What drives the solar wind and where does the coronal magnetic field originate from?

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1 What drives the solar wind and where does the coronal magnetic field originate from? a remote-sensing perspective for on-disk observations Giulio Del Zanna Senior Research Associate DAMTP, University of Cambridge, UK

2 A zoo of models/ideas Expansion factor Interchange reconnection Abbo+2016

3 In-situ Velocities Abundances (FIP effect) Freezing-in Temperatures Clear changes from fast to slow wind in velocities and temperatures. Also: magnetic field, particle distributions How do we link the in-situ measurements to the remote sensing? Remote-sensing on-disk observations are of the low corona, mostly of closed structures. How can we use them?

4 Remote-sensing of connection point Uncertainty in the location of the connection point: large FOV! PHI: vector magnetograms boundary to models EUI: Full- and partialframe (high-resolution) EUV images Models combining PHI and in-situ SPICE: Doppler flows, Te, abundances for cool plasma (<1 MK) One of the SPICE spectral windows Observational plans (SOOPS) are being prepared, but inter-instrument workshops are needed to work out details which cannot be left to the last minute. Keep plans simple!

5 Quiet Sun Jul 2008 solar minimum where are the source regions?

6 Coronal hole (CH) boundary Hassler et al. (1999) It should be possible to combine PHI+EUI+SPICE with the in-situ measurements to study the boundary (e.g. interchange reconnection) of the slow/fast wind in equatorial CH. Need EUI H171 1min cadence for at least 6-12h, high-res PHI, large SPICE raster. Doppler velocities (SPICE) and Te information (from where?) useful. SPICE can measure FIP bias in the TR, but FIP bias variations in the QS/CH network and cell-centres are small (Del Zanna+1999,2001,2003).

7 CH plumes and the fast solar wind Plumes Del Zanna (1999) (DeForest et al. 2001) Plumes: long-lasting open-field structures, should be identified in-situ (Helios) Disentangling the plume/interplume sources will not be easy, as they have similar Te (Del Zanna+, unpublished), abundances (Del Zanna 1999, +2001,+2003). Good news is that plume bases are bright in SPICE lines. Need EUI H171 10min cadence, high-res PHI, large SPICE raster.

8 CH jets contributions to the fast solar wind? Dynamic events such as jets would be useful. Need EUI H171 with high cadence (1m), high-res PHI, large SPICE raster. Can we afford the high-cadence?

9 Open fields from active regions? Potential field extrapolations often show open field regions near AR. Liewer+(2004)

10 AR contributions to the SSW ACE in-situ measurements ( ) of SSW near active regions (Wang, Ko, Grappin 2009). Low wind speeds Higher freezing-in O 7+ /O 6+ temperatures Higher Fe/O abundance (large scatter). AR cores: FIP bias of π (Del Zanna & Mason 2014) Photospheric: (Asplund+2009)

11 AR contribution to the solar wind? Del Zanna et al (2011) AR jets are common here Hinode/EIS: long-lasting coronal upflows, stronger at 3 MK, located in the middle of sunspots and plage (Del Zanna 2007,2008). Physical interpretation (Del Zanna+2011): interchange reconnection close to the null point, upflows driven by a rarefaction wave (Bradshaw, Aulanier & Del Zanna, 2011). See also Harra et al. 2008, Doschek et al. 2008, Baker et al. 2009,Demoulin et al. 2013, van Driel-Gesztelyi et al., 2012 and many more!

12 More on interchange reconnection Antiochos+2011 S-Web of QSL Fisk (2005,+2006) Sheely + (1975) based on Skylab observations Rappazzo+2012

13 AR jets Mulay+2015 (A&A), 20 jets: 1) near sunspots, in coronal outflow regions 2) in open field (PFSS) 3) have Type-III associated, which confirms they are in open field. High-cadence EUI HR171, PHI,SPICE needed. Can we afford?

14 Linking in-situ with remote-sensing Several studies on the relation between the in-situ and remote-sensing AR observations: Baker+(2015) van Driel-Gesztelyi+(2012), Brooks & Warren (2011), Culhane+2014, Mandrini+2014, Brooks et al. (2015), Zangrilli+2016, and many more.. Can we improve them with Solar Orbiter? We will need coordinated observations with other missions. Brooks+2015: Hinode EIS Doppler maps, PFSS model and FIP bias

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16 Te in coronal holes Te in plumes and lanes might be similar. Del Zanna, Teriaca, Wilhelm (unpublished) SPICE off-limb Te measurements of Mg IX might be useful. Te in CH are are higher than commonly thought; e.g.: Te=0.85 MK at 1.3R revised to 1.2 MK (Del Zanna+2008)

17 Culhane+2014

18 SPICE lines for on-disk abundance studies CHIANTI Mg VIII, Ne VIII Fe VIII (?), Ar VIII Obtaining abundances is not straightforward. Several lines will need to be observed.

19 Due to telemetry limits, most studies will record only a few selected line profiles. Need for careful planning! See SPICE posters: 1) Andretta et al., 2) Teriaca et al.

20 Elemental abundances with SPICE Incorrect abundances (by a factor of 10) can be obtained. Multiple ionization stages form the same element needed. Skylab plume Iobs Ab( Y ) Gji( Te) Iobs Gji( Te) dt FIP=0 FIP=10 Widing & Feldman (1992) Te of maximum emissivity in ionization equilibrium Actual Te Del Zanna et al. (2003)