Effects of Solar Storms on the Venusian Ionosphere

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Effects of Solar Storms on the Venusian Ionosphere International Venus Conference April 7, 2016

Effects of Solar Storms on the Venusian Ionosphere International Venus Conference April 7, 2016 Candace Gray - New Mexico State University Nancy Chanover, Tom Slanger, Karan Molaverdikhani, Kerstin Peter, Bernd Häusler, Silvia Tellman, Martin Pätzold, Oliver Witasse, Pierre-Louis Blelly, Glyn Collinson NASA Earth and Space Science Fellowship Award #NN 12 AM 70 H

 How does Venusian 557. 7 nm intensity respond to solar storms? Emitting altitude

How does Venusian 557. 7 nm intensity respond to solar storms? Emitting altitude and key chemical processes? How does the Venusian ionosphere respond to CMEs? How do these results compare with Mars?

 Variable Solar wind Charge particle precipitation ― Electron impact ― O 2+ +

Variable Solar wind Charge particle precipitation ― Electron impact ― O 2+ + e → O(1 S, 1 D) + O(3 P) Zhang et. al 2012

 Emission expected to be present Not detected in 1970 s

Emission expected to be present Not detected in 1970 s

Venus Earth Keck Venus Slanger et al. 2001

Venus Earth Keck Venus Slanger et al. 2001

 X-class solar flares ― Strongest flares ― Brightest EUV emission ― Nightglow ―

X-class solar flares ― Strongest flares ― Brightest EUV emission ― Nightglow ― Short duration (min - hours) Coronal mass ejections (CMEs) ― Plasma ejection ― Aurora ― 1 - 2 day arrival time

 3. 5 m Astrophysical Research Consortium (ARC) Telescope ARC Echelle Spectrograph High resolution

3. 5 m Astrophysical Research Consortium (ARC) Telescope ARC Echelle Spectrograph High resolution (R ~ 35, 000) 3500 – 10, 000 Å Two 6 -week windows / 2 years

 Telescope override 3 nights/window Storm chasing

Telescope override 3 nights/window Storm chasing

Gray et. al 2014

Gray et. al 2014

Date Target of Opportunity Solar Flare Dec 21, 2010 Dec 27, 2010 Solar Flare

Date Target of Opportunity Solar Flare Dec 21, 2010 Dec 27, 2010 Solar Flare + CME Solar Flare Before and after CME Apr 17, 2012 Apr 18, 2012 CIR X X Apr 22, 2012 May 01, 2012 May 06, 2012 X X X X Nov 07, 2013 Nov 08, 2013 Nov 09, 2013 X X X Nov 18, 2013 Nov 29, 2013 Dec 12, 2013 Mar 17, 2014 X X X Green Line X (Weak) X X Jul 14, 2012 Jul 15, 2012 Jul 16, 2012 Feb 13, 2014 Feb 14, 2014 Feb 15, 2014 CME X X X (Medium) X (Weak) X X (Strong) X (Medium) CIR X (Weak) X X X (Medium) X (Weak)

June 15 and June 16, 2012 Electron Energy Density Before and after CME flare

June 15 and June 16, 2012 Electron Energy Density Before and after CME flare June 15, 2012 June 16, 2012 Nightside Flux (cm-2 sr-1 s-1) Energy (e. V) 105 1000 104 10 103 1 106 105 12 e. V 104 10 1033 1 10 100 Electron Energy (e. V) Differential Energy Flux (cm-2 sr-1 ev-1 s-1) 107 106 105 50 e. V 70 e. V 104 10 1033 1 10 Gray et al. 2016, submitted 100 1 10 100 Electron Energy (e. V)

 Dayside – Persistent V 1 and V 2 layers – Solar flux Nightside

Dayside – Persistent V 1 and V 2 layers – Solar flux Nightside – Variable – Ion flow across terminator Martin Pätzold et al. 2007

200 Before CME After CME 180 Altitude (km) 557. 7 nm detection 160 V

200 Before CME After CME 180 Altitude (km) 557. 7 nm detection 160 V 2 140 V 1 120 100 0 0. 5 1. 0 1. 5 Electron Density x 104 (cm-3) 2. 0

M 2 M 1

M 2 M 1

 TRANSCAR VEX electron flux and energy inputs Compare pre/post CME green line emission

TRANSCAR VEX electron flux and energy inputs Compare pre/post CME green line emission Increase in 557. 7 nm emission O + e strongest source No increase in V 1 layer electron density

What happens to Venus after a CME impact? Increased solar wind dynamic pressure Compressed

What happens to Venus after a CME impact? Increased solar wind dynamic pressure Compressed ionosphere “Disappearing” V 2 layer Electron precipitation Auroral emission Russell et. al 2006

Brace and Kilore 1999 200 Before CME After CME Altitude (km) 180 160 V

Brace and Kilore 1999 200 Before CME After CME Altitude (km) 180 160 V 2 140 V 1 120 100 0 0. 5 1. 0 1. 5 4 Electron Density x 10 (cm-3) 2. 0

 Green line a unique aurora O + e likely source of green line

Green line a unique aurora O + e likely source of green line emission Increase in dynamic pressure from a CME – Compress ionopause, restricting ion flow – Reduce V 2 electron density – Drive plasma to the nightside – Increase green line emission Typical of non-magnetic planets?