References of "Neupert, W. M"
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See detailObservations of Coronal Structures Above an Active Region by EIT and Implications for Coronal Energy Deposition
Neupert, W. M.; Newmark, J.; Delaboudinière, J.-P. et al

in Solar Physics (1998), 183

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the ... [more ▼]

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the temperature range of 1.0-2.0MK. Such observations permit estimates of longitudinal temperature gradients (if present) in the corona and, consequently, estimates of thermal conduction and radiative losses as a function of position in the features. We examine two relatively cool features as recorded in EIT's Feix/x (171Å) and Fexii (195Å) bands in a decaying active region. The first is a long-lived loop-like feature with one leg, ending in the active region, much more prominent than one or more distant footpoints assumed to be rooted in regions of weakly enhanced field. The other is a near-radial feature, observed at the West limb, which may be either the base of a very high loop or the base of a helmet streamer. We evaluate energy requirements to support a steady-state energy balance in these features and find in both instances that downward thermal conductive losses (at heights above the transition region) are inadequate to support local radiative losses, which are the predominant loss mechanism. The requirement that a coronal energy deposition rate proportional to the square of the ambient electron density (or pressure) is present in these cool coronal features provides an additional constraint on coronal heating mechanisms. [less ▲]

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See detailEIT Observations of the Extreme Ultraviolet Sun
Moses, D.; Clette, Frédéric; Delaboudinière, J.-P. et al

in Solar Physics (1997), 175

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line ... [more ▼]

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination of the instrument flatfield, the instrument scattering function, and the instrument aging were necessary for the reduction and analysis of the data. The observed structures and their evolution in each of the four EUV bandpasses are characteristic of the peak emission temperature of the line(s) chosen for that bandpass. Reports on the initial results of a variety of analysis projects demonstrate the range of investigations now underway: EIT provides new observations of the corona in the temperature range of 1 to 2 MK. Temperature studies of the large-scale coronal features extend previous coronagraph work with low-noise temperature maps. Temperatures of radial, extended, plume-like structures in both the polar coronal hole and in a low latitude decaying active region were found to be cooler than the surrounding material. Active region loops were investigated in detail and found to be isothermal for the low loops but hottest at the loop tops for the large loops. [less ▲]

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See detailFirst Results from EIT
Clette, Frédéric; Delaboudiniere, J.-P.; Artzner, G. E. et al

in 1st Advances in Solar Physics Euroconference. Advances in Physics of Sunspots (1997)

The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec ... [more ▼]

The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec. By using four different emission lines, it provides the global temperature distribution in the quiet corona, in the range 0.5 to 3*E(6) K. Its excellent sensitivity and wide dynamic range allow unprecedented views of low emission features, even inside coronal holes. Those so-called ``quiet'' regions actually display a wide range of dynamical phenomena, in particular at small spatial scales and at time scales going down to only a few seconds, as revealed by all EIT time sequences of full- or partial-field images. The initial results presented here demonstrate the importance of this wide-field imaging experiment for a good coordination between SOHO and ground-based solar telescopes, as well as for science planning. [less ▲]

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See detailImaging the solar corona in the EUV
Delaboudiniere, J.-P.; Stern, R. A.; Maucherat, A. et al

in Advances in Space Research (1997), 20

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the ... [more ▼]

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the Sun. As one of the instruments onboard SOHO, the EIT (Extreme ultraviolet Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The He II filter at 304 AË images the chromosphere and the base of the transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X filter at 171 AË images the corona at a temperature of ~ 1.3 x 10^6 K; the Fe XII filter at 195 AË images the quiet corona outside coronal holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284 AË images active regions with a temperature of ~ 2.0 x 10^6 K. About 5000 images have been obtained up to the present. In this paper, we describe also some aspects of the telescope and the detector performance for application in the observations. Images and movies of all the wavelengths allow a look at different phenomena present in the Sun's corona, and in particular, magnetic field reconnection. [less ▲]

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See detailEIT: Extreme-Ultraviolet Imaging Telescope for the SOHO Mission
Delaboudinière, J.-P.; Artzner, G. E.; Brunaud, J. et al

in Solar Physics (1995), 162

The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field images of the corona and transition region on the solar disc and up to 1.5 Ro above the solar limb. Its normal incidence multilayer ... [more ▼]

The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field images of the corona and transition region on the solar disc and up to 1.5 Ro above the solar limb. Its normal incidence multilayer-coated optics will select spectral emission lines from Fe IX (171 Å), Fe XII (195 Å), Fe XV (284 Å), and He II (304 Å) to provide sensitive temperature diagnostics in the range from 6 × 10[SUP]4[/SUP] K to 3 × 10[SUP]6[/SUP] K. The telescope has a 45 x 45 arcmin field of view and 2.6 arcsec pixels which will provide approximately 5-arcsec spatial resolution. The EIT will probe the coronal plasma on a global scale, as well as the underlying cooler and turbulent atmosphere, providing the basis for comparative analyses with observations from both the ground and other SOHO instruments. This paper presents details of the EIT instrumentation, its performance and operating modes. [less ▲]

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