The Solar Dark Energy Problem -- Measuring Coronal Magnetic Fields and Our Infrared Frontier

1. The Solar Dark Energy Problem -- Measuring Coronal Magnetic Fields and Our Infrared Frontier • We know relatively less about the solar IR spectrum, but it is very important for future coronal observations • Our newest telescopes and instruments on Haleakala are aimed at measuring these fields J.R. Kuhn, Associate Director Institute for Astronomy

2. Pictures aren’t enough: (from Chen et al., Low, Gibson, Roussev et al.)

3. SOLARC: Why an IR (reflecting) off-axis coronagraph? • Zeeman magnetic sensitivity • Lower scattered sky background • Lower scattered instrument optics background • Lowered scattered dust background

4. Ideal B measurement sensitivity 5 min observation, 10” pixel

5. Scattering sources • Atmosphere • “seeing” • aerosols • atomic molecular scattering • Telescope • diffraction • mirror roughness • mirror dust

6. Optical backgrounds Mirror roughness Diffraction 4.0m 0.5m

7. Atmospheric backgrounds

8. SOLAR-C Gregorian focus 8m f.l. M2 F/20, efl 8m, prim-sec 1.7m 0.5m, 1.5m fl primary 55mm, secondary l/10 p-v figure diff. Limited @ 1micron over 15’fov 10.4 deg tilt angle M1: 0.5m F/3.7

9. SOLAR-C Optics

11. Measured secondary PSF Over 5 orders of magnitude no mirror or other spurious scatter terms detected l = 656 nm Short exposure images nearly diffraction limited

12. “blue” disk photometry

13. IR expectations • Judge, Casini, Tomczyk, Burkepile... (http://comp.hao.ucar.edu/how.html)

14. The IR corona Kuhn et al. 1995, 1999 Also Judge et al., 2002

15. The IR Coronal triple whammy • Magnetic sensitivity increases with wavelength • All significant scattered light sources decrease with wavelength (mirror, dust, atmosphere) • Bright CELs and atmospheric opacity windows coincide

16. Echelle Grating Camera Lens Collimator NICMOS3 IR camera Fiber Bundle SOLARC Lessons Secondary mirror Prime focus inverse occulter/field stop Re-imaging lens LCVR Polarimeter Input array of fiber optics bundle Primary mirror

17. April 6 2004 Observations • Full Stokes vector observations were obtained on April 6, 2004 on active region NOAA 0581 during its west limb transit. • Stokes I, Q, U, & V Observation: • 20arcsec/pixel resolution • 70 minutes integration on V • 15 minutes integration on Q & U • Stokes Q & U Scan: • RV = 0.25 R • From PAG 250° to 270° • Five 5° steps • Lin et al. (in press) Fe X 171Å image of the solar corona at approximately the time of SOLARC/OFIS observation from EIT/SOHO. The rectangle marks the target region of the coronal magnetic field (Stokes V) observation.

18. IR Spectropolarimetry

19. FeXIII IR Coronal Polarimetry Q I B=4.6G V U

20. IR Coronal Stokes V

21. Results: Coronal Magnetograms B=4,2,0,-2 G

22. Coronal model B comparison From MURI Collaboration Abbett, Ledvina, Fisher,… These observations

23. Trace EUV ‘Poster’ Image

24. What light’s up the loops?

25. Conclusions • Coronal field measurements are feasible with current technology • Fundamental limitations to spatial and temporal resolution will persist until we have larger aperture coronal telescopes • These capabilities are coming

27. Ground-based Coronal Research: Why and Where?

28. Institute for Astronomy, Mees, Haleakala Observatory Prof. Haosheng Lin, Maui, IR solar physics Prof. Jeff Kuhn Oahu, IR solar physics Dr. Don Mickey Oahu, Solar Instrumentation Magnetic field studies Dr. Jing Li Oahu, Magnetic field studies Prof. Shadia Habbal Solar, solar terrestrial

29. Haleakala Observatory

30. Haleakala Future • Ground-based coronal and high resolution physics • New technologies for telescopes and infrared detectors

31. Our “dark energy” problem

32. Ground-based coronal science?

33. Corona: Space --Complementarity

34. Stellar Differential Image Motion Seeing Tests at Haleakala

35. Observatory Seeing Comparison:Solar Seeing Site Survey Measurements

36. Sky brightness measurements

37. ATST SSWG Top Site Characteristics Summary

38. Why off-axis telescopes? • Pupil is filled and unobstructured – high order adaptive optics uncorrupted • Pupil is constant in altitude-azimuth optical configuration • Secondary heat removal and optics are accessible • Scattered light and image contrast are higher

39. Telescope pupil and wavefront errors

40. Off-axis telescopes Off-axis angle

41. Off-axis telescope “myths” • “Aberrations are worse than conventional telescopes” • “They can’t be aligned” • “Large off-axis mirrors aren’t manufacturable”

42. Aberrations • This is not an asymmetric optical system, it is a “decentered” system • The full aperture is not illuminated Q dy e f For small angles, Q, blur is astigmatic and only weakly dependent on off-axis distance. SOLARC is diffraction limited over 15 arcmin field

43. A new generation of low-scattered light coronagraphic and adaptive optics telescopes • SOLARC (UH) • Coronagraph, 0.5m, 10.5 deg off-axis • New Solar Telescope (BBSO/UH/KAO/Others?) • Disk, 1.7m, 30 deg off-axis • Advanced Technology Solar Telescope (NSO/UH/NJIT/HAO/UChic+others?) • Coronagraph/disk, 4m, 32 deg off-axis

44. SOLAR-C Gregorian focus 8m f.l. M2 F/20, efl 8m, prim-sec 1.7m 0.5m, 1.5m fl primary 55mm, secondary l/10 p-v figure diff. Limited @ 1micron over 15’fov 10.4 deg tilt angle M1: 0.5m F/3.7

46. SOLARC Status • Worlds largest solar coronagraph • Used for IR coronal studies • Coronal Magnetic fields • Imaging Fiber Bundle Spectrograph and spectropolarimeter • SOLARC demonstrates the potential of an optically fast off-axis optical telescope, new coronal studies underway, collaborators welcome

47. The New Solar Telescope BBSO UH Korea

48. NST Concept

49. NST Concept Sketch of the NST showing the optical path, optical support structure, and primary mirror cell. Only the top floor of the observatory building is shown, since the existing dome will be replaced to fit the telescope envelope and provide better means of wind flushing and overall thermal control.

50. Optics will “pace” the project The 10 cm thick primary mirror of the NST is made from Zerodur and has a 1.7 m diameter. It was shaped and configured by EASTMAN KODAK and has been shipped to the Steward Observatory of the University of Arizona, where it awaits polishing. The concave surface radius of the off axis parabola is 8140 mm with a conic number of -1.0, a vertex radius of 7700 mm, and an off-axis distance of 1840 mm. Figure 6 (top). The 10 cm thick primary mirror of the NST is made from Zerodur and has a 1.7 m diameter. It was shaped and configured by EASTMAN KODAK and has been shipped to the Steward Observatoryof the University of Arizona, where it awaits polishing. The concave surface radius of the off axis parabola is 8140 mm with a conic number of -1.0, a vertex radius of 7700 mm, and an off-axis distance of 1840 mm. Figure 6 (top). The 10 cm thick primary mirror of the NST is made from Zerodur and has a 1.7 m diameter. It was shaped and configured by EASTMAN KODAK and has been shipped to the Steward Observatoryof the University of Arizona, where it awaits polishing. The concave surface radius of the off axis parabola is 8140 mm with a conic number of -1.0, a vertex radius of 7700 mm, and an off-axis distance of 1840 mm.