Discussions on the initial observing plan

6th SOLAR-B science meeting

Solar B Spacecraft IllustrationCopyright 2002, 2004 B. E. JohnsonAll Rights Reserved

Discussion items

• What is IOP?(3min)

• Operational issues(0min)

• Key instrument features(3min)

• Key instrument science(3min)

• Methodology for data analysis(5min)

• Science issues(36min)

• Comments from XRT, EIS, SOT(10min)

Initial Observing plan (IOP)

• IOP is for first 30 days, 1month, 3 months…of SOLAR-B science observations starting approx. 1month after launch.

• Two conceptual ways of approaches– IOP should be targeted to the most important

specific sciences by carefully-designed sophisticated observing sequences.

– IOP should be simple uniform observing sequences, that provide many (serendipitous) discoveries.

Our strategy(1)• First stage: One month after launch, we

start with simple and clear observing sequences on progressive trial basis. As learning curve increases, these initial observing sequences would evolve to sets of the standard observing sequences.– We should have as many discoveries as

possible in this phase.

Our strategy(2)

• Second stage: In addition to these standard sequences, we will implement observing plans for specific scientific purposes – to further pursue the initial discoveries. – To implement prepared and new proposals

Our strategy(3)

• SOLAR-B instrument team will be responsible for initial observing plan, which should be released well before the launch, being subject to criticism for improvement– As a first step, each instrument team prepare

the initial observing plan for further iteration on Solar-B observatory level.

Operational issues

• Down-link data rate constraint– Baseline data rate (8:SOT,2:XRT,1EIS) vs de

dicated-mode

• Rapid maneuver to sun-center for XRT full Sun observations OPEN

• Time-scale for performance degradation due to contamination (SOT, EIS)

• These issues affect initial observing plans, but will not be discussed here.

Single sentence instrument features

• SOLAR-B continuous observations• SOT

– High resolution: 0.2 arcsec – Very stable and continuous PSF for magnetic observations (vs g

round-based observations)

• XRT– 1 arcsec pixel size/2 arcsec resolution – Provides TRACE-like(1-2MK) and SXT-like images(2-10MK)

• EIS– 1 arcsec pixel size, considerably better than CDS– log T = 4.7, 5.4, 6.0 - 7.3 K– X 10 more sensitive than CDS– a few km/sec sensitivity, considerably better than CDS

TRACE-”like” images!?We do not what we will see with

XRT thin filters Low temperature ( 1 MK) diagnostics≦

High-temperature plasmas

EIS (360”x512”)

XRT(2048”x2048”)

E W

S

SOT:NFI/SP(328”x164”)

SOT: BFI(205”x102”)

N

Solar-B Fields of View

SOHO/EIT FeXII 195A

Single sentence Science features

• XRT– Sensitive to temperature range that EIT/TRACE/SDO can not

see (> 2MK)– Detector of any small magnetic dissipation (heating)

• EIS– Detection of reconnection flows– Detection of waves (non-thermal width)– Diagnostics: temperature, density, differential emission measure

• SOT– Elemental flux tube– Emerging and submerging flux– Disintegration of sunspot– Detection of MHD waves– Subsurface B and flows

Multi-temperature structure of active regions

2MK1MK 10MK

Hot

Stationary heating

5MK

Transient heatingflares, microflares

(magnetic reconnection)

Cool

Coronal Temperature

Heating input is one order of magnitude different

Hot (T > 2MK ) ~107 erg cm-2 s-1Cool (T ~ 1MK) ~106 erg cm-2 s-1

loop-loop interaction

Yoshida & Tsuneta (1996)

Any transient heating is due to magnetic reconnection.Energetically dominant steady heating remains unknown.

Cusp Loop-loop interaction

Yoshida & Tsuneta (1996)

Synergy of 3 telescopes

• SOLAR-B mission goal: systems approach to understand generation/transport and ultimate dissipation of solar magnetic fields with 3 coordinated advanced telescopes.

• So far discussions centered on science with individual telescope

• Synergy of instruments need to be stressed

Methodology development for data analysis

• Existing methodology for data analysis may not be adequate for Solar-B analysis.

• Nff-coronal magnetic field extrapolation

• Local-helio seismic observations

• Fast Stokes inversion

• Non-equilibrium temperature diagnostics

Nff-coronal magnetic field extrapolation

• Nff-coronal magnetic field extrapolation– Snapshot extrapolation (independent of time)– Full MHD treatment (initial-boundary problem)

• Continuous high-quality vector-B and V data allows us to perform first full MHD calculation of coronal magnetic fields

• Concern: SOT small field of view– Can we use information from the whole sun instrumen

ts (SOLIS, SDO…) to better predict the coronal fields?

Stokes inversion

• Do we observe simple Milne-Eddington profile in 0.2arcsec regime?– Yes, because multiple components in a pixel become

s single component in higher resolution.– No, effects such as vertical gradient of LOS velocity p

roduce asymmetric profiles without averaging effect of lower resolution

– We are not sure on what we will observe.• How can we better prepare for the Solar-B stoke

s inversion?– Very fast Milne-Eddington inversion software required

• 180 degree ambiguity issue critical – Beyond-Milne-Eddington methodlogy required too

Advantage of high-resolution obs.•　 No apparent cancellation of Stokes signal •　 Filling factor no longer needed

Stokes profile more complex or simpler?• Simpler due to high resolution• More complex due to higher gradient

725 km 1”

observer

line of sight

Resolution Element

magnetic field vector

725 km 1”

observerobserver

line of sight

Resolution Element

magnetic field vector

Continuous high-cadence high-resolution observationsfor Elemental flux tubes and flow

SOT resolution

mag

mag

mag

magnmag

obs

obs

obs

obs

0

0

01

V

U

Q

I

f

I

f

V

U

Q

I

Local-helio seismic observations

• Small FOV but can diagnose – Depth:10 Mm, Time res.:2 hours, Spatial res.:

1000km

• Do we need Sun-quakes or ubiquitous acoustic waves?

• In addition to SOT-alone observations, joint observations with MDI, SDO should be considered.

Petschek reconnection takes placeSweet-Parker Petschek

Estimated inflow speed0.07VA (Tsuneta 1996)0.03VA (Yokoyama 2001)Petscheck-> constant

diffusion region

2L

2δ

vA

Inflow goes through diffusion region.

ux0 A

m

Ax

vR

vL

u

6

0

10~1

Inflow goes through slow shock, bypassing diffusion region.

Very slow inflow

AAx vvy

u 01.0~*0

Fast inflow

vA

2y*

2δ

Slow Shock

Too slow

Standard 2-D pictureof solar flares

Inflow 1MK

How do we see outflows?

• Inflow=1-2MK• Outflow=10-20MK• Ions may be preferenti

ally heated (Geotail, Laboratory experiment)

• Energy exchange time for e-p is very long.

• We should observe cool lines rather than hot lines to see outflows.

Science issues

• Elemental flux tubes and flows• Emerging flux regions• Formation and Disintegration of Sunspot• Active region observations• Magnetic fields with different origins• Coronal heating

– MHD waves– Pico-flares

• Magnetic reconnection

Formation of PoreVertical fieldStrong Bf-factor: Low->High

Formation of SunspotVertical fieldStrong BVery High f-factor

Convective collapse? Clustering by flow?

Horizontal->VerticalB: strongerf-factor: lower

EmergenceHorizontal fieldVery high f-factor

Emerging fluxLites et al, Leka et al, Kubo et al

ー ＋ ＋ ＋

Emerging flux region Developing sunspot Decaying sunspot

Converging magneticelements

Leaving magneticelements

Flows around sunspot（ Zhao et al. 2001）

Convergingdown-flow(1.5 – 5 Mm)

Outwardflow

Flow acrosssunspot(>10 Mm)

Flow may makeclustering of magneticelements

?

Life cycle of sunspot

Formation and Disintegration of Sunspot

• What is the role of convective collapse (Parker) and flows for the formation of pores and sunspots?

• Leighton-type diffusion may start with detached spine fields of penumbra in a form of isolated co-polarity MMFs. What is the role of initial inflow(?) and subsequent outflow in the moat region for the formation and disintegration of sunspots?

• What is the sub-surface magnetic and flow configuration leading to flux emergence and eventual disintegration?

• What makes such a spectacular flute structure of penumbra?

Active region observations

• Continuous Stokes observations from before its emergence to disappearance

• Simultaneous with local helio-seismology observations on sub-surface magnetic fields and flow– Depth:10 Mm, Time res.:2 hours, Spatial res.: 1Mm– Covers critical sub-surface area

• Observing sequence– Helio-seismology->B->Helio-seismology– -B->……

Kubo Thesis (2005) Sea-serpent fields MMF

G-band BPs

Ephemeral fields

Mixed fields

Co-polarity MMF:Source of large scaleDiffused fields?Disintegration of sunspot

Magnetic fields with different origins

Demography for magnetic fields with different origins

• Lagrangian tracking of many individual elemental fields from its birth to disappearance

• Fields diffused from active regions– Are diffused fields detached from co-polarity MMF?

• Bipolar ephemeral fields– indication of local dynamo?– detached sea-serpent MMF?– failed emerging flux?

•SOT: observes both and .This may allow us to identify polarizationand mode of MHD waves emitted to corona.

•PSD of photospheric flow field•Open-loop corona may be heated by Alfven waves with mode conversion: Norequirement on driving frequency.

•Active region heating requires very high f-driver (10sec).

6x105km

Detection of MHD waves

AVB

vB

0

•EIS: detection of nonthermal velocity

v B

Time run out here