Abstract
The partially earth-directed coronal mass ejection (CME) event of 1997
February 6-7 originated
from the southwest quadrant of the sun. The CME accelerated from 170
km/s to about 830 km/s
when it reached a distance of 25 solar radii. The CME was an arcade
eruption followed by bright
prominence core structures. The prominence core was tracked continuously
from the solar surface
to the interplanetary medium by combining data from
the Nobeyama
radioheliograph
(microwaves),
Mauna Loa Solar Observatory (He 10830 { Angstroms}),
SOHO/EIT (EUV) and
SOHO/LASCO (white light). The CME was accompanied by an arcade
formation, fully observed
by the YOHKOH/SXT (soft X-rays) and SOHO/EIT (EUV). The X-ray and EUV
observations
suggest that the reconnection proceeded from the northwest end to the
southeast end of a filament
channel. In the SOHO/EIT images, the the feet of the soft X-ray arcade
were observed as EUV
ribbons. The CME event also caused a medium sized geomagnetic storm: The
hourly equatorial
Dst values attained storm level during 18:00-19:00 UT on February 09.
This means the
disturbance took about 2.25 days to reach the Earth. The first
signatures of an IP shock was a
pressure jump in the WIND data around 13:00 UT on Feb 09, 1997 which
lasted for about 14
hours, followed by flux rope signatures. This CME event confirms a
number of ideas about CMEs:
The three part structure (frontal bright arcade, dark cavity and
prominence core), disappearing
filament, elongated arcade formation, and terrestrial effects. We make
use of the excellent data
coverage from the solar surface to the Earth to address a number of
issues regarding the origin
and propagation of the geoeffective solar disturbances.
We benefited from discussions at the first SOHO-Yohkoh Coordinated Data
Analysis Workshop,
held March 3-7, 1997, at Goddard Space Flight Center.