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Pasachoff J.M.,Williams College | Pasachoff J.M.,California Institute of Technology | Rusin V.,Slovak Academy of Sciences | Saniga M.,Slovak Academy of Sciences | And 10 more authors.
Astrophysical Journal | Year: 2015

Continuing our series of observations of coronal motion and dynamics over the solar-activity cycle, we observed from sites in Queensland, Australia, during the 2012 November 13 (UT)/14 (local time) total solar eclipse. The corona took the low-ellipticity shape typical of solar maximum (flattening index ε = 0.01), a change from the composite coronal images we observed and analyzed in this journal and elsewhere for the 2006 and 2008-2010 eclipses. After crossing the northeast Australian coast, the path of totality was over the ocean, so further totality was seen only by shipborne observers. Our results include velocities of a coronal mass ejection (CME; during the 36 minutes of passage from the Queensland coast to a ship north of New Zealand, we measured 413 km s-1) and we analyze its dynamics. We discuss the shapes and positions of several types of coronal features seen on our higher-resolution composite Queensland coronal images, including many helmet streamers, very faint bright and dark loops at the bases of helmet streamers, voids, and radially oriented thin streamers. We compare our eclipse observations with models of the magnetic field, confirming the validity of the predictions, and relate the eclipse phenomenology seen with the near-simultaneous images from NASA's Solar Dynamics Observatory (SDO/AIA), NASA's Extreme Ultraviolet Imager on Solar Terrestrial Relations Observatory, ESA/Royal Observatory of Belgium's Sun Watcher with Active Pixels and Image Processing (SWAP) on PROBA2, and Naval Research Laboratory's Large Angle and Spectrometric Coronagraph Experiment on ESA's Solar and Heliospheric Observatory. For example, the southeastern CME is related to the solar flare whose origin we trace with a SWAP series of images. © 2015. The American Astronomical Society. All rights reserved.

Hanaoka Y.,Japan National Astronomical Observatory | Nakazawa J.,Yamanashi Cement Company | Ohgoe O.,Solar Eclipse Information Center | Sakai Y.,Chiba Prefectural Kazusa High School | Shiota K.,Solar Eclipse Information Center
Solar Physics | Year: 2014

White-light observations of the total solar eclipse on 13 November 2012 were made at two sites, where the totality occurred 35 min apart. The structure of the corona from the solar limb to a couple of solar radii was observed with a wide dynamic range and a high signal-to-noise ratio. An ongoing coronal mass ejection (CME) and a pre-CME loop structure just before the eruption were observed in the height range between 1 - 2 R⊙. The source region of CMEs was revealed to be in this height range, where the material and the magnetic field of CMEs were located before the eruption. This height range includes the gap between the extreme ultraviolet observations of the low corona and the spaceborne white-light observations of the high corona, but the eclipse observation shows that this height range is essential for the study of CME initiation. The eclipse observation is basically just a snapshot of CMEs, but it indicates the importance of a continuous coverage of CME observations in this height range in the future. © 2014 Springer Science+Business Media Dordrecht.

Hanaoka Y.,Japan National Astronomical Observatory | Kikuta Y.,Yamanashi Prefectural Science Center | Nakazawa J.,Yamanashi Cement Company | Ohnishi K.,Nagano National College of Technology | Shiota K.,Solar Eclipse Information Center
Solar Physics | Year: 2012

We measured the brightness of the white light corona at the total solar eclipses on 1 August 2008 and 22 July 2009, when solar activity was at its lowest in one hundred years. After careful calibration, the brightness of the corona in both eclipses was evaluated to be approximately 0. 4×10 -6 of the total brightness of the Sun, which is the lowest level ever observed. Furthermore, the total brightness of the K+F-corona beyond 3R ⊙ in both eclipses is lower than some of the previous measurements of the brightness of the F-corona only. Our accurate measurements of the coronal brightness provide not only the K-corona brightness during a period of very low solar activity but also a reliable upper limit of the brightness of the F-corona. © 2012 Springer Science+Business Media B.V.

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