1 / 30

Stephen White

Gyroresonance emission in FORWARD & Developments in radio telescopes. Stephen White. Free-Free Opacity. Two different “modes,” or circular polarizations ( s =+1 o-mode, s = - 1 x-mode)

rachel
Download Presentation

Stephen White

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gyroresonance emission in FORWARD & Developments in radio telescopes Stephen White

  2. Free-Free Opacity • Two different “modes,” or circular polarizations (s=+1 o-mode, s=-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 = (TR-TL)/(TR+TL) = 0 for isothermal atmosphere because temperature is same in both layers • In “real” atmosphere get polarization due to temperature gradient

  3. 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

  4. Gyroresonance opacity at low harmonics

  5. Model sunspot gyroresonance layers

  6. OVSA Expansion Project Dale E. Gary Professor, Physics, Center for Solar-Terrestrial Research New Jersey Institute of Technology

  7. Prototype Review Meeting EOVSA

  8. Prototype Review Meeting magnetic and plasma structure of active regions

  9. LOFAR’s first solar image

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

  11. MWA station and 32T layoutConsortium with PAPER project in the future

  12. The Long Wavelength Array US project involving Naval Research Laboratory, U. New Mexico, Los Alamos, Virginia Tech, U. Texas, NRAO, AFRL, …

  13. “Zebra” patterns more common in flares

  14. Unexpected fine structure above 60 MHz

  15. “Wrigglers” at 10 millisecond resolution

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

  17. At LWA1 resolution

  18. Allen Telescope Array

  19. ATA solar image LOFAR’s first solar image

  20. Siberian Solar Radio Telescope (SSRT)

  21. EVLA: better frequency, time coverage

  22. EVLA observation of the Sun at F10.7

  23. ALMA

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

  25. Solar Submillimeter Telescope (Argentina/Brazil)

  26. The Sun

  27. The Sun

More Related