Energy and Mass Transfer
through the Chromosphere
Bart De Pontieu
Lockheed Martin Solar & Astrophysics Lab
Palo Alto, CA, USA

Wednesday, March 10, 2010

Why do we care about the chromosphere?
The chromosphere is where most of the nonthermal energy that creates the corona andsolar wind is released or transformed.
Chromosphere requires 50 times heating rateof corona, and provides all mass toheliosphere
A. What types of non-thermal energy
dominate in the chromosphere andbeyond?
B. How does the chromosphere regulate
the mass and energy supplied to thecorona and heliosphere?
C. How does magnetic flux and matter
rise through the lower atmosphere,
and what role does flux emergenceplay in powering flares and massejections?
movies courtesy of Alan Title
Wednesday, March 10, 2010

Why do we care about the chromosphere?
Thechromosphereiswheremostofthenon• Compatible high spatial and thermal energy that creates the corona andtemporal resolution fromsolar wind is released or transformed.

photosphere to corona• Wide spectral coverage• Magnetic Field inChromosphere

Chromosphere requires 50 times heating rateof corona, and provides all mass toheliosphere
A. What types of non-thermal energy
dominate in the chromosphere andbeyond?

• Context/Complementarity

B. How does the chromosphere regulate
the mass and energy supplied to thecorona and heliosphere?

• Numerical Simulations

C. How does magnetic flux and matter
rise through the lower atmosphere,
and what role does flux emergenceplay in powering flares and massejections?

(Great Observatory)

Tremendous
discovery space
Wednesday, March 10, 2010

Solar C plan B will provide major breakthrough science
1.Source, propagation and dissipation of Alfven waves
that help drive solar wind,
2.Connection between chromosphere and corona:mass cycle, constrain coronal heating models,
3.Magnetic field extrapolations from chromosphericvector-magnetic data into heliosphere will allow
detailed accounting of helicity and magnetic freeenergy that drive solar activity,
4.Heating of quiescent and active chromosphere.
5....
Wednesday, March 10, 2010

To determine energy and mass transfer fromchromosphere into corona/heliosphere, we need
1.A large observatory that obtains spectra and images thatsimultaneously cover the photosphere, chromosphere, TR andcorona (from 4,000K to 10 MK),
2.simultaneously at high spatial resolution (~0.2 arcsec),
3.temporal resolution (<10 s) over a large FOV (120 arcsec),
4.and spectral resolution (0.5 km/s in TR/corona fromcentroiding)
5.without issues of co-alignment (i.e., different instruments withpredefined co-alignment strategies, slit-jaw),
6.with high S/N polarimetry in photosphere and chromosphere.
Wednesday, March 10, 2010

The chromosphere then... vs now...

1 arcsec, 30 s resolution vs 0.2 arcsec, 1.6 s resolution

Heating to coronal temperatures?
(chromosphere & corona mass cycle)
Transverse motions(Alfven wave supply to atmosphere)
Dissipation of magnetic energy(reconnection)

Pre-Hinode

HinodeChromospheric dynamics occurringon timescales of order 1-10 s
Finescale structures on scales of <0.2 arcsec
Wednesday, March 10, 2010

Observing the Roots of Coronal Heating -- In The Chromosphere
Chromosphere-corona connection visible only
Faint propagating disturbancesin strong, but faint upflows, heated and propelled in chromosphere/TR,(evaporated spicules)
enough mass to fill coronatime

EIS TR & corona (0.5-2 MK)Blue Asymmetries
in TR/coronal lines

Bright,gentle Faint upflowsup/downflows 50-100 km/s
~10 km/s

space

XRT corona (3 MK)

IntensityDoppler

Asymmetry

SOT Ca II H chromosphere
TRACE 171 corona (1 MK)

TRACE 1600 chromosphere (20,000 K)“Evaporating” Spicules

SOT Ca II H image

Chromosphere-Corona connection visible in faint upflows (3rd and 4th moment of spectral lines)
Wednesday, March 10, 2010

Using Line Asymmetries to Study Coronal Upflows
3. Subtract signals in spectral windows
equi-distant from core: Blue-Red asymmetry

Low-lyingloops Moss

2. Calculate centroid position
Hinode/EIS (2 MK)
Wednesday, March 10, 2010

1. Fit single Gaussian to profile

Using Line Asymmetries to Study Coronal Upflows
3. Subtract signals in spectral windows
equi-distant from core: Blue-Red asymmetry

Ubiquitous,faint (5-10%) upflows of 50-100 km/s seen in many TR
Low-lying
and coronal lines
aboveMoss
AR/QS/CH network/plage with EIS, SUMER
loops(incompatible w/current coronal nanoflare models)Requires: High S/N spectroscopy from chromosphere to corona athigh spatial resolution (0.2-0.3 arcsec) and cadence (<10 s)

2. Calculate centroid position
Hinode/EIS (2 MK)
Wednesday, March 10, 2010

1. Fit single Gaussian to profile

Outflows have been seen with TRACE and XRT,
sometimes interpreted as propagating slow-mode waves“blobs” of plasma propelled outwards
sometimes quasi-periodic ~3-20 minutes
V : 75-150km/s

TRACE171Å
Hinode/XRTSchrijver et al., Sol. Phys., TRACE first results, 1999
Sakao et al. 2007, Science, 318, 1585
De Pontieu, McIntosh, Hansteen & Schrijver 2009, ApJL, 701, 1
McIntosh & De Pontieu 2009, ApJL, 706, 80

Asymmetries in EIS/SUMER profiles suggest TRACE/XRT/AIA should see shortlived (~100s) upflows of 100 km/s at 1-10% of background loop emission:
Requires high S/N coronal imaging for wide range of T at high spatial resolution
Wednesday, March 10, 2010

Loops with propagating “blobs” show strong blueward line
asymmetries (EIS) at the footpoints for T=0.5 to 2 MK

0.5 MK

Compare EIS & XRT
Wednesday, March 10, 2010

1.2 MK

1.6 MK

5% Asymmetry - Same velocity!
Visible in Unipolar Magnetic Regions
Across Many Temperatures
Co-spatial/temporal with “blobs”
De Pontieu, McIntosh, Hansteen & Schrijver 2009, ApJL, 701, 1
McIntosh & De Pontieu 2009, ApJL, 706, 80

Plage below TR/coronal upflows (100 km/s) shows type IIspicules in Ca H at similar speeds
Hinode/SOT/BFI Ca IIH 20−Feb−2007 11:55:08.491

Compare EIS & SOT

50

−55

−65
−70−50Hinode/SOT/BFI Ca IIH Background Subtracted

−55
−60
−65

50

403030100 km/s
Counts−60−75

Solar Y [arcsecs]

Hinode/SOT/BFI CaIIH Bg. Sub. [8s Cadence, 0.4s Exposure]

Time Elapsed Since 11:55:08.491 [Minutes]

Solar Y [arcsecs]−502010−10−30−5010−700−75−480−470−460
Solar X [arcsecs]−450−440−484−482−480−478−476
Solar−X [arcsecs]−474−472

5% Asymmetry - Same velocity!
Visible in/from unipolar magnetic regions!
Type-II Spicules!
Co-spatial/temporal with “blobs”
De Pontieu, McIntosh, Hansteen & Schrijver 2009, ApJL, 701, 1
McIntosh & De Pontieu 2009, ApJL, 706, 80
Wednesday, March 10, 2010

Chromosphere/Corona Mass Cycle
Disk Center View

Coronal Emission LineI(λ)
Blue-ShiftedComponent

No Long Type-II Spicules in Ca II HAsymmetric Coronal Line Profiles

Coronal outflows
λλ0
Heated Material

Type-IISpicules

Type-ISpicules

Courtesy
Scott McIntosh
Oblique/Limb View

Tall Type-II Spicules in Ca II H
Symmetric Coronal Line Profiles

Heated Material

CoronaCooling Material

Upflows in thechromosphere

Coronal Emission LineI(λ)λ0λBuffeting Convective Flows

1. Emission in core of coronal lines dominated by emission from previously filledloops (slowly cooling/evaporating plasma)
2. Chromosphere-Corona connection visible in faint upflows (3rd and 4thmoment of spectral lines)
3. Constrains coronal heating theories: coronal heating occurring at low heights?

Requires: High S/N spectroscopy & imaging from chromosphere tocorona at high spatial resolution (~0.2 arcsec) and cadence (<10 s)

Wednesday, March 10, 2010

Measuring line profile shapes important

Simulations courtesy Viggo Hansteen

Requires: High S/N spectroscopy & imaging from chromosphere tocorona at high spatial resolution (~0.2 arcsec) and cadence (<10 s)
Wednesday, March 10, 2010

Compatible resolutions for all T crucial
STEREO movie
171 A (1 MK)
80 s cadence
2.5 arcsec
pixelsCRISP overlayHα (0.01 MK)
10 s cadence
0.08 arcsec pixels

Wednesday, March 10, 2010

High throughput crucial for slit-scanning spectrograph to allow
rapid rasters that track chromospheric/TR/coronal evolution
Simulated rasters on HINODE background

spectralraster“SUMER” raster
Wednesday, March 10, 2010

context
image

6 arcsec“IRIS” spectral raster &context slit-jaw images “EIS” raster16

Solar C plan B will have great synergies with
Interface Region Imaging Spectrograph (IRIS) Small Explorer
IRIS Electronics
Box (IEB)Spacecraft Bus
Assembly

Guide Telescope

Science TelescopeSpectrograph17

Wednesday, March 10, 2010

IRIS in brief
Realistic Radiative
3D MHD models…

UV slit-jaw Images
Si IV (65,000K)
C II (30,000K)
Mg II h/k (10,000K)
Mg II h/k wing (6,000K)

2790 2800
2800 2810
28102820
28202830
2830
Wednesday, March 10, 2010

kbit/sec

UV Spectra
Far-UV 12.5 mÅ pixels
Near-UV 25 mÅ pixels…to guide interpretation
20 cm UV telescope:
700
Highpixels
nominal data rate
6001/6 arcsec
multi-channel spectrograph500
far-UV: 1332-1358 Å, 1390-1406
Å,139040040 mÅ resolution, effective area 2.8 cm2300near-UV:2785
2785-2835- 2834 Å,
20080 mÅ resolution, effective area 0.3 cm2100
slit-jaw imaging
01335 Å & 1400 Å with 40 Å bandpass each;
SUMER
CDS
SOT-SPIRIS
2796
Å & 2831
Å with EIS
44 Å bandpass
each.
2831
SOHO
Hinode18

IRIS spectra and slit-jaw imaging covers
the photosphere, chromosphere, transition region

Wednesday, March 10, 2010

Wednesday, March 10, 2010

IRIS

Solar Cb

Solar C plan B will be able to resolve
structures from chromosphere to corona

Compared to IRIS, Solar C plan B will1.provide better spatial resolution for a wide range oftemperatures,
2.provide critical magnetic field measurements(photosphere, chromosphere),
3.will have much larger FOV (using FPI) compared toIRIS’ slit-based spectrograph: flares, large-scaleevolution,...
4.provide the high temperature coverage that IRISlacks (much higher S/N spectra and imaging).

Wednesday, March 10, 2010

Fabry-Perot Interferometers (FPI) required
to track rapid chromospheric dynamics~3 line positions/s → 25 positions in 6.8 s

FWHM 66 mÅmovie courtesy of Luc Rouppe van der VoortWednesday, March 10, 2010

Hα -1.3Å (-60 km/s)

Hα line core

Fabry-Perot Interferometers invaluable to study rapid, fine-scalechromospheric dynamics (e.g, disk counterparts of type II spicules)
movie courtesy of Luc Rouppe van der Voort
Wednesday, March 10, 2010

FPI observations reveal rapid blueshifted events, constraining formation
mechanism of type II spicules by showing heating and acceleration

Chromospheric Observations

Hα-50 km/s

Hα Line center

Doppler Velocity

WidthCa 8542 Dopplergram

Ca 8542 Line center

Doppler Velocity

WidthTypical Hα ProfileTypical Ca 8542 Profile

Rouppe van der Voort, Leenaarts, De Pontieu, Carlsson,Vissers, 2009
Wednesday, March 10, 2010

Seeing-free observations critical for chromospheric studies

Case study: Alfven waves carried by spicules(with enough flux to power solar wind)
Wednesday, March 10, 2010

Time [s]Very general: many inclined lines in xt-cuts of unsharp masked data
Typically: thin spicules moving laterally by 0.5 Mm, at ~10-25 km/s

Space (x [Mm])Wednesday, March 10, 2010

These transverse motions had been detected before in ground-based data

Transverse motions of order 0.1-0.5 arcsec ~ same scale as seeing distortions
Seeing-free observations crucial
Wednesday, March 10, 2010

Non-thermal energy deposition: Alfven waves
Hinode/SOT Ca II H data
(10,000 K)
CoMP data: Fe XIII
(1.5 MK)

Alfvenic Waves with
Amplitudes of ~ 20 km/s
and Periods 100-1000 s

Coronal Amplitude should beof order 30-50 km/s, not 0.5-1 km/s

Flux ~ 100 erg/cm2/s
Enough to power solar wind
De Pontieu et al., 2007

Solar C chromospheric
data will help reveal
origin of these waves

Alfvenic Waves with Amplitudes of ~ 0.5-1 km/s
and Periods 100-1000 s
Tomczyk et al., 2007, Tomczyk & McIntosh, 2009, McIntosh et al., 2010

High-resolution CoMP-like observations of transverse incompressible
waves in the corona can provide seismology, but also insight in nonthermal energy deposition
Wednesday, March 10, 2010

How do magnetic fields impact chromosphere dynamics?
Formation of type II spicules
StokesVStokesQ

StokesU

H-alpha-1.2 A

Ca II H3968 A

Need chromospheric vector magnetic data at various heights tostudy non-thermal energy deposition in chromosphere
HinodeSPHinode
NFI

HinodeBFIConnection between photospheric magnetic fields
and chromospheric energy deposition difficult to establish
Wednesday, March 10, 2010

Importance of chromospheric field measurements

green: Joule heating
grey: TR

courtesy Juan Martinez Sykora(LMSAL, UiO)

3D radiation MHD simulations indicate
jet formation triggered at chromospheric heights
Wednesday, March 10, 2010

Magnetic Field
non-linear force free field extrapolations

Extrapolation from photospheric field magnetograms problematicImages from DeRosa et al., 2009
Wednesday, March 10, 2010

Magnetic Field
non-linear force free field extrapolations

Extrapolation from photospheric field magnetograms problematic
courtesy DeRosa et al., 2009
Wednesday, March 10, 2010

Non-linear force free field (NLFFF) extrapolations•NLFF algorithms do not yield consistent solutions forsolar data
•Photosphere is not force-free, i.e., many (most?) currents
seen at the photosphere do not reach the corona•Successful application likely requires :•large field of view at high resolution (connectivity tosurroundings)•'preprocessing’ of lower-boundary vector field (non-force
free to force-free)•measurement of vector field at top of chromosphere?
• [Schrijver et al. 2006 (SPh 235, 161), 2008 (ApJ 675, 1637), Metcalf et al. 2008 (SPh 247, 269), DeRosa et al. (2008,ApJ 696, 1780).
Wednesday, March 10, 2010

To determine energy and mass transfer fromchromosphere into corona/heliosphere
1.A large observatory that obtains spectra and images thatsimultaneously cover the photosphere, chromosphere, TR andcorona (from 4,000K to 10 MK),
2.simultaneously at high spatial resolution (~0.2 arcsec),
3.temporal resolution (<10 s) over a large FOV (120 arcsec),
4.and spectral resolution (<0.3 km/s in TR/corona)
5.without issues of co-alignment (i.e., different instruments withpredefined co-alignment strategies, slit-jaw),
6.with high S/N polarimetry in photosphere and chromosphere(FPI, seeing-free).
Wednesday, March 10, 2010