Observations of Polar Plumes with the SUMER Instrument on SOHO

by D.M. Hassler, K. Wilhelm, P. Lemaire, U. Schuehle

• Fig.2 (~0.1Mb) The first part of the sequence used the 0.3 x 120 arcsecond slit to make two raster images or spectroheliograms (16 x 2 arcmin²) with 1.5 arcsecond steps extending ± 8 arcminutes from central meridian, shown in the bottom half of the figure. (The scale is 1.5 arcsec/pixel along the x-axis and 1 arcsec/pixel along the y- axis) In these raster images, one can see narrow jets or macrospicules originating from bright points near the limb and extending 30-60 arcseconds above the limb on both the east and west side of central meridian. The second part of the sequence, using the 1 x 300 arcsecond slit, extending from 30 arcseconds above the limb out to 1.33 solar radii, obtained a single raster image or spectroheliogram extending ± 5 arcminutes from central meridian, shown in the top half of the figure. One can see in this image, along with the larger scale plume structures, two small jets or macrospicules near central meridian which appear to originate from bright points at the limb in the lower images and extend 15-20 arcseconds into this upper image.

• Fig.3 (~0.2Mb) The corresponding SOHO/EIT image in FeXII at 195 Å taken at 02:06 UT May 22 shown for reference. As can be seen in the figure, the polar coronal holes in both the north and south extend far enough onto the disk (toward low latitudes) to permit unambiguous line-of-sight observations above the limb without risk of contamination from foreground or background structures. (Courtesy of the EIT Consortium)

• Fig.7 (~0.1Mb) An image of the O VI 1032 Å line intensity and line width (assuming a single Gaussian profile) as a function of height and position above the limb obtained during the raster scan on May 22, 1996. The most notable feature is the striking anti-correlation between line intensity and line width near central meridian.