GALILEO MEETING

Nobeyama 10/11 July, 2002

UK BCS PRESENTATION

Len Culhane

Mullard Space Science Laboratory

University College London

SUMMARY

• Brief history of BCS concept

• Summary of instrument properties

• Some scientific highlights

• People involved in Galileo project

• Proposed contribution from BCS team

Original BCS Prototype Flown on NASA Aerobee Sounding Rockets

First results from the prototype published in:"A New Type of Crystal Spectrometerfor Solar X-ray Studies", J.L. Culhane, R.C. Catura, E.G. Joki, J.C. Bakke and C.G. Rapley, 1974, Mon. Not. R. astr. Soc., 168, 217.

Prototype used a curved KAP crystal and operated in the range 8 – 17Å.

It obtained solar active region spectra with several strong Fe lines.

Demonstration of BCS operationled to its selection as part of the X-ray Polychromator instrument,with L.W. Acton as PI, on NASA’sSolar Maximum Mission

Mounting of the BCS in Yohkoh

Plasma Upflow Velocities for Flare of 16 December, 1991(Culhane, Inda, et al., 1994, Solar Physics)

Velocities are determined from twocomponent fits to the Ca XIXresonance line profile

High velocity flow is initiatedfollowing energy depositionby non-thermal electron impactin the Chromosphere. Hard X-ray burst light curve profiles the electron beam impact.

Plasma upflow occurs during and just after the hard X-rayburst but the upflow velocityreturns to the AR value after the peak of the Ca XIX light curve

Evolution of Ca XIX Resonance Line Profile for the Flare of 16-12-91

Evaporation and the Slope of the Accelerated Electron Spectrum (McDonald, Culhane, Harra, 1999, Sol. Phys.)

16th December, 1991 2nd February, 1992

_____ Total Energy

-------- Evap. Energy

= 4.0 = 3.0

Accelerated electron spectrum:dN/dE = kE-

Steep spectrum leads to enhancedevaporation

Vnt = [2k (TLW - Te)/M]0.5

= 0 for TLW = Te

Line Broadening and Non-thermal VelocityFor a limb flare there can be no line of sightvelocity components.

Excess width (TLW

>Te)

above the thermal Doppler value could be due to turbulence in upflowing plasma or directly related to energy release.(Khan et al., Ap. J., 1995)

Yohkoh BCS Ca XIX impulsive phase spectrum is illustrated.

SXT

HXT

Flare A BCS S XV Spectrum Flare B

SXT

HXT

HXT and BCS S XV Light Curves

Pre-flare Development of Vnt in AR 7590 on 3 Oct., 1993

(Harra, Matthews, Culhane, 2001, Ap. J. Lett.)

Flare AFlare B

Vnt

HXT

Vnt and HXT (15 – 25 keV) plotted against time for two

Flares on 3 Oct., 1993 (Harra et al., 2001)

Vnt falls after flare A to a

minimum of 40 km/s at09:13 UT. This value ischaracteristic of activeregion plasma.

It then rises steadily over 11 min. to reach ~ 100 km/s at 09:25 UT - the start of hard X-ray emission by flare B.

There is evidence for pre-flare B magnetic flux emergence in AR 7590

Coronal Plasma Parameter Scaling with Photospheric Magnetic Field(van Driel-Gesztelyi et al. ) Tests of Heating Models (Demoulin et al.)

The evolution of AR 7978 hasbeen studied over five rotationsfrom birth to decay

Only AR 7978 was present, so BCS was used to measure plasma parameters as was SXT. Spectrashow Te evolution

MDI measured total magneticflux for emergence and six CMPs

Observations show <T>AR and

<EM>AR = a Bavb. Values of b

were established for <T>, <EM>, <n> and <p> that are consistent for BCS and SXT.

Models allowed by the range ofexponents favour magnetic fieldstressing models rather than thosebased on wave heating

People Involved

MSSL NRL- Bentley - Brown- Culhane - Doschek - Foley - Mariska

- Harra

RAL NAOJ

- Lang - Watanabe

Summary of Proposed BCS Contribution - I

• BCS data in agreed FITS Format

• Input to Legacy book:– Full instrument description– Updated instrument guide– Report on instrument calibration– Spectral fitting routines with comments– Summary of discoveries with major BCS role– BCS contribution to a mission-wide bibliography

Summary of Proposed BCS Contribution - II

• BCS spectra – photon units vs wavelength

• BCS SXV and Ca XIX time spectrograms – one per orbit

• BCS flare catalogue that matches GOES event list above a “tbd” threshold

• In flight cal data – approx 10 calibration data sets through the mission

WavelengthTime

Spectrogram – approach I

Spectrogram – approach II

Interaction with UK SURF and European Grid of Solar Observatories (EGSO)

• The Solar UK Research Facility (SURF) is the new name for Yohkoh Data Archive Centre (YDAC)

• UK BCS Galileo activities will be organized within SURF• There is also a UK ASTROGRID project with solar data

involvement – SURF will maintain contact with ASTROGRID• Galileo FITS headers should ideally be compatible with EGSO

catalogues• EGSO FITS headers should contain certain key words• The EGSO project is at an early stage and seeks a continued dialog

with Galileo - RDB is interacting with the Galileo FITS working group

• Continuing dialog is sought in particular on data provision, access and related security issues

• A draft FITS header document has been distributed to the attendees at this meeting

END OF PRESENTATION

Flare A Flare BBCS S XV Spectrum

HXT

SXT

HXT

SXT

Pre-flare Development of Vnt in AR 7590 on 3 Oct., 1993

(Harra, Matthews, Culhane, 2001, Ap. J. Lett.)

HXT and BCS S XV Light Curves