The Sun online and solar activity. 15.10.2014

солнце 15 октября

Two M flares occurred during the past 24 hours. The first, short duration,

M1.1 flare was released by a backside region close to the east limb at 10 S

(probably the return of M-flaring region NOAA AR 2173) and peaked at 18:37

UT on October 14. During the flare, very hot plasma (only visible in the

hottest SDO passbands) was ejected into space. The second M flare

corresponds to the post eruption arcade of the previous flare, started at

19:07 UT, reached its peak value of M2.2 at 21:21, and lasted until 00:19

UT on October 15. The GOES X ray flux curve has still not decreased to

background levels at the time of this forecast. The M1.1 flare is

associated with a halo CME first detected by LASCO C2 at 19:00 UT on

October 14. The CME had an angular width of about 270 degrees, with the

main bulk propagating towards the southeast at a speed of about 1700 km/s

according to the CACTUS software. The associated ICME is not expected to

become geo-effective since it is backsided. In the next 48 hours, M flares

are probable, especially from the region near the east limb that has

produced both M flares.Over the last 24 hours, solar wind speed observed by

ACE was highly variable between about 370 and 580 km/s, with current values

around 430 km/s. The magnitude of the Interplanetary Magnetic Field (IMF)

varied between 2 and 16 nT, with current values around 4 nT. This may be

the effect of the arrival of the CME from October 10. NOAA Kp indicated a

minor geomagnetic storm between 18h UT on October 14 and 3h UT on October

  1. K Dourbes was above 3 from 17h till 21h UT and went to minor storm

values between 20h and 21h UT. This is the result of the increased solar

wind speed combined with Bz values below -10 nT or thereabouts. Quiet

geomagnetic levels (K Dourbes < 4) are expected on October 15, 16 and 17.