Stephen White

Gyroresonance emission in FORWARD

&Developments in radio telescopes

Free-Free Opacity

• Two different “modes,” or circular polarizations (=+1 o-mode, =1 x-mode)

• X-mode has higher opacity, so becomes optically thick slightly higher in the chromosphere, while o-mode is optically thick slightly lower

• Polarization P = (TRTL)/(TR+TL) = 0 for isothermal atmosphere because temperature is same in both layers

• In “real” atmosphere get polarization due to temperature gradient

Gyroresonance emission

• Opacity results from electrons gyrating in coronal magnetic fields at fB = 2.8 106 B Hz: linear scaling of B with frequency.

• In the non-flare (non-relativistic) corona this produces narrow resonances, i.e. physically very thin layers (tens of km).

• Opacity n B/(B/l) (T/mc2 sin2)s-1 where s = 1, 2, 3, … is the harmonic

• Because T/mc2 is 1/3000, opacity drops by 3 orders of magnitude from one layer to the next

• Big difference in opacity of two polarizations of electromagnetic waves: extraordinary mode interacts more with electrons than ordinary mode

Gyroresonance opacity at low harmonics

Model sunspot gyroresonance layers

OVSA Expansion Project

Dale E. GaryProfessor, Physics, Center for Solar-Terrestrial Research

New Jersey Institute of Technology 7

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•09/24/2012•Prototype Review Meeting

•09/24/2012•Prototype Review Meeting

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LOFAR’s first solar image

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Murchison Widefield ArrayJoint US/Australian project located at the candidate SKA site in Western Australia (miles and miles from anywhere)US players are Haystack, Harvard/CfA, MITAustralian players are CSIRO/ATNF, Curtin University (WA) with a lot of support from Australian (federal) and West Australian (state) governmentsCovering the high-frequency end of the LOFAR range, same technique, same science goals.Using GPU units to do their data processing! 12

MWA station and 32T layout

Consortium with PAPER project in the future

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The Long Wavelength Array

US project involving Naval Research Laboratory, U. New Mexico, Los Alamos, Virginia Tech, U. Texas, NRAO, AFRL, …

“Zebra” patterns more common in flares

Unexpected fine structure above 60 MHz

“Wrigglers” at 10 millisecond resolution

“Type III” burst at RSTN (3 seconds, 0.15 MHz)

•At LWA1 resolution

Allen Telescope Array

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LOFAR’s first solar image

ATA solar image

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Siberian Solar Radio Telescope (SSRT)

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EVLA: better frequency, time coverage

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EVLA observation of the Sun at F10.7

ALMA

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ALMA can observe the Sun! Will be wonderful for flares (but small FOV) and chromosphere studies IF we can get observing time … 27

Solar Submillimeter Telescope (Argentina/Brazil)

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The Sun

The Sun