• 천문학논총
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• 제15권spc1호
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• pp.31-38
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• 2000

We have presented detected molecules, atoms, radicals, ions, and dimers in the atmospheres of planets and comets from Earth-based and spaceborne observatories during the last 3 decades. We have reviewed spectroscopic studies on the auroral emissions and air glows of the giant planets, and briefly summarized spectroscopic observations of dimers in the atmospheres of the giant planets and Titan. In particular, we highlighted the recent detections of new molecular emissions and absorptions in the spectra of the giant planets, Titan, and recent bright comets from spaceborne or ground-based observatories. We also reviewed current models and theories of the origin and evolution of the solar system, and implications of isotopic ratios in these atmospheres.

• Journal of Astronomy and Space Sciences
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• 제18권2호
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• pp.95-100
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• 2001

We have presented an ab initio model of the $2{mu}m$ spectral features of $(H_2)_2$ based on the far-infrared models of McKellar & Schaefer (1991). We have shown that the intensity variations of the $2{mu}m;(H_2)_2$ features depend on the ortho/para ratios of $H_2$ We have discussed the applicability of the variations to the atmospheres of the giant planets for the derivations of the ortho/para ratios. The signal to noise ratios of currently available spectra of the giant planets are not sufficient enough to derive accurate ortho/para ratios of these planets. Observations with longer exposure times and larger telescope apertures are required to obtain better spectra for the derivations of the ortho/para ratios of $H_2$ in the atmospheres of the giant planets.

• 천문학회보
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• 제25권2호
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• pp.61-61
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• 2000

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.61-61
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• 2000

No Abstract, See Full Text

• Journal of Astronomy and Space Sciences
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• 제14권2호
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• pp.251-258
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• 1997

The detection of jovian hydrogen-hydrogen dimers through the clear telluric 2-micron window(Kim et al. 1995, Trafton et al. 1997( suggests possibility to detect noble gases in the form of dimer with hydrogen in jovian atmospheres. Since noble noble gases do not have spectral structures in the infrared, it has been difficult to derive their abundances in the atmospheres of jovian planets. If there is a significant component of noble gases other than helium in the jovian atmospheres. it might be detected through its dimer spectrum with hydrogen molecule. The relatively sharp spectral structures of hydrogen-argon and hydrogen-neon dimers compared with those of hydrogen-hydrogen dimers are useful for the detection, if an adequate signal-to-noise (S/N) is obtained. If we use a large telescope, such as the Keck telescope, with a long exposure time (>24 hours), then $H_2-Ar$ spectral structure may be detected.

• 천문학회지
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• 제34권1호
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• pp.25-29
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• 2001

We have constructed a non-spherical model for the hot oxygen corona of Mars by including the effects of planetary rotation and diurnal variation of the Martian ionosphere. Exospheric oxygen densities are calculated by integrating ensemble of ballistic and escaping oxygen atoms from the exobase over the entire planet. The hot oxygen atoms are produced by dissociative recombination of $O^+_2$, the major ion in the Martian ionosphere. The densities of hot oxygen atoms at the exobase are estimated from electron densities which have been measured to vary with solar zenith angle. Our model shows that the density difference of hot oxygen atoms between noon and terminator is about two orders of magnitude near the exobase, but reduces abruptly around altitudes of 2000 km due to lateral transport. The diurnal variation of hot oxygen densities remains significant up to the altitude of 10000 km. The diurnal variation of the hot oxygen corona should thus be considered when the upcoming Nozomi measurements are analyzed. The non-spherical model of the hot oxy-gen corona may contribute to building sophisticate solar wind interaction models and thus result in more accurate escaping rate of oxygens from Mars.

• 천문학회지
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• 제33권2호
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• pp.127-135
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• 2000

We investigate the effects of planetary rotation on the exospheres of the earth and Mars with simple collisionless models. We develope a numerical code that computes exospheric densities by integrating velocity functions at the exobase with a 10 point Gauss method. It is assumed in the model that atoms above the exobase altitude move collisionlessly on an orbit under the planet's gravity. Temperatures and densities at the exobase over the globe are adopted from MSIS-86 for the earth and from Bougher et al's MTGCM for Mars. For both the earth and Mars, the rotation affects the exospheric density distribution significantly in two ways: (1) the variation of the exospheric density distribution is shifted toward the rotational direction with respect to the variation at the exobase, (2) the exospheric densities in general increase over the non-rotating case. We find that the rotational effects are more significant for lower thermospheric temperatures. Both the enhancement of densities and shift of the exospheric distribution due to rotation have not been considered in previous models of Martian exosphere. Our non-spherical distribution with the rotational effects should contribute to refining the hot oxygen corona models of Mars which so far assume simple geometry. Our model will also help in analyzing exospheric data to be measured by the upcoming Nozomi mission to Mars.

• 천문학논총
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• 제9권1호
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• pp.111-166
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• 1994

I have developed a UV and visible spectroscopic database (UVSD) for atoms and molecules, which are found in interstellar medium, stars, galaxies, and in the atmospheres of the earth, planets, satellites, and comets. This UV and visible database, which is machine-readable, consists of three different sub-databases depending upon the characteristics of the sub-databases: (A) atomic and molecular line listings from laboratory observations or theoretical studies; (B) absorption spectra measured in laboratories; and (C) solar UV, visible, and infrared spectral atlases. The UVSD is in a very initial stage of development compared with other well organized and established infrared and microwave databases. In order to make a good quality and complete database, substantial efforts should be made for the acquisition of scattered important data from laboratories or institutions, and then the acquired heterogeneous data should be peer-reviewed and standardized.

• 천문학회보
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• 제36권2호
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• pp.82.2-82.2
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• 2011

Major solar eruptive events, consisting of both a large flare and a near simultaneous fast coronal mass ejection (CME), are the most powerful explosions in the solar system, releasing $10^{32}-10^{33}$ ergs in ${\sim}10^{3-4}\;s$. They are also the most powerful and energetic particle accelerators, producing ions up to tens of GeV and electrons up to hundreds of MeV. For flares, the accelerated particles often contain up to ~50% of the total energy released, a remarkable efficiency that indicates the particle acceleration is intimately related to the energy release process. Similar transient energy release/particle acceleration processes appear to occur elsewhere in the universe, in stellar flares, magnetars, etc. Escaping solar energetic particles (SEPs) appear to be accelerated by the shock wave driven by the fast CME at altitudes of ~1 40 $R_s$, with an efficiency of ~10%, about what is required for supernova shock waves to produce galactic cosmic rays. Thus, large solar eruptive events are our most accessible laboratory for understanding the fundamental physics of transient energy release and particle acceleration in cosmic magnetized plasmas. They also produce the most extreme space weather - the escaping SEPs are a major radiation hazard for spacecraft and humans in space, the intense flare photon emissions disrupt GPS and communications on the Earth, while the fast CME restructures the interplanetary medium with severe effects on the magnetospheres and atmospheres of the Earth and other planets. Here I review present observations of large solar eruptive events, and future space and ground-based measurements needed to understand the fundamental processes involved.

• 천문학회보
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• 제44권2호
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• pp.44.3-44.3
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• 2019

Since the detection of 3.3-micron PAH (polycyclic aromatic hydrocarbon) and 3.4-micron aliphatic hydrocarbon features in the spectra of Titan (Bellucci et al. 2009; Kim et al. 2011) and Saturn (Kim et al. 2012), respectively, the 3.3-micron feature of gaseous CH4 has been thought to be still the important spectral feature in the 3-micron absorption structures of Titan and Saturn. However, the analyses of the 3.3-and 3.4-micron emission structures of Saturn revealed that the influence of the gaseous CH4 on the structures is rather minimal (Kim et al. 2019). We present synthetic spectra of gaseous CH4, and the PAH and aliphatic haze particles in order to show the degree of influence of their spectra on the 3.3-and 3.4-micron emission structures of Saturn, and we compare these synthetic spectra with currently available observations. We constructed these synthetic spectra using newly developed radiative transfer equations. These equations are able to address detailed radiative processes in the atmospheres containing various gases and haze particles. We expect these radiative transfer equations can also be widely applied to the investigation of radiative transfer processes and the analyses of the spectra of celestial objects such as the Earth, the Moon, planets, and interstellar nebulae.