• Title/Summary/Keyword: CMEs

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CME mean density and its change from the corona to the Earth

  • Na, Hyeonock;Moon, Yong-Jae
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.50.2-50.2
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    • 2019

  • Understanding three-dimensional structure and parameters (e.g., radial velocity, angular width, source location and density) of coronal mass ejections (CMEs) is essential for space weather forecast. In this study, we determine CME mean density in solar corona and near the Earth. We select 38 halo CMEs, which have the corresponding interplanetary CMEs (ICMEs), by SOHO/LASCO from 2000 to 2014. To estimate a CME volume, we assume that a CME structure is a full ice-cream cone which is a symmetrical circular cone combined with a hemisphere. We derive CME mean density as a function of radial height, which are approximately fitted to power-law functions. The average of power-law indexes is about 2.1 in the LASCO C3 field of view. We also obtain power-law functions for both CME mean density at 21 solar radii and ICME mean density at 1AU, with the average power-law index of 2.6. We estimate a ratio of CME density to background density based on the Leblanc et al.(1998) at 21 solar radii. Interestingly, the average of the ratios is 4.0, which is the same as a default value used in the WSA-ENLIL model.

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Comparison of the radial velocities of Halo CMEs based on a flux rope model and an ice cream cone model

  • Kim, Tae-Hyeon;Moon, Yong-Jae;Na, Hyeon-Ock
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.95.1-95.1
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    • 2011

  • Halo Coronal Mass Ejections (HCMEs) are crucial for space weather, since they can produce severe geomagnetic storms when they interact with the Earth's magnetosphere. It is thus very important to infer their directions, radial velocities, and their three-dimensional structures. In this study, we apply two different models to HCMEs since 2008 : (1) an ice cream cone model by Xue et al (2005) using SOHO/LASCO data, (2) a flux rope model by Thernisien et al. (2009) using STEREO/SECCHI data. In addition, we use the flux rope model with zero separation angle of flux rope, which is morphologically similar to the ice cream cone model. The comparison shows that the CME radial velocities from three models have very good correlations (R>0.9) one another. We are extending this comparison to other partial halo CMEs observed by STEREO and SOHO.

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Protein Carboxylmethylation in Porcine Spleen is Mainly Mediated by Class I Protein Carboxyl O-Methyltransferase

  • Cho, Jae-Youl;Kim, Sung-Soo;Kwon, Myung-Hee;Kim, Seong-Hwan;Lee, Hyang-Woo;Hong, Sung-Youl
    • Archives of Pharmacal Research
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    • v.27 no.2
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    • pp.206-216
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    • 2004

  • The functional role of protein carboxylmethylation (PCM) has not yet been clearly elucidated in the tissue level. The biochemical feature of PCM in porcine spleen was therefore studied by investigating the methyl accepting capacity (MAC) of natural endogenous substrate proteins for protein carboxyl O-methyltransferase (PCMT) in various conditions. Strong acidic and alkaline-conditioned (at pH 11.0) analyses of the MAC indicated that approximately 65％ of total protein methylation seemed to be mediated by spleen PCMT. The hydrolytic kinetics of the PCM products, such as carboxylmethylesters (CMEs), under mild alkaline conditions revealed that there may be three different kinds of CMEs [displaying half-times (T$_{1}$2/) of 1.1 min (82.7％ of total CMEs), 13.9 min (4.6％), and 478.0 min (12.7％)], assuming that the majority of CME is base-labile and may be catalyzed by class I PCMT. In agreement with these results, several natural endogenous substrate proteins (14, 31 and 86 kDa) were identified strikingly by acidic-conditioned electrophoresis, and their MAC was lost upon alkaline conditions. On the other hand, other proteins (23 and 62 kDa) weakly appeared under alkaline conditions, indicating that PCM mediated by class II or III PCMT may be a minor reaction. The MAC of an isolated endogenous substrate protein (23-kDa) was also detected upon acidic-conditioned electrophoresis. Therefore, our date suggest that most spleen PCM may be catalyzed by class I PCMT, which participates in repairing aged proteins.

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