Science Project to study Solar Terrestrial Physics

1. Science Project to study Solar Terrestrial Physics September – December 2010

2. Radio & X Ray observations of the Sun • We will build a radio receiver that can give us information on the X Rays emitted from the Sun • We will learn about the Physics of the Sun, interplanetary space, and the impact of X rays and the Solar Wind on the earth. • We will set up a 24/7 observing programme and use software to analyse data

3. Radio & X Ray observations of the Sun

4. PROJECT STEP - Monmouth Boys School (Sept – Dec 2010) Solar Terrestrial Environment Physics S T E P

5. Radio & X Ray observations of the Sun • The project will have a number of stages: • Introduction to Solar – Terrestrial Physics • Building a suitable radio receiver • Testing & calibrating the receiver • Monitoring & analysis software • Observing & logging data • Data analysis & physical insights • Comparing with Satellite data • Setting up an observing programme

6. Introduction to Solar – Terrestrial Physics • The introduction will cover: • The Solar – Terrestrial environment • The Earths Ionosphere & Magnetosphere • Effects of Solar X rays on the Ionosphere • Using Military Transmitters as probes • The electronics needed • The software required • Examples of what will be observed • Comparing with Satellite Data

7. year 1865 2015 Our Sun • The Sun is a gravitationally bound nuclear reactor • It is largely stable, but has some variability • There is the 11year sunspot cycle • Strong magnetic fields wind up around the equator as the Sun spins • The field lines SNAP and trapped energy is thrown into space

8. Sun spins faster at the equator • Field lines get twisted with differential rotation Field lines dragged along equator Eventually the lines ‘snap’ and release stored energy Lines get wound up like an elastic band

9. Solar instabilities - flares • Sun rotates once every 27 days • Flares last minutes or hours • Notice the ‘flashes’

10. Solar Flares • When the flare occurs the changing magnetic fields propel millions of tons of charged particles into space • Sometimes in the direction of the Earth • Energetic X Rays are also emitted & travel at the speed of light • This ‘prompt’ radiation reaches earth in ~ 9 minutes – particles take several hours or days

11. material ejected into space From Kanya Kusano JAMSTEC reconnection ‘pinch’ constriction flare loop Magnetic field lines Surface of Sun sun spot sun spot Production of hard X rays in magnetic ‘pinch’ • Sun spot fields make X rays

12. Solar Flares • The fast particles first encounter the Earths Magnetosphere at up to 10x the radius of the Earth & form a shock wave boundary • Charged particles cannot cross field lines – they travel around & along them

13. Earth’s Magnetic Field • The magnetic field of the Earth is thought to be generated in the rotating molten iron core • Without the Solar wind it would be a Dipolar Field - like a bar magnet

14. Earth’s Magnetosphere • Configuration of magnetic fields in the Magnetosphere

15. Charged particles H H Magnetically neutral Polar Cusps • Charged particles can flow into the Polar Cusps • Can flow down into the Atmosphere

16. Particles create an aurora in Polar regions • Example of Aurora Borealis in Alaska

17. Aurora are almost symmetrical around poles • Auroral Oval – Aurora Australis 11/9/2005

18. Earth’s magnetic field Horizontal (x) Horizontal (y) Particles Solar Particles hit 3- 4 / 8/ 2010 Magnetosphere is like a ‘jelly’ • Magnetosphere is compressed by impact of solar particles & vibrates or wobbles BAA (RAG) 2010

19. X Rays from the Sun • X rays are very energetic photons • Produced when electrons are accelerated very rapidly when solar magnetic field ‘snaps’ • Travel at light speed to Earth 9 minutes

20. X rays penetrate the Magnetosphere • X rays are not charged – they can penetrate magnetic fields • When they reach the earth they pass through the Magnetosphere into the Ionosphere • They only start to interact with the atmosphere when it becomes dense enough • 100km altitude

21. Diurnal solar energy deposition in ionosphere • UV and X rays ionise the day side ionosphere

22. The Ionosphere • Consists of layers of charged particles – Plasma in bands at various heights • Some layers disappear at night when solar UV energy is cut off • These plasma layers reflect radio waves from surface of the earth • Low frequency waves cannot pass through D Region

23. Positive ion + + + + + + + + + + electron - - - - - - - - - - - - - What is a Plasma ? • Plasma is the name given to matter that is ionised • It is neutral in bulk but is composed of electrons & ions and neutral atoms • The electrons can react to radio waves • The electrons take in energy and speed up • Energy is taken back by collisions with neutral atoms and ions & released as heat Neutral atom

24. Radio wave propagation • In daytime the LW & MW signals are reflected and ABSORBED • At night the plasma density is less and the waves are preferentially reflected • Propagation through a plasma depends on two things: • Electron density • Collisions with neutrals • Both vary with plasma density & height

25. We will look in some detail at the D region & Very Low Frequency waves Radio waves & reflecting plasma layers • Height and density of layers varies diurnally & with sunspot cycle – function of input energy from Sun

26. High frequencies escape – low are reflected • Low frequency waves are reflected Direct signal partly blocked by curvature of the earth

27. VLF reflection from D Region • VLF radio waves are reflected by the D Region Bottom of D Region @ 90km Receiver Transmitter

28. Location of Military VLF transmitters • Used to communicate with Naval ships & submarines • Low frequencies travel around the world & penetrate water QUFE 18.1kHz JXN 16.4kHz GBZ 19.6kHz GQD 22.1kHz DHO 23.4kHz HWU 18.3kHz ICV 20.27kHz NAA 24kHz

29. Frequencies of VLF Military transmitters Military transmitters 15 – 24kHz GQD GBZ UFQE DHO NAA Radio Spectrum 15 to 24kHz JXN

30. h D receiver Dependence on height of reflecting layer • The reflection point depends on h & D • The height ‘h’ depends on the plasma density

31. Using the ionosphere as a X ray detector • The plasma density depends on the input energy – UV and Xrays • X rays ionise the D region and increase the plasma density • The D region gets thicker & the base moves to lower altitude • The reflection geometry changes ! • Signals from the VLF transmitters change !

32. The outcome • The Earth’s ionosphere can be used as a SOLAR X RAY DETECTOR There is an additional path length for the sky wave When summed with the ground wave we get an interference pattern between the two waves that depends on ‘h’

33. Calculating signal strength with height of D region Difference in path length between sky & ground wave is just L-D Giving a phase difference in Radians of : Add in phase inversion on reflection From eqn. 1 – 3 we can calculate received signal strength as a function of height ‘H’ Work by Mark Edwards

34. Diurnal variation of VLF signal Strength Signal Strength measured Calculation of VLF signal Strength @ 19.6kHz 78km 78km 71km D region height km Signal Strength calculated

35. Evidence of X ray impact - S.I.D. • Sudden Ionospheric Disturbance (SID) due to Solar X ray flares • Normal diurnal variation shown in blue • Two SID events just after mid day • Characteristic ‘shark fin’ shape Measured VLF signal level SIDs ~ I day

36. GEO LEO Practical value of monitoring Solar –Terrestrial Environment • Solar generated Geomagnetic storms kill sensitive satellites in Low Earth Orbit and in Geostationary orbits • Large scale power grids have been overloaded by surges on long power lines caused by geomagnetic storms

37. Building a receiver • Requires an antenna - a loop aerial • An amplifier - high gain & wide band • A waveform digitiser - computer sound card • Spectrum analyser - Fourier software • Data logger - data file software • Graph plotter - graphing software • Data analysis - Microsoft XL We will build a couple of receivers and set up a SID Monitoring Station in Monmouth In future we may connect it to the internet

38. Spectrum Lab software Basic layout of VLF receiver Display High Gain Amplifier PC with sound card Loop Antenna 1m x 1m

39. Receiving Antenna 1m x 1m pegs to wind coil around wooden joining plate coil – 40 turns wooden bracing arms fixing screws central wooden support pole in ground or fixed to tripod slips inside hole

40. High gain Amplifier Initial VLF Receiver Amplifier (Gain ~ 333x or 50dB) ~33x Gain Amplifier ~3x Gain Amplifier X1 Gain Buffer +6 to +12V +V 1m 33k 100k 10k input + 1000uF 1 7 2 2 2 7 7 Approx 40 turns (~200m wire) 5 6 6 6 1m CA3140 CA3140 CA3140 4 4 3 4 3 3 Buffered output IC2 IC1 10nF 1k 10k output 0V + 1000uF -6 to -12V -V Coaxial cable Terminal block Gain=33x Gain=10x The 10k trim pot is used to adjust the offset null The buffer output stage is only required if using > 50m of output coaxial cable

41. Amplifier construction WIRING LAYOUT OF INITIAL APMLIFIER BOARD +ve rail 10 trim pot notch notch 1 8 1 8 Output IC2 IC1 In 5 4 5 4 ground ground -ve rail

42. Output from Spectrum Lab software Typical Spectrum of Received Signal 0 to 24kHz general man made radio noise (mains) VLF Transmitting stations * 40dB or X 100 Signal Level dB Frequency Hz *Typical voltage from resonant antenna = 0.14mV rms

43. Graph plotting software A plot of 10 VLF transmitter signal strengths as a function of time Signal Strength dB) Time (hours)

44. SID captured on 12th June 2010

45. Live Satellite data • To confirm a true SID we need X Ray flux data • This can be obtained from the GOES satellite • Near real time download via the internet

46. Solar X ray burst - generates SID • Solar X Ray burst - GOES spacecraft

47. STEREO satellite - multi wavelength pictures of Sun • Two spacecraft STEREO (ahead) & STEREO (behind) • Together give 3D data on Solar activity

48. Solar Dynamic Observer satellite • SDO view of Sun on 13/7/2010 SDO Generates high definition movies of Solar activity

49. Comparing our results • SID monitoring site in Italy • Enables us to compare our results • We need to collect data every day and log all results • Can give talks at Astronomical society meetings SID SID GOES 14 X Ray Flux Time of day

50. We will have a working system by Christmas • Massive flare on limb of Sun