AAS 204th Meeting, June 2004
Session 47 When the Sun Went Wild
Topical Session, Tuesday, June 1, 2004, 2:30-4:00pm, 4:15-6:00pm, 702/704/706

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[47.12] Near Infrared Obsevations at 1.56 \mum of the 2003 October 29 X10 White-Light Flare

Y. Xu, W. Cao, C. Liu, G. Yang, J. Qiu, J. Jing, C. Denker, H. Wang (Center for Solar-Terrestrial Research, NJIT)


We present high resolution observations of an X10 white-light flare in solar active region NOAA 10486 obtained with the Dunn Solar Telescope (DST) at the National Solar Observatory/Sacramento Peak (NSO/SP) on 2003 October 29. Our investigation focusses on flare dynamics observed in the near-infrared (NIR) continuum at 1.56 \mum. This is the first report of a white-light flare observed in the NIR. The spatial resolution was close to the diffraction limit of the 76 cm aperture DST. The data benefited from a newly developed high order adaptive optics (AO) system and a state-of-the-art NIR complex metal oxide semiconductor (CMOS) focal plane array (FPA). In addition, we compared hard X-ray (HXR) data of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and magnetograms of the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SoHO) with the NIR continuum images. Since the NIR data were observed at the opacity minimum, only the most energetic electrons can penetrate to this layer in the deep photosphere. As a consequence, the flare ribbons appear to be very thin (<2 arcseconds) and well defined. During the impulsive phase of the flare, two major flare ribbons moved apart, which were both temporally and spatially correlated with RHESSI HXR ribbons. The two ribbons ranges are 18% to 25% brighter than the quiet sun NIR continuum. The separation speed of the ribbons is about 38 km/s in regions with weak magnetic fields and decreases to about 19 km/s, where stronger magnetic fields are encountered. The derived reconnection electric field Ec is of order 50 Vcm-1 at the flare maximum.

The author(s) of this abstract have provided an email address for comments about the abstract: yx2@njit.edu

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