Long-Lasting 3 He-Rich Solar Energetic Particle Sources R. Bučík, D. E. Innes, U. Mall, A. Korth (MPS) G. M. Mason (JHU) R. Gómez-Herrero (UAH) STEREO SEP meeting - JHU/APL September 25 see Bučík et al. 2014, ApJ 786; Bučík et al. 2013, in Proc. 33 rd ICRC, paper 0552

3 He-rich SEPs : some features abundances arise from resonant wave-particle interaction in flare sites (e.g. Temerin & Roth 1992; Miller 1998) different waves/mechanisms for 3 He and heavier ions association with type III radio bursts - better than with energetic electrons (Nitta et al. 2006) association with EUV jets & minor X-ray flares (Nitta et al. 2006, 2008; Wang et al., 2006) Reames & Ng (2004) 2-10 MeV/n 3 He-rich events \ corona abund. (3 MK) unenhanced enhanced f. 2-3 enhanced f. 10 enhanced f. <10 4 ! 2

3 He-rich SEPs : multiple events Wang et al. (2006) jet times 195 ÅC2 multiple events from the same AR observed by a single s/c (Reames & Stone 1986; Mason et al. 1999, 2000; Wang et al. 2006) – injections seen during about 1 day! these recurrent events have suggested more steady production of 3 He- rich SEPs (Pick et al. 2006) 3 ~1.2 day of injections

4 but how long these injections continue in a single AR? difficult to answer this with single s/c observations – because of Sun rotation we could be connected to a single AR only for a limited time multiday 3 He-rich SEP periods have been observed where often multiple injections were not obvious (Reames et al. 1985; Wiedenbeck et al. 2003; Kocharov et al. 2006; Mason 2007) – not clear if continuous emission is going on since other effects (e.g.; IP propagation, re- acceleration by CMEs) may be important multiple injections might be closely spaced in time and therefore hardly resolved therefore we do a multipoint study of recurrent events Motivation

2011 July 1-7 & July He-rich recurrent events (ACE) 7.1 days co-rotation 7.5 days co-rotation s/c position in July 2011 during the recurrent events delay between events on different s/c corresponds to a co- rotation time July 1-7 events consecutively observed on STEREO-B and ACE July 9-16 events consecutively observed on ACE & STEREO-A 5

STEREO-B 3 He-rich event (2011 July 1) SIT ( MeV/n) mass histogram reveals clear 3 He peak LET (2.3-8 MeV/n) shows no 3 He increase 3 He-rich SEPs preceded by an electron event; associated with B4.1 X- ray flare in AR1244 (NOAA SWPC), located at W97° from STB view 6 3 He 4 He CIR MeV/n

Solar Source Identification 1AU * flare s/c Schatten et al. (1969) 7 with similar approach as in prior studies (Wang et al. 2006; Nitta et al. 2006; Klein et al. 2008; Rust et al. 2008) Identified connection region on the Sun (e.g., Neugebauer et al. 1988) Parker spiral - determines the s/c foot-point longitude on imaginary source surface PFSS model of corona with 6 hr resolution (based on SDO magnetograms - Schrijver & DeRosa 2003) determines location on the Sun consistency check with in-situ magnetic polarity examined SDO/STEREO EUV images for temporal coincidence with type III bursts around expected ion injection time

Solar Source Identification 8 improved source identification with SDO because of (1) – full solar disk EUV images with unprecedented high temporal resolution (2) – new 94 and 131 Å wavelength channels better suited to identify high temperature EUV emissions whole Sun surface in view with STEREO and SDO since Feb 2011 – leads to a further improvement in the source identification; but STEREO-A connection regions not covered by SDO magnetogram observations making the PFSS extrapolations less reliable

Carrington Longitude (deg) Sine of Heliolatitude STEREO-B 3 He-rich event: Solar Source B4.1 4-min difference image around X-ray flare onset in-situ polarity suggests connection to both ARs 1243 & 1244 but B4.1 flare originated in AR 1244 marked brightening in AR 1244 at the time of B4.1 flare/type III burst, but no activity in AR 1243 STB PFSS coronal field lines open to ecliptic

ACE 3 He-rich events (2011 July 7 & July 9) 10 dispersive onset associated with multiple electron events, type III bursts and B-class flares presumably in AR 1244 enrichments seen in SIS ( MeV/n) July 7 3 He-rich SEPs July 9 3 He-rich SEPs dispersionless onset no electron event or X-ray flare associated presumably associated with jets & type III bursts in newly emerging AR 1246 no obvious event in SIS jet LEMS120

ACE July 7 3 He-rich event: Solar Source Carrington Longitude (deg) Sine of Heliolatitude B7.6 B ACE connected to AR 1244 X-ray flares/type III coincident with EUV brightening in AR 1244 source AR checked also with STEREO-A EUVI images same AR produced energetic electrons & 3 He-rich SEPs after almost 7 days this is 1st ever example of such long lasting source 4-min diff. images around X-ray flares 11 ACE

ACE July 9 3 He-rich event: Solar Source Sine of Heliolatitude Carrington Longitude (deg) 1246 In-situ polarity suggests connection to AR1246 / low-latitude coronal hole but no assoc. X-ray flare or solar electrons + event dispersionless → time of SEPs release on the Sun unknown examined whole Sun for EUV brightenings coincident with (the event preceding) type III bursts emergence of AR 1246 at coronal hole ACE 12hrs later

ACE July 9 3 He-rich event: Solar Source 1246 jet time type III burst at 16:25 UT, ~8 hrs prior to the event start, coincides with the jet in newly emerging AR 1246 another prominent type III burst at 11:37 UT also coincides with brightening in AR

STEREO-A 3 He-rich event (2011 July 16) 14 dispersionless onset no solar electrons associated event presumably associated with EUV brightenings & type III bursts in AR 1246 LET shows 3 He increase in MeV/n but not above 4.3 MeV/n brightening/jet MeV/n

STEREO-A 3 He-rich event: Solar Source Sine of Heliolatitude Carrington Longitude (deg) 1246 STEREO-A connected to the same coronal hole / AR 1246 time of SEPs release on the Sun unknown new regions A1, A2 appeared nearby coronal hole (open field region) but notably active is only AR STA 1246 open field region ordinary image difference image

jet STEREO-A 3 He-rich event: Solar Source 3 prominent type III bursts coincide with brightenings in AR 1246 these bursts occurred >14 hrs prior to event what could retain these ions in IP space? STEREO-A

17 STEREO-A 3 He-rich event: association with the CIR SEPT Sunward sensor Anti-sunward sensor Stream interface the event occurred within CIR with well defined stream interface & trailing boundary 3 He intensities start at the stream interface and show a maximum in the vicinity of CIR trailing edge – commonly observed in CIR events SEPs confinement in CIRs simulated by Kocharov et al. 2003, 2006, 2008

Summary & Further investigations the first report of multiple 3 He-rich SEPs outbursts in single active regions for relatively long time periods, lasting at least a quarter of a solar rotation the physical processes responsible for particle acceleration and escape from the Sun appear to be more continuous than previously thought other recurrent 3 He-rich SEP events are being examined what (conditions) in the solar sources cause re- appearance of 3 He-rich SEP emission? 18