NoRH Observations of Prominence Eruption

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

2. 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 NoRH Observations of Prominence Eruption

3. 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. NoRH Observations of Prominence Eruption

4. 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. NoRH Observations of Prominence Eruption

5. Advantages of NoRH Observation: 2 • Large Field of View • ~ 1 Rsun • High Time Resolution • Flare Observation : 100 msec • Normal Observation : 1 sec Courtesy of Y. Hanaoka NoRH Observations of Prominence Eruption

6. 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. NoRH Observations of Prominence Eruption

7. 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. NoRH Observations of Prominence Eruption

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

9. 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 NoRH Observations of Prominence Eruption

10. 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 NoRH Observations of Prominence Eruption

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

12. 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 NoRH Observations of Prominence Eruption

13. 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 NoRH Observations of Prominence Eruption

14. Original Image Daily Average Image The skyblue cross indicates the center of gravity of the image. Enhance Pixel Image > 6. Delete faint features Image Enhance Pixel Image 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. NoRH Observations of Prominence Eruption

15. 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. NoRH Observations of Prominence Eruption

16. 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 NoRH Observations of Prominence Eruption

17. 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. NoRH Observations of Prominence Eruption

18. 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/ NoRH Observations of Prominence Eruption

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

20. Solar Cycle and Prominence Activities:2The 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 NoRH Observations of Prominence Eruption

21. Solar Cycle and Prominence Activities:3Filament 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) NoRH Observations of Prominence Eruption

22. Solar Cycle and Prominence Activities:4The distribution of filaments and prominence activities • Prominence activities occurred on the neutral filament bands. Background : The distribution of neutral lines 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) NoRH Observations of Prominence Eruption

23. Solar Cycle and Prominence Activities:5When 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) NoRH Observations of Prominence Eruption

24. Solar Cycle and Prominence Activities:5When 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. NoRH Observations of Prominence Eruption

25. Solar Cycle and Prominence Activities: 6Size 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. NoRH Observations of Prominence Eruption

26. Solar Cycle and Prominence Activities: 7Size of Active Prominence and Solar Cycle Neutral lines at Solar Minimum • 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 Maximum The scatter plot of date and size of prominence eruption The diamond marks indicate the average prominence size of the year. NoRH Observations of Prominence Eruption

27. 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. NoRH Observations of Prominence Eruption

28. 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. NoRH Observations of Prominence Eruption

29. 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. NoRH Observations of Prominence Eruption

30. Automatic detection using 3 minuets time resolution images Coming soon!! Using 10 min time resolution images Using 3min time resolution images NoRH Observations of Prominence Eruption