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; 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

Yohkoh HXT Flares in

Predicted Solar Corona in Sep(minimum ) 2005 Nov 1994 Nov 2005 Nov ? 1996 Sep (minimum) 2007 Sep ?

Coronal Heating Alfven wave vs Nanoflare Alfven Wave heating Nanoflare heating

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 ＝ ＜２ Shimizu, Shimojo, Aschwanden, …. => insufficient for coronal heating α ＞２ Krucker & Benz

Alfven Wave Heating ? Yashiro (2000) Ph. D. Thesis Ｌｘ（ active region ） ∝ Ｂ＾１．０ ７ Ｆ ∝ Ｂ ＝＞ Alfven wave heating ?

Alfven wave theory of Spicules and 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 ③④ 5:40 - 5:31 5:58 - 5:40 6:14 - 5:586:31 - 6:14

Moreton wave and EIT wave Moreton wave EIT 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 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= – 0.01

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 Region Emerging Flux Region (EFR) is important for (1) Dynamic Phenomena (2) Dynamo (3) Coronal Heating

TRACE Observation of Emerging Flux Dark : Chromosphere Bright : Corona Wavelength ～ 171 Ａ Time cadence ～ 1 min Spatial 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.