The Structure and Dynamics of a Bright Point as seen with Hinode, SoHO and TRACE
David Perez-Suarez Submitted: 2008-10-09 08:49
Our aim is to determine the plasma properties of a coronal
and compare its magnetic topology extrapolated from magnetogram data
with its appearance in X-ray images.
We analyse spectroscopic data obtained with EIS/Hinode, Ca II H and
G-band images from SOT/Hinode, UV images from TRACE, X-ray images from
XRT/Hinode and high-resolution/high-cadence magnetogram data from MDI/SoHO.
The BP comprises several coronal loops as seen in the X-ray images,
while the chromospheric structure consists of tens of small bright
points as seen in Ca II H. An excellent correlation exists between the
Ca II BPs and increases in the magnetic field, implying that the Ca II H
passband is a good indicator for the concentration of magnetic
flux. Doppler velocities between 6 and 15 km s-1 are derived from the
Fe XII and Fe XIII lines for the BP region, while for
Fe XIV and Si VII
they are in the range from -15 to +15 km s-1. The coronal electron density is
3.7 imes109 cm-3. An excellent correlation is found between
the positive magnetic flux and the X-ray light-curves.
The remarkable agreement between the extrapolated magnetic field
configuration and some of the loops composing the BP as
seen in the X-ray images suggests that a large fraction of the
magnetic field in the bright point is close to potential. The close
correlation between the positive magnetic flux and the X-ray emission
suggests that energy released by magnetic reconnection is stimulated by
flux emergence or cancellation.
Authors: D. P'erez-Su'arez, R.C. Maclean, J.G. Doyle and M.S. Madjarska
Publication Status: A&A (in press)
Last Modified: 2008-10-09 08:49