1 The Astrophysical Journal, 601:L195–L198, 2004 February RAPID PENUMBRAL DECAY FOLLOWING THREE X-CLASS SOLAR FLARES H. Wang, 1,2 C. Liu, 1 J. Qiu, 1 N. Deng, 1 P. R. Goode, 1,2 and C. Denker 1,2 Received 2003 November 10; accepted 2003 December 19; published 2004 January 28 1 Center for Solar Research, New Jersey Institute of Technology 2 Big Bear Solar Observatory, New Jersey Institute of Technology 太陽雑誌会 T.T.Ishii

2 ABSTRACT Penumbral segments decayed rapidly and permanently right after three X-class solar flares. (X17 on 2003-Oct-28, X10 on 2003-Oct-29 in NOAA X2.3 on 2000-Jun-6 in NOAA 9026) Difference images highlighting the rapid changes between pre- and post- flare states of the flaring active region show distinct decaying penumbral segments and neighboring umbral cores becoming darker. Magnetic fields change from a highly inclined to a more vertical configuration within approximately 1 hr after the flares; i.e., part of the penumbral magnetic field is converted into umbral fields.

3 NOAA SOHO / MDI intensitygram & magnetogram 500 Gauss contour ( face-on )

4 NOAA SOHO / MDI magnetogram face-on (500 Gauss contour)

5 NOAA 10486

6 SOHO MDI / mag. H-alpha BBSO H-alpha & mag (500G) and Kwasan Sartoirus red: positive blue: negative

7 SOHO MDI / mag. H-alpha BBSO H-alpha & mag (500G) and Kwasan Sartoirus red: positive blue: negative

8 Difference image (pre-flare minus post-flare state), which was smoothed by a window of 10”×10”. Any dark feature in the difference image indicates a brightening in the post-flare image, e.g., an area of decaying penumbra, whereas any bright feature corresponds to a darkening in the post-flare image, e.g., the darkening of an umbral core. TRECE white light Difference image X10 flare on Oct. 29 peak 20:49 UT

9 RHESSI hard X-ray contours: X10 flare on 2003-Oct-29 peak 20:49 UT 15–20 keV channel (red) 50–100 keV channel (blue) TRACE 1600 Å TRACE 195 Å

10 TRECE white lightDifference image X10 flare on Oct. 28 peak 11:10 UT Difference image (pre-flare minus post-flare state), which was smoothed by a window of 10”×10”. Any dark feature in the difference image indicates a brightening in the post-flare image, e.g., an area of decaying penumbra, whereas any bright feature corresponds to a darkening in the post-flare image, e.g., the darkening of an umbral core.

11 RHESSI hard X-ray contours: X17 flare on 2003-Oct-28 peak 11:10 UT 15–20 keV channel (red) 50–100 keV channel (blue) TRACE 1600 Å TRACE 195 Å

12 NOAA June

13 X2 flare on 2000 June 6 peak 15:25 UT

14 Summary 1. Penumbral decay was found for each event on a timescale of about 1 hr or less. 2. The locations of the penumbral decay are associated with flare emissions, but with distinct differences for each event. X10 on Oct-29 : coincides with one of the two 50–100 keV hard X-ray sources X17 on Oct-28 : not associated with any hard X-ray source. However, the decaying segment is related to a section of one of the two TRACE 1600 flare ribbons. X2 on June-6: adjacent to but did not coincide with two TRACE white-light kernels 3. For each of the decaying areas, there is a darkening of adjacent umbrae marked as E1, E2, and E3, respectively.

15 A&A 411, L497–L500 (2003) The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface K. M. Hiremath 1 and G. S. Suryanarayana 2 1 Indian Institute of Astrophysics, Bangalore , India 2 Indian Institute of Astrophysics, Kodaikanal , India Received 26 September 2003 / Accepted 14 October 2003

16 Observational data They use Kodaikanal observatory white light pictures to study the association between the rotation rates of the bipolar sunspots and triggering of the flares. For the years , they compute daily rotation rates of the leading and the following spots of the bipolar sunspot groups during their life span. Definition of abnormal rotation rate Rotation rate l : helographic longitude t : time of observation Abnormal rotation rate : average rotation rate

17 Left: The occurrence dates of abnormal rotation rates and the flares. The continuous line is the linear least square fit. Here R represents occurrence date of abnormal rotation rates and F is the occurrence date of the flares. Right: The occurrence day of the abnormal rotation rates and the flares during the evolution of the bipolar spots.

18 Left: The scatter diagram illustrating the association between the occurrence days of the abnormal rotation rates and the flares during the evolution of the spot group. Right: The magnitude of abnormal rotation rates for different classes of the flares: the □ represents f (faint), the ◇ is n (normal) and the △ represents b (bright). Here 0 along the x axis represents the S subclass flare. The numbers 1, 2, 3, 4 are higher subclass flares.