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Proposal ID Handy_134

Date of Proposal
97/10/31

firstname
Brian

lastname
Handy

institute
Montana State University

address
Department of Physics
College of Letters and Science
Montana State University-Bozeman
P.O. Box 173840
Bozeman, MT 59717-3840

email
handy@physics.montana.edu

phone
650-354-5768

fax
650-424-3994

proposal
(B.N. Handy, C.J. Schrijver, H.J. Hagenaar)

Description:
A huge volume of literature has been generated since Coronal Bright Points
were first discovered in the pre-Skylab era. A large body of work was
initially based on Skylab observations and much recent work has been done with
Yohkoh/SXT data. While Yohkoh made much more rapid observations possible, it
is clear that the timescales of events in the photospheric magnetic field are
in general always faster than observing cadence. Recent observations from MDI
(Schrijver et al. 1997) have shown that network concentrations exist as a unit
for only fractions of a day, and substantial reorganization of the magnetic
field often happens in less than 30 minutes.

SoHO has made it possible to improve the resolution and temporal cadence of
these observations. Schrijver et al. (1997) have studied the evolution of the
photospheric magnetic field from recent MDI data; their observations note that
magnetic flux emerges, collides with opposite polarity flux and cancels on
time scales of the order of minutes to hours. MDI and EIT recently ran a
joint campaign (10-OCT-97 14:00 to 14-OCT-97 03:00GMT) collecting MDI and EIT
partial-frame images in the MDI high resolution field of view. MDI cadence
was nominally one image per minute. EIT collected one image in the 195 A
channel every 7-8 minutes.

We propose to follow the time evolution of the photospheric magnetic field and
correlate these events with brightenings seen in the quiet corona in the EIT
195 A channel. We will further compare the coronal structures to various
extrapolations of the photospheric magnetic field, following potential field
models or other force free models to attempt to produce an acceptable match to
the EIT images. We will compare the brightness with the magnetograms to
quantify the (statistical) relationship between local magnetic and radiative
flux densities.

The reformatted data for both instruments from this campaign presently
available and no further observations are required for this study. This data
will be analyzed with an eye towards improving observing sequences for the
upcoming TRACE mission.

-----------
Schrijver, C.J., Shine, R.A., Hurlburt, N.E., Tarbell, T.D. and Lemen, J.R.,
1997, in "Proceedings of the SoHO Workshop, Oslo, Norway, June 1997."

inside_collab
James R. Lemen lemen@sag.lmsal.com

consortium
no

topic
Quiet Sun

topic

title
A Dynamic Study of Coronal Brightenings


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