Observations of Moreton waves with Solar-B NARUKAGE Noriyuki Department of Astronomy, Kyoto Univ / Kwasan and Hida Observatories M2 The 4 th Solar-B Science Meeting Recent Advances in Solar Physics and Solar-B February 3-5, 2003

flare-associated wave observed to propagate across the solar disk in H , especially in the wing of H  (Moreton, 1960, 1961). propagate in somewhat restricted angle at the speed of 500 ~ 1500 km/s with arc-like fronts. identified as the intersections of a coronal MHD fast shock front and the chromosphere (Uchida, 1968, 1970). At Hida Observatory, more than 10 Moreton waves have been observed. And they were associated with about 10% of X or M-class flares. Moreton wave is …

Eto et al., 2002 Moreton wave 1997/11/04 solar Flare Monitor Telescope (FMT) Hida Obserbatory, Kyoto Univ. The FMT observes four full disk images, in H  (line center and ＋ / － 0.8 Å ) and continuum, and one solar limb image in H  center.

Uchida model (1968) shock front Moreton wave X-ray wave, coronal counterpart of Moreton wave flare site solar disk

Introduction SOT : chromospheric Moreton waves XRT : main topic coronal X-ray waves EIS : line-of-sight velocity of waves Observation of flare waves with Solar-B

Observable region of flare waves Flare waves usually become visible only at a distance of more than 100,000 km from the flare site. Some flare waves can propagate up to distance exceeding 500,000 km. solar disk flare site Moreton wave & X-ray wave Observable region of flare waves

SOT The field of view is too small to observe the propagation of waves. We expect to detect the origin of Moreton waves. flare site 164” x 328” Solar Optical Telescope Observable region of flare waves

Narukage et al., 2002 X-ray wave 1997/11/03 Hida obs / FMT [H  +0.8 Å ] Running difference Yohkoh / SXT [Soft X-ray] Quarter resolution Half resolution

Using Yohkoh / SXT images, we can estimate the quantities of the X-ray wave. Advantage of Yohkoh / SXT

I X1 T 1 B 1 θ 1 v 1 I X2 T 2 B 2 θ 2 v 2 Is the X-ray wave a MHD fast shock? BEHINDAHEAD Shock front Using MHD Eq. (1)--(7), the quantities ahead of the shock (I X1,T 1,B 1,θ 1,v 1 ) determine those behind (I X2,T 2,B 2,θ 2,v 2 ).

Is the X-ray wave a MHD fast shock? BEHINDAHEAD Shock front In other words, if we know (I X1,T 1,B 1,θ 1,I X2 ), we can find (v 1,T 2,B 2,θ 2,v 2 ). I X1 T 1 B 1 θ 1 v 1 I X2 T 2 B 2 θ 2 v 2 observed parameter I X1 Yohkoh / SXT T 1 = 2.25±0.25 MK (thin Al & AlMg) B 1 = 1/2 or 1/3 B p1 (SOHO / MDI) θ 1 = 90° or 60° (parameter) I X2 Yohkoh / SXT

Is the X-ray wave a MHD fast shock? Using this method, we can estimate the quantities of the X-ray wave. These results suggest that the X-ray wave is an MHD fast shock propagating through the corona and hence is the coronal counterpart of the Moreton wave. Narukage et al. 2002, ApJ Letters 572, 109 e.g. The estimated fast shock speed is 400 ~ 760 km/s, which is roughly agreement with the observed propagation speed of the X-ray wave, 630 km/s. The fast mode Mach number is 1.15 ~ 1.25.

Solar-B Using this method, we can examine how X-ray waves are observed with Solar-B / XRT (and EIS).

XRT – field of view The observations of X-ray waves require the field of view as larger than 512” x 512”. flare site 512” x 512” Observable region of flare waves X-Ray Telescope 1024” x 1024”

XRT – cadence & pixel size The propagation speeds of X-ray wave are 500 ~ 1500 km/s. The thickness of the wave is about 20,000 km. X-Ray Telescope →We can observe for less than 270 ~ 800 sec. The observation needs as high cadence as possible (= 2 sec). →The pixel size should be smaller than 4” x 4”. BEHIND Ix 2 AHEAD Ix 1

XRT – filter X-Ray Telescope XRT has 9 filters.

XRT – filter selection BEHIND Ix 2 AHEAD Ix 1 To recognize the shock against the background, the intensity ratio (=Ix 2 / Ix 1 ) should be larger than 3. (e.g. In case of my Yohkoh X-ray wave, Ix 2 / Ix 1 = 3.27) →I select the suitable filters for X-ray waves. X-Ray Telescope

B (G)3.99 T (MK)2.25  2.78 n (cm -3 )10^8.5  1.31 x 10^8.5 [DN sec -1 arcsec -2 ] Ix 1 Ix 2 Ix 2 / Ix 1 Entrance Thin Al Mesh Thin Al poly C poly Ti poly Thin Be Medium Be Medium Al Thick Al00-- Thick Be00-- B (G)3.99 T (MK)2.25  2.78 n (cm -3 )10^8.5  1.31 x 10^8.5 [DN sec -1 arcsec -2 ] Ix 1 Ix 2 Ix 2 / Ix 1 Entrance Thin Al Mesh Thin Al poly C poly Ti poly Thin Be Medium Be Medium Al Thick Al00-- Thick Be00-- XRT – filter selection These filters satisfy the condition (Ix 2 / Ix 1 > 3). Considering the intensity ratio and sensitivity, the best filter is Thin Be. I calculate the XRT intensities (Ix 1 and Ix 2 ) and their ratios, using my result of Yohkoh X- ray wave.

XRT – exposure time X-Ray Telescope I examine the enough exposure time ( t ) to suppress the effect of photon noise. (Ix 2 – Ix 1 ) t > 3  (t)  (t) = (5 Ix 1 t) ^ 0.5 : dispersion of Ix 1 Ix [DN / sec / pixel]

B (G)3.99 T (MK)2.25  2.77 n (cm -3 )10^8.5  1.31 x 10^8.5 pixel size1” x 1”2” x 2”4” x 4” Ix 1 [DN / pixel] Ix 2 [DN / pixel] exposure time [msec] C poly Ti poly Thin Be Medium Be Medium Al B (G)3.99 T (MK)2.25  2.77 n (cm -3 )10^8.5  1.31 x 10^8.5 pixel size1” x 1”2” x 2”4” x 4” Ix 1 [DN / pixel] Ix 2 [DN / pixel] exposure time [msec] C poly Ti poly Thin Be Medium Be Medium Al XRT – exposure time For highest cadence, the exposure time should be shorter than 2 sec. X-Ray Telescope

observational plan for X-ray waves note : The influence of flare-loop brightness is not considered. Question : When XRT is operated in flare-mode, are these exposure times safe? pixel size1” x 1”2” x 2”4” x 4” minimum image size 512 x x x 128 minimum exposure time [msec] C poly Ti poly Thin Be Medium Be Medium Al

XRT – Discussion X-Ray Telescope If the X-ray wave frequency is the same as Moreton waves, X-ray waves would occur associated with 10% of X or M-class flares. If the flare frequency is the same as 11 years before, until 2009 there would be only a few X- ray waves per year. (This is underestimation.) Good observational plan is very important. Year X-ray wave311211

XRT – Conclusion X-Ray Telescope XRT is the best telescope for X-ray wave (coronal shock wave). When filter selection for flare-mode is discussed, the detectability of X-ray wave should be considered.

EIS From my analysis, we can estimate the coronal plasma velocity just behind the Moreton wave (fast-mode MHD shock), v 1 -v 2, to be about km/s, which would be observed at km/s along the line-of-sight with Solar B / EIS. BEHINDAHEAD EUV Imaging Spectrometer

END Thank you very much for your attention.

Simultaneous observation 1997/11/03

EIT wave: 170 km/s Moreton wave: 490±40 km/s X-ray wave: 630±100 km/s start 04:32 / peak 04:38 AR8100 – S20, W13 GOES-C8.6 Simultaneous observation 1997/11/03

start 04:32 / peak 04:38 AR8100 – S20, W13 GOES-C8.6 Moreton & X-ray wave 1997/11/03

start 04:32 / peak 04:38 AR8100 – S20, W13 GOES-C8.6 EIT wave 1997/11/03