ar031.hanaoka06 Posted: 03-Sep-92 (as ar031.irimajiri01) Updated: 01-Nov-92, 31-Jan-93, 23-Apr-93, 26-Nov-93
Prominence Eruption and Brightening of Arcade Loop on July 31,1992
Collaboration: Y. Irimajiri, Y. Hanaoka, K. Shibasaki, H. Nakajima (Nobeyama Radio Observatory, NAOJ)
Question: What is the relation between prominence eruptions and flares ?
Motivation: Prominence eruptions are often associated with flares or
brightenings of arcade loop. There are two types of relation
between prominence eruptions and flares or brightenings. One
case is that the flare or the brightening occur after about
1-2 hours later the eruption, the other case is that the
eruption seems to be triggered by the flare. To understand
the birth of flares or brightenings, it is important to study
prominence eruptions.
Approach: Promience eruption was observed on Jul 31,1992 at the north-east
limb with the Nobeyama Radio Heliograph, Yohkoh, H-alpha
telescope. This event is summarized as follows.
We will study about what is the mechanism of brightenings (or flares) relating to the prominence eruption.
of the prominence after about 1 hour later the eruption. At the same position, near the same time, the brightening was also observed with the SXT. This brightening was located at the top of the arcade loop which started forming after about 1 hour later the eruption.
- The main body of the eruptive prominence was observed at the 17GHz and H-alpha. But this feature did not be observed with the SXT.
- The brighrening was observed at the 17GHz around the footpoint
Update 26-Nov-93
I have submitted a paper on my proposal ar031.hanaoka06 to PASJ and the revised manuscript is now inspected by referees.
Update 23-Apr-93 (abstract of the paper under way)
Title: Simultaneous Observations of a Prominence Eruption followed by a Coronal Arcade Formation in Radio, Soft X-ray and H-alpha
PI and Collaborators: Y. Hanaoka, H. Kurokawa,
S. Enome, H. Nakajima, K. Shibasaki, T. Takano, M. Nishio, C. Torii, H. Sekiguchi, T. Bushimata, S. Kawashima, N. Shinohara, Y. Irimajiri, Y.-S. Choi, H. Koshiishi, T. Kosugi, Y. Shiomi, M. Sawa, K. Kai, Y. Nakai, Y. Funakoshi, R. Kitai, K. Ishiura, and G. KimuraAbstract: A prominence eruption followed by a coronal brightening was simultaneously observed in radio (17GHz), soft X-ray, and H-alpha on July 30-31, 1992. This event is a typical Kopp-Pneuman type phenomenon. The observations were performed by newly developed high performance instruments, or the Nobeyama Radioheliograph, the SXT on the Yohkoh satellite, and the Flare Patrol Telescope of the Hida Observatory and some other H-alpha telescopes. Therefore it gives us much more detailed picture of this type of event than previously observed ones. The erupting prominence, which occurred in quiet region and was observed in H-alpha and radio, ascended with a velocity of about 100 km s^-1. The general structure of the erupting prominence seen in 17GHz is very similar to that in H-alpha. While the prominence expanded rapidly, the radio total flux of the erupting prominence did not change largely. Since a prominence consists of fine threads, this fact means that each thread does not expand or keeps its surface area, while the prominence expands. Therefore the surface filling factor of the prominence decreases during the eruption. The high resolution pictures of the coronal brightening, which seems as a clear arcade structure, was taken in soft X-ray and radio, and the physical parameters of the arcade were derived from these pictures. The temperature was 3.5x10^6K in the early phase, and decreased to 2.6x10^6K in seven hours. The total emission measure reached the maximum value of 1.6x10^48 cm^-3 after three hours from the beginning of the arcade brightening, when the electron density at the ridge of the arcade is estimated as 2.4x10^9 cm^-3. It is generally accepted that the magnetic field is elongated by the prominence and the arcade shows the result of reconnection of the elongated magnetic field. Since both the erupting prominence and the arcade were observed, we present the magnetic field configuration during this event in a real scale.
Update 31-Jan-93 (PI changed from Y. Irimajiri to Y. Hanaoka)
Title: A prominence eruption followed by an arcade formation
PI and Collaborators: Y. Hanaoka and Nobeyama Radioheliograph group SXT team, Hida and Mitaka/Norikura people
Motivation and Preliminary Results: On 31 July 1992, during 00UT-10UT, a prominence eruption and a soft X-ray arcade formation, which is a typical example of Hirayama type or Kopp-Pneuman type events, was observed by Yohkoh SXT, Nobeyama Radioheliograph(17GHz), and the H-alpha telescopes at Hida, Mitaka, and Norikura simultaneously. The ejected prominence seen in H-alpha and 17GHz cannot be seen in soft X-ray, but a shock-front-like thin ejecta was found in the SXT images by K. Shibata. Total radio flux of the prominence did not change during the eruption. This fact shows that each thread which consists of the prominence did not expand during the eruption, because the expansion of threads leads to incease the radio flux. About one hour later of the prominence eruption, we can see a beautifull soft X-ray arcade, which was also observed in 17GHz. This arcade expanded with the velocity of 2-4 km/sec until about ten hours later when the arcade faded out. Unfortunately, during first 6 hours of the evolution of the arcade, soft X-ray pictures of the arcade was taken with the Al0.1 filter only, therefore we cannot derive temperature and emission measure with the filter ratio method. However, using the SXT images and the radio images of the Nobeyama Radioheliograph, we can derive these physical parameters. The temperature of the arcade loops decreases from 3.4x10^6 K to 2.8x10^6 K during six hours, and its maximum emission measure is 1.5x10^48 cm^-3.
Update 1-Nov-92
Title: Prominence Eruption and Brightening of Arcade Loop on July 31,1992
Collaboration: Y. Irimajiri, Nobeyama Radio Heliograph group, Yohkoh Team, Mitaka Team
Following is the detail about the prominence eruption on July 31.
1. A quiescent prominence which consists of some loop structures was seen at the north-east limb. There was no sunspot under the quiescent prominence. About 0 UT on July 31, the footpoint of the northern part of the prominence began to erupt from the limb to the outside of the Sun. The southern footpoint was still connected to the solar disk. The arch like structure expanded with the velocity of the ascending prominence of about 100km/second which was observed at the radio wavelength and in the H-alpha line. The very faint structure was seen in the soft X-ray during the eruption. There was no flare before the eruption at this region. The polarization was not observed at the radio wavelength.
2. The brightening on the disk was observed near the footpoint of the eruptive prominence about one hour after the eruption at the radio wavelength. This brightening was also observed in the soft X-ray. In the soft X-ray, the arcade loop whose ridge is the brightest was seen. The position of the bright region moved from the north to the south along the ridge of the arcade. In the H-alpha line, the two ribbon bright structure was observed.
3. From the comparison of the prominence at the radio wavelength and that in the H-alpha line, the position and the shape of the prominence at the radio wavelength coincided with that in the H-alpha line. The position of the faint structure observed in the soft X-ray seems to coincide with that of the main body of the prominence.
4. From the comparison of the position of the bright region on the disk, it was found that the position of the bright region at the radio wavelength coincide with that of the ridge of the arcade loop which was observed in the soft X-ray. The position of the two ribbon structure in the H-alpha line coincided with that of the footpoints of the arcade loop. This phenomena can be explained by the model by Carmichael(1964), Sturrock (1968), Hirayama (1974), and Kopp and Pneuman (1976). The main body of the prominence observed at the radio wavelength was also observed in the H-alpha line, and does not have polarized component. In the soft X-ray, only the very faint structure was seen. Therefore, we can conclude that the prominence observed at the radio wavelength was mainly produced from the thermal emission from the low temperature plasma (about ten thousand K). The arcade loop was built by the reconnection of the magnetic loop (Carmichael,1964; Sturrock, 1968; Hirayama, 1974; and Kopp and Pneuman, 1976). The high temperature plasma (about several million K) which fills the arcade loop was seen at the radio wavelength and in the soft X-ray. The heatflow was transmitted down to the chromosphere along the magnetic field of the arcade loop, then the two ribbon brightening was observed in the H-alpha line.
References
Carmichael, H.: 1964, AAS-NASA Symp. on the Physics of Solar
Flares (NASA SP-50), 377.
Hirayama, T.: 1974, Solar Phys. 34, 323.
Kopp, R. A. and Pneuman, G. W.: 1976, Solar Phys. 50, 85
Sturrock, P. A., IAU Symp., 35, 471.