Hazel Bain

THE 2010 AUGUST 1 TYPE II BURST: A CME-CME INTERACTION AND ITS RADIO AND WHITE-LIGHT MANIFESTATIONS

We present observational results of a type II burst associated with a CME-CME interaction observed in the radio and white-light (WL) wavelength range. We applied radio direction-finding techniques to observations from the STEREO and Wind spacecraft, the results of which were interpreted using WL coronagraphic measurements for context. The results of the multiple radio direction-finding techniques applied were found to be consistent both with each other and with those derived from the WL observations of coronal mass ejections (CMEs). The results suggest that the type II burst radio emission is causally related to the CMEs interaction.

RADIO IMAGING OF SHOCK-ACCELERATED ELECTRONS ASSOCIATED WITH AN ERUPTING PLASMOID ON 2010 NOVEMBER 3

We present observations of a metric type II solar radio burst that occurred on the 3rd of November 2010 in association with an erupting plasmoid. The eruption was well observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and the Reuven Ramaty High Energy Solar Spectroscopic Imager, while the burst occurred in the frequency range of the Nancay Radioheliograph (NRH). Such events, where the type II emission occurs in the NRH frequency range, allowing us to image the burst, are infrequent. Combining these data sets, we find that the type II is located ahead of the hot (∼11 MK) core of the plasmoid, which is surrounded by a well-defined envelope of cool (few MK) plasma. Using two methods, we determine the propagation velocity of the shock: (1) fitting the type II emission observed in PHOENIX and HUMAIN radio spectrogram data; (2) direct imaging of the type II source location using NRH observations. We use LASCO C2 polarized brightness images to normalize our coronal density model. However, we find that information from imaging is required in order to fine-tune this normalization. We determine a shock propagation velocity between 1900 km s −1 and 2000 km s −1 . This is faster than the plasmoid observed at extreme-ultraviolet wavelengths by AIA (v = 670-1440 km s −1 , where the cooler plasma propagates faster than the hot core). The positioning of the type II, ahead of the plasmoid, suggests that the electrons are accelerated in a piston-driven shock.

The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungstenalloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150–650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica.

OBSERVATION OF HEATING BY FLARE-ACCELERATED ELECTRONS IN A SOLAR CORONAL MASS EJECTION

We report a Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observation of flare-accelerated electrons in the core of a coronal mass ejection (CME) and examine their role in heating the CME. Previous CME observations have revealed remarkably high thermal energies that can far surpass the CMEs kinetic energy. A joint observation by RHESSI and the Atmospheric Imaging Assembly of a partly occulted flare on 2010 November 3 allows us to test the hypothesis that this excess energy is collisionally deposited by flare-accelerated electrons. Extreme ultraviolet (EUV) images show an ejection forming the CME core and sheath, with isothermal multifilter analysis revealing temperatures of ~11 MK in the core. RHESSI images reveal a large (~100 × 50 arcsec2) hard X-ray (HXR) source matching the location, shape, and evolution of the EUV plasma, indicating that the emerging CME is filled with flare-accelerated electrons. The time derivative of the EUV emission matches the HXR light curve (similar to the Neupert effect observed in soft and HXR time profiles), directly linking the CME temperature increase with the nonthermal electron energy loss, while HXR spectroscopy demonstrates that the nonthermal electrons contain enough energy to heat the CME. This is the most direct observation to date of flare-accelerated electrons heating a CME, emphasizing the close relationship of the two in solar eruptive events.

OBSERVATIONS OF LINEAR POLARIZATION IN A SOLAR CORONAL LOOP PROMINENCE SYSTEM OBSERVED NEAR 6173 Å

White-light observations by the Solar Dynamics Observatorys Helioseismic and Magnetic Imager of a loop-prominence system occurring in the aftermath of an X-class flare on 2013 May 13 near the eastern solar limb show a linearly polarized component, reaching up to

Detector and imaging systems for the gamma-ray imager/polarimeter for solar flares (GRIPS) instrument

\sim

PLASMA UPFLOWS AND MICROWAVE EMISSION IN HOT SUPRA-ARCADE STRUCTURE ASSOCIATED WITH AN M1.6 LIMB FLARE

20% at an altitude of

Harnessing AIA Diffraction Patterns to Determine Flare Footpoint Temperatures

\sim

Chromospheric and Coronal Observations of Flares with HMI

33 Mm, about the maximal amount expected if the emission were due solely to Thomson scattering of photospheric light by the coronal material. The mass associated with the polarized component was 8.2

Microwave Emission of Supra-arcade Structure associated with M1.6 Limb Flare

\times