire de première, deuxième ou troisième ordre, en fonction de l’angle d’incidence, de la vitesse et de la direction du vent, ou des combinaisons de ceux-ci. Ces modèles fournissent un ensemble de valeurs de comparaison avec la glace de mer; ou d’autres éléments sur, ou à proximité de, l’eau libre. Les résultats de cette étude seront importants pour le Service canadien des glaces du Service météorologique du Canada, ainsi que pour d’autres ministères du gouvernement du Canada, pour mettre en œuvre les données SAR en CP dans leur flux de travaux opérationnels, une fois la MCR lancée.

Polarization correlations for electron-impact excitation of neon at 50 eV

We present measurements and calculations of linear and circular polarization correlations for angle-differential electron-impact excitation of the neon resonance transition at an impact energy of 50 eV, most importantly extended to large scattering angles up to 105°. The measured linear polarization parameters of the vacuum ultra-violet transition are in very good agreement with a number of theoretical predictions at all angles. At intermediate scattering angles, however, the circular polarization parameter measurements are only found to be in excellent agreement with theoretical results obtained with the B-spline R-matrix theory, but not with those from other models.

Analytical algorithm for modeling polarized solar radiation transfer through the atmosphere for application in processing complex lidar and radiometer measurements

Inversion algorithms and program packages recently created for processing data of the ground-based radiometer spectral measurements along with lidar multi-wavelength measurements are extremely multiparametric. Therefore, it is very important to develop an efficient program module for computations of functions modeling measurements by a sun-radiometer in the inversion procedure. In this paper, we present the analytical version of such efficient algorithm and analytical code on C++ designed for performance of algorithm testing. The code computes multiple scattering of the Sun light in the atmosphere. Data output are the radiance and linear polarization parameters angular patterns at a preselected altitude. The atmosphere model with mixed aerosol and molecular scattering is given approximately as the homogeneous atmosphere model. The algorithm testing has been carried out by comparison of computed data with accurate data obtained on the base of the discrete-ordinate code. Errors of estimates of downward radiance above the Earth surface turned out to be within 10%–15%.. The analytical solution construction concept has taken from the scalar task of solar radiation transfer in the atmosphere where an approximate analytical solution was developed. Taking into account the fact that aerosol phase functions are highly forward elongated, the multi-component method of solving vector transfer equations and small-angle approximation have been used. Generalization of the scalar approach to the polarization parameters is described.

Su2014 A Multichannel Wireless Mapping System for Monitoring Gastric Slow Wave Propagation

Aim To investigate the relative importance of both linear and circular polarization parameters, derived from 4x4 Mueller matrix measurements, in discriminating gastric cancer from normal gastric tissues over the visible spectral region from 470 nm to 632 nm. Methods A total of 46 tissue samples, obtained from 40 patients, were examined in this study, in which 26 normal gastric samples were obtained as endoscopic biopsies while 20 gastric cancer samples were obtained from gastrectomy. Informed consent was obtained before tissue samples were used in this study. For multiple normal samples from one single patient, the values of polarization parameters were averaged to represent only one sample in each classification. This yielded a total of 20 sets of data for normal samples and 20 sets of data for cancer samples, one set for each patient. Each sample was fixed using 10%-formalin solution before it was embedded in paraffin. Then two 4-μm vertical sections immediately next to each other were made in the sample. One tissue section was routinely stained with Hematoxylin and Eosin (H&E) to generate a pathological report. The other tissue section was not stained, which was placed on a microscope slide without a cover slip for polarimetry measurements. Results The studied polarization parameters were retardance, diattenuation and depolarization of normal and cancerous gastric samples at nine wavelengths from 470 nm to 632 nm. The average retardance of normal samples was smaller than that of cancer samples. There was no overlap in the error bars between normal samples and cancerous samples at all nine wavelengths, suggesting that retardance could be used to effectively differentiate normal and cancer samples. In contrast, there were significant overlaps in the error bars of diattenuation and depolarization between normal and cancer samples at all wavelengths. It was found that the combination of linear depolarization and linear retardance showed the highest overall accuracy (95.00%) among all the possible combinations of two parameters. This combination also demonstrated considerable improvement in overall accuracy compared to that for either linear retardance (82.50%) or linear depolarization (77.50%) alone. Conclusion There were significant differences in most polarization parameters between normal and cancer tissue samples. The combination of linear depolarization and linear retardance yielded the highest accuracy in sample classification.

Roles of linear and circular polarization properties and effect of wavelength choice on differentiation between ex vivo normal and cancerous gastric samples.

Multispectral Mueller matrix imaging was performed over a spectral range from 470 to 632 nm on 4-μm unstained gastric tissue sections. A complete set of polarization parameters was derived. The combination of linear depolarization and linear retardance yields the highest accuracy in sample classification. When the depolarization of linearly polarized light due to scattering is independent of the orientation angle of the incident linear polarization vector, the derivation of linear polarization properties will require only 3×3 Mueller matrix, which would significantly reduce the complexity of the polarimetry imaging system. When additional parameters are needed to complement the two linear polarization parameters, retardance, circular depolarization, and depolarization can be included in classification in the order of preference. However, these additional parameters would require the measurement of 4×4 Mueller matrix. In addition, it appears that wavelength is not a critical factor in terms of classification accuracy for thin tissue sections in this study.

Measurements and simulations of polarization states of underwater light in clear oceanic waters

Polarization states of the underwater light field were measured by a hyperspectral and multiangular polarimeter and a video polarimeter under various atmospheric, surface, and water conditions, as well as solar and viewing geometries, in clear oceanic waters near Port Aransas, Texas. Some of the first comprehensive comparisons were made between the measured polarized light, including the degree and angle of linear polarization and linear Stokes parameters (Q and U), and those from Monte Carlo simulations that used concurrently measured water inherent optical properties and particle volume scattering functions as input. For selected wavelengths in the visible spectrum, measured and model-simulated polarization characteristics were found to be consistent in most cases. Measured degree and angle of linear polarization are found to be largely determined by an in-water single-scattering model. Model simulations suggest that the degree of linear polarization (DoLP) at horizontal viewing directions is highly dependent on the viewing azimuth angle for a low solar elevation. This implies that animals can use the DoLP signal for orientation.

White-light channeled imaging polarimeter using broadband polarization gratings

A white-light snapshot channeled linear imaging (CLI) polarimeter is demonstrated by utilizing polarization gratings (PGs). The CLI polarimeter is capable of measuring the two-dimensional distribution of the linear Stokes polarization parameters by incorporating two identical PGs, in series, along the optical axis. In this configuration, the general optical shearing functionality of a uniaxial crystal-based Savart plate is realized. However, unlike a Savart plate, the diffractive nature of the PGs creates a linear dependence of the shear versus wavelength, thus providing broadband functionality. Consequently, by incorporating the PG-based Savart plate into a Savart plate channeled imaging polarimeter, white-light interference fringes can be generated. This enables polarimetric image data to be acquired at shorter exposure times in daylight conditions, making it more appealing over the quasi-monochromatic channeled imaging polarimeters previously described in the literature. Furthermore, the PG-based device offers significantly more compactness, field of view, optical simplicity, and vibration insensitivity than previously described white-light CLI polarimeters based on Sagnac interferometers. Included in this paper are theoretical descriptions of the linear (S(0), S(1), and S(2)) and complete (S(0), S(1), S(2), and S(3)) channeled Stokes imaging polarimeters. Additionally, descriptions of our calibration procedures and our experimental proof of concept CLI system are provided. These are followed by laboratory and outdoor polarimetric measurements of S(0), S(1), and S(2).

Estimation of linear wave polarization of the auroral kilometric radiation

There is a general view that the auroral kilometric radiation (AKR) polarization is fully circular with dominating right‐hand extraordinary mode and some admixture of the left‐hand ordinary mode. Most of up‐to‐date determinations of the wave modes of the AKR have been based on measurements of the circular component of the wave polarization, leaving the linear polarization parameters unknown. In space observations the polarimeter is usually not directed to the AKR source. However, having determined the polarization parameters in each of the three perpendicular planes, one is able to determine the polarization ellipse in the 3‐D space. Results of statistical estimations of the AKR polarization parameters in the wave plane are presented. Data were provided by the Interball‐2/Polrad triaxial polarimeter. It is the first time the dynamic spectra of all four Stokes parameters of the AKR are displayed in the wave plane. The AKR polarization is mostly circular with an estimated mean value of the semiaxes ratio of 0.99 ± 0.10 rms error, with a small contribution of the linear component at a level of 0.07 ± 0.09 rms error, and an unpolarized component at a level of 0.10 ± 0.08. The uncertainties of these estimations are too large to definitely conclude on presence or absence of some small contributions of the linear and upolarized components in the AKR. However, in the limits of the above uncertainties these estimations do not contradict expectations that the linear polarization is absent in the AKR. Some small contribution of the unpolarized component can be explained by a relatively high level of noise and board interefences.

Hubble Space Telescope imaging polarimetry of Mars during the 2003 opposition

We report results of polarimetric imaging observations of Mars with the Hubble Space Telescope during the 2003 opposition. Through careful calibration, the observations with the ACS camera allow measurements of the polarization degree with an absolute accuracy better than 0.5% and detection of features with polarization degree contrast as small as 0.2%. The general distribution of linear polarization parameters over the Mars disk and their dependence on phase angle and wavelength are well explained qualitatively by a combination of scattering separately by the martian surface and atmosphere. We have discovered transient polarization phenomena interpreted as clouds that are best observed in ultraviolet light. These clouds are optically thin but strongly polarizing, and their origin may be related to atmospheric ice condensation processes.

Linear polarization of the $\ion{O}{iv}$λ1031.92 coronal line

Numerical computation results of the linear polarization parameters of the Ovi1031:92 coronal line are presented. They are based on theoretical results obtained by Raouafi (2002 and 2000), which give the Stokes parameters of a resonance scattering spectral line sensitive simultaneously to the Hanle eect and to the Doppler redistribution. In the present coronal case, the Hanle eect is due to the coronal magnetic field and the Doppler redistribution to the macroscopic motion of the scattering O 5+ coronal ions (solar wind velocity field vector). Constraints on the coronal magnetic field vector and on the solar wind velocity field vector are obtained by comparing the numerical results and the linear polarization measurements of the Ovi1031:92 coronal line obtained through particular observations performed by SUMER/SoHO.

Linear polarization of the $\ion{O}{vi}$ λ1031.92 coronal line

In the first part of the present work, we report on the determination of the linear polarization parameters of the O vi 1031:92 coronal line (hereafter O vi D2). Spectropolarimetric observations done by the SUMER spectrometer on board the spacecraft SoHO during minimum activity of the solar cycle (March, 1996) in the south coronal hole were used to analyze the partial linear polarization of the D2 resonance line scattered by the O vi coronal ions. Widths of the O vi D2 and O vi 1037:61 (hereafter O vi D1) lines and limb-brightening determined from data observations of SUMER/SoHO are also presented. The second part of this work is devoted to the interpretation of the determined polarization parameters in terms of the macro- scopic velocity field vector of the O vi coronal ions that can be assimilated to the solar wind velocity field. Numerical results of the linear polarization parameters of the O vi D2 coronal line are presented. Constraints on the strength and direction of the solar wind velocity vector are obtained by comparing the numerical and the observational results of the O vi D2 coronal line polarization parameters. In conclusion, the eect of the macroscopic velocity field vector of the scattering ions (Doppler redistribution) provides a first set of results compatible with the observations. However, the inclination of the derived set of compatible field vectors, with respect to the solar vertical, is higher than expected in a coronal hole. The result will be improved by the inclusion of the magnetic field eect (Hanle eect), which will be treated in a further paper.

Stokes parameters of resonance lines scattered by a moving, magnetic medium

The aim of the present work is to present theoretical results on the Stokes parameters of a resonance spectral line, scattered by moving atoms (or ions) in the presence of a local magnetic field. We assume that the scattered line is sensitive to the Hanle effect due to the magnetic field and also to Doppler redistribution due to the atomic motions. The present theory is developed for a two-level atom, in the framework of the density matrix formalism Blum (1981). Analogous results given in Sahal-Bréchot et al. (1986) for the magnetic-field effect alone, and in Sahal-Bréchot et al. ([CITE]) for the velocity-field effect alone, can be obtained from our theory by cancelling in the equations, respectively, the velocity field or the magnetic field. The results of our theory are general and can be used for astrophysical studies concerning the Hanle effect and the Doppler redistribution effect on the linear polarization parameters of the scattered radiation. They can be used particularly to interpret linear polarization of coronal spectral lines to get a complete determination of vectorial quantities such as the coronal magnetic field and the solar wind velocity field vectors. As an application, the atomic velocity field distribution is supposed to be Maxwellian with a drift velocity field vector. This latter describes the macroscopic motion of the scattering atoms. In the solar corona, it can be assimilated into the solar wind velocity field vector.

Circular and linear polarization of the SiO masers in VY Canis Majoris

view Abstract Citations (14) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Circular and Linear Polarization of the SiO Masers in VY Canis Majoris McIntosh, G. C. ; Predmore, C. Read ; Patel, Nimesh A. Abstract The circular and linear polarization parameters of the SiO masers in VY CMa have been measured in the v = 1, J = 2 - 1 (86 GHz) and v = 1, J = 1 - 0 (43 GHz) transitions. The higher frequency is less circularly polarized than the lower frequency transition. Publication: The Astrophysical Journal Pub Date: June 1994 DOI: 10.1086/187385 Bibcode: 1994ApJ...428L..29M Keywords: Astronomical Photometry; Circular Polarization; Interstellar Masers; Linear Polarization; Stellar Envelopes; Radio Astronomy; Zeeman Effect; Astronomy full text sources ADS | data products SIMBAD (1)