SOLAR-C Plan-B
Mission Description
Y. Katsukawa (NAOJ)
SOLAR-C WGSOLAR-C Plan-B
•! Understanding coupling between chromosphere andcorona through observations by combination ofspectroscopic (and polarimetric) and imaging
instruments.
•! Fundamental mechanism in MHD and plasma physics:
waves, turbulence, and magnetic reconnection, i.e.
dissipation of magnetic energies•! To achieve them,–! From imaging to spectroscopy (+polarimetry): obtain precise
information on dynamics such as waves and magnetic
reconnection, and on magnetic fields in the entire solaratmosphere.
–! Extend the wavelength coverage: cover the entire solar
atmosphere from photosphere to corona through chromosphereand transition region.

Mission-wide science goals
1.! Understand elementary structures of the magnetic
atmosphere and determine how they are created andevolve.
2.! Trace energy and mass flows from the photospherethrough the chromosphere into the corona.
3.! Understand how small-scale physical processes initiate
large scale dynamic phenomena creating space weather.
4.! Understand physical processes responsible for magnetic
dissipation in astrophysical plasmas.
These are still preliminary. It is important to combinescience goals raised by each subWG.

Understand elementary structures of the magnetic atmosphereand determine how they are created and evolve (1)•! How magnetic solar atmospheresare created and evolve.
–! Emergence and evolution ofmagnetic fields in QS and AR fromthe photosphere through thechromosphere into the corona.
–! Structures and dynamics inprominences

It is still poorly known
how cool materials aresustained in the upper
atmosphere. Little
observational knowledge
on magnetic field
configuration. Monochromatic image of the solar chromosphere seenin chromospheres. There are varieties of structures(fibrils, filaments, spicules etc.) regulated by magnetic
fields. But the intensity image does not provide any
quantitative information on magnetic fields. Understand elementary structures of the magnetic atmosphereand determine how they are created and evolve (2)•! Elemental structures of coronal fine structures–! Observations with ~1” resolution indicate that there are sub-arcseconds
structures (i.e. filling factor <1).
–! It is essential to have a spatial resolution comparable to observations ofphotosphere/chromosphere to identify elemental heating events andtrace energy flows from feet of coronal structures.

Targets of high resolution X-ray imaging telescope

Bright point in a polar coronal hole.
Elementary heating events are notresolved with the 1” resolution.

Trace energy and mass flows from the photosphere throughthe chromosphere into the corona (1)•! Chromosphere–! Dominant physics changes fromhydrodynamic (! >1) to magnetic forces (!
<1). Most of the non thermal heating takeplace.
–! Energy transfer and mode conversion by
MHD waves.
–! Liberation of magnetic energies throughmagnetic reconnection.

Oscillation of threads in a prominences (Okamoto et al.
2007). Quantitative measurements of magnetic fields
are crucial for identifying wave modes.

Wedemeyer-Bohm et al. (2009)

Trace energy and mass flows from the photosphere throughthe chromosphere into the corona (2)•! Where are coronal plasmas heated
and accelerated and how?
–! How much energies can propagate throughthe chromosphere.
–! Where are magnetic energies converted
into thermal and kinetic energies?
–! It is critically important to have a spatialresolution comparable to the observation ofphotosphere and chromosphere withcoverage from chromosphere, TR, tocorona.

Most of the Alfvenic energies dump in thechromosphere. It is demanded to observe
magnitude of energy transfer in the upper
chromosphere and TR (Suzuki et al. 2005).

Outflows identified in a HINODE EUV
spectroscopic observation. A driving
mechanism is still an open question.

Understand how small-scale physical processes initiate large
scale dynamic phenomena creating space weather.
•! High resolutional and detailed observations
combined with large-FOV obs are a powerfultool to study initiation of big explosions
affecting space weather.
–! NLFFF and possibly MHDS modelingand extrapolation using photosphericand chromospheric magnetic fields.
–! Small scale phenomena may be
responsible for triggering massiveexplosions.

NLFFF extrapolation (Schrijver et al. 2008)

Coronal mass ejection, shock propagation andparticle acceleration are sources of the spaceweather (Shiota et al. 2009).

Understand physical processes responsible formagnetic dissipation in astrophysical plasmas
•! The solar atmosphere as a plasma
laboratory with varieties of conditions.
–! High ! (photosphere) low ! (corona)–! Partially ionized  Fully ionized–! Collisional  Collisionless•! Measure how fast magnetic fields
dissipate in the solar atmosphere–! What plasma parameters determine areconnection rate–! Shocks and particle acceleration–! Non-thermal equilibrium, non-ionization
equilibrium
Ion temperature distribution (Imada et al. 2009)
High throughput and high temporal cadence
essential to resolve evolution of ionization.

We know that rapid liberation of magnetic
energies happens even in the collisional andpartial ionized plasma. Measurements ofphysical parameters around a reconnection
site may provide us a breakthrough.

Solar atmosphere as a plasma laboratory"Fully ionized
#Partially ionized

SOLAR-CHINODEn" = 13D

Plan-B: Concepts of mission instruments•! Advanced instruments to explore the solar
magnetic atmosphere:–! Precise spectroscopic & polarimetric observations forunderstanding nature of magnetic fields, especially inthe chromosphere–! High time resolution, high throughput spectroscopic
observations for understanding nature of dynamics–! Seamless observations over the entire atmosphere,i.e., from photosphere to corona, for understanding theentire pictures of heating and dynamics–! High spatial resolution observations for resolving
elementary physical processesMission Instruments•! UV-Visible-NIR telescope–! 1.5m! diffraction-limited telescope with advanced imaging andspectro-polarimetric instruments–! Wide wavelength coverage with capabilities of observing spectral
lines useful for diagnosing the solar atmosphere from photosphereto the upper chromosphere (and transition region)•! High throughput UV/EUV spectrograph–! High throughput to achieve high temporal cadence–! High spatial resolution (better than 0.5")–! Wide temperature coverage from the chromosphere, the transition
region, low corona and flare temperatures.

•! Next generation X-Ray imaging (spectroscopic) telescope–! Imaging of emissions from >1MK coronal plasma–! Grazing incidence telescope with 0.5" resolution with thespectroscopic (photon counting) capability–! Normal incidence telescope with ultra-high resolution of 0.1"

# of photons

Sensitivity

Why we need the 1.5m! aperture
SOLAR-C

HINODE

107

10-3

10-2106

He I 10830 for diag. of B in chromo.
Fe I 5250 for diag. of B & V in photo.
H I 6563 for imaging in chromo.
Ca II 8542 for diag. of B & V in chromo.

105

Ca II K 3884 for diag. of V in chromo.
Mg II k 2796 for diag. of V in chromo.

104103
0.5

•!

1.0

Based on preliminary design ofthe telescope–! 4 mirrors coated with Al+MgF2–! Spectrograph efficiency 0.2

1.5

•!

Diameter (m)Sampling–! Spatial: 0.06"/pix–! Temporal : 1sec–! Wavelength: "/#"=2x105

Why we need the 1.5m! aperture•! S/N~104 for high precision spectro-polarimetry–! He I 10830Å & Ca II 8542Å: 0.18"/pix, 10sec
integration
We can temporally and spatially resolve dynamical
phenomena in the chromosphere (spicules, jets, etc.)with magnetic field diagnostics.

•! S/N~102 for high-speed spectroscopy–! Mg II k 2796Å: 0.06"/pix, <0.5sec integration
We can achieve the highest spatial and temporal
resolution in spectroscopic diagnostics of thechromosphere.

Sub WG activities in FY 2009•! International sub-WGs are established to investigate specific scientificand technical items for each mission instrument.
•! Chromospheric/coronal magnetic field measurements–! 1st meeting at HAO on 5-6 Apr.
–! 2nd meeting at IAC on 5-6 Oct.

•! High throughput UV/EUV spectroscopy–! 1st meeting at GMU on 20-21 Mar.
–! 2nd meeting at MPS on 29-30 Jun.

•! Next generation X-Ray telescope–! 1st meeting at SAO on 12-13 Mar.
–! 2nd meeting at SAO on 10-12 Aug.

•! Science cases and specifications of each instrument become muchclearer through the discussion in the subWG.
•! The subWG have compiled documents reporting what they discussed
in terms of scientific and technical points of view. The documents are
groundwork for making a mission proposal.

Basic specifications of the three telescopes
Pixel size and FOV
UV-Vis-NIR telescope

Pixel size

Exposure

Note.

Broadband

164" x 164"0.04"

< 1sec•! 2.5 pix sampling of 0.1" res.
•! 4Kx4K detector

Narrowband

246" x 246"

0.06"

< 1sec•! 2.5 pix sampling of 0.16" res.
•! 4Kx4K detector

Spectrometer246" x 246"

0.06"

1sec
(S/N~1600)•! 2.5 pix sampling of 0.16" res.
•! 4K pix along slit

0.12"

10sec(S/N~104)Spectrometer

1024"x 1024"

0.5"

0.5sec (AR)
5sec(QS)•! 0.5"pixel size•! 2Kx2K MCP+CMOS detector

NIImaging

410"x410"

0.1"

1sec (AR)10sec (QS)•! High res imaging with NI telescope•! 4Kx4K detector

GIImaging1024"x1024"

0.5"

1sec

Photon count1024"x1024"

2.0"

60sec

•! Imaging spectroscopy with GI•! 2Kx2K CMOS detector

UV/EUV imaging
spectrometer
X-ray telescope

FOV

Size Size(mm)Weight (kg)UV-Vis-NIR telescope (telescope)!2300x4300

500

UV-Vis-NIR telescope (focal plane instruments)

2500x400x3000

200

UV/EUV imaging spectrometer

400x800x4000

120

X-ray telescope

400x400x4000

100

Engineering study for SOLAR-C •!
•!

SOLAR-C WG has started to investigate engineering issues of the1.5m!
telescope based on the design concept of HINODE/SOT to clarify what
major technical differences are in the bigger telescope.
Telescope•!

Focal-plane instrument•!

High throughput UV/EUV spectroscopic telescope
Next Generation X-ray telescope–! Optical design of the 1.5m! telescope–! Thermal issues–! Conceptual studies on the instrument configuration–! Narrow-band tunable filter (Lyot filter or Fabry-Perot)–! Mechanisms with high reliability–! International subWGs are studying strawman configuration of the telescope.

•!

Spacecraft system–! Spacecraft configuration–! High data rate telemetry (X-band or Ka-band) to achieve the average telemetry
amount of >10Mbps–! Orbit (Sun-synchronous orbit, Geostationary orbit)–! Attitude control system and for high pointing stability

Hinode heritage: space craft system•!

Spacecraft design, including S/C attitude control, micro-vibration control
techniqueRequirements of pointing stability comparedwith Hinode achievements(see presentation by Y. Masada)

Hinode heritage: optical telescope•! Optical and thermal designs

see presentation by Y. Suematsu
Preliminary optical design of the telescope
1.5m! aplanatic Gregorian with a heat dump
mirror at the primary focus.

Thermal study of the telescope.
Large heat load at the primary mirror is one of the criticaltechnical items to be solved.

•! Image stabilization system, correlation tracker
Servo OFF
Servo ON

Performance of the image stabilization systemNext Generation X-ray TelescopeSummary•! SOLAR-C Plan-B: Mission to investigate dissipation ofmagnetic energies in astrophysical plasmas with
spectroscopic (+polarimetric) instruments•! Science targets are begin clarified through thediscussion in each subWG.
(We may need more discussion to define mission wide
science goals.)•! We have now conceptual designs of the spacecraft andthe mission instruments.