Solar Flares and Alan GabrielSolar Flares and Alan Gabriel

byG. A. Doschek

Space Science DivisionNaval Research Laboratory

Presented at

Atomic physics, plasma spectroscopy, and solar physics from space: Celebrating the achievements

of Alan Gabriel

Institut d’Astrophysique SpatialeCNRS-Université Paris-Sud

Orsay, France20 June 2013

presented by video link from Washington, DC, USAWork supported by 6.1 NRL/ONR funds

byG. A. Doschek

Space Science DivisionNaval Research Laboratory

Presented at

Atomic physics, plasma spectroscopy, and solar physics from space: Celebrating the achievements

of Alan Gabriel

Institut d’Astrophysique SpatialeCNRS-Université Paris-Sud

Orsay, France20 June 2013

presented by video link from Washington, DC, USAWork supported by 6.1 NRL/ONR funds

The X-ray Spectrum of Solar FlaresThe X-ray Spectrum of Solar Flares

• Alan made seminal contributions towards understanding the X-ray spectrum of solar flares, particularly the so-called “satellite lines” produced by dielectronic recombination and electron impact excitation.

• A. H. Gabriel – “Dielectronic Satellite Spectra for Highly-Charged Helium-like Ion

Lines, Mon. Not. R. astr. Soc., 160, 99 (1972)529 citations as of 17 June 2013

• Alan made seminal contributions towards understanding the X-ray spectrum of solar flares, particularly the so-called “satellite lines” produced by dielectronic recombination and electron impact excitation.

• A. H. Gabriel – “Dielectronic Satellite Spectra for Highly-Charged Helium-like Ion

Lines, Mon. Not. R. astr. Soc., 160, 99 (1972)529 citations as of 17 June 2013

The Standard Flare Model:What are the Non-thermal and Bulk Motions?

The Standard Flare Model:What are the Non-thermal and Bulk Motions?

The NASA OSOs and Solar Maximum Mission, the JapaneseHinotori Mission and the US DoD P78-1 Mission

The NASA OSOs and Solar Maximum Mission, the JapaneseHinotori Mission and the US DoD P78-1 Mission

From Gabriel 1972, Mon. Not. R. astr. Soc., 160, 99From Gabriel 1972, Mon. Not. R. astr. Soc., 160, 99

Solar Flare Iron Line SpectraSolar Flare Iron Line Spectra

Chromospheric Evaporation and Non-thermal Motions in FlaresChromospheric Evaporation and Non-thermal Motions in Flares

Non-thermalmotions inflares

Non-thermalmotions inflares

But alas, it is rather tragic that the high spectral resolution X-ray investigation of flares ceased after Yohkoh!

However, highly ionized ironlines appear in the EUV, wherespectral-imaging with multi-layer optics can be used (SOHO/CDS, Hinode/EIS)

But alas, it is rather tragic that the high spectral resolution X-ray investigation of flares ceased after Yohkoh!

However, highly ionized ironlines appear in the EUV, wherespectral-imaging with multi-layer optics can be used (SOHO/CDS, Hinode/EIS)

Fe XXIII Flare Profiles (EIS)Fe XXIII Flare Profiles (EIS)

150 km/s

Flare Image and Mass MotionsFlare Image and Mass Motions

Flare Observed by Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS)Flare Observed by Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS)

What Next with Highly Ionized Iron Lines?

What Next with Highly Ionized Iron Lines?

• We need sensitive imaging X-ray spectrometers that can observe the Fe XXV + satellite lines near 1.9 Å and the Fe XXVI + satellite lines near 1.8 Å in the reconnection region.– More sensitive Bragg spectrometers with imaging

capabilities?– Microcalorimeters?

• We need more sensitive and higher spatial resolution EIS-type instruments (Solar-C?) with hard X-ray imaging observations (advanced RHESSI?)

• Summary: Alan Gabriel was a key individual in the ground floor investigation of the high temperature components of solar flares

• We need sensitive imaging X-ray spectrometers that can observe the Fe XXV + satellite lines near 1.9 Å and the Fe XXVI + satellite lines near 1.8 Å in the reconnection region.– More sensitive Bragg spectrometers with imaging

capabilities?– Microcalorimeters?

• We need more sensitive and higher spatial resolution EIS-type instruments (Solar-C?) with hard X-ray imaging observations (advanced RHESSI?)

• Summary: Alan Gabriel was a key individual in the ground floor investigation of the high temperature components of solar flares