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Harrison, R. A.; Fludra, A.; Pike, C. D.; Payne, J.; Thompson, W. T.; Poland, A. I.; Breeveld, E. R.; Breeveld, A. A.; Culhane, J. L.; Kjeldseth-Moe, O.; Huber, M. C. E.; Aschenbach, B.

doi:10.1023/a:1004913326580

Cited by 65 publications

(20 citation statements)

References 0 publications

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“…This is also evident from Fig. 5 of Harrison et al (1997) showing the He  58.43 nm line in a QS region.…”

Section: Spectral Observationssupporting

confidence: 64%

On the nature of the unidentified solar emission near 117 nm

Wilhelm¹,

Schühle²,

Curdt³

et al. 2005

A&A

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Abstract. Spectral observations of the Sun in the vacuum-ultraviolet wavelength range by SUMER on SOHO led to the discovery of unusual emission features -called humps here -at 116.70 nm and 117.05 nm on either side of the He  58.43 nm line. This resonance line is seen in the second order of diffraction, whereas the humps are recorded in the first order with the SUMER spectrometer. In its spectra both orders are superimposed. Two less pronounced humps can be detected at 117.27 nm and near 117.85 nm. After rejecting various possibilities of an instrumental cause of the humps, they are studied in different solar regions. Most of the measurements, in particular those related to the limb-brightening characteristics, indicate that the humps are not part of the background continuum. An assembly of spectrally-unresolved atomic or ionic emission lines might be contributing to the hump at 117.05 nm, but no such lines are known near 116.7 nm. It is concluded that we detect genuine radiation, the generation of which is not understood. A two-photon emission process, parametric frequency down conversion, and molecular emissions are briefly considered as causes of the humps, but a final conclusion could not be reached.

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“…This is also evident from Fig. 5 of Harrison et al (1997) showing the He  58.43 nm line in a QS region.…”

Section: Spectral Observationssupporting

confidence: 64%

On the nature of the unidentified solar emission near 117 nm

Wilhelm¹,

Schühle²,

Curdt³

et al. 2005

A&A

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“…The recent studies performed with the Coronal Diagnostic Spectrometer (Brekke, Hassler, & Wilhelm 1997;Harrison et al 1997;Wikstøl et al 1997) and the Solar Ultraviolet Measurement of Emitted Radiation instrument (SUMER; Innes et al 1997) on the Solar and Heliospheric Observatory (SOHO) confirmed the ubiquitous nature of the diverse jets of material from weak steady flows of a few tenths of a kilometer per second up to unsteady explosive events with velocities of several hundreds of kilometers per second and revealed more details in their properties. But the mechanisms producing these phenomena were unknown.…”

Section: Introductionmentioning

confidence: 97%

On the Transition Region Explosive Events

Ryutova

Tarbell

2000

The Astrophysical Journal

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We describe the properties of high-velocity and explosive events in the solar transition region determined from time series of data taken by the Transition Region and Coronal Explorer and the SUMER instrument on the Solar and Heliospheric Observatory (SOHO) simultaneously in several chromospheric and transition region lines co-aligned with high-resolution Michelson Doppler Imager (SOHO) magnetograms. We outline what the various features of these events can tell us about the heating mechanisms and formation of plasma flows. Our results strongly support the mechanism of hydrodynamic cumulation of energy associated with the cascade of shock waves produced by colliding and reconnecting flux tubes in the photospheric network (as recently discussed by T. D. Tarbell et al.). We find that the majority of the explosive events are caused by the explosive instability occurring in the presence of the behind-shock downflows, and less than 10% can be explained by the direct collision of shock fronts.

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“…The characteristics of CDS are described by Harrison et al (1995Harrison et al ( , 1997. CDS consists of a grazing-incidence Wolter-Schwartzchild Type-2 telescope feeding a normalincidence spectrometer (NIS) and a grazing-incidence spectrometer (GIS).…”

Section: The Cds Normal-incidence Spectrometermentioning

confidence: 99%