X-ray and EUV images give
indications of steady features like
coronal holes (the sources of
long-lived high speed solar wind
streams), as well as dynamic
features like flares, prominence
eruptions, and possibly CMEs.
Radiation at these wavelengths
also ionizes the upper atmosphere.
For example, SOHO Difference
images in the EUV have revealed
extended signatures of eruptive
activity in the solar atmosphere,
while large eruptive events in the
low corona are sometimes seen in
the soft x-ray images from the
ISAS/NASA Yohkoh spacecraft.
Localized active region dynamics
are observed in the Extreme
Ultraviolet at high spatial
resolution by the TRACE mission
telescope operated by Lockheed.
These observations challenge the
models, which must reproduce
coronal hole and CME locations,
and unravel the connections
between flares and CMEs.
The EUV images (top) were made
available by the SOHO EIT
investigation team via the ISTP
event pages on the WWW. The
Yohkoh SXT x-ray image for
4/14/94 is from the YPOP Yohkoh
Public Outreach site, and the
TRACE EUV picture showing an
active region near the limb is from
the TRACE open data archive
web-site. Berkeley Space Sciences
Lab will be using the HESSI
spacecraft to image active region
hard x-rays and gamma rays
starting in 2000, adding to the high
energy end of this information.
Click on the top three images to the left to view the corresponding
animation. Click on the bottom image to enlarge.
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