Earth under fire!

UPDATE - 15 May 2013, 7:30UT - NOAA1748 produced its 4^th X-class flare, this time an X1.2 peaking at 01:48UT (movie). At the time of this writing, the already enhanced proton flux is on the rise again, maybe reaching event threshold in the course of the day. Preliminary analysis from coronagraphic images indicates that the associated coronal mass ejection (CME) seems partially directed towards Earth, with most likely arrival tomorrow or early Friday. Note some geomagnetic activity is already expected today as we may receive a glancing blow from yesterday's CME.

The latest visual and magnetic imagery indicates sunspot region NOAA1748 has loosened up a bit, but still contains at least 2 locations with opposite magnetic polarity sunspots close together. Thus, more (major) flares remain likely, with increased geoeffectiveness from high energetic protons and from CMEs as the region rotates further onto the solar disk.

14 May 2013 - A relatively small but compact sunspot group has rounded the east solar limb, producing 3 X-class solar flares in less than 24 hours. Yesterday, NOAA1748 produced an X1.7 peaking at 02:17UT, and an X2.8 peaking at 16:05UT. Then last night, it was also the source of an X3.2 flare peaking at 01:11UT. The three flares were accompanied by coronal mass ejections (CMEs), with the last two having high speeds of resp. 1800 and 1600 km/s. However, all these CMEs were directed mostly away from Earth, and at most a glancing blow is expected on 15 May, with little geomagnetic disturbances.

The SDO images underneath show for each flare the outlook of the region 1.5 hours before the maximum, the maximum itself, and 1.5 hours after the x-ray peak (resp. left, middle and right frame). There's also a movie that shows besides a zoom on the flares, also the associated CMEs as seen by SOHO/LASCO.

The X3.2 is the third strongest flare of this solar cycle so far, after the X6.9 on 9 August 2011 and X5.4 on 7 March 2012. We have to go back already to 23 October last year for the previous X-class flare (X1.8 in NOAA1598). Further details on the 15 previous SC24 X-class flares can be found in this STCE Newsitem. The last time there were 3 X-flares in one day was on 9 September 2005 when NOAA0808 produced X1, X3 and X6 flares. That region was actually also the last to have produced an X10+ flare (X17 on 7 September 2005).

The latest visual and magnetic imagery indicates sunspot region NOAA1748 is a small, but compact nest of opposite magnetic polarity sunspots. Also a slight enhancement of proton levels was observed, probably related to the second X-class flare. In view of the eruptive history of NOAA 1748, more (major) flares can be expected, with a gradual increase in geoeffectiveness from high energetic protons and from CMEs as the region rotates further onto the solar disk.