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Proposal ID Gurman_21

Date of Proposal
96/07/27

firstname
Joseph

lastname
Gurman

institute
NASA Goddard

address
NASA Goddard Space Flight Center
Code 682.3
Greenbelt MD 20771

email
gurman@gsfc.nasa.gov

phone
(301) 286-4767

fax
(301) 286-8403

proposal
EIT has observed a new class of transient phenomena in the solar corona:
transient, jetlike events ("microjets") in polar plumes. The most distinct of
these events has been measured to traverse the range 0.05 - 0.20 solar radii at
an a apparently constant speed of 300 km/s. In some sense, this is the first
really new coronal phenomenon observed by EIT.

We propose to use the Fe XII 195 A time sequences of the solar poles
obtained by EIT to examine the nature of microjets in the polar holes. The
observations obtained so far cover 16 x 5 pixel blocks (i.e., 512 pixels
east-west x 160 pixels north-south) and have been run at a cadence of one
frame every 70 s as part of the two-month, "synoptic" plan that severely
limited out flexibility in data taking.

We intend to obtain further observations to attempt to understand why Fe
XII, at 1.5 MK, shows the transient events better than Fe IX/X, at 0.8 - 1 MK.
The Fe IX/X observations should also help determine whether pre-existing plumes
are affected by the transients microjets, whether plumes can be formed by
microjets, and/or whether plume lifetimes can end in microjets.

With the current OBE load (V.148) or later, we hope to use the additional
flexibility of the planning and scheduling software tools to extend the length
of the observations beyond the ~ 40 minute maximum so far obtained for the Fe
XII time series.

We will compare the observed microjets with models of kink-induced
plasmoid ejections predicted by Mullan and Ahmad (1982, Solar Physics 75, 347),
as well as any other mechanisms that seem physically reasonable, but our
objective is to get this new and exciting result into the refereed literature as
soon as possible, and leave extensive modelling efforts for follow-on studies.

inside_collab
Any and all consortium members welcome!

consortium
yes

topic
Polar Plumes

topic
microjets

title
The properties of microjets in EUV plumes

update added on 1998/03/14 at 11:15:49
1996 Fall AGU talk:
Gurman, J.B.,J.P. Delaboudinihre, G.E. Artzner, A.H. Gabriel, K.P. Dere, R. Howard, D. Michels, J.D. Moses,
C. St. Cyr, R. Catura, J. Lemen, R. Stern, P. Cugnon, F. Clette, J.M. Defise, C. Jamar, P. Rochus, A. Maucherat,
J. Newmark, B. Thomps: 1996, Eos, Transactions, SH71B-11, "Microjets in Coronal Holes"


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