Dr. Matthew Penn
California State University Northridge

Tuesday, June 22, 1999
IfA Auditorium ***2:00, Refreshments 1:45***

Title

"Combining Ground- and Space-based Observations of an Erupting Filament"

Abstract

The Sun produced an erupting filament on 13 June 1998, which left the solar
surface and traveled through interplanetary space associated with a coronal
mass ejection.  The filament happened to cross the field-of-view of a
quiet-Sun Joint Observing Program, and two satellites and one ground-based
observatory collected data on the event.  Imaging spectro-polarimetric
infrared observations from the NSO Kitt Peak Vacuum Telescope are combined
with EUV imaging spectral observations from the SoHO Coronal Diagnostic
Spectrometer and EUV filtergraph images from the SoHO Extreme-ultraviolet
Imaging Telescope and EUV filtergraph images from the Transition Region and
Coronal Explorer.

Preliminary analysis shows that the filament left the solar surface
traveling at about 250 km per sec at roughly a 45 degree inclination. Over
most of the observed path the filament has a constant velocity with
virtually no acceleration.  The filament displays internal azimuthal
velocities of up to plus/minus 25 km per sec as various (4?) threads
unravel.  The filament shows emission at plasma temperatures from 10^4
through 10^6 Kelvins, and shows continuum EUV absorption which will be used
to measure the proton density in the filament. (This special event will
answer questions about the continuum absorption process seen in quiescent
filaments.) Polarimetric measurements from NSO/KP show no line-of-sight
magnetic fields in the filament but an upper limit will be computed from
that data.

Understanding the ejection path of this and other filaments is essential
for determining the relationship between filament eruptions and coronal
mass ejections.  The physics of the plasma during the eruption is also
poorly understood, and these measurements of the velocities, temperatures
and densities in this filament will help to constrain theorectical efforts
to model these events.