3 research outputs found
Morphological study of penumbral formation
Penumbrae are known to be area of mainly horizontal magnetic field
surrounding umbrae of relatively large and mature sunspots. In this paper, we
observationally studied the formation of penumbrae in NOAA10978, where several
penumbral formations were observed in G-band images of SOT/Hinode. Thanks to
the continuous observation by Hinode, we could morphologically follow the
evolution of sunspots and found that there are several paths to the penumbral
formation: (1) Active accumulation of magnetic flux, (2) Rapid emergence of
magnetic field, and (3) Appearance of twisted or rotating magnetic tubes. In
all of these cases, magnetic fields are expected to sustain high inclination at
the edges of flux tube concentration longer than the characteristic growth time
of downward magnetic pumping.Comment: accepted for publication in PAS
Synoptic solar observations of the Solar Flare Telescope focusing on space weather
The solar group at the National Astronomical Observatory of Japan is
conducting synoptic solar observations with the Solar Flare Telescope. While it
is a part of a long-term solar monitoring, contributing to the study of solar
dynamo governing solar activity cycles, it is also an attempt at contributing
to space weather research. The observations include imaging with filters for
H, Ca K, G-band, and continuum, and spectropolarimetry at the
wavelength bands including the He I 1083.0 nm / Si I 1082.7 nm and the Fe I
1564.8 nm lines. Data for the brightness, Doppler signal, and magnetic field
information of the photosphere and the chromosphere are obtained. In addition
to monitoring dynamic phenomena like flares and filament eruptions, we can
track the evolution of the magnetic fields that drive them on the basis of
these data. Furthermore, the magnetic field in solar filaments, which develops
into a part of the interplanetary magnetic cloud after their eruption and
occasionally hits the Earth, can be inferred in its pre-eruption configuration.
Such observations beyond mere classical monitoring of the Sun will hereafter
become crucially important from the viewpoint of the prediction of space
weather phenomena. The current synoptic observations with the Solar Flare
Telescope is considered to be a pioneering one for future synoptic observations
of the Sun with advanced instruments.Comment: 18 pages, 6 figure