The Physical Properties of Coronal Streamers. II.

Abstract

In this paper the plasma properties of three streamers observed in 2003 by the Ultraviolet Coronagraph Spectrometer (UVCS) are presented for five heights from 1.75 to 5.0 R☉. The kinetic temperatures for protons (Tk,p) and the O5+ ions (Tk,O) are derived as a function of height with preferential heating of O5+ over protons recorded. By examining how Tk,p varies with latitude at each height, an idea of the magnetic field morphology is found. At 1.75 R☉ the elemental abundances (O, S, Ar, and Fe), electron temperature, and electron density are derived from the UV spectral data. All three streamers were quiescent with typical abundance values; however, no depleted cores were found. The first ionization potential (FIP) effect was detected for all three streamers with a bias of ~4. This is consistent with slow solar wind in situ measurements, thereby supporting the hypothetical connection between the two. All three streamers had a higher than expected electron temperature. The electron densities above 1.75 R☉ are derived from the Large Angle Spectroscopic Coronagraph (LASCO) C2 polarized brightness data. Estimates for the O5+ outflow velocities are obtained using the O VI λ1032 over λ1037 intensity ratios and the estimated electron densities. All three streamers showed evidence of significant outflows at 4.0 and 5.0 R☉.