Ultraviolet Observations of Solar Fine Structure

Dere, K. P.; Bartoe, John-David F.; Brueckner, G. E.; Cook, J. W.; Socker, D. G.

doi:10.1126/science.238.4831.1267

Cited by 13 publications

(8 citation statements)

References 8 publications

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“…Figure 1 (Plate 1) shows maps of the line peak intensities (top) and line width 6 (bottom) from the GA fits for the SUMER spectra of C iv and Ne viii. The C iv map shows that the values are v 1/e often enhanced by ∼10 km s Ϫ1 around network (NW) locations compared to internetwork (IN) areas (note that some internetwork locations do not have sufficient counts to reliably fit a Gaussian to the spectra), an effect noted by Dere et al (1984) among others. We also note that the nonthermal line broadening increases toward the limb for C iv and Ne viii.…”

Section: Sumer Observations and Data Analysismentioning

confidence: 96%

Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries

McIntosh

Pontieu

Tarbell

2008

ApJ

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We provide a new interpretation of ultraviolet transition region emission line widths observed by the SUMER instrument on the Solar and Heliospheric Observatory (SOHO). This investigation is prompted by observations of the chromosphere at unprecedented spatial and temporal resolution from the Solar Optical Telescope (SOT) on Hinode revealing that all chromospheric structures above the limb display significant transverse (Alfvénic) perturbations. We demonstrate that the magnitude, network sensitivity, and apparent center-to-limb isotropy of the measured line widths (formed below 250,000 K) can be explained by an observationally constrained forward model in which the line width is caused by the line-of-sight superposition of longitudinal and Alfvénic motions on the small-scale (spicular) structures that dominate the chromosphere and low transition region.

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Section: Sumer Observations and Data Analysismentioning

confidence: 96%

Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries

McIntosh

Pontieu

Tarbell

2008

ApJ

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“…The first observational inferences of the elusive cool loops came from high spatial resolution observations of the transition region from the rocket flights of transition region camera (TRC) and high-resolution telescope and spectrograph (HRTS) and from the SUMER spectrometer on SOHO (e.g., Bonnet et al 1980;Dere et al 1987;Feldman et al 1999;Landi et al 2000). These observations showed the existence of very thin threads, with a thickness of about 1 00 Y2 00 , straddling the network boundaries.…”

Section: Introductionmentioning

confidence: 99%

“…This includes double-component TR spectra (Peter 2001), spatially and temporally scale-invariant intensity power spectra (e.g., Berghmans et al 1998) and differential emission measure distributions (e.g., Griffiths et al 1999), small filling factors and unresolved mass motions (e.g., Dere et al 1987;Dere & Mason 1993;Chae et al 1998), small-scale dynamics (e.g., Dere et al 1987;Dere 1994;Innes et al 1997;Patsourakos & Vial 2001;Teriaca et al 2004;Winebarger et al 2002), temporal and spatial intermittency (Patsourakos & Vial 2002;Buchlin et al 2006), and arcsecond-scale differences in measured intensities, Doppler and nonthermal velocities in TR lines with different formation temperatures (Akiyama et al 2005;Doschek et al 2004;Doschek 2006). …”

Section: Introductionmentioning

confidence: 99%

The Quiet Sun Network at Subarcsecond Resolution: VAULT Observations and Radiative Transfer Modeling of Cool Loops

Patsourakos

Gouttebroze

Vourlidas

2007

ApJ

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One of the most enigmatic regions of the solar atmosphere is the transition region ( TR), corresponding to plasmas with temperatures intermediate of the cool, few thousand K, chromosphere and the hot, few million K, corona. The traditional view is that the TR emission originates from a thin thermal interface in hot coronal structures, connecting their chromosphere with their corona. This paradigm fails badly for cool plasmas (%T < 10 5 K ), since it predicts emission orders of magnitude less than what it is observed. It was therefore proposed that the ''missing'' TR emission could originate from tiny, isolated from the hot corona, cool loops at TR temperatures. A major problem in investigating this proposal is the very small sizes of the hypothesized cool loops. Here, we report the first spatially resolved observations of subarcsecond-scale looplike structures seen in the Ly line made by the Very High Angular Resolution Ultraviolet Telescope (VAULT). The subarcsecond (%0.3 00 ) resolution of VAULT allows us to directly view and resolve looplike structures in the quiet Sun network. We compare the observed intensities of these structures with simplified radiative transfer models of cool loops. The reasonable agreement between the models and the observations indicates that an explanation of the observed fine structure in terms of cool loops is plausible.

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“…Velocities of up to 500 km/s, far in excess of the local sound speed, were observed by Brueckner and Bartoe (1978). Dere et al (1987) also used spatially resolved spectra from the High Resolution Telescope and Spectrograph (HRTS) to provide evidence of the complex fine structure of the transition region.…”

Section: The Chromosphere and Transition Regionmentioning

confidence: 99%

Recent Progress and Future Prospects in Solar Physics, and Their Relevance for Planet Earth

Bonnet

Pauluhn

2004

Surv Geophys

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Understanding our star, the Sun, is of fundamental interest for life on Earth. In this paper, the status of knowledge in solar physics of roughly two decades ago is summarised, and the most recent developments in this very active field are shown, many of them achieved by means of space based missions. The Sun-Earth connection is described and, finally, an outlook on future solar research is given.

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Ultraviolet Observations of Solar Fine Structure

Cited by 13 publications

References 8 publications

Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries

Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries

The Quiet Sun Network at Subarcsecond Resolution: VAULT Observations and Radiative Transfer Modeling of Cool Loops

Recent Progress and Future Prospects in Solar Physics, and Their Relevance for Planet Earth

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