Radoslav Bucik (MPS) in collaboration with Davina E. Innes (MPS) & Glenn M. Mason (JHU)

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1 -MPS SGS 2014 Oct 14- MPS PRESS RELEASE STEREO & ACE SCIENCE HIGHLIGHTS nominated to NASA HELIOPHYSICS GPRAMA ITEM Radoslav Bucik (MPS) in collaboration with Davina E. Innes (MPS) & Glenn M. Mason (JHU) 1

2 OUTLINE Solar Energetic Ions Motivation Repeated Impulsive Events Features of Two Long-Lasting Sources Solar Source Identification Other Long-Lasting Sources What Drives Ion Production in Long-Lasting Sources? Summary & New Implications 2

3 SOLAR ENERGETIC IONS -- IMPULSIVE EVENTS HXR HXR HXR Shimojo & Shibata ApJ 542, 2000 this mechanism for solar electron events independently seen in hard X-ray images as 3 foot-point bremsstrahlung source (e.g., Krucker et al. ApJ 742, 2011) ion acceleration in solar flares or in impulsive SEP events not clear at all association with EUV/X-ray jets (Wang et al. ApJ 639, 2006; Nitta et al. ApJL 675, 2008) or fast & narrow CMEs (Kahler et al. ApJ 562, 2001; Nitta et al. ApJ 650, 2006) has suggested the interchange reconnection (Shibata et al. PASJ 44, 1992; where emerging loop annihilates with overlying open field) as a primary energy source 3

4 2-10 MeV/n 3 He-rich events \ corona abund. SOLAR ENERGETIC IONS -- IMPULSIVE EVENTS enhanced f. <10 4! kev electrons often accompany these events although acceleration sites are likely different (Hurford et al. ApJL 644, 2006) enhanced f. 10 enhanced f. 2-3 unenhanced (3 MK) Reames & Ng ApJ 610, 2004 type III radio bursts better associated with these events than their parent electrons (Nitta et al. ApJ 650, 2006) abundance observations suggest that mechanism must be highly selective enormously enhances 3 He & ultra heavies but not H, 4 He, C, N, O; most theories involve resonant interaction with waves (e.g.; Temerin & Roth ApJL 391, 1992) or turbulence (e.g.; Miller SSRv 86, 1998) 4

5 SOLAR ENERGETIC IONS -- IMPULSIVE EVENTS none of the current theories explains all the observed features of impulsive events they do not include charge stripping effects or address enhancements of UH nuclei no consistent theory explaining simultaneous enrichment of both 3 He and heavy ions one reason why small impulsive events are not well understood - the acceleration has not been studied in-situ even Solar orbiter or Solar probe+ missions will likely not reach the acceleration sites: Rs above the photosphere (e.g.; DiFabio et al. ApJ 687, 2008; Wang et al. ApJ 759, 2012) based on ionic charge states & solar electron observations 5

6 SOLAR ENERGETIC IONS -- A NOTE ON GRADUAL EVENTS Desai et al. ApJ 611, 2004 Reames SSRs 90, 1999 acceleration in gradual events better understood CME shocks with particle acceleration can be observed in-situ in addition, the shock acceleration has been studied in-situ in other sites CIRs, the Earth s bow shock or even the Termination shock 6

7 MOTIVATION successive events from the same AR observed by a single s/c only during about 1 day (Reames & Stone ApJ 308, 1986; Mason et al. ApJL 525, 1999; Mason et al. ApJL 545, 2000; Wang et al. ApJ 639, 2006) successive events have suggested more steady production/release of energetic ions from solar source regions (Pick et al. ApJ 648, 2006) how long these ion injections continue in an AR? difficult to answer with single s/c observations because of Sun rotation we could be connected to the AR only for a limited time 7

8 MOTIVATION other (indirect) evidence for more steady ion production (rare) long duration (< 0.4 day) solar γ-ray line/neutron emissions (e.g., Ryan SSRv 93, 2000; Feldman et al. JGR 115, 2010) explained by ion trapping in AR magnetic loops (Mandzhevidze & Ramaty ApJ 396, 1992; Hudson et al. ApJL 698, 2009) or continuous acceleration (Rank et al. A&A 378, 2001; Ajello et al. ApJ 789, 2014) or maybe due to multiple events (?) homologous hard X-ray flares (e.g.; Sui et al. ApJ 612, 2004 reports multiple HXRs in 1.5 day period) impulsive events associated with minor soft X-ray flares (e.g., Reames et al. ApJ 327, 1988) - these events should be quite frequent in an AR 8

9 REPEATED IMPULSIVE EVENTS?? Rarely identified but multiple electron events frequently occurred in data. Reames et al. ApJ 292,

10 MeV/n REPEATED IMPULSIVE EVENTS The 1 st observation of repeated events. 0.6 day of injection W44 W69 gradual SEP events from the same AR Reames & Stone ApJ 308,

11 REPEATED IMPULSIVE EVENTS 1.5 day of injection new connection Mason et al. ApJL 545, 2000 loss of the connection He I 10830Å Fe I 8688Å Wang et al. ApJ 639,

12 REPEATED IMPULSIVE EVENTS 1.2 day of injections 380 kev/n 195Å flares white-light ejections jet times Wang et al. ApJ 639, 2006 Wang et al. ApJ 639,

13 REPEATED IMPULSIVE EVENTS 270 kev/n periods of continuous 3 Herich SEP presence are observed (e.g., Wiedenbeck et al. AIP Conf. Proc. 679, 2003) not clear if single solar sources are responsible Mason SSRv 130, 2007 not clear how these multiday periods are formed unresolved injections closely spaced in time? IP propagation effects masking the injections? confinement of ions in large scale structures in solar wind (Kocharov et al. ApJS 176, 2008)? no consecutive injections but steady escape? 13

14 FEATURES OF TWO LONG-LASTING SOURCES identified several long-lasting sources; examined in detail/published two when STEREOs were near the greatest elongation FEATURES AR 1244 AR 1246 sunspot Y Y age newly emerging newly emerging spatial size relatively large small/spot-like soft X-ray flare several B-class N Hα flare Y N EUV jets no obvious numerous recurrent material eruption surge-like no obvious photospheric field irregularly distributed compact shape reported long-lasting sources AR & AR do not show any unusual features! Any active region could be a long lasting energetic ion source (?) 14

15 AR1246 Bucik et al. ApJ 786,

16 AR He 4 He CIR B4.1 B7.6 Bucik et al. ApJ 786,

17 AR1244 B4.1 B7.6 17

18 FEATURES OF TWO LONG-LASTING SOURCES AR 1244 in SDO HMI 720s magnetograms 220 x 170 arcsecs; 1hr step 60 x 60 arcsecs; 0.5hr 6 Jul 15:00 7 Jul 05:20 prior to 2nd impulsive event 29 June 21:00 1 July 13:00 (~1.7d) from emergence till 1st impulsive event Impulsive event in old AR preceded by new flux emergence! 18

19 FEATURES OF TWO LONG-LASTING SOURCES AR 1246 in SDO HMI 720s magnetograms 160 x 160 arcsecs; 0.5hr step 60 x 100 arcsecs; 0.5hr 10 Jul 19:00 11 Jul 18:20 2nd emergence + several other re-emergences when out of the Earth s view 7 July 16:00 8 July 15:22 (~1d) from emergence till 1st impulsive event 19

20 SOLAR SOURCE IDENTIFICATION key task for this study; 1 of the 3 focused science topics in LWS program for 2014 similar approach as in prior studies (Wang et al. ApJ 639, 2006; Nitta et al. ApJ 650, 2006; Klein et al. A&A 486, 2008; Rust et al. ApJ 687, 2008) identify connection region on the Sun (e.g., Neugebauer et al. JGR 103, 1998) Parker spiral - determines s/c foot-point longitude on the model s source surface PFSS model of corona (with 6 hr resolution - Schrijver & DeRosa SoPh 212, 2003) determines location on the Sun tracking open field lines consistency check with in-situ magnetic polarity s/c 1AU flare * examine EUV images for temporal coincidence with type III bursts around Schatten et al. SoPh 6, expected ion injection time

21 SOLAR SOURCE IDENTIFICATION improved 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 improved as whole Sun surface has been in view with STEREO and SDO since Feb 2011; but STEREO-A connection regions not covered by magnetogram observations making the PFSS extrapolations less reliable many recent publications have employed this two-step approach in searching for solar wind sources (e.g.; Culhane et al., SoPh 289, 2014 & references therein); the advantages in source identification for SEPs compared to solar wind type III bursts, EUV brightening & clear SEPs intensity onsets (detected in-situ) 21

22 SOLAR SOURCE IDENTIFICATION AR 1244 AR 1246 STB ACE ACE STA Bucik et al. ApJ 786,

23 OTHER LONG-LASTING SOURCES : L1 STEREO-A 32 impulsive events on STEREO-A in He relative enrichment: compared to its thermal abundance all corresponding events observed earlier at L1 events with common source AR marked by x 23

24 OTHER LONG-LASTING SOURCES : L1 STEREO-A Helium mass peaks for all 32 STEREO-A events (#4 - #35) 24

25 OTHER LONG-LASTING SOURCES : L1 STEREO-A Bucik et al. in Proc. 33 rd ICRC, 2013 isotopic ratios correlate for common solar sources ; it implies temporal stability in relative 3 He enrichment in the source AR previous studies do not show this for multiple events in short-sequences but our result is not in contrast with this as we integrated abundances over whole event 25 (i.e. over all injections in a short sequence when present)

26 WHAT DRIVES ION PRODUCTION/ESCAPE IN LONG-LASTING SOURCES? AR11045 long lasting (10 days) source Feb 6-7, Feb 8 3 He onsets 2.8 MeV/n Feb 6, 7 Feb 8 Feb 14, 16 3 s/c with favorable separation and angular spread of escaping field lines allows uninterrupted connection to AR for a long-time at least with one s/c! Wiedenbeck et al. ApJ 762,

27 WHAT DRIVES ION PRODUCTION/ESCAPE IN LONG-LASTING SOURCES? s/c connections Feb STEREO-A gradual SEPs STEREO-A ACE D.E. Innes next impulsive event seen after 6 days (on Feb 14) although we remained connected; what happened with this AR? G.M. Mason 27

28 WHAT DRIVES ION PRODUCTION/ESCAPE IN LONG-LASTING SOURCES? STEREO-B, ACE impulsive events AR AR11045 out of the Earth view STEREO-A event day 14.3 Feb Li et al. A&A 539, 2012 energetic ions events initiated during emergence phase only; we do not see any injections (although connected) in decay phase unknown magnetic flux evolution in AR for the STEREO-A event (no magnetometer data) 28

29 WHAT DRIVES ION PRODUCTION/ESCAPE IN LONG-LASTING SOURCES? STEREO-A 304Å -- new emergence on AR11045 west edge? 2010 Feb 12 12: Feb 13 12:36 STEREO-A impulsive SEP event on Feb 14.3 associated with new emergence? 2010 Feb 14 12: Feb 15 12:36 29

30 SUMMARY & NEW IMPLICATIONS (i) first evidence that energetic particles could be produced in solar active regions on long time scales new results open question whether energetic ions are emitted into IP space during whole active region lifetime (weeks) related Q: how frequent are these emissions in solar ARs (or are they continuous)? There have been reports suggesting on-going reconnection (e.g., Baker et al. ApJ 705, 2009) based on observations of persistent AR plasma outflows (Sakao et al. Science 318, 2007) - is this process able to produce also ion outflows with speeds of 10 x solar wind? 30

31 SUMMARY & NEW IMPLICATIONS (ii) the mechanism which accelerates these ions in flares must be quite ordinary i.e. conditions for ion production persist for a long time or could be easily established is the magnetic flux emergence necessity for ion production on open field lines? conclusion similar to this has been drawn by Nitta & Hudson, GRL 28, 2001 for recurrent CMEs in impulsive homologous flares Thanks! 31