Milli Arcsecond Imaging of the Solar Corona

Joseph, Davila
Öktem, Sevinç Figen
Farzad, Kamalabadi
Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets is visible in coronal EUV emission lines, however, this spatial scale is unresolved in existing imaging instruments. Conventional optics cannot be easily manufactured with sufficient surface figure accuracy to obtain the required resolution. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few milli-arcsec (mas) resolution, with much more relaxed tolerances than conventional imaging technology. Images from photon sieves will not only show the structure of the corona at a resolution never before obtained, they will also allow a study of the temperature structure in the dissipation region. Several photon sieves have been designed, fabricated, and tested by us at Goddard Space Flight Center. To fully exploit the potential of these devices two new technologies, (1) formation flying and (2) computational image deconvolution must be used. Recent progress on photon sieve development as well as these issues will be discussed. A simple design for a sounding rocket payload is presented that obtains 80 mas (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335 which would provide a demonstration of this technology.
41st COSPAR Scientific Assembly


Milli Arcsecond MAS Imaging of the Solar Corona
Davila, Joseph M; Öktem, Sevinç Figen; Kamalabadi, Farzad; Oneill, John; Gradac, Anne Marie Novo; Daw, Adrian N; Rabin, Douglas M (2016-05-01)
Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments, so these dissipation sites have never been observed individually. Conventional optics cannot be manufactured with sufficient surface figure accuracy to obtain the required spatial resolution in the extreme-ultraviolet whe...
Estimation of total solar radiation from bright sunshine hours in Turkey
Taşdemiroğlu, Erol; Sever, Rita (Elsevier BV, 1989-12)
Measurements of total solar radiation and bright sunshine hours in six different climatological locations in Turkey are used to develop an Angstrom type equation. The coefficients are found for a linear equation from regression analysis for these locations. A simple overall equation, which yields the solar radiation in any location in Turkey for bright sunshine hours, is developed. The results of this equation, together with the results obtained from five similar, internationally accepted correlations, are ...
Excitation intensity- and temperature-dependent photoluminescence in layered structured Tl2GaInSe2S2 crystals
Hasanlı, Nızamı (AIP Publishing, 2013-02-21)
Photoluminescence spectra of Tl2GaInSe2S2 layered crystals have been registered in the temperature range of 17-62 K and in the wavelength region of 525-690 nm. A broad visible photoluminescence band centered at 590 nm (2.10 eV) was observed at T 17 K. Variation of emission band has been studied as a function of laser excitation intensity in the 0.1-55.7 mW cm(-2) range. The analysis of the spectra reveals that the peak energy position changes with excitation intensity (blue shift). The radiative transitions...
Refractive index and oscillator parameters in TlGaS2, TlGaSe2 and TlInS2 layered crystals
Hasanlı, Nızamı (2011-01-01)
The optical properties of TlGaS2, TlGaSe2, and TlInS2 crystals have been investigated through the transmission and reflection measurements at room temperature in the wavelength range of 400-1100 nm. These measurements allowed determination of spectral dependence of the refractive index for all crystals studied. The dispersion of the refractive index is discussed in terms of the Wemple-DiDomenico single-effective-oscillator model. The refractive index dispersion parameters: the oscillator energies, the dispe...
Very high energy gamma rays from the composite SNR G0.9+0.1
Aharonian, F; et. al. (EDP Sciences, 2005-03-01)
Very high energy (> 100 GeV) gamma-ray emission has been detected for the first time from the composite supernova remnant G0.9+ 0.1 using the HESS instrument. The source is detected with a significance of approximate to 13sigma, and a photon flux above 200 GeV of ( 5.7 +/- 0.7(stat) +/- 1.2(sys)) x 10(-12) cm(-2) s(-1), making it one of the weakest sources ever detected at TeV energies. The photon spectrum is compatible with a power law ( dN/dE proportional to E-Gamma) with photon index Gamma = 2.40 +/- 0.1...
Citation Formats
D. Joseph, S. F. Öktem, and K. Farzad, “Milli Arcsecond Imaging of the Solar Corona,” presented at the 41st COSPAR Scientific Assembly, İstanbul, Türkiye, 2016, Accessed: 00, 2021. [Online]. Available: