• 제목/요약/키워드: $u_{CN}$

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RADIAL ABUNDANCE GRADIENT IN GLOBULAR CLUSTERS

  • Chun, M.S.
    • 천문학회지
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    • 제14권1호
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    • pp.13-17
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    • 1981
  • The observed radial UBV colour variations (both B-V and U-B) of some globular clusters are examined for correlations with radial variations in the integrated spectra. The results show that the presence of a radial colour gradient is correlated with the presence of a gradient of the CN (and possibly the G-band) line strength, in the sense that the CN (and possibly the G-band) is stronger in the centre (where the cluster is redder) and becomes weaker in the outer region of the cluster (where the cluster is bluer). This may suggest that a primordial abundance, possibly nitrogen and carbon gradient was set up in the early stage of cluster formation.

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Optical Emission Studies of a Plume Produced by Laser Ablation of a Graphite Target in a Nitrogen Atmosphere

  • Park, Hye-Sun;Nam, Sang-Hwan;Park, Seung-Min
    • Bulletin of the Korean Chemical Society
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    • 제25권5호
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    • pp.620-624
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    • 2004
  • Optical emission studies were performed to investigate thermal and dynamical properties of a plume produced by laser ablation of a graphite target in a nitrogen atmosphere. Experimental spectra of $C_2(d^3{\Pi}_g{\to}a^3{\Pi}_u$, ${\Delta}_V$=1) and CN ($B^2{\Sigma}^+{\to}X^2{\Sigma}^+,{\Delta}_V=0)$ were simulated to obtain the vibrational and rotational temperatures of the electronically excited species at various laser fluences and distances from the target. The spectroscopic temperatures of both molecules were found to be nearly independent of the laser fluence. The temperature of CN molecules was peaked in the middle of the plume while that of $C_2$decreased with increase in the distance. At a given distance, the temperature of CN molecules was clearly higher than that of $C_2$.