Hida-Yohkoh Campaign Observation
"Study of Microflares and Nanoflares in Emerging Flux Regions"
Date: Sat, 23 May 1998 11:18:23 +0900 (JST)
Subject: Hida-Yohkoh campaign
Title of Campaign:
Study of microflares and nanoflares in emerging flux regions
Campaign periods: (1) 8-16 June, 1998 (2) 29 July - 8 August, 1998
(1) How and Which type of magnetic flux emergence or Hα AFS loops can
produce an SXR microflare or a nanoflare?
The previous coordinated observations of four emerging flux regions
(EFRs) with Hida Hα and Yohkoh SXT revealed the following results :
(Yoshimura, Kurokawa and Hudson 1998)
(a)All bright loops are short-lived and transient in the EFRs.
The life time of a loop is in most cases less than 30 minutes.
Even a loop ,which is seen longer in the same location, shows
multiple brightness fluctuations, which suggests an overlap of
transient smaller loops.
(b)Close spatial correspondence was found between Hα emerging dark
loops (arch filament system (AFS) loops) and SXR brightening loops
(microflares) in the EFRs. Close to most of SXR bright loops Hα
AFS loops were found. In many cases two or three small AFS loops
spatially correspond to one larger SXR loop.
(c)Temporal relations between emergence of AFS loops and brightening
of SXR loops were not clear in many cases, though a rising motion
of an Hα AFS loop was clearly found to be followed by a brightening
of SXR loop in a few examples.
For the next step, this campaign aims to study further how, when and
which emerging magnetic loop triggers an SXR loop brightening.
(2)Study of SXR jets and Hα surges in EFRs, and their relations.
X-ray jets were frequently found with the Yohkoh SXT (Shibata et al.
1992) and statistically studied by Shimojo et al.(1996).
Hα surges were found to be the first active manifestation of emerging
magnetic field in some EFRs and suggested to be produced by magnetic
field reconnections (Kurokawa and Kwai 1993).
The relations between x-ray jets and Hα surges were studied by some
authors, but are not clear yet. This campaign aims to observe
simultaneously EFR-surges and EFR-jets, and to examine that they are
both explained by the same reconnection senario in the emerging flux
(a)High Resolution Hα images with Hida DST
FOV: φ〜400 seconds of arc
wavelengths:Hαcenter and Hα-0.6
exposure cadence:1 frame every 2 s
temporal resolution for a single wavelength: about 4 s
(b)Hα line spectrum with Hida DST Vertical Vacuum Spectrograph.
(c)Hα full disc images with CRL Hiraiso Solar Telescope
(d)Hα filtergrams of Mitaka Flare Telescope of NAOJ
(2)Yohkoh SXT data
(a)spatial resolution:full resolution
(b)filter: one filter (AlMg) observations with high time resolution
one more filter image at every 5 minutes
(c)field of view: 128 x 128 pixels
(d)temporal resolution: 4 seconds, if possible
It is important to observe very the initial stage of a microflare.
I believe a microflare or an SXR loop brightening will start at the
footpoints of the loop. It is essential to examine the temporal and
spatial relation among Hα AFS rising motion, the impulsive
brightenings of the footpoints and the following loop brightenings.
By this reason we need high time resolution.
(e)exposure time: two different exposures, alternatively to see both
of ordinary bright and transiently flashing features.
Very long exposure, which may be useful to see faint connections
between active regions, is not necessary in this project, because
an overexposure destroys fine structures in the microflare loops
(3)Magnetic Field Data
(a)Vector Magnetograph of Mitaka Flare Telescope (NAOJ)
(b)Vector Magnetograph of Huarou Station, Beijing Obs.
(c)MDI magnetogram of SOHO
K. Yoshimura, T. Magara, S. Sano, S. UeNo, T. Morimoto,
H. Kozu, R. Kitai, H. Kurokawa, 他( Kyoto Univ. )
M. Shimojo, T. Sakurai(NAOJ), M. Akioka(CRL Hiraiso)
H. Zhang,(Beijing Obs. Huairou)
Date: Wed, 10 Jun 1998 22:17:32 +0900
The followings are active phenomena noticed in the Hida Halpha images
obtained during the first day of the EFR campaign from 2330UT 7 June
through 7UT 8 June.
The targets were two small EFRs, namely EFR1 and EFR2 which were located
close to a large sunspot in NOAA 8232, and at the north and at the north-east
of the sunspot, respectively.
The position of each event is indicatd by its direction pointed from the
center of the main sunspot. Start, Maximum and End times of each phenomenon
are given in hh:mm UT.
We would like to study which type of high temperature phenomena were
asociated with these Halpha transients.
Times Location Characteristics of phenomena
(start, max. end)
(1) (23:37, , 23:53) North Small bright point and small surge in EFR1.
(2) (23:48, 23:59, 00:15) North Dark filament in Halpha-0.6 followed by a
brightening in Halpha center.
(3) (00:10, 00:36, 00:54) West Dark filament activation, explosion, and
brightenings at its base.
(4) (00:00, 00:16, 00:30) SE-S Dark filament activation alog the filament
(5) (00:30, 00:35, 01;15) S Explosive dark feature at the south end of
the filament (4).
(6) (00:26, , 00:42) NE Small dark loop in Halpha -0.6. Small AFS
(7) (00:25, 00:36, 01:01) NE Small dark loop emergence and brightening
in EFR2. Small AFS loop emergence.
(8) (00:53, 00:56, 01:10) N-NW Subflare followed by fast bright(in Halpha
center) and dark (in Halpha-0.6) ejections.
Vel. about 130km/s.
(9) (01:03, 01:26, 0140) N Small dark loop emergence in EFR2
(10)(01:37, 01:43, 02:05) N Subflare around EFR1 and dark matter
ejection along the same pass as No.9 event.
(11)(01:15, 01:20, 01:24) N Small dark loop emergence at the outer
boundary of the sunspot penumbra.
(12)(02:11, 02:21, 02:36) N Small dark loop emergence in EFR1
(13)(02:31, 02:45, 03:04) N Small dark loop emergence with a small
and faint brightening at the footpoint
(14)(02:16, 02:22, 02:39) NE Two small dark loops emergence between EFR1
and EFR2 near the penumbar boundary.
(15)(01:57, 02:17, 02:42) E Rising motion of a superpenumbral filament.
(16)(02:30, 02:43, 02:49) E Dark matter activation like a surge without
any footpoint emission.
(17)(02:48, 02:59, 03:35) S Dark matter activation along the filament
channel, similar to No.4
(18)(02:50, 03:38, 04:55) N Dark matter ejection and subflare
(19)(03:32, 03:32, 03:36) NE Microflare. Two small and short emissions
at both side of a filament near EFR2.
(20)(04:21, 04:30, 04:47) NE Small dark loop emergence in EFR1
(21)(05:08, 05:18, 05:28) NE Small dark loop emergence and
small ejection with small brightening.
(22)(04:59, , 05:48) N Several small dark loop emergences at the
the boundary of the sunspot penumbra.
(23)(06:35, 06:43, 06:50) N Dark matter ejection from the north end of
3. Event List