1 SEP sources investigations with PHI aboard Solar Orbiter (SO) R. Bucik, D.E. Innes, J. Hirzberger, S.K. Solanki first ever investigations of the SEPs association with the Sun’s surface magnetic field

does the magnetic flux emergence (cancelation) play fundamental role in energetic particles production and release from the Sun? note this science objective conforms with the ‘stand-alone‘ PHI objective - how do ARs evolve? would we detect 3He-rich SEPs from frequent small emerging bipoles (although without significant EUV flaring as speculated by Wang et al. 2006) at closer distances to Sun? SO will be able to detect the events with smaller intensities than at 1AU (a factor of 10 if applying a simple inverse square law); this is perhaps relevant also for solar minimum – less active periods (this might lead to a new discovery? we may see 3He-rich SEPs from new sources) how growth rate of AR emergence affects the SEP production/release? (e.g. rapid growth – high intensities/enrichments, shorter time to SEP production/release ? ) (this can’t be properly investigated with the (near) Earth based observations as the SEP sources are near the west limb & STEREOs do not contain surface field observations (is it really true that SO brings such benefit? -- approaching to the Sun the connected sources may be seen under higher angles-check this) Science objective 2

This science objective was included in: the project offered at the University of Göttingen Bachelorbörse for physics students (July 25, 2014) the submitted (June 6, 2014) to DFG project BU 3115/1-1 ‘Origin of 3He- rich Solar Energetic Particles’ (Bucik –applicant; D.E. Innes & N.H. Chen – co-applicants) 3

weak 3He-rich events can be better investigated and new events not detected at 1AU can be observed; more convinced source identification because of reduced IP transport effects (but only with support of ground-based full-disk, higher cadence EUV and magnetogram observations?); uninterrupted (better longer) connection to the source region because of the SO ’some’ co-rotation with the Sun? what for PHI (0.5 arc sec)? compared to the SDO HMI (with 45 sec cadence and 1arc sec pixel size) we can track a region with PHI/SO for a longer time (because of that co-rotation) What are the benefits of SO observations compared to 1AU for that science question? 4

Requirements primarily required B LOS (PHI), EUV and 3He (EPD/SIS)observations maximum 1 minute cadence is enough (5 min cadence is sufficient but we worry about p-modes); observations at 1AU suggests (Wang et al. ApJ 2006; Li et al. A&A 2012; Wiedenbeck et al. ApJ 2013; Bucik et al. ApJ 2014) the first SEPs are injected hrs after the emergence - this sets also lower limit to the duration of the observations of a single AR (about 1 day at least); EUV brightening occurs 1-2 hrs after flux emergence (Ref.) - therefore we expect SEPs would be produced earlier how to catch such an emergence with limited FOV (or point to the right place)? 48° is an average longitude of 3He-rich SEP sources (Reames SSRv, 1999) and latitude is about ±15°(?); on quite Sun we have many flux emergences, so there is hope we catch the connected region when flux is emerging; SO full-disk (4 x per day nominal) will miss the emergence - regions could be identified with Earth based synoptic observations for some parts of the orbit); observations when FOV increases will be useful at some parts of the orbit this science goals will utilize the magnetic field extrapolations of open field synoptic observations for proper source identification – 4 per day not enough (24 per day B LOS needed) 5

MDI December 2002 Wang et al. ApJ 2006 EUV jets 380 keV/n 3He onsets: day 12.3 (injection at ~12.0 – 20 hrs after mag. flux emergence) and day 12.8 (injection at ~12.5 – this one related to cancelation or re-emergence? ); EUV jets coincide with the 3He injections Wang et al. ApJ Dec He-rich SEP source 6 EXAMPLE 1

12 Dec He-rich SEP source 7 EXAMPLE 1 injection times

Bucik et al. ApJ 2014 injection ~17hrs after the AR emergence! 9 July He-rich SEP source AR EXAMPLE 2 emergence start emergence stop AR 1246 injection Bucik et al. ApJ 2014

29 June 21:00 – 1 July 13:00 SDO HMI 220 x 170 arcsecs; 1hr step AR July He-rich SEP source 3He injection at ~12:30 July 1– 1.5 day after mag. flux emergence Bucik et al. ApJ EXAMPLE 3

7 July He-rich SEP source 6 Jul 15:00 – 7 Jul 05:20 SDO HMI 60 x 60 arcsecs; 0.5hr AR clear emergences July 6 19 UT & July 7 01 UT precede in 19 hrs SEP injections there are likely multiple (more than 2) emergences, perhaps corresponding to multiple electron events 10 EXAMPLE 4

11 EXAMPLE 5 STEREO-B, ACE impulsive events Li et al. A&A, 2012 Feb Wiedenbeck et al. ApJ, MeV/n 6-8 Feb He-rich SEP source Feb 6 -7, Feb 8 3 He onsets AR first injection ~1.5 day after the AR emergence

12 EXAMPLE Feb 12 12: Feb 13 12: Feb 14 12: Feb 15 12:36 14 Feb He-rich SEP source 3He-rich event in old AR when likely new magnetic flux emerge (no magnetograms available) STEREO-A AR 11045

13 Synoptic Support 1.Which science programs would profit PHI synoptic data? Source of SEPs 2.How often will these programs be carried out? Continuously 3.What are typical durations and cadences for each synoptic program? Cadence 1 hour 4.Which PHI observables are needed for each synoptic program? B los 5.What spatial resolution should PHI data have to achieve the various science goals? 4 Mm 6.What accuracy of PHI observables (digital depth, SNR, suppression of systematic noise) allows to achieve the individual science goals? 7.Are additional high-resolution synoptic programs useful? Yes response to S.K. Solanki et al PHI questionnaire

14 High Resolution Support 1.Which science programs would profit from PHI high-resolution support? Abundance and energy variations due to flux emergence/cancellation. 2.How often will these programs be carried out? Quiet Sun observations during perihelion remote sensing windows. Active region observations during any remote sensing windows. Newly emerging active region would benefit from supporting observations from Earth or near Earth spacecraft so should be done when SO is on the front (from Earth) of the Sun. Co-ordination with EUI is essential. 3.What are the typical durations and cadences for each program? Observations should be made over several days. Cadences of 5-10 min to capture flux changes. Quiet Sun may require higher cadence to remove p-mode oscillations. 4.Which PHI observables are essential/beneficial for each science program? B los 5.What spatial resolution and FOV would allow achieving the various science goals? Quiet Sun and active region with spatial resolution 0.5 Mm and FOV at least 200x200 Mm 2. Newly emerging active regions -spatial resolution 1 Mm, FOV as large as possible so best run during the remote sensing windows when SO is furthest from the Sun. 6.What accuracy of PHI observables (digital depth, SNR, suppression of systematic noise) would allow the individual science goals to be achieved?