Characteristics of the Jupiter Io D Decametric Radio Source

Transcription

1 Characteristics of the Jupiter Io D Decametric Radio Source Chuck Higgins, Middle Tennessee State University Tracy Clarke, Naval Research Lab Francisco Reyes, U. of Florida Dave Typinski, AJ4CO Observatory Collaborators: M. Imai, Kyoto University K. Imai, Kochi National College of Technology, Japan J. Thieman, U. Md Baltimore R. Flagg, RF Associates W. Greenman, WG Consulting Acknowledgements: U. New Mexico TN Space Grant Consortium Long Wavelength Array (LWA1), Socorro, NM MOP

2 from Ellingson, IEEE, 2013 The LWA1 Array Location Socorro, NM, near VLA Bandwidth MHz Antennas 256 crossed dipoles (sky noise dominated) Polarizations Dual linear Bandwidth 16 MHz x 2 tunings X 4 beams Beams Beam FWHM Instrument Sensitivity Beam Sensitivity 4 independently steerable 2 tunings per beam < 3.2 [(74 MHz)/ ] 6 kjy at zenith System Equiv. Flux Density (SEFD) [1 Jy = W/m 2 /Hz] 8 Jy (5σ) for 1 s, 16 MHz, Z = 0 (inferred from SEFD) A collaboration of the following institutions: U. New Mexico, Virginia Tech, Los Alamos NL, JPL, the Naval Research Lab, Caltech, Harvard, NRAO, and the Air Force Research Lab Array Geometry 256 Antenna stands, 100 m x 110 m elliptical footprint + 2 outrigger antennas for calibration Pseudo random arrangement to suppress aliasing Imai et al.,

3 01 Dec 2012 RHC Polarization Io A Upper Tuning Lower Tuning LHC Polarization Io C Stokes V Jupiter Spectra LWA1 Instrument Excellent observing conditions Fine Temporal & Spectral Resolution: 0.21 ms and 5 khz Data Volume: up to ~1 TB/hour For more information Poster #8 T. Clarke: Probing Jovian DAM with the LWA1 Poster #9 M. Imai: Jupiter DAM common observations with LWA1, NDA, and URAN-2 Poster #41 K. Imai: Jupiter s modulation lanes observed by LWA1 3

4 AJ4CO Observatory 8 element TFD Array Polarizations: dual circular HPBW 24 MHz: 30 EW, 12 NS at zenith Beam steering: max 45 from zenith Dual polarization Spectrograph (DPS), MHz Tunable, 2 MHz IF bandwidth Terminated Folded Dipoles (TFD) 4

5 Radio Sources bkom broadband kilometric emission Non Io DAM decametric (related to HOM) HOM hectometric emission Io DAM decametric emission tied to Io flux tube and Io torus Background Color Map: 50 years of University of Florida Radio Observatory (UFRO) data 5

6 Io D Studies Southern hemisphere source f = < MHz X mode emission Highly LH circularly polarized ( 0.85) Isolated arc structures (vertex early) Io C/Io D emission cone Envelope shape caused by source along southern Io flux tube (Io s frame) Io D Beaming angle 80 Io B Io D Io D Queinnec and Zarka,

7 AJ4CO Observatory 20 Jan 2015 RCP AJ4CO Observatory 20 Jan 2015 LCP Io D Io B Io D Observations LH Circularly Polarized Vertex Early arc structure Excellent correlation between AJ4CO (Florida) and LWA1 (New Mexico) Frequency (MHz) LWA1 Observatory 20 Jan 2015 Io D Io B Stokes V 7

8 Io D Observations LWA1 Observatory 14 Nov 2013 S bursts L bursts Stokes V LWA1 10 Jan 2015 Io D Modulation Lanes S bursts f max = 26 MHz 8 Frequency (MHz)

9 Io D Observations Io A Io C CML and Io phase ranges need redefinition (f dependent) Peak frequency can tell us something about the emission cone Io D Io D Io B LWA Io D Observations * Peak frequency non Io A 9

10 Io D S bursts RCP Io B S bursts AJ4CO Observatory 20 Jan 2015 LCP Io D S bursts LCP Io D narrow band S bursts Span: 110 s Res.: 157 ms 53 khz Span: 210 ms, Bandwidth: 2 MHz Resolution: 205 us, 4.88 khz S burst drift rates: 10.5 MHz/s at 18 MHz 10

11 Io D S Bursts 27 Dec 2012 From Clarke et al., 2014 Resolution: 0.25 ms and 10 khz Timespan: 1.44 s S burst Drift Rates: 12 MHz/s at 19 MHz 11

12 Io D S burst Drift Rates Io related emission High Intensity millisecond bursts S burst Drift Rate vs Frequency LWA1 & AJ4CO Io D Observations CMI emission: 5 kev electrons accelerated from Io to Jupiter Mirrored near Jupiter resulting in a loss cone of amplified X mode waves X X Adiabatic theory predicts the maximum drift rates ( 30 MHz/s) From Zarka et al., (1996) How do the drift rates correlate with the sources? 12

13 Summary Io D emission is prevalent Io D CML and Io phase ranges need redefinition (f dependent) Io D peak frequency = 26 MHz > the southern hemisphere emission cone structure Io D modulation lanes S bursts in Io D source are common useful for emission theories LWA1 is an excellent instrument for Jupiter decameter studies Excellent spectral and temporal resolution Shows fine structures and polarization (Modulation lanes, L and S bursts, narrow band (N) events and S burst/n event interactions) LH and RH emission can be used for Faraday rotation studies Juno Mission Ground based DAM Coordinated observations are being planned 13

14 Data Reduction and Analysis North Basis change to r, l X Y East Use Fourier transforms to convert to frequency spectra Convert to Stokes V V=R 2 L 2 Output 14