transient and long-term solar activity: origin and impact on the€¦ · • increased spectral...

14th Solar-Terrestrial Physics Symposium – SCOSTEP – July 9-13, 2018, York University, Toronto, Canada

Transient and long-term solar activity: Origin and impact on the

Earth’s atmosphere

Jean-Pierre Raulin

Centro de Radioastronomia e Astrofísica Mackenzie - CRAAMEngineering School

Universidade Presbiteriana MackenzieSão Paulo

Brazil

Outline

• Why is it important to study solar flares at high radio frequencies ?

• Key observations at w, mm-, submm- - opened questions

• New Long IR observations and planned Mid-IR experiment

• Transient and long-term solar (and non-solar) activity imprints in the lower

ionosphere – D region – VLF technique

• SEP diagnostic

• Conclusions


Flare emission at very high radio frequencies

Particle acceleration is a fundamental problem in astrophysics (cosmic rays,

active sun, Earth’s magnetosphere and atmosphere, etc ….)

High-frequency (mm, sub-mm) radio diagnostic of solar emission:

• give access to the highest energy particle accelerated during solar flares

(s = /B ~ 3 where B (Hz) = 2.8 106 B (Gauss))

• provide information on the dynamics of the lower solar atmosphere, below

the transition region (ff # Ne .T-3/2)

• increased spectral coverage

Particle Acceleration Radiation

Mechanisms


SOLAR FLARE PHYSICS:

INDICATION OF ANOTHER SOLAR BURST

CONTINUUM SPECTRUM IN THz

OBSERVATIONS IN THE THz RANGE ARE NEEDED TO UNDERSTAND THE EMISSION MECHANISMS INVOLVED

0.010.001

U-shaped spectrum (Castelli 1972)

Assumed as typical and common to all bursts

?

?

MHz

0.1 1.0 10.0 100.0

New solar burst spectral component(s)

observed in the THz range

THz


POEMAS

SST

SOLAR-T

30 THz

ALMA LLAMA HATS

BEMRAK

Radio Emission at very high frequencies: Flare Impulsive phase

Kaufmann et al. (2004; 2009) Luethi et al. 2004; Trottet et al. 2008; 2011); Silva et al. 2007; Raulin et al. (2003; 2004; 2014)

?? Sub-THz event ?? ?? Sub-THz event ?? Sub-THz event

Sub-mm impulsive radio emission associated with high-energy -ray continuum emission (CORONAS)

SST BEMRAK SST

Sub-THz event: increasing fluxes with increasing frequencies above 100 GHz


Radio Emission at very high frequencies

Trottet et al. 2008: Synchrotron

radiation by positrons from charged-

pion decay is likely to be too small to

account for the observed 210 GHz

emission (see also Silva et al.2007)

Radio source position ~ position of 2.2 MeV line

(Trottet et al. 2008)

2003/10/28

TransportTransport of secondary particles

Knock-on electrons (-rays) below few MeV

Not enough to explain 04/11/2003

(Tuneu et al. 2017)


HXR observations High-energy e- and p

transport energy to the lower layers

(chromosphere, photosphere) ?

30 THz emission another “THz event” ?

Genuine 30 THz (10 µm) solar emission during the impulsive phase of flare on 13/03/2012

(Initial results published in Kaufmann et al. 2013, ApJ)

12000 SFU

(Kaufmann et al. 2013)

Thermal emission from the chromosphere heated by accelerated particles provides a plausible

quantitative interpretation of the 30 THz emission during the impulsive phase.

SOL2012-03-13 is the first event detected at 30 THz.

HXR/GR are detected up to 10 MeV.

20 – 200 GHz radio spectrum is radiated by e- > 800 keV,

i.e. the harder part of the HXR/GR emitting distribution of e-.

(Trottet et al., 2015)

30 THz quiescent emission an optically thick layer at ~ 5000 K below the temperature minimum region.

30 THz flare emission is consistent with that expected from the F2 (Machado, Mauas) model: (i) 80%

optically thin source at ~ 8000 K well above the temperature minimum region; (ii) 20% optically thick

source below the temperature minimum region. In agreement with old models (Ohki & Hudson, 1975).


2014, Sept. 24, GOES C7, M. Penn

et al. (2016), McMath, NSO

McMath instrumental facilities observations +

measurements at 3 and 7 GHz by Solar-T (Kaufmann et

al., 2014) understanding of the chromospheric

response to flare energy release.

After Trottet et al. 2015, 10-100 THz

spectrum is expected to be rather flat.

Observations at > 30 THz (McMath-Pierce)

validated of such an expectation (Penn et al.,

2016).


• Results demonstrate that 3 and 7 THz SOLAR-T

photometers were responding well and were properly

calibrated

• Solar disk brightness fit fairly well to other observation

at a poorly known range of frequencies 4800 K and 4700

K at 3 THz and 7 THz


(Kaufmann et al. 2015)(Kaufmann et al. 2013)

(Penn et al. 2016)

(2017/09/06) (2011/02/14)

MIR flare emission versus

white-light

HATS: High Altitude Terahertz Solar telescope

(Simões et al. 2017)

0.871630 1.5 0.4 0.2

870 GHz, 1.5 THz

< 20% transmission at > 5000 m for PWV

<< 0.5 mm < 1 month/y

Opaque for PWV > 0.6 mm

Famatina (5500 m): characterization

16 THz ? OK at 2550 m, asl

~ 10s% temperature excess (OTTB)

LLAMA (first light 2019 ?)

SOLAR-T onboard ISS, accepted


Ionospheric Disturbances

Photons and/or energetic particles ionization excesses changes of the electrical conductivity

Localized particle precipitation

VLF propagation anomalies VLF phase and amplitude changes

Solar: quiescent, Ly-, X-rays (flares), particles (SEPs); Non-Solar: X-rays, GRB, flares from SGR

TGF

Few Mm


Transmitters (1-50 kHz)

Receivers

Solar flares can be detected over a large longitudinal sector

PLO


the higher the solar activity the

higher Px

Lyman- solar radiation maintains the quiet (non-disturbed) ionospheric D-region (Nicolet & Aikin 1960)

TRANSIENT SOLAR FORCING: FLARES

≥ B4 Class events are detected with 100

% probability

B Class C Class M Class

Ionospheric índice for the solar Ly- radiation

B 2.5

C 5

Fmin is well correlated with reproduces

the solar Lyman- photon flux

Photons and/or energetic particles ionization excesses changes of the electrical conductivity

VLF propagation anomalies VLF phase and amplitude changes

Solar: quiescent, Ly-, X-rays (flares), particles (SEPs); Non-Solar: X-rays, GRB, flares from SGR



(Palit et al. 2013)

(Palit et al. 2018)

- Photons versus particles

- Riometers of high latitude

- Photon energies

- ionosondes

Tshisaphungo and Danskin, 2016

The AFINSA network

*

operating

in 2017

+ Comandante Ferraz

Antarctic Station

(EACF)

(2)

https://theafinsa.wordpress.com/

Atmospheric Electric Field - GAEC

(Raulin et al. 2013)

GAEC


The AFINSA network https://theafinsa.wordpress.com/

Atmospheric Electric Field - GAEC

Superimposed method for

~ 150 solar flares Superimposed method

for 20 SEP events


Daily Atmospheric EF Excesses from fair weather curves

No detected effect ~ 10 % increase

Solar flare continuum observations from the mid-infrared domain (a few tens of THz) to the

millimeter-sub-millimeter radio domain provide in principle unique diagnostics of energy transport

processes from the flare energy release region to the chromosphere and of the most energetic

flare accelerated particles.

Solar Submillimeter Telescope (SST), KOSMA + BEMRAK and more recently high-cadence

imaging observations at 30 THz, SOLAR-T.

High frequency radio emissions in the mm- to submm- are produced by the highest energy

particles accelerated during solar flares: radiation processes, acceleration mechanisms

High frequency radio emissions in the mm- to submm- inform on the properties and the

dynamics of the cool and dense plasma in the chromosphere

Connection, if any, with mid-infrared emission spectrum is still not clear. MIR ? ? WL

OThinTB and OThickTB candidates to explain IR observations; chromospheric/photospheric

plasma heated by accelerated particles

More observations in the far- and mid-infrared are needed (HATS, Space SOLAR-T…)

The VLF technique provides a powerful diagnostic of the long-term and short-term solar activity,

including disturbances from cosmic bursts promising tool to study many aspects of the Space

Weather dynamics and provide Space Weather products

New diagnostics of solar energetic phenomena in the atmosphere of the Earth are available

Conclusions


transient and long-term solar activity: origin and impact on the€¦ · • increased spectral...

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