Limb prominences seen in UV, EUV and SXR
P. Heinzel (1,2), F. Farnik (1), U. Anzer (2) and I. Dammasch (3)
(1) - Ondrejov Observatory, Czech Republic
(2) - MPA Garching, Germany
(3) - MSSL, Great Britain
We use SOHO/SUMER,EIT and Yohkoh SXT prominence observations to
study the absorption and/or volume blocking (see Anzer and
Heinzel, ApJ 622, 714, 2005) of UV, EUV and SXR radiation by cool
prominence plasma. As an example for his type of behaviour we
study the limb prominence observed on 5 Sept. 1996. The SUMER
spectrograph has detected two coronal lines, MgX at 625 A which is
absorbed by the hydrogen Lyman continuum and blocked within a
volume occupied by cool prominence plasma, and FeXII at 1242 A
where the prominence appears dark due to blocking only (since
there is negligible absorption at this wavelength). A similar
behaviour is visible also in the EUV images taken by EIT. We find
that a darkening comparable to that detecetd in the FeXII line can
be seen in the SXR images obtained by Yohkoh/SXT. Since the
absorptions by the Lyman continuum, the resonance continua of HeI
and HeII and also by the metals are all small in the energy range
of SXT we explain the darkening seen by SXR as being entirely due
to volume blocking. Based on a quantitative analysis of these
data, we discuss the physical conditions in cool prominences and
in their coronal environment. Finally, we propose new high-
resolution EUV and SXR observations of prominences and filaments
by Solar-B, using the EUV imaging spectrometer (EIS) and the X-ray
telescope (XRT) as a basis for a more detailed investgation of
such cool structures.
Correspondence
Frantisek Farnik (ffarnik@asu.cas.cz)
presentation
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