New Views of the Solar Corona with Hinode X-Ray Telescope (XRT) Taro Sakao (ISAS/JAXA) and the XRT Team (ISAS/JAXA, SAO, NAOJ, NASA/MSFC)

XRT Sciences Photosphere-Corona connection Formation and heating of the corona incl. energy transport, storage, and dissipation Outer-corona investigation extending to CME and solar wind investigations Imaging observation of the soft X-ray/XUV corona with advanced imaging/temperature-diagnostic capabilities Vast varieties of active, or even non-active, phenomena in the corona:

Hinode XRT Front Door and Hinge Assembly Electrical Box Ascent Vents 2 places Graphite Tube Assembly CCD Camera and Radiator Grazing Incidence X-ray Mirror Back-Illuminated CCD Optimized set of focal-plane filters Sophisticated observation control by MDP

Al/Mesh Al/Poly C/Poly Ti/Poly Thin-Be Med-Be Med-Al Thick-Al Thick-Be Optimized filter selection and layout Adjacent filter pairs for temperature diagnostics Both SXT-like and TRACE-like filters included in the set Low temperature ( ≦ 1 MK) diagnostics High-temperature plasmas Temperature Diagnostics with XRT

Scientific Location of Hinode XRT (Angular resolution and temperature range) Angular resolution (CCD Pixel Size) Temperature range 0.5” 1” 2.5” Yohkoh/SXT (Full Sun) SoHO/EIT (Full Sun) TRACE (Partial) Hinode/XRT (Full Sun) ～ 2 MK

Observing FOV Size (arcsec) Cadence (sec) (Hardware limit by Telescope) (w/o filter motion) (w/ adjacent filter motion) Non-flare Flare Full-Sun Coverage XRT Yohkoh SXT Flare Core Active Region FOV vs Cadence (orbit-ave.) Global Corona / Heliospheric Outer corona investigation Cover SOT FOV 2” pxl size, or Q~75 (3 bit/pxl) Flare core with high spatial/temporal resolution High-cadence observation on magnetic configuraiton and temperature evolution An-order-of-magnitude increased exposure cadence particularly for non-flare observations

28 October 2006Hinode XRT ■ Superior images with high spatial resolution and with high contrast ■ High cadence exposures ■ Imaging capability for low temperature (~1 MK) plasmas …ROI covering SOT/EIS FOV plus Synoptic full-Sun FOV (4 times a day) 1,000–2,000 exposures per day Started observation from Oct. 23 last year ＊ Numerous XBPs now showing loop structures ＊ X-ray jet activities in polar regions ＊ Activities in ‘quiet’ regions and coronal holes ＊ Structure in diffuse corona ＊ Transient brightenings (microflares) in ARs ＊ Loop structure for flares Hinode X-Ray Telescope (XRT)

Hinode XRT and Yohkoh SXT Images at a Same Solar Activity Phase Hinode XRTYohkoh SXT

Hinode XRTYohkoh SXT Active Region Imaging

Hinode XRT Yohkoh SXT Quiet Regions

Hinode XRTYohkoh SXT X-ray Bright Points Bright points now resolved into ensemble of loops

2007/04/16–17 Al/Mesh 8 s Exposures; 20 min Cadence

X-ray Jets in Polar Regions ~10 events/hr …40,000 times higher detection rate than Yohkoh SXT - Relationship with polar photospheric mag. field? - Implication to high speed solar wind? (Apparent jet velocity ~200 km/s) (Cirtain et al. 2007, Savcheva et al. 2007, Shimojo et al. 2007)

(Al/Poly Filter) Activity in Quiet Sun and Coronal Holes (Ti/Poly Filter)

Transient Brightenings (Microflares)

Continuous Upflow of Plasmas - Apparent upflow velocity ~140 km/s along (apparently open) field lines. [Subsonic] - Temperature ~1.3 MK Density ~2 x 10 9 /cm 3 -Mass loss rate ~2 x g/s [Good fraction of mass loss rate by solar wind] (Ti/Poly Filter) (Sakao et al. 2007)

Cusp Structure for LDE Loops Dec :00Dec :00Dec :00 C B M (Al/Poly Filter)

Loop Structure for an Impulsive Flare Dec :00 12:0006:00 (Thin-Be Filter) C X M

Temperature Distribution/Evolution Across the Whole Sun (Narukage et al. 2007)

Height Dependence of Coronal Temperatures around a Polar Coronal Hole 2007 Feb.17 温度 Coronal Hole Temperature: 1.0–1.5 MK 密度 Remove Mirror Scattering Effect by Utilizing Eclipse Data (Kano et al. 2007) Corona Hole Density: 0.5 ～ 1.0 ｘ 10 8 cm -3

Height Dependence of Coronal Temperatures around a Polar Coronal Hole 2007 Feb.17 温度 Coronal Hole Temperature: 1.0–1.5 MK Corona Hole Density: 0.5 ～ 1.0 ｘ 10 8 cm -3 密度 (Kano et al. 2007) Remove Mirror Scattering Effect by Utilizing Eclipse Data 密度 gradient(?) 0.9x10 6 〜 1.5x10 6 erg sec -1 cm -2. 加熱源 0.1 Rs0.2 Rs

Summary (1) XRT holds a unique position among solar SXR/EUV telescopes currently on orbit or being planned: * Continuous coverage of the entire temperature range in the corona for ≳ 1 MK plasmas … Capable of observing entire plasma processes that take place in the corona, with temperature diagnostic capability * High angular resolution/contrast observations for high temperature ( ≳ 2 MK) plasmas High cadence observations … dynamics in quiet Sun/coronal hole regions

Summary (2) Structure and evolution of coronal magnetic fields and their associated temperatures Expected to serve as a key tool for investigating photosphere-corona connection. At the same time, may have non-negligible impact on heliospheric study.

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