JOINT CDS/MDI/SUMER PROGRAMME
Connection between Transition Region Lines and the Photospheric Magnetic
Field
Per Maltby & Olav Kjeldseth-Moe ITA, University of Oslo, Richard
A. Harrison, RAL, Klaus Wilhelm, MPI-Ae, & Philip H. Scherrer,
Stanford University.
Scientific Justification:
The state of the solar plasma located in the transition
region, is likely to be controlled by the magnetic field penetrating the
region. Knowledge about the magnetic field in the transition region is scanty
and confined to the sunspot region. Accordingly, the connection between
transition region line characteristics and the magnetic field thus has to
be based on measurements of the magnetic field at photospheric heights.
It has been argued Schrijver (1990) that a point to point comparison of
transition region line intensities and the photospheric magnetic field is
not physically meaningful. Recently, Brynildsen, Kjeldseth-Moe, &
Maltby (1994, 1996) have studied the quiet Sun relation between the C IV
resonance line parameters and the photospheric magnetic field with a spatial
resolution of 1''x 1''. They ordered the material into groups according
to the magnitude of the magnetic flux density |B|, calculated conditional
probabilities and found that redshifted profiles with either high intensity,
large Doppler shift, or large line broadening occupy an increasing fraction
of the area when |B| increases. These results were contrasted by blueshifted
profiles which indicated a slight decrease with increasing magnetic flux
density.
Further studies of the connection between transition line parameters and
the photospheric magnetic field are required in order to explore the potential
of the conditional probability calculations and study in detail the connection
between transition region lines and the photospheric magnetic field, both
in the quiet Sun and in active regions.
References:
Brynildsen, N., Kjeldseth--Moe, O., & Maltby, P. 1994, Proc. Third SOHO
Workshop, ESA SPC--373, 413
Brynildsen, N., Kjeldseth--Moe, O., & Maltby, P. 1996, ApJ (in press)
Schrijver, C. J. 1990, A & A, 234, 315
No additional text was submitted for this proposal.