1. NoRH Observations of Prominence Eruption Masumi Shimojo Nobeyama Solar Radio Observatory NAOJ/NINS 2004/10/28 Nobeyama Symposium 2004 @ SeiSenRyo

2. 2004/10/28NoRH Observations of Prominence Eruption2 Today’s Topic Introduction  What are advantages of prominence eruption observations using Nobeyama Radioheliograph? 12 years NoRH Observations of Prominence Activities  Automatic Detection of Prominence Activities  Solar Cycle and Prominence Activities

3. 2004/10/28NoRH Observations of Prominence Eruption3 Introduction NoRH observes the thermal microwave (17/34GHz) emission from prominences.  The typical brightness temperature of a prominence before the eruption is about 10,000K.  The prominence is usually optically thick plasma. Hence, the filament is also the dark feature in radio images.

4. 2004/10/28NoRH Observations of Prominence Eruption4 Advantages of NoRH Observation: 1 The influence of the weather is small.  NoRH can observe the Sun on cloudy and rainy days !! Ex. The transit of Venus  But, snow and heavy rain influence the image quality.

5. 2004/10/28NoRH Observations of Prominence Eruption5 Advantages of NoRH Observation: 2 Large Field of View  ~ 1 R sun High Time Resolution  Flare Observation : 100 msec  Normal Observation : 1 sec Courtesy of Y. Hanaoka

6. 2004/10/28NoRH Observations of Prominence Eruption6 Advantages of NoRH Observation: 3 The effect of the Doppler shift is very small for NoRH Observations, since NoRH observe the thermal microwave emission.  The brightness temperature of prominence is depend only temperature and emission measure of prominence plasma.  NoRH can observe the high-speed prominence eruption.

7. 2004/10/28NoRH Observations of Prominence Eruption7 Disadvantages of NoRH Observation It is difficult to resolve the fine structures in the prominence.  Usually, we can find moving features in the prominence. But, the features are made from the side-lobes.

8. 2004/10/28NoRH Observations of Prominence Eruption8 Advantages of NoRH Observation > The influence of the weather is small. Large Field of View High time resolution The effect from Doppler shift is small. The property is very good for the monitoring observation. The properties are very good for the eruptive prominence observation. We try to develop the automatic detection system for the prominence eruption.

9. 2004/10/28NoRH Observations of Prominence Eruption9 Today’s Topic Introduction  What are advantages of prominence eruption observations using Nobeyama Radioheliograph? 12 years NoRH Observations of Prominence Activities  Automatic Detection of Prominence Activities  Solar Cycle and Prominence Activities

10. 2004/10/28NoRH Observations of Prominence Eruption10 Automatic Detection Method: Step 1 NoRH makes 44 17GHz images, everyday.  The time resolution of the images is 10mins.  The images are made in quasi real-time.  The automatic detection program runs after the daily observation. 28 Aug, 2000 00:46:26 UT Original Image

11. 2004/10/28NoRH Observations of Prominence Eruption11 Automatic Detection Method: Step 2 Erase faint features and disk.  T b of faint features is smaller than 2000K.  T b of faint features is smaller than 1/100 of the maximum T b in each image.  We delete the major side-lobe effect on the method through the process. Original Image After deleted faint features and disk

12. 2004/10/28NoRH Observations of Prominence Eruption12 Automatic Detection Method: Step 3 Make a daily average image.  We use all 17GHz images on the day.  Before calculate the average, we delete disk. average daily average image 44 images

13. 2004/10/28NoRH Observations of Prominence Eruption13 Automatic Detection Method: Step 4 Find enhanced pixels in each image.  The criterion of enhancements is 6 times larger than the daily average image at each pixel. ÷ After deleted faint features Daily average image = > 6

14. 2004/10/28NoRH Observations of Prominence Eruption14 Automatic Detection Method: Step 5 If there are the enhance pixels in the images, the center of gravity of enhanced pixels is calculated from each images. The skyblue cross indicates the center of gravity of the image. Original ImageDaily Average Image Enhance Pixel Image Delete faint features Image Enhance Pixel Image > 6.

15. 2004/10/28NoRH Observations of Prominence Eruption15 Automatic Detection Method: Step 6 Define the structure as the limb events, if the structure satisfies the following criterions.  The center of gravity of enhanced pixels is not in the disk  The lifetime of the structure in the NoRH's FoV is over 30 min.  The number of enhance pixels is larger than 400.

16. 2004/10/28NoRH Observations of Prominence Eruption16 The method catches these phenomena Prominence activities  Eruptive Prominence  Disappearance of Prominence (not Eruption)  Morphology changing of Prominence Limb flare  Flare Loop on the Limb

17. 2004/10/28NoRH Observations of Prominence Eruption17 The undetectable events using the method Very fast eruptive events (v > 300km/s)  Because we use 10 min resolution Very long duration events  Because we use the daily average as the quiet state. Simultaneous eruptive events.  Because we use the center of gravity for the identification. Weak brightness event  The NoRH dynamic range is 1/100.

18. 2004/10/28NoRH Observations of Prominence Eruption18 The results of the Automatic Detection System Survey period : 1992/07/01 – 2004/10/12  Over one Solar Cycle  Observation time: 08:00 – 15:30 (JST) The number of detected events : 389  The percentage of limb flares is less than 5 %. You can see the list on our web. http://solar.nro.nao.ac.jp/norh/html/prominence/

19. 2004/10/28NoRH Observations of Prominence Eruption19 Solar Cycle and Prominence Activities:1 Number Variation during One Solar Cycle Cross + : Prominence Activities Red line: Sun spot Number The number variation of prominence activities is similar to that of sunspots. The raise phase of prominence activities is shorter than that of sunspot. /6month

20. 2004/10/28NoRH Observations of Prominence Eruption20 Solar Cycle and Prominence Activities:2 The distribution of prominence activities of Cycle 21/22 Background: KP Magnetogram + : limb event Size of + : Size of Activities + :1992 +:1999 + :1993 +:2000 + :1994 +:2001 + :1995 +:2002 + :1996 +:2003 + :1997 +:2004 + :1998

21. 2004/10/28NoRH Observations of Prominence Eruption21 Solar Cycle and Prominence Activities:3 Filament bands and Prominence Activities The distribution of the activities is similar to the neutral filament bands. Contour: Standard deviation of coronal green line Thick Line: the migration trajectories of neutral filament bands for cycle 20 (Makarov and Sivaraman, 1989 Solar Phys. 123, 367)

22. 2004/10/28NoRH Observations of Prominence Eruption22 Solar Cycle and Prominence Activities:4 The distribution of filaments and prominence activities Prominence activities occurred on the neutral filament bands. The distribution of filaments of Cycle 21 and 22 Aa: Active Region Filaments, Aq: Quiescent Filaments Ap: Polar Filaments (Mouradian and Soru-Escaut, 1994, A&A, 290, 279) Background : The distribution of neutral lines

23. 2004/10/28NoRH Observations of Prominence Eruption23 Solar Cycle and Prominence Activities:5 When a polar-crown prominence erupt? : 1 The polar crown prominences erupted, when the polarity of the polar magnetic field reverse. (Gopalswamy, et al., 2003, ApJ. 598, L63)

24. 2004/10/28NoRH Observations of Prominence Eruption24 Solar Cycle and Prominence Activities:5 When a polar-crown prominence erupt? : 2 The polar-crown prominences erupted when some magnetic poles appeared near the polar- crown neutral line. Prominence/filament eruptions need magnetic activities, like an emerging flux (Feynman and Martin, 1995, JGR, 100, A3,3355), the intrusion of opposite polarity magnetic fields.

25. 2004/10/28NoRH Observations of Prominence Eruption25 Solar Cycle and Prominence Activities: 6 Size of Active Prominences The frequency distribution of size of active prominences show the power-law (like) distribution. The correlation between the latitude and size is weak.

26. 2004/10/28NoRH Observations of Prominence Eruption26 Solar Cycle and Prominence Activities: 7 Size of Active Prominence and Solar Cycle The variation of average active prominence size similar to the solar cycle. The size of active prominence seems to relate the complexity of the neutral line on photosphere. Neutral lines at Solar Minimum Neutral lines at Solar Maximum The scatter plot of date and size of prominence eruption The diamond marks indicate the average prominence size of the year.

27. 2004/10/28NoRH Observations of Prominence Eruption27 Summary: 1 We developed the automatic detection system for limb events, mainly prominence activities. The system found 398 events from July, 1992 to Oct, 2004. The number variation during solar cycle of prominence activities is similar to that of sunspots.

28. 2004/10/28NoRH Observations of Prominence Eruption28 Summary: 2 Prominence activities occurred on the neutral filament bands. The frequency distribution of size of active prominences show the power-law (like) distribution. The size of active prominence seems to relate the complexity of the neutral line on photosphere.

29. 2004/10/28NoRH Observations of Prominence Eruption29 The undetectable events using the method Very fast eruptive events (v > 300km/s)  Because we use 10 min resolution Very long duration events  Because we use the daily average as the quiet state. Simultaneous eruptive events.  Because we use the center of gravity for the identification. Weak brightness event  The NoRH dynamic range is 1/100.

30. 2004/10/28NoRH Observations of Prominence Eruption30 Automatic detection using 3 minuets time resolution images Using 3min time resolution images Using 10 min time resolution images