scholarly journals New deep coronal spectra from the 2017 total solar eclipse

2019 ◽  
Vol 632 ◽  
pp. A86 ◽  
Author(s):  
S. Koutchmy ◽  
F. Baudin ◽  
Sh. Abdi ◽  
L. Golub ◽  
F. Sèvre
Keyword(s):  
Solar Wind ◽  
Solar Eclipse ◽  
Coronal Holes ◽  
Solar Limb ◽  
Total Solar Eclipse ◽  
Emission Lines ◽  
High Spectral Resolution ◽  
Doppler Shifts ◽  
Dust Component ◽  
The Continuum

Context. The origin of the high temperature of the solar corona, in both the inner bright parts and the more outer parts showing flows toward the solar wind, is not understood well yet. Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum white-light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona), and the dust component with F-lines (F-corona). Aims. By sufficiently dispersing the W-L spectrum, the Fraunhofer (F) spectrum of the dust component of the corona appears and the continuum Thomson radiation can be evaluated. The superposed emission lines of ions with different degrees of ionization are studied to allow the measurement of temperatures, non-thermal velocities, Doppler shifts, and abundances to constrain the proposed heating mechanisms and understand the origin of flows that lead to solar wind. Methods. We describe a slit spectroscopic experiment of high spectral resolution to provide an analysis of the most typical parts of the quasi-minimum type corona observed during the total solar eclipse of Aug. 21, 2017 from Idaho, USA. Streamers, active region enhancements, and polar coronal holes (CHs) are measured well using deep spectra. Results. Sixty spectra are obtained during the totality with a long slit, covering ±3 solar radii in the range of 510 nm to 590 nm. The K+F continuum corona is exposed well up to two solar radii. The F-corona can be measured even at the solar limb. New weak emission lines were discovered or confirmed. The rarely observed Ar X line is detected almost everywhere; the Fe XIV and Ni XIII lines are clearly detected everywhere. For the first time hot lines are also measured inside the CH regions. The radial variations of the non-thermal turbulent velocities of the lines do not show a great departure from the average values. No significantly large Doppler shifts are seen anywhere in the inner or the middle corona. The wings of the Fe XIV line show some non-Gaussianity. Conclusions. Deep slit coronal spectra offered an opportunity for diagnosing several aspects of coronal physics during a well observed total eclipse without extended investments. The analysis of the ionic emission line profiles offers several powerful diagnostics of the coronal dynamics; the precise measurement of the F-continuum component provides insight into the ubiquitous dust corona at the solar limb.

Near infrared spectral and polarization imaging observation of coronal emission lines during the 2008 total solar eclipse

2009 ◽  
Vol 52 (11) ◽  
pp. 1794-1798 ◽  
Author(s):  
XingMing Bao ◽  
ZhiYong Zhang ◽  
Jian Deng ◽  
KeLiang Hu ◽  
WeiJia Xuan ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Near Infrared ◽  
Total Solar Eclipse ◽  
Emission Lines ◽  
Coronal Emission ◽  
Polarization Imaging ◽  
Imaging Observation ◽  
Infrared Spectral

Fine Structures of the Inner Corona Observed at the 1991 Total Solar Eclipse

1994 ◽  
Vol 144 ◽  
pp. 565-566 ◽  
Author(s):  
A. Takeda ◽  
H. Kurokawa ◽  
R. Kitai ◽  
K. Ishiura
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Baja California ◽  
Total Solar Eclipse ◽  
Emission Lines ◽  
Coronal Loops ◽  
Temperature Structure ◽  
Baja California Sur ◽  
High Resolution Images ◽  
Fine Structures

Extended AbstractThe Kwasan and Hida Observatories team (three of the authors but A. T.) observed the total solar eclipse of 11 July, 1991 with the multi-channel telescope at UABCS (Universidad Autonoma de Baja California Sur) campus in La Paz, Baja California Sur, Mexico. The primary purpose of our obsevation is to get high-resolution images of the inner corona at the wavelength of coronal emission lines and continuum shown in Table 1. Thanks to the clear sky and good seeing condition, we successfully got many images of high spatial resolution with photographic cameras and video recorders. Details of the observation have already been published by Kurokawaet al. (1992). In this paper, we present the results obtained from the photographic data reduction on fine structures of the inner corona. The procedure of photometrical measurement and image processing are fully described in another paper (Takeda, 1993).There have been published several observational works on the temperature structure of the coronal loops. Some authors proposed that hot coronal loops have cool cores (Foukal, 1975; Hanaokaet al., 1988), but others denied such coaxial models (Chenget al., 1980; Dere, 1982). Our high-resolution images obtained at the eclipse enables us to compare the positions of the loops seen in different emission lines of different ionization temperatures more precisely than any other previous observations. Main results are summarized as follows.

scholarly journals Solar Prominence Diagnostics From the November 3, 1994 Eclipse

1998 ◽  
Vol 167 ◽  
pp. 201-204
Author(s):  
B.H. Foing ◽  
J.E. Wiik ◽  
L. Duvet ◽  
N. Henrich ◽  
S. Cravatte ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Coronal Holes ◽  
Ccd Camera ◽  
Total Solar Eclipse ◽  
Equivalent Temperature ◽  
Solar Prominence ◽  
The North ◽  
Solar Prominences ◽  
Outer Corona ◽  
The Military

AbstractWe report results on solar prominences from our observations of the November 3, 1994 total solar eclipse from the North Chile alteplano. From the military base at Putre, we used our transportable CCD camera and telescope, as well as support photographic digitised observations from Putre and Parinacota volcano. The variation of density and equivalent temperature were derived in coronal holes (plumes and interplumes) and in equatorial streamers. We obtained images from the inner to the outer corona, as well as low-resolution spectra of prominences and of the inner corona. We present the analysis of images and spectra of prominences in the Balmer, He I and Ca II lines, and in the Thomson scattered continuum.

scholarly journals Observation of the prominence cavity region using slitless eclipse flash spectra and space borne EUV filtergrams

2013 ◽  
Vol 8 (S300) ◽  
pp. 151-154
Author(s):  
Cyrille Bazin ◽  
Serge Koutchmy ◽  
Philippe Lamy ◽  
Ehsan Tavabi
Keyword(s):  
Electron Density ◽  
Plasma Density ◽  
Solar Eclipse ◽  
Intensity Ratio ◽  
Radial Direction ◽  
Hydrostatic Equilibrium ◽  
Total Solar Eclipse ◽  
First Time ◽  
The Continuum

AbstractWe used total solar eclipse free of parasitic light for studying the prominence to corona interface, and the corresponding cavity in the context of the coronal physics. We analysed the visible continuum between the prominences to directly look at the electron density. We demonstrate some enhanced heating in the cavity region. Some similarities with the interface regions are shown: the photosphere to the chromosphere and the prominence to the corona interface. The optically thin neutral Helium at 4713 Å and the singly ionized Helium 4686 Å Paschen α lines are considered. We summed 80 slitless visible eclipse flash spectra that we compare with simultaneously obtained EUV SWAP/Proba2 174 Å images of ESA and AIA/SDO 171Å 193 Å 304 Å and 131 Å filtergrams. Intensity profiles in a radial direction are studied. We deduce the variation of the intensity ratio I(He I 4713) / I(He II 4686). Discussion: the temperature rises at the edge of the prominences. We evaluate for the first time with spectrophotometric accuracy the continuum modulations in prominence spectra. W-L intensity deficits are observed near the prominence boundaries in both eclipse spectra and in EUV images, confirming that the prominence -cavity regions correspond to a relative depression of plasma density of the surrounding corona. Conclusion: we demonstrate some enhanced heating occurring in these regions assuming hydrostatic equilibrium.

Submillimeter solar limb profiles determined from observations of the total solar eclipse of 1988 March 18

1991 ◽  
Vol 381 ◽  
pp. 288 ◽  
Author(s):  
T. L. Roellig ◽  
E. E. Becklin ◽  
J. T. Jefferies ◽  
G. A. Kopp ◽  
C. A. Lindsey ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Solar Limb ◽  
Total Solar Eclipse

scholarly journals Accurate 3-D radiative transfer simulation of spectral solar irradiance during the total solar eclipse of 21 August 2017

2020 ◽  
Vol 20 (4) ◽  
pp. 1961-1976 ◽  
Author(s):  
Paul Ockenfuß ◽  
Claudia Emde ◽  
Bernhard Mayer ◽  
Germar Bernhard
Keyword(s):  
Monte Carlo ◽  
Solar Eclipse ◽  
Solar Irradiance ◽  
Monte Carlo Model ◽  
Solar Limb ◽  
Relative Difference ◽  
Total Solar Eclipse ◽  
Monte Carlo Code ◽  
Increased Sensitivity ◽  
Spectral Solar Irradiance

Abstract. We calculate the variation of spectral solar irradiance in the umbral shadow of the total solar eclipse of 21 August 2017 and compare it to observations. Starting from the Sun's and Moon's positions, we derive a realistic profile of the lunar shadow at the top of the atmosphere, including the effect of solar limb darkening. Subsequently, the Monte Carlo model MYSTIC (Monte Carlo code for the phYSically correct Tracing of photons In Cloudy atmospheres) is used to simulate the transfer of solar radiation through the Earth's atmosphere. Among the effects taken into account are the atmospheric state (pressure, temperature), concentrations of major gas constituents and the curvature of the Earth, as well as the reflectance and elevation of the surrounding area. We apply the model to the total solar eclipse on 21 August 2017 at a position located in Oregon, USA, where irradiance observations were performed for wavelengths between 306 and 1020 nm. The influence of the surface reflectance, the ozone profile, the mountains surrounding the observer and aerosol is investigated. An increased sensitivity during totality is found for the reflectance, aerosol and topography, compared to non-eclipse conditions. During the eclipse, the irradiance at the surface not only depends on the total ozone column (TOC) but also on the vertical ozone distribution, which in general complicates derivations of the TOC from spectral surface irradiance. The findings are related to an analysis of the prevailing photon path and its difference compared to non-eclipse conditions. Using the most realistic estimate for each parameter, the model is compared to the irradiance observations. During totality, the relative difference between model and observations is less than 10 % in the spectral range from 400 to 1020 nm. Slightly larger deviations occur in the ultraviolet range below 400 and at 665 nm.

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