scholarly journals Magnetic Fields Measured with the 10830 Å HeI Line

1971 ◽  
Vol 43 ◽  
pp. 279-288 ◽  
Author(s):  
J. Harvey ◽  
D. Hall
Keyword(s):  
Fine Structure ◽  
Magnetic Fields ◽  
Near Infrared ◽  
Active Regions ◽  
Field Measurements ◽  
Spectral Lines ◽  
Magnetic Field Measurements ◽  
Infrared Spectral ◽  
Polarity Reversals ◽  
Absorption Features

Several advantages of near infrared spectral lines for magnetic field measurements are listed. In particular, the 10830 Å multiplet of HeI is well suited for observations of chromospheric magnetic fields.New photoelectric spectroheliograms made with the 10830 Å line reveal a large amount of filamentary fine structure in active regions. This fine structure has important consequences on the interpretation of 10830 Å magnetograms. Except for an association of 10830 Å disk filaments with polarity reversals there is little correlation between absorption features and the 10830 Å longitudinal field. Comparisons of chromospheric and photospheric observations show that the chromospheric field is spatially more diffuse and weaker than the photospheric field.

Stellar magnetic field measurements utilizing infrared spectral lines

1985 ◽  
Vol 297 ◽  
pp. 710 ◽  
Author(s):  
Ph. Gondoin ◽  
M. S. Giampapa ◽  
J. A. Bookbinder
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Spectral Lines ◽  
Magnetic Field Measurements ◽  
Infrared Spectral

scholarly journals On the manifestation in the Sun-as-a-star magnetic field measurements of the quiet and active regions

2010 ◽  
Vol 6 (S273) ◽  
pp. 56-60 ◽  
Author(s):  
Mikhail Demidov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Active Regions ◽  
Field Measurements ◽  
Solar Observatory ◽  
Spectral Lines ◽  
The Sun ◽  
Time Data ◽  
Full Disk

AbstractThe best way to test the stellar magnetic field mapping codes is to apply them, with some changes, to the Sun, where high-precision disk-integrated and disk-resolved observations are available for a long time. Data sets of the full-disk magnetograms and the solar mean magnetic fields (SMMF) measurements are provided, for example, by the J.M.Wilcox Solar observatory (WSO) and by the Sayan Solar observatory (SSO). In the second case the measurements in the Stokes-meter mode simultaneously in many spectral lines are available. This study is devoted to analysis of the SSO quasi-simultaneous full-disk magnetograms and SMMF measurements. Changes of the SMMF signal with rotation of the surface large-scale magnetic fields are demonstrated. Besides, by deleting of selected pixels with active regions (AR) from the maps their contribution to the integrated SMMF signal is evaluated. It is shown that in some cases the role of AR can be rather significant.

Properties of Magnetic Features from the Analysis of Near-Infrared Spectral Lines

1994 ◽  
Vol 154 ◽  
pp. 393-405
Author(s):  
Sami K. Solanki
Keyword(s):  
Near Infrared ◽  
Velocity Structure ◽  
Spectral Lines ◽  
The Past ◽  
Diagnostic Potential ◽  
Theoretical Predictions ◽  
Infrared Spectral ◽  
Magnetic Features

An overview is given of the structure and the physics of magnetic features in solar plages, as derived from observations of near-infrared lines. First, the diagnostic potential of near-infrared lines is compared with that of lines in the visible and at 12 μm. Then, the results on the magnetic and velocity structure of magnetic features obtained from 1.5 μm lines are described, discussed and compared with results of observations in the visible and with theoretical predictions. Finally, the past and present achievements of near-infrared investigations of Zeeman-split lines are summarized.

scholarly journals Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy

2019 ◽  
Vol 630 ◽  
pp. A99 ◽  
Author(s):  
A. Lavail ◽  
O. Kochukhov ◽  
G. A. J. Hussain
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Magnetic Fields ◽  
Large Scale ◽  
Near Infrared ◽  
Field Measurements ◽  
T Tauri Stars ◽  
Small Scale ◽  
Surface Magnetic Field ◽  
T Tauri

Aims. In this paper, we aim to characterise the surface magnetic fields of a sample of eight T Tauri stars from high-resolution near-infrared spectroscopy. Some stars in our sample are known to be magnetic from previous spectroscopic or spectropolarimetric studies. Our goals are firstly to apply Zeeman broadening modelling to T Tauri stars with high-resolution data, secondly to expand the sample of stars with measured surface magnetic field strengths, thirdly to investigate possible rotational or long-term magnetic variability by comparing spectral time series of given targets, and fourthly to compare the magnetic field modulus ⟨B⟩ tracing small-scale magnetic fields to those of large-scale magnetic fields derived by Stokes V Zeeman Doppler Imaging (ZDI) studies. Methods. We modelled the Zeeman broadening of magnetically sensitive spectral lines in the near-infrared K-band from high-resolution spectra by using magnetic spectrum synthesis based on realistic model atmospheres and by using different descriptions of the surface magnetic field. We developped a Bayesian framework that selects the complexity of the magnetic field prescription based on the information contained in the data. Results. We obtain individual magnetic field measurements for each star in our sample using four different models. We find that the Bayesian Model 4 performs best in the range of magnetic fields measured on the sample (from 1.5 kG to 4.4 kG). We do not detect a strong rotational variation of ⟨B⟩ with a mean peak-to-peak variation of 0.3 kG. Our confidence intervals are of the same order of magnitude, which suggests that the Zeeman broadening is produced by a small-scale magnetic field homogeneously distributed over stellar surfaces. A comparison of our results with mean large-scale magnetic field measurements from Stokes V ZDI show different fractions of mean field strength being recovered, from 25–42% for relatively simple poloidal axisymmetric field topologies to 2–11% for more complex fields.

scholarly journals Spectropolarimetry with PEPSI at the LBT: accuracy vs. precision in magnetic field measurements

2008 ◽  
Vol 4 (S259) ◽  
pp. 663-664
Author(s):  
Ilya Ilyin ◽  
Klaus G. Strassmeier ◽  
Manfred Woche ◽  
Axel Hofmann
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Spectral Lines ◽  
Stokes Parameters ◽  
Limiting Factors ◽  
Magnetic Field Measurements

AbstractWe present the design of the new PEPSI spectropolarimeter to be installed at the Large Binocular Telescope (LBT) in Arizona to measure the full set of Stokes parameters in spectral lines and outline its precision and the accuracy limiting factors.

scholarly journals Magnetic Field Measurements for Fast-Changing Magnetic Fields

2005 ◽  
Author(s):  
Animesh Jain ◽  
John Escallier ◽  
George Ganetis ◽  
Wing Louie ◽  
Andrew Marone ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Measurements ◽  
Magnetic Field Measurements

scholarly journals Усиленная фотолюминесценция сильно легированных слоев Ge/Si(001) n-типа проводимости

2019 ◽  
Vol 53 (9) ◽  
pp. 1293
Author(s):  
Д.С. Прохоров ◽  
В.Г. Шенгуров ◽  
С.А. Денисов ◽  
Д.О. Филатов ◽  
А.В. Здоровейщев ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Near Infrared ◽  
Chemical Vapor ◽  
Active Regions ◽  
Photoluminescence Spectra ◽  
Hot Wire ◽  
Light Emitting ◽  
Infrared Spectral ◽  
Maximum Electron Concentration

AbstractThe photoluminescence spectra of epitaxial n ^+-Ge:P/Si(001) structures are studied. The structures are grown by hot-wire chemical vapor deposition and doped with phosphorus to the maximum electron concentration 1 × 10^20 cm^–3 from a source based on thermally decomposed GaP. The effects of the doping level and rapid thermal annealing of n ^+-Ge:P layers on the photoluminescence spectra are studied. It is demonstrated that the epitaxial n ^+-Ge:P/Si(001) layers grown by hot-wire chemical vapor deposition are promising for application as active regions of light-emitting optoelectronic devices operating in the near-infrared spectral region.

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