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Title: The EUV Imaging Spectrometer for Hinode

Abstract

The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona and upper transition region emission lines in the wavelength ranges 170?-?210 Angstroms and 250?-?290 Angstroms . The line centroid positions and profile widths will allow plasma velocities and turbulent or non-thermal line broadenings to be measured. We will derive local plasma temperatures and densities from the line intensities. The spectra will allow accurate determination of differential emission measure and element abundances within a variety of corona and transition region structures. These powerful spectroscopic diagnostics will allow identification and characterization of magnetic reconnection and wave propagation processes in the upper solar atmosphere. We will also directly study the detailed evolution and heating of coronal loops. The EIS instrument incorporates a unique two element, normal incidence design. The optics are coated with optimized multilayer coatings. We have selected highly efficient, backside-illuminated, thinned CCDs. These design features result in an instrument that has significantly greater effective area than previous orbiting EUV spectrographs with typical active region 2?-?5 s exposure times in the brightest lines. EIS can scan a field of 6x8.5 arc?min with spatial and velocity scales of 1 arc?sec and 25 km?s-1 per pixel. The instrument design, its absolute calibration, andmore » performance are described in detail in this paper. EIS will be used along with the Solar Optical Telescope (SOT) and the X-ray Telescope (XRT) for a wide range of studies of the solar atmosphere.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
960141
Report Number(s):
BNL-83127-2009-JA
Journal ID: ISSN 0038-0938; SLPHAX; TRN: US201016%%1285
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Solar Physics; Journal Volume: 243
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CALIBRATION; COATINGS; DESIGN; ELECTRON TEMPERATURE; ELEMENT ABUNDANCE; HEATING; ION TEMPERATURE; LINE BROADENING; MAGNETIC RECONNECTION; OPTICS; PERFORMANCE; PLASMA; SOLAR ATMOSPHERE; SOLAR CORONA; SPECTRA; SPECTROMETERS; TELESCOPES; VELOCITY; WAVE PROPAGATION; WAVELENGTHS; national synchrotron light source

Citation Formats

Culhane,J., Harra, L., James, A., Al-Janabi, K., Bradley, L., Chaudry, R., Rees, K., Tandy, J., Thomas, P., and et al. The EUV Imaging Spectrometer for Hinode. United States: N. p., 2007. Web. doi:10.1007/s01007-007-0293-1.
Culhane,J., Harra, L., James, A., Al-Janabi, K., Bradley, L., Chaudry, R., Rees, K., Tandy, J., Thomas, P., & et al. The EUV Imaging Spectrometer for Hinode. United States. doi:10.1007/s01007-007-0293-1.
Culhane,J., Harra, L., James, A., Al-Janabi, K., Bradley, L., Chaudry, R., Rees, K., Tandy, J., Thomas, P., and et al. Mon . "The EUV Imaging Spectrometer for Hinode". United States. doi:10.1007/s01007-007-0293-1.
@article{osti_960141,
title = {The EUV Imaging Spectrometer for Hinode},
author = {Culhane,J. and Harra, L. and James, A. and Al-Janabi, K. and Bradley, L. and Chaudry, R. and Rees, K. and Tandy, J. and Thomas, P. and et al},
abstractNote = {The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona and upper transition region emission lines in the wavelength ranges 170?-?210 Angstroms and 250?-?290 Angstroms . The line centroid positions and profile widths will allow plasma velocities and turbulent or non-thermal line broadenings to be measured. We will derive local plasma temperatures and densities from the line intensities. The spectra will allow accurate determination of differential emission measure and element abundances within a variety of corona and transition region structures. These powerful spectroscopic diagnostics will allow identification and characterization of magnetic reconnection and wave propagation processes in the upper solar atmosphere. We will also directly study the detailed evolution and heating of coronal loops. The EIS instrument incorporates a unique two element, normal incidence design. The optics are coated with optimized multilayer coatings. We have selected highly efficient, backside-illuminated, thinned CCDs. These design features result in an instrument that has significantly greater effective area than previous orbiting EUV spectrographs with typical active region 2?-?5 s exposure times in the brightest lines. EIS can scan a field of 6x8.5 arc?min with spatial and velocity scales of 1 arc?sec and 25 km?s-1 per pixel. The instrument design, its absolute calibration, and performance are described in detail in this paper. EIS will be used along with the Solar Optical Telescope (SOT) and the X-ray Telescope (XRT) for a wide range of studies of the solar atmosphere.},
doi = {10.1007/s01007-007-0293-1},
journal = {Solar Physics},
number = ,
volume = 243,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • A wavelength calibration of solar lines observed by the high resolution EUV Imaging Spectrometer (EIS) on the Hinode satellite is reported. Spectral features of the quiet sun and of two mildly active areas were measured and calibrated. A listing of the stronger observed lines with identification of the leading contributor ions is presented. 41 lines are reported, with 90% identified. Wavelength precisions (2{sigma}) of {+-}0.0031 Angstroms for the EIS short band and {+-}0.0029 Angstroms for the EIS long band are obtained. These lines, typical of 1-2x10{sup 6} K plasmas, are recommended as standards for the establishment of EIS wavelength scales.more » The temperature of EIS varies by about 1.5 C around the orbit and also with spacecraft pointing. The correlation of these temperature changes with wavelength versus pixel number scale changes is reported.« less
  • The origin of the solar wind is one of the most important unresolved problems in space and solar physics. We report here the first spectroscopic signatures of the nascent fast solar wind on the basis of observations made by the EUV Imaging Spectrometer on Hinode in a polar coronal hole in which patches of blueshift are clearly present on Dopplergrams of coronal emission lines with a formation temperature of lg(T/K)>5.8. The corresponding upflow is associated with open field lines in the coronal hole and seems to start in the solar transition region and becomes more prominent with increasing temperature. Thismore » temperature-dependent plasma outflow is interpreted as evidence of the nascent fast solar wind in the polar coronal hole. The patches with significant upflows are still isolated in the upper transition region but merge in the corona, in agreement with the scenario of solar wind outflow being guided by expanding magnetic funnels.« less
  • Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations of current atomic calculations, particularly those for Fe, all conspire to make this task very difficult. A critical assessment of plasma diagnostics in the corona is essential to making progress on the coronal heating problem. In this paper, we present an analysis of temperature and density measurements above the limb in the quiet corona using new observations from the EUV Imaging Spectrometer (EIS) on Hinode. By comparing the Simore » and Fe emission observed with EIS we are able to identify emission lines that yield consistent emission measure distributions. With these data we find that the distribution of temperatures in the quiet corona above the limb is strongly peaked near 1 MK, consistent with previous studies. We also find, however, that there is a tail in the emission measure distribution that extends to higher temperatures. EIS density measurements from several density sensitive line ratios are found to be generally consistent with each other and with previous measurements in the quiet corona. Our analysis, however, also indicates that a significant fraction of the weaker emission lines observed in the EIS wavelength ranges cannot be understood with current atomic data.« less
  • This paper presents a detailed study of chromospheric evaporation using the EUV Imaging Spectrometer (EIS) onboard Hinode in conjunction with hard X-ray (HXR) observations from Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). The advanced capabilities of EIS were used to measure Doppler shifts in 15 emission lines covering the temperature range T = 0.05-16 MK during the impulsive phase of a C-class flare on 2007 December 14. Blueshifts indicative of the evaporated material were observed in six emission lines from Fe XIV-XXIV (2-16 MK). Upflow velocity (v{sub up}) was found to scale with temperature as v{sub up} (km s{sup -1})more » {approx} 8-18T(MK). Although the hottest emission lines, Fe XXIII and Fe XXIV, exhibited upflows of >200 km s{sup -1}, their line profiles were found to be dominated by a stationary component in contrast to the predictions of the standard flare model. Emission from O VI-Fe XIII lines (0.5-1.5 MK) was found to be redshifted by v{sub down} (km s{sup -1}) {approx} 60-17T (MK) and was interpreted as the downward-moving 'plug' characteristic of explosive evaporation. These downflows occur at temperatures significantly higher than previously expected. Both upflows and downflows were spatially and temporally correlated with HXR emission observed by RHESSI that provided the properties of the electron beam deemed to be the driver of the evaporation. The energy flux of the electron beam was found to be {approx}>5 x 10{sup 10} erg cm{sup -2} s{sup -1}, consistent with the value required to drive explosive chromospheric evaporation from hydrodynamic simulations.« less
  • In this work, we report on a cold, bright portion of an active region observed by the Hinode/EUV Imaging Spectrometer. The emitting plasma was very bright at transition region temperatures, and the intensities of lines of ions formed between 10{sup 5} and 10{sup 6} K were enhanced over normal values. The data set constitutes an excellent laboratory where the emission of transition region ions can be tested. We first determine the thermal structure of the observed plasma, and then we use it (1) to develop a spectral atlas, and (2) to assess the quality of CHIANTI atomic data by comparingmore » predicted emissivities with observed intensities. We identify several lines never observed before in solar spectra, and find an overall very good agreement between CHIANTI-predicted emissivities and observations.« less