Lm. Kozlova et Bv. Somov, Studying coronal holes through observations of an HeI infrared line and the H-alpha line, ASTRON REP, 44(6), 2000, pp. 401-406
New results from electrophotometric scanning of the solar disk in the HeI l
ambda 10830 Angstrom and H-alpha lines are presented. The intensity at the
center of the HeI lambda 10830.30 Angstrom line is 1-3% higher in the regio
ns of coronal holes than in quiescent regions; this is accompanied by a dec
rease in the size and contrast of the chromospheric network compared to the
network in quiescent regions. Our observations in the HeI line revealed ch
ains of "dark points" surrounding coronal holes. The H-alpha +/- 0.5 observ
ations show increased velocities of ascent near the dark points compared to
the velocities inside coronal holes and in quiescent regions. It is propos
ed that the intensification and acceleration of the hows of solar plasma fr
om the dark points are due to reconnection of the magnetic fields of the bi
polar chromospheric network and the predominantly unipolar magnetic field i
nside the coronal holes. Our observations suggest that the same reconnectio
n process takes place near the temperature minimum, in the presence of cert
ain conditions at the boundary between coronal holes and bipolar active reg
ions. The reconnection process produces plasma flows from the chromosphere
to the corona, which are sufficient to form prominences. (C) 2000 MAIK "Nau
ka/Interperiodica".