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Solar-B XRT

Solar-B XRT. A High Resolution Grazing Incidence Telescope for the Solar-B Observatory. Presenter: Leon Golub Smithsonian Astrophysical Observatory. U-Side Leon Golub U.S.-P.I. Jay Bookbinder P.M. Peter Cheimets P.E. Ed DeLuca P.S. Alana Sette Mark Weber. J-Side

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Solar-B XRT

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  1. Solar-B XRT A High Resolution Grazing Incidence Telescope for the Solar-B Observatory Presenter: Leon Golub Smithsonian Astrophysical Observatory

  2. U-Side Leon Golub U.S.-P.I. Jay Bookbinder P.M. Peter Cheimets P.E. Ed DeLuca P.S. Alana Sette Mark Weber J-Side Kiyoto Shibasaki P.I. Taro Sakao Secretariat Ryouhei Kano Secretariat XRT Team … and many others in US and Japan.

  3. The Solar B Mission The X-Ray Telescope on Solar B Science Requirements Instrument Design Sample Observing Plans XRT “firsts” Talk Overview

  4. Solar B Spacecraft • Mass: 875 kg • Power: 1000W • Telemetry: 4Mbps • Data Recorder: 8Gbit • Attitude: Solar pointed • Stability: 0.3 arcsec per 1s • Launch: Summer 2006 • Orbit: Polar, Sun-Sync, 600km

  5. Solar-B XRT Flight Design Graphite Tube Assembly Ascent Vents 2 places CCD Camera and Radiator Electrical Box Front Door and Hinge Assembly

  6. X-Ray Telescope Mirror inner diameter: 35 cm Focal Length 2700 cm Geometric Area 5 cm2 Shutter/Analysis Filters τexp 1ms to 10s 9 X-ray, 1 WL filter Camera 2Kx2K back-illuminated CCD 1 arcsec pixels (13.5μm) XRT Instrumentation

  7. Open Open Med Al Thin Be Al/Mesh Thick Be Al/Poly Thick Al Med Be C/Poly White Light Ti/Poly Focal Plane Filter Wheels

  8. XRT Exposure Times Focal Plane Intensities for XRT Passbands

  9. Coronal Mass Ejections Coronal Heating Reconnection and Jets Flare Energetics Photospheric-Coronal Coupling XRT Science Goals

  10. Coronal Mass Ejections How are they triggered? High time resolution What is their relation to the magnetic structures? High spatial resolution What is the relation between large scale instabilities and the dynamics of small structures? Large FOV Broad temperature coverage XRT Science Goals 1

  11. CME Movie

  12. Coronal Heating How do coronal structures brighten? High time resolution What are the wave contributions? High Spatial Resolution Do loop-loop interactions cause heating? Large FOV Broad temperature coverage XRT Science Goals 2

  13. Coronal Heating: Sample Observation • What needs to be explained: • Outflows • Motions along field • Separatrices and QSLs • Intermingled hot and cool plasma

  14. Reconnection and Jets Where and how does reconnection occur? Is it related to slow CMEs? High time resolution Large FOV What are the relations to the local magnetic field? High spatial resolution Broad temperature coverage Coordinated observing with EIS/SOT XRT Science Goals 3

  15. Slow CME-associated Flare Events

  16. Flare Energetics Where and how do flares occur? High time resolution What are the relations to the local magnetic field? High spatial resolution Large FOV Broad temperature coverage High temperature response Large dynamic range XRT Science Goals 4

  17. Flare Energetics - Example

  18. Photospheric-Coronal Coupling Can a direct connection between coronal and photospheric events be established? High time resolution High spatial resolution How is energy transferred to the corona ? Large FOV Does the photosphere determine coronal fine structure? Broad temperature coverage Coordinated observing with SOT-FPP/EIS SXT Science Goals 5

  19. Example: Rotating Spot Courtesy A. Title The time has come to move beyond “loops” and “isolated mini-atmospheres”!

  20. The XRT “Firsts” New XRT Instrumental Capabilities: • Unprecedented combination of spatial resolution, field of view and image cadence. • Broadest temperature coverage of any coronal imager to date. • High data rate for observing rapid changes in topology and temperature structure. • Extremely large dynamic range to detect entire corona, from coronal holes to X-flares. • Flare buffer, large onboard storage and high downlink rate provide unique observing capability.

  21. Anticipated XRT Science “Firsts” • Flares & Coronal Mass Ejections. • How are they triggered, and what is their relation to the numerous small eruptions of active region loops? • What is the relationship between large-scale instabilities and the dynamics of the small-scale magnetic field? • XRT will determine the topology, physical parameters (T, ne) and interrelatedness of the regions integral to flare/CME formation. • Coronal heating mechanisms. • How do coronal loops brighten? TRACE has observed loop oscillations associated with flares (Nakariakov et al. 1999). Are other wave motions visible? Are they correlated with heating? • Do loops heat from their footpoints upward, or from a thin heating thread outward? Do loop-loop interactions contribute to the heating? • XRT will exhibit the evolution and activity of both active and quiet inner coronal structures on MHD (seconds) to surface B diffusion (days) timescales.

  22. Anticipated XRT Science “Firsts” • Solar flare energetics. • Solar-B will observe many flare event. The XRT can test the reconnection hypothesis that has emerged from the Yohkoh data analysis. • XRT will greatly extend the sample of observed flares in intensity, spatial and temporal resolution, allowing stringent tests of flare theories. • Reconnection & Coronal Dynamics. • Yohkoh observations of giant arches, jets, kinked and twisted flux tubes, and microflares imply that reconnection plays a significant role in coronal dynamics. With higher spatial resolution and with improved temperature response, the XRT will help clarify the role of reconnection in the corona. • XRT will determine importance of flows, B-field–plasma interactions, relevance of null points, reconnection sites and separatrix (or QSL) surfaces. • Photosphere/corona coupling. • Can a direct connection be established between events in the photosphere and a coronal response? • To what extent is coronal fine structure determined at the photosphere?

  23. Typical XRT Observing Plan • Assumptions: • X-ray data compress to 3 bits/pixel • White light data compress to 5 bits/pixel • Filter move and settle time 1.2 s per step • Shutter prep time 0.2 s • Parallel shift @ 10krows/s read time 512kpixels/s • => 3.075 s to read 768x768 FOV • Exposure times: 1s for filters 1 & 2; 3s for filter 3 • Data Rate: 53 kB/s Compressed data

  24. Sample XRT Program • Emerging Flux Program • Understand the interaction of emerging magnetic flux into • the existing coronal magnetic field. • Implementation: • Follow an AR as it crosses disk center (~1 week) • Use 768x768 FOV (13'x13') • Use 3 filters to obtain basic temperature coverage • Run at a 60-sec. cadence to follow coronal structures • Take WL images every 45 min for context & alignment

  25. Use of On-Board Storage Typical observing program requires >6 downlinks per day.

  26. End Presentation

  27. Instrument Requirements

  28. Analysis Filter Set

  29. Focal Plane Intensities for XRT Passbands XRT Exposure Times

  30. Diagnostics via Focal Plane Analysis Filters and Filter Ratios Throughput vs. T for C, Al, and Ti Filter ratios vs. T for some representative focal plane filter pairs.

  31. XRT DEM Widget Interface No. knots is no. bands - 1 Initial guess: Flat (unit) DEM No errors included In this example!

  32. “Real” AR DEM 4 filters 7 filters Solid line: Input DEM Dashed lines: Best-fit Model DEMs 100×

  33. Entrance Filter Design PROTECTIVE COVER ATTACHMENT POINTS LIGHT SUPRESSION RIB CAPTIVE SCREW ATTACHMET FILTER FRAME FRONT SURFACE BACK SURFACE

  34. XUV Filter Design Aluminum-Nickel Mesh Aluminum-Polyimide Titanium-Polyimide Beryllium-Nickel Mesh

  35. Rear Assembly Overview FILTER WHEEL AND SHUTTER ASSEMBLY GRAPHITE TUBE CAMERA FOCUS INTERFACE FOCUS MECHANISM REAR ADAPTER FLANGE

  36. Solar-B Artist’s Conception The Real Thing

  37. Spot Size for Various Focus Positions

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