Huge Coronal Structure and Heating Constraints Determined from SERTS Observations

Abstract

Intensities of the extreme-ultraviolet (EUV) spectral lines were measured as a function of radius o † the solar limb by two Ñights of the GoddardÏs Solar Extreme-Ultraviolet Rocket Telescope and Spectrograph (SERTS) for three quiet-Sun regions. Density scale heights were determined for the di †erent spectral lines. Limits on the Ðlling factor were determined. In the one case where an upper limit was determined it was much less than unity. Coronal heating above 1.15 solar radii is required for all three regions studied. For reasonable Ðlling factors, local heating is needed.

Are “EIT Waves” Fast‐Mode MHD Waves?

“…Various studies have determined plasma conditions for the base of the quiet corona. Magnetic field strengths have been measured at anywhere from 2.2 G (Fludra et al 2002;Falconer & Davila 2001) to 10 G (Pauluhn & Solanki 2003), while multiple studies have found density measurements close to 2×10 8 cm −3 (Aschwanden & Acton 2001;Feldman et al 1999;Doscheck et al 1997).…”

MHD waves in the solar north polar coronal hole

“…They used the heat conduction coefficients bearing electron collisional time, τ e . They retained the perpendicular heat conduction coefficient κ ⊥ in their analysis, unlike the various other investigators who dropped κ ⊥ claiming that κ ⊥ /κ ≈ 10 −10 (Falconer & Davila 2001). UVCS/SOHO observations on Mg IX and O VI lines of NPCH showed that the plasma turns from collisional to collisionless within the range 1.75-2.1 R (Doyle et al 1999).…”