CHROMOSPHERIC RAPID BLUESHIFTED EXCURSIONS OBSERVED WITH IBIS AND THEIR ASSOCIATION WITH PHOTOSPHERIC MAGNETIC FIELD EVOLUTION
- Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States)
- National Solar Observatory, Sacramento Peak, Sunspot, NM 88349-0062 (United States)
- Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302-5142 (United States)
- Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
- Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China)
Chromospheric rapid blueshifted excursions (RBEs) are suggested to be the disk counterparts of type II spicules at the limb and believed to contribute to the coronal heating process. Previous identification of RBEs was mainly based on feature detection using Dopplergrams. In this paper, we study RBEs on 2011 October 21 in a very quiet region at the disk center, which were observed with the high-cadence imaging spectroscopy of the Ca II 8542 Å line from the Interferometric Bidimensional Spectrometer (IBIS). By using an automatic spectral analysis algorithm, a total of 98 RBEs are identified during an 11 minute period. Most of these RBEs have either a round or elongated shape, with an average area of 1.2 arcsec{sup 2}. The detailed temporal evolution of spectra from IBIS makes possible a quantitative determination of the velocity (∼16 km s{sup –1}) and acceleration (∼400 m s{sup –2}) of Ca II 8542 RBEs, and reveals an additional deceleration (∼–160 m s{sup –2}) phase that usually follows the initial acceleration. In addition, we also investigate the association of RBEs with the concomitant photospheric magnetic field evolution, using coordinated high-resolution and high-sensitivity magnetograms made by Hinode. Clear examples are found where RBEs appear to be associated with the preceding magnetic flux emergence and/or the subsequent flux cancellation. However, further analysis with the aid of the Southwest Automatic Magnetic Identification Suite does not yield a significant statistical association between these RBEs and magnetic field evolution. We discuss the implications of our results in the context of understanding the driving mechanism of RBEs.
- OSTI ID:
- 22364184
- Journal Information:
- Astrophysical Journal, Vol. 799, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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