# Presentation: 653760

## Solar-B XRT 

- Solar-B / X-Ray Telescope

- Solar-B XRT

- Mark Weber (Smithsonian Astrophysical Observatory)
- for the International XRT Team

**Notes:**
Introduction of presentation

## XRT Performance Requirements

## PSF after corrections for 1-G and finite source distance.

## New XRT Instrumental Capabilities

- Broadest temperature coverage of any coronal imager to date.
- High data rate for observing rapid changes in topology and temperature structure.
- Extremely large dynamic range to detect entire corona, from coronal holes to X-flares.
- Flare buffer, large onboard storage, and high downlink rate provide unique observing capability.

## Anticipated XRT Science “Firsts”

*Flares & Coronal Mass Ejections.*
- How are they triggered, and what is their relation to the numerous small eruptions of active region loops?
- What is the relationship between large-scale instabilities and the dynamics of the small-scale magnetic field?
- XRT will determine the topology, physical parameters (T, ne), and interrelatedness of the  inner coronal regions integral to flare/CME formation.
*Coronal heating mechanisms.*
- How do coronal loops brighten? TRACE has observed loop oscillations associated with flares (Nakariakov et al. 1999). Are other wave motions visible? Are they correlated with heating?
- Do loops heat from their footpoints upward, or from a thin heating thread outward? Do loop-loop interactions contribute to the heating?
- XRT will exhibit the evolution and activity of both active and quiet inner coronal structures  on MHD (seconds) to surface **B **diffusion (days) timescales.

## Anticipated XRT Science “Firsts”

*Solar flare energetics.*
- Although Solar-B will launch well before the next solar maximum, there will still be many flare events seen. The XRT is designed so that it can test the reconnection hypothesis that has emerged from the *Yohkoh* data analysis.
- XRT will extend the sample of observed flares by orders of magnitude in combined sensitivity, spatial, and temporal resolution, allowing stringent tests of flare theories.
*Reconnection & Coronal Dynamics.*
*Yohkoh *observations of giant arches, jets, kinked and twisted flux tubes, and microflares imply that reconnection plays a significant role in coronal dynamics. With higher spatial resolution and with improved temperature response, the XRT will help clarify the role of reconnection in the corona.
- XRT* *will determine importance of flows, B-field–plasma interactions, relevance of null points, reconnection sites, and separatrix (or QSL) surfaces.
*Photosphere/corona coupling.*
- Can a direct connection be established between events in the photosphere and a coronal response?
- To what extent is coronal fine structure determined at the photosphere?

## XRT Science Goals 1

- Coronal Mass Ejections
- How are they triggered?
- High time resolution
- What is their relation to the magnetic structures?
- High spatial resolution
- What is the relation between large scale instabilities and the dynamics of small structures?
**Large FOV**
- Broad temperature coverage

## CME Movie

## XRT Science Goals 2

- Coronal Heating
- How do coronal structures brighten?
- High time resolution
- What are the wave contributions?
**High Spatial Resolution**
- Do loop-loop interactions cause heating?
- Large FOV
- Broad temperature coverage

## Coronal Heating: Sample Observation

*What needs to be explained:*
-  Outflows
-  Motions along field
-  Separatrices and QSLs
-  Intermingled hot and cool plasma

## XRT Science Goals 3

**Reconnection and Jets**
- Where and how does reconnection occur? Is it related to slow CMEs?
- High time resolution
- Large FOV
- What are the relations to the local magnetic field?
- High spatial resolution
- Broad temperature coverage
- Coordinated observing with EIS/SOT

## Reconnection and Jets

## XRT Science Goals 4

- Flare Energetics
- Where and how do flares occur?
**High time resolution**
- What are the relations to the local magnetic field?
- High spatial resolution
- Large FOV
- Broad temperature coverage
**High temperature response**
**Large dynamic range**

## Flare Energetics - Example

## SXT Science Goals 5

- Photospheric-Coronal Coupling
**Can a direct connection between coronal and photospheric events be established?**
- High time resolution
- High spatial resolution
**How is energy transferred to the corona?**
- Large FOV
**Does the photosphere determine coronal fine structure?**
- Broad temperature coverage
**Coordinated observing with SOT-FPP/EIS**

## Photospheric-Coronal Coupling

- Courtesy A. Title

## XRT on the FAM @ XRCF

## Slide 18