Solar Wind Structure from Pseudostreamers: Connecting Remote and in situ Observations Nicholeen Viall NASA/GSFC In collaboration with : Larry Kepko, Angelos Vourlidas, Spiro Antiochos, Sue Lepri, Aleida Higginson, and Jon Linker

Connecting the Sun to the Heliosphere Pseudostreamer and helmet streamer Which solar structures become structures in the Heliosphere? Success with large-scale (e.g. CIRs; CMEs), but less so on mesoscales.

Success indirectly linking solar structures to heliosphere (in situ) with mesoscales ~tens of minutes up to a few hours/100s Mm up to a few thousand Mm radial length scale ‘small’ – compared to current heliospheric imager resolution and in situ composition measurements ‘large’ – compared to turbulence (‘mesoscale’-> generally larger than the inertial range) and Earth’s magnetosphere/space weather Rouillard Once Made direct connection Parker Solar Probe and Solar Orbiter will finally give a DIRECT link of these mesoscale structures

Is the HCS/Helmet streamer a special boundary where mesoscale structures are injected into an otherwise steady solar wind? S-web says there are other locations where magnetic reconnection ought to be injecting structures Our/others’ previous in situ solar wind work says there are other locations [e.g. Viall et al. 2008] We see periodic proton density structures in 70-80% of slow solar wind, suggesting that such structures are a substantial component of the ssw. If this is true, then we should see proton density structures (with compositional changes confirming solar source) not only at the HCS crossing, but other places as well.

PFSS as viewed by STEREO A August 2008 HCS is aimed south of Earth; pseudostreamer is aimed north PFSS as viewed by STEREO A That eclipse image from first slide and spiro

Images and in situ data show pseudostreamer continually releases ‘blobs’/‘puffs’/structured solar wind Still circumstantial; indirect

HI1 images show pseudostreamer continually releases ‘blobs’/‘puffs’/ solar wind structures DeForest processed HI1 – on STEREO/SECCHI webpage

250 km/s (Faster ones are 400 km/s) Time-distance plots show continuous release of structures from pseudostreamer 250 km/s (Faster ones are 400 km/s) Like Jmaps

250 km/s (Faster ones are 400 km/s) Time-distance plots show continuous release of transient structures from pseudostreamer 250 km/s (Faster ones are 400 km/s)

In situ, Wind/ACE observe a stream interface, many slow In situ, Wind/ACE observe a stream interface, many slow wind structures, and no HCS Ace C & O Ace C6+/C5+ Charge State 14 days without a HCS Slow wind shows highly structured proton density, alpha, carbon, oxygen, charge state - solar source T sector A sector Two traces are 3DP and SWE

Two-day zoom-in shows series of ~2.5 hour structures Alphas and C and O track one another with similar ~2.5 hr variation: structures are from solar source Typical hour cadence would have lead to false conclusion of steady solar wind Define boundaries based on compositional changes

Magnetic reconnection releases coronal loops with different heating histories Composition boundaries generally correspond to B field tangential discontinuities and rotations, but not in a predictable orientation- i.e. not Alfven waves or waves between flux tube (see also Viall et al. 2009 alpha event; Laming poster) Two heat flux drop outs in the train of periodic density structures are signs of connectivity changes to very long field lines (e.g. through interchange rxn; Chollet et al. Pagel et al) Laming talk

In situ Event Maps to Complex S-web Arcs- Not the HCS Predictive Science Inc

Prediction for Parker Solar Probe and Solar Orbiter: There is no such thing as ‘the steady solar wind’ No such thing as steady solar wind, just like in magnetosphere they learned (with better data) that there is no such thing as steady magnetospheric convection. Magnetic fields always store and then release energy. PSP and SO will finally be able to make DIRECT link between solar source and heliospheric structures Key is to get high time resolution composition/alphas + modeling Take away 1 Crooker et al.

Structures from the Sun drive dynamics in Earth’s magnetic field. Quasi-periodic reconnection at the Sun directly drives oscillations in Earth’s Magnetosphere (4 days later) Here’s the kicker: this event was observed in magnetosphere 18 years ago… initially they thought it was internal dynamics. (we know CMEs impact earth, but not small guys). The Earth was fully analyzed 15 years ago and shown to be SW (still not sure if it came from Sun though) Finally with STEREO and some new data processing techniques to pull out the smaller guys, able to connect the dots.

Solar Wind Structures Formed at Sun through Reconnection Proton density changes coincide with changes in composition– solar origin Specially processed, high time resolution ACE composition; typical resolution averages over these structures, and leads to incorrect interpretation of ‘steady’ slow solar wind Heat flux and B field changes associated with structures (one structure in the train is a flux rope!) this indicates magnetic reconnection (S-web) We observed perdiocid density structures in situ Note ‘periodic’ = characteristic time scale, these are not waves Kepko, Viall, Antiochos, Lepri, Kasper, Weberg 2016

Connecting helmet streamer structures and in situ structures in the Heliospheric Current Sheet In situ at 1 AU Last year studies Viall & Vourlidas 2015 Kepko, Viall, Antiochos, Lepri, Kasper, Weberg 2016 Left –STEREO images of helmet streamers creating density structures Indirect (not even from same time) link of Helmet streamer-> HCS structures

Indirect link solar structures with structures in solar wind hitting Earth. Current observational gap Get full information about temperutature, density, velocity, magnetic field, energetic particles, composition

Solar wind structures drive dynamics in Earth’s magnetic field. Understanding the dynamic space environment in general –these waves come all the way down to the ground - specifically Radiation Belts

These dynamics may have just the right timescales (ULF waves) to fill and drain Earth’s Van Allen Belts and provide ‘preconditioning’.

‘Small Things Can do Big Damage’ Small Blackholes Small Dogs Small Kids Small Carpenter Ants Small Hail ‘Small’ Structures from the Sun- which are constantly emitted- can have big, cumulative, impacts on Earth (terrestrial planets in general) Small leaks Take awat 2 Even though this structure and variability is small compared to CMEs…they can still have a big impact on Earth and the space environment. Constant barrage; thunderstorms of spaceweather

Extra

PFSS as viewed by STEREO A Images and PFSS show HCS is depressed and aimed south of Earth; pseudostreamer directed north of Earth PFSS as viewed by STEREO A So what exactly are we mapped to at 1 AU?