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Proposal ID Staude_42

Date of Proposal
96/10/23

firstname
Juergen

lastname
Staude

institute
Astrophys. Inst. Potsdam

address
Astrophysikalisches Institut Potsdam
Sonnenobservatorium Einsteinturm
D-14473 Potsdam
Germany

email
jstaude@aip.de , jstaude@solar.stanford.edu

phone
(+49) 331-288-2300

fax
(+49) 331-288-2310

proposal
Investigation of the structure and dynamics of the main sunspot
of the large active region of August 29 (and perhaps 30), 1996
close to the centre of the disk:

- Comparison of vector magnetograms from the Astrophys. Inst.
Potsdam (Aug. 29 - 30) and their force-free extrapolations with
full-resolution EIT images;

- investigation of the spatial structure of sunspot oscillations
observed simultaneously in different spectral lines, using a
time series of two-dimensional spectra from SUMER (see SUMER
Red Book Proposal 8.1.2.4) obtained on Aug. 29 and a time series
of EIT images.

inside_collab
Work together with Joe Gurman proposed

consortium
no

topic
Sunspots

topic

title
Sunspot oscillations and magnetic field structure

update added on 1998/03/19 at 12:56:13
The EIT data of Aug. 29, 1996 have been processed using the
solarsoft routines they include a time series (09-11 UT) of
200 pictures of the active region NOAA 7986 in the Fe IX/X 171 A
line and high-resolution images of the whole solar disk obtained
in the 4 EIT lines between 00:15 and 01:12 UT.

The EIT time series has been recorded simultaneously to the first
period of a longer time series (09:08-13:31 UT) obtained on SUMER
by scanning the large sunspot of NOAA 7986 with the spectrograph
slit perpendicular to the slit direction. The three-dimensional
spectra include the spectral regions at 770.4 A (Ne VIII) and
1548.1 A (C IV). Supplementary data of the same date and active
region are from CDS and from the magnetograph of the Potsdam
Einsteinturm' solar observatory.

In a preliminary data analysis the temporal fluctuations of
intensity of the 2 SUMER lines at the sunspot centre have been
investigated. Both lines show significant power at frequencies
of 7.4...7.7mHz (periods of 130-135s), moreover, a slow temporal
decrease of the oscillatory power in the Ne VIII line but an
increase in the C IV line is observed. So far the EIT data have
been used to define the position of the SUMER data with their
small field of view within the active region.

The future analysis will extend the investigation of the
intensity oscillations to the EIT line and to the velocity
(Doppler) oscillations in the SUMER lines, looking for phase
differences and correlations. Moreover, the spatial distribution
of the oscillations will be related to the magnetic structure
of the active region.

A report on the preliminary results will be presented in a poster
at the conference A Crossroads for European Solar and
Heliospheric Physics: Recent Achievements and Future Mission
Possibilities' at Tenerife, March 23-27, ,1998. It will be
published in ESA SP-417 with the title:
Sunspot Oscillations from SUMER Spectra' by
J. Rendtel, J. Staude, D. Innes, K. Wilhelm, and J.B. Gurman.


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