# Presentation: 262508

## The Solar-B EUV Imaging Spectrometer:Science with EIS and Stereo with Focus on Velocity Measurement

**J. L. Culhane **
**Mullard Space Science Laboratory**
**University College London**

## Solar-B
Optical telescope has a field of view that gives optimum AR coverage
EIS  can cover a larger field
Must raster with slits for high spectral resolution
Can image with slots
40” FOV with some spectral resolution
250” FOV to detect transient events
XRT provides full Sun filter images, AR context and flare alerts
STEREO
Coronagraphs observe CMEs after launch 
EUVI provides full Sun coverage at lower Te than XRT
STEREO/WAVES characterizes shocks and shock velocities
Summary
Solar-B emphasizes detailed studies of potential launch sites
STEREO emphasizes global coverage of CME events
XRT and EUVI together provide solar images over a very broad Te range

- Optical telescope has a field of view that gives optimum AR coverage
- EIS  can cover a larger field
- Must raster with slits for high spectral resolution
- Can image with slots
- 40” FOV with some spectral resolution
- 250” FOV to detect transient events
- XRT provides full Sun filter images, AR context and flare alerts
- STEREO
- Coronagraphs observe CMEs after launch
- EUVI provides full Sun coverage at lower Te than XRT
- STEREO/WAVES characterizes shocks and shock velocities
- Summary
- Solar-B emphasizes detailed studies of potential launch sites
- STEREO emphasizes global coverage of CME events
- XRT and EUVI together provide solar images over a very broad Te range

**Solar-B and STEREO Features**

## Solar-B and STEREO

- Solar-B will observe the smaller-scale magnetic and velocity fields from the photosphere to the corona

## EIS Performance Gains

- Following SOHO CDS, the EIS instrument will provide the next steps in 150 – 300 Å spectral imaging of the corona:
- x 10 enhancement in Aeff from use of multilayers and CCDs
- x  5 enhancement in spectral resolution
- x  2-3 enhancement in spatial resolution
- Like CDS; absolute calibration performed to ± 20%

##  EIS Field-of-View 

## Some Relevant EIS Observations

-  Solar-B/EIS can contribute to studies of:
-  CME-associated dimming outflows
-   CME acceleration
-   Coronal waves and CMEs
-   CME-asociated trans-equatorial structures
-  Examples are presented from:
-  SOHO CDS with TRACE, EIT and Yohkoh images
-  Necessary data from:
-  Observations of active region CME launch sites
-   Spectral images of active regions during flares/CMEs
-   Measurement of Te, ne and  especially v as f(Te) in e.g. dimming sites
-   Velocity measurements on disc for e.g. acceleration of ejected material

## CME Dimming Outflows

-  Using EIS:
-    - select HeII, SiVII, Fe X, Fe XIII, Si
-      X, Fe XIV, Fe XV, Ca XVII lines
-    - raster slit over 6’ x 8’ in 30 min.
-    - raster 40” slot over 6’ x 8’ in 1 min.

-  Coronal dimming directly associated  with outflow (Harra & Sterling, 2001)

-  Bottom panel shows a CDS  O V
-   velocity map for a disc event where
-   ~ 80 km/s outflow is seen from the
-   edge of the dimming region

-  EIT and CDS limb event observations
-    show  intensity reduction and outflow
-    velocities in He I, O V, Mg IX and
-    Fe XVI

-  Respond quickly to dimming onsets

## CME Velocities for Disc Events

**CME Velocities for Disc Events**

-   High velocity CME seen on limb by TRACE,
-    UVCS and LASCO (Gallagher et al., 2003)
-   Exponential acceleration and deceleration
-    with constant velocity phase observed in
-    LASCO – often the case

-   Similar acceleration behaviour seen
-    in erupting flux-rope (Williams et al.,
-    2005)
-   Velocities from TRACE
-       - SOHO CDS has seen similar
-         structures but with poor cadence

-  EIS will measure velocity for on-disc events

-  EIS will operate at much higher cadence

## Coronal Wave and Ejection Observations

-   Harra and Sterling, 2003, using TRACE and SOHO CDS, observed a flare
-     with associated Coronal Wave and CME

-  EIT 195Å image with TRACE and SOHO CDS FoVs
-      - waves in TRACE; v ~200 and 500 km/s
-      - erupting filament material; v ~ 150 - 300 km/s measured from CDS O V, He I and
-         Mg X lines

-  Optimised EIS raster will respond faster to waves and erupting filament material

## Large Scale Coronal Features

- Large-scale trans-equatorial coronal loops and filaments have been observed for decades
- They are sometimes related to coronal mass ejections (Khan and Hudson, 2000)
- Zhou et al. (2005) find that trans-equatorial filaments erupt with 13% of halo CMEs while for trans-equatorial loops, the  association is for 40% of cases

**Notes:**
The third ribbon moves away from the flare site at speeds of 300-100 km/s (larger speeds than the normal 2 ribbons). 

## CMEs and 

**CMEs and **
**Transequatorial **
**Loops**

-  Sequence of three transequatorial
-   loop disappearances observed with
-  Yohkoh SXT (Khan and Hudson, 2000)

-  Each disappearance closely
-   associated with a major flare (X2.7,
-   M3.1, M7.7) and a CME

-  X-ray loop plasma masses are
-   similar to those released in CMEs

-  Waves from the flare region (AR 8210)
-   play a role in the disappearances

- AR 8214
- AR 8210

-  EIS could measure velocities at flare AR
-   site or at intermediate position on loop

## Erupting Filaments

-     Bastille day flare not isolated
-     to the active region
-   Activation of the huge
-     trans-equatorial filament
-     precedes the filament
-     eruption and flare that
-     occur simultaneously in
-     the source active region
-  Positioning of EIS raster and operating mode choice are crucial

**Erupting Filaments**

## CONCLUSIONS

- Studies of the CME launch process are important
- Solar-B can investigate launch-related phenomena in some detail
- EIS can measure the properties of coronal and transition region plasma and its flow velocity at potential launch sites
- Combination of slit and slot registration allows spectral imaging or optimized raster scanning for high spectral resolution
- While EIS can be re-pointed E-W limb-to-limb, N-S coverage is limited to ± 4.25 arc min from spacecraft Sun-pointing axis
- Solar-B spacecraft pointing will therefore need to be specified for particular CME-related targets
- Joint Observing Programmes involving EIS will be appropriate for at least:
-     - Dimming outflows    	- Coronal waves
-     - CME acceleration   	- Large-scale structure eruptions

## 

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