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

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

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

Ideal B measurement sensitivity 5 min observation, 10” pixel

Scattering sources Atmosphere –“seeing” –aerosols –atomic molecular scattering Telescope –diffraction –mirror roughness –mirror dust

Optical backgrounds 0.5 m 4.0 m Diffraction Mirror roughness

Atmospheric backgrounds

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

SOLAR-C Optics

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

“blue” disk photometry

IR expectations Judge, Casini, Tomczyk, Burkepile... ( 

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

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

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

April Observations 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. 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)

IR Spectropolarimetry

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

IR Coronal Stokes V

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

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

Trace EUV ‘Poster’ Image

What light’s up the loops?

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

Ground-based Coronal Research: Why and Where?

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

Haleakala Observatory

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

Our “dark energy” problem

Ground-based coronal science?

Corona: Space -- Complementarity MISSIONDATESINSTR.TYPEWAVEARCSEC per PIXEL FOV SOLARB EISSpec.17-29nm STEREO COR1/COR2pBBroadband ( nm) EUVISpec.17-30nm SDO AIA/ Magritte Filter7 channels nm AIA/SpectreSpec. (one line) O V 63nm KCOR/ECORpBBroadband ( nm) NEXUS Spec45-65nm ATST (several)Filter, Spec, Pol, pB nm SOLAR ORBITER ?(several)pB, EUV Spec? (several)(in situ)

Stellar Differential Image Motion Seeing Tests at Haleakala

Observatory Seeing Comparison: Solar Seeing Site Survey Measurements

Sky brightness measurements

ATST SSWG Top Site Characteristics Summary

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

Telescope pupil and wavefront errors

Off-axis telescopes Off-axis angle

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

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

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

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

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

The New Solar Telescope BBSO UH Korea

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.

Optics will “pace” the project 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 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. 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.

NST Status Mirror awaiting UA mirror lab secondary polishing system, begin Dec. 2004, end July 2005 Dome replacement detailed optical support structure design and construction under way International collaborators welcome

Advanced Technology Solar Telescope PI: –Steve Keil Co-PI’s –Michael Knoelker (HAO) –Jeff Kuhn (IfA) –Phil Goode (NJIT) –Bob Rosner (Univ. Chicago) NSO ATST Staff –Thomas Rimmele (Project Scientist) –Jeremy Wagner (Interim project manager)

Formal collaborators: USAF (Richard Radick, Nathan Dalrymple) The University of Rochester (Jack Thomas) California Institute of Technology (Paul Bellan) California State College, Northridge (Gary Chapman, Christina Cadavid, Steve Walton) Michigan State University (Bob Stein) Stanford University (Alexander Kosovichev) Montana State University (Dana Longcope) Princeton University (Frank Cheng) University of Colorado (Tom Ayres, Juri Toomre) University of California, San Diego (Bernard Jackson, Andy Buffington) Lockheed Martin (Tom Berger, Alan Title, Ted Tarbell) NASA Marshall Space Flight Center (John Davis, Ron Moore, Alan Gary) NASA Goddard Space Flight Center (Don Jennings) University of California, Los Angles (Roger Ulrich) Colorado Research (K. D. Leka) Harvard-Smithsonian CFA (Ballegooijen, Nisenson, Esser, Raymond) Southwest Research Institute (Craig Deforest, Donald Hassler) International Partners being sought – involvement through SWG and site work now

System Parameters 1.6 microns)

Telescope Optics 3-5 arc minute field –Few percent of solar disk DM Collimator M1 M2 F/13 collimator –200 mm collimated beam Elevation and Azimuth axis Deformable mirror at pupil

Primary Mirror Assembly 4.3 meter substrate –100 mm thin meniscus –Low expansion material 120 active supports Forced cooled air temperature control

ATST Status Design and development proposal (11M$) ends during 2005 Construction phase proposal (161M$) now being considered by NSF and US National Science Board. Major funding start date late 2006 or early 2007 International partners sought ATST Science working group (as of 10/14/04) has recommended a primary site for the ATST – Haleakala, and backup sites (LaPalma and BBSO)

Summary Measured by major new facilities, solar astrophysics is on the verge of healthy growth – competing and attracting resources in the US community comparable to the much larger nighttime astronomical science community.

Magnetic linear polarization sensitivity Q Q+U B E

Coronal Hanle measurements Raouafi, Sahal-Bréchot, Lemaire, A&A 396, 1019, –OVI 103.2nm polarization measurement using CDS in a coronal hole (9%, 9 degree from limb tangent) –Analysis: non-unique solution requires both B of a “few gauss” and velocity of “few 10’s km/s”

QU forbidden line observations Habbal, Woo, Arnaud, Ap.J. 558, 825, 2001 –FeXIII HAO/NSO KELP project 1980’s

Coronal forbidden line Zeeman Observations Lin, Penn, Tomczyk, ApJ, 541, L83 (2000) –FeXIII V polarimetry

Ongoing Coronal B efforts COMP, Ground-Based Coronal Research Project (HAO lead) ATST (NSO) SOLARC (IfA)

SOLARC Roy Coulter, Jeff Kuhn, Haosheng Lin, Don Mickey 100nm spectrograph filter bandpass 3.93 micron

Magnetic field measurements......will be achieved in the quiet corona with a sensitivity of better than 1 G...from IR coronal observations obtained by several research groups using sensitive polarimetry techniques...on a timescale of one year

Vector Inversions FF and potential model from Low (1993) –External potential field+FF at r<R + dipole Radon transform using Algebraic Reconstruction Technique s Q z y

The projection problem

The inversion 10 iterations over 12 projections spaced 15 degrees...

Another inversion 6 projections, 0-90 degrees...

Potential field...

Long Wavelengths SOLARC Prime or Gregorian Focus chopWarm IR Spectrograph Fast 1-5mu IR Camera Cold Narrow-band filter