Solar-B Science Objectives- Overview of the Mission -

Kazunari Shibata(Kyoto Univ.)

Science Objectives of Solar-B Mission

Kosugi (1999)– coronal heating

– coronal dynamics and structure

– elementary processes such as reconnection

- emerging flux and dynamo

chromospheric heating, spicules, …

jets, prominence, CME, solar wind, waves/shocks,…

reconnection jet, inflow, slow/fast shocks,…

flux tubes, sunspots, convection, …

These Objectives are also important for astrophysics and space weather

• To explore solar MHD as a laboratory of astrophysical MHD

• To explore solar activity as a basis of space weather research

Plan of this talk

• Introduction – Main Instruments• Main Objectives

– Coronal and Chromospheric Heating Nanoflares, Alfven Waves, Spicules

– Coronal Dynamics and Structure Jets, CMEs, Coronal Waves/Shocks

– Reconnection – Emerging Flux

• Summary

Solar-B Mission

• Solar Optical Telescope (SOT)• X-Ray Telescope (XRT)• EUV Imaging Spectrometer (EIS)

• Launch Date: 2005 J-fiscal year• Mission Lifetime: > 3 years• Orbit: Polar, Sun Synchronous

Solar Optical Telescope (SOT)

• 50 cm Aplanatic Gregorian – Japan• Focal Plane Package – US(LMATC) (Filtergram+Spectro-polarimeter)• => 0.2 arsec resolution; 380-700 km vector magnetic field

measurements

X-Ray Telescope (XRT)

• Grazing-Incidence Optics – US(SAO)

• CCD Camera – Japan• => 1 arcsec resolution; 1 – 30 MK

EUV Imaging Spectrometer (EIS)

• 15 cm Offset Parabolic Mirror, Slit/Slot & Multilayer Grating – US (NRL, GSFC)

• Camera – UK(MSSL,RAL,Birmingham)• Controller – Japan• 20 km/s nonthermal motion• 2 arcsec spatial resolution• Temperature coverage

0.1 – 20 MK

太陽活動の１１年周期

黒点数

2005 - 2007

Yohkoh HXT Flares in 1991-1998

Predicted Solar Corona in 2005-2007

2007Sep(minimum)

2005 Nov

1994 Nov2005 Nov ?

1996 Sep (minimum) 2007 Sep ?

Coronal HeatingAlfven wave vs Nanoflare

• Alfven Wave heating

　 • Nanoflare heating

BVVfF A 2

22 4/ BVfBF

Nanoflare Heating ?

• Shimizu (1995) Ph. D. Thesis

　 active region corona is filled

with microflare/nanoflare 　　　　 ＝＞　 nanoflare

heating ? • Kano (1997) Ph. D. Thesis

loop top heating ?

• Priest et al. (1998) nanoflare heating ?

Microflare/Nanoflare Occurrence Frequency

α ＝ 1.6-1.7 ＜２Shimizu, Shimojo, Aschwanden,

…. => insufficient for coronal heating

)(2

1 2min

2max

max

min

EE

EdEdE

dNE

EdE

dN

E

E

total

α ＞２Krucker & Benz

Alfven Wave Heating ?

• Yashiro (2000) Ph. D. Thesis

　Ｌｘ（ active region ∝ ） Ｂ＾１．０７　　　

　Ｆ　 ∝　　Ｂ ＝＞　　 Alfven wave heating ? 78.0Bp

07.1xL

Alfven wave theory of Spiculesand Coronal Heating

(Hollweg et al. 1982, Kudoh-Shibata 1999)

Hα (Hida DST)

Alfven wave model of spicules:numerical simulation (Kudoh-Shibata 1999)

Energy Flux Carried by Alfven Waves into Corona (Saitoh, Kudoh, Shibata 2001)

Nonthermal Line Width(Kudoh & Shibata 1999)

Coronal Heating(Kudoh &Shibata 1999)

Question on Coronal Heating

• What is the true occurrence frequency of nanoflare ?

• What is the heating rate and its dependence upon magnetic field ?

• What is the energy flux carried by Alfven waves into the corona ?

• What is the origin of Alfven waves ? Photospheric turbulence or reconnection ?

Coronal Dynamics and Structure: X-ray Jet

Yokoyama & Shibata (1995)

Zoo of Solar Jets

• H alpha jets (surges)

• EUV macrospicules

• EIT jets

• LASCO jets

CDS spinning jet (Pike&Mason)

H alpha spinning jet (Kurokawa)

EIT-LASCO jet (Wang, Y. M.)

Cosmic jet (HST)

Polar plume

Evaporation flow produced by reconnection heating ?(Wang, Y.M. 1999)

Moreton Wave(Hα ： Hida FMT, Eto et al. 2001)

Moreton wave

= Fast mode

MHD shock

(Uchida 1968)

Wave front of Moreton wave

5 ： 55

Propagation speed ~ 720km/s

① ②

③ ④

5:40 - 5:31 5:58 - 5:40

6:14 - 5:58 6:31 - 6:14

Moreton wave and EIT wave

Moreton wave

EIT waveEIT wave(Thompson et al. 1998)

Photospheric flare wave(SOHO/MDI, Kosovichev)

Question on Coronal Dynamics and Structure (Jets and Waves)

• What is the true velocity of X-ray jets ?

• What is the acceleration mechanism of X-ray jets ? ( => Shimojo’s talk)

• What is the relation to coronal heating and acceleration of high speed solar wind ?

• What is EIT wave ?

• What is the origin of Moreton wave ?

Reconnection

• Yohkoh found plenty of evidence of reconnection in flares.

• But we have not seen reconnection jet and inflow in SXT images.

(but see Yokoyama et al. 2000 ApJ Let.)

Reconnection Rate of a Cusp-Shaped Flare on

May 12, 1997 (Isobe et al. => poster)

Reconnection rate is high even in a very late decay phase V_inflow/V_A=

0.001 – 0.01

Question on Reconnection

• Are there really high speed reconnection jets with 1000 km/s ?

• What is the reconnection rate (inflow speed) in solar flares, jets, and coronal mass ejections ?

• What determines the reconnection rate ?

=> Yokoyama’s talk

Emerging Flux RegionEmerging Flux

Region (EFR) is important for

(1) Dynamic Phenomena

(2) Dynamo(3) Coronal

Heating

TRACE Observation of Emerging Flux

Dark : ChromosphereBright : Corona

Wavelength ～171 Ａ Time cadence ～1 minSpatial Resolution ～ 2 arcsec

Comparison with SXT(Yashiro-Shibata)

TRACE

SXT

Emergence of twisted flux tube - most fundamental driver of solar

activity ? -

(Matsumoto et al. 1998)

Question on Emerging Flux

• How and when are kG intense flux tubes created in emerging flux ?

• How and why are twisted emeging flux tubes generated ?

• Will we observe flare-like explosive reconnection (with jets and shocks) in photospheric reconnection associated with emerging flux ?

Summary

• More, smaller, and faster jets, plasmoids, waves, and shocks would be found by Solar-B.

• High time cadence velocity field observations (with EIS and SOT) with good coordination with XRT is extremely important.