Observations of coronal structures above an active region by EIT and implications for coronal energy deposition

被引：45

作者：

Neupert, WM ^{[1
]}

Newmark, J ^{[1
]}

Delaboudinière, JP ^{[1
]}

Thompson, BJ ^{[1
]}

Catura, RC ^{[1
]}

Moses, JD ^{[1
]}

Gurman, JB ^{[1
]}

Portier-Fozzani, F ^{[1
]}

Gabriel, AH ^{[1
]}

Artzner, G ^{[1
]}

Clette, F ^{[1
]}

Cugnon, P ^{[1
]}

Maucherat, AJ ^{[1
]}

Defise, JM ^{[1
]}

Jamar, C ^{[1
]}

Rochus, P ^{[1
]}

Dere, KP ^{[1
]}

Howard, RA ^{[1
]}

Michels, DJ ^{[1
]}

Freeland, S ^{[1
]}

Lemen, JR ^{[1
]}

Stern, RA ^{[1
]}

机构：

[1] NOAA, SEC, Code RESE, Boulder, CO 80303 USA

来源：

SOLAR PHYSICS | 1998年 / 183卷 / 02期

基金：

美国国家航空航天局;

关键词：

D O I：

10.1023/A:1005045512509

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Solar EUV images recorded by the EW 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 1.0-2.0 MK. Such observations permit estimates of longitudinal temperature gradients (Lf 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 Fe IX/X (171 Angstrom) and Fe XII (195 Angstrom) 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.

引用

页码：305 / 321

页数：17

共 33 条

[1] THE DISCRETE AND LOCALIZED NATURE OF THE VARIABLE EMISSION FROM ACTIVE REGIONS [J].