• Journal of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.55-63
• /
• 1999

NGC 6537 is an extremely high excitation bipolar planetary nebula. It exhibits a huge range of excitation from lines of [N I] to [Si VI]or [Fe VII], i.e. from neutral atoms to atoms requiring an ionization potential of $\~$167eV. Its kinematical structures are of special interest. We are here primarily concerned with its high resolution spectrum as revealed by the Hamilton Echelle Spectrograph at Lick Observatory (resolution $\~0.2{\AA}$) and supplemented by UV and near-UV data. Photoionization model reproduces the observed global spectrum of NGC 6537, the absolute H$\beta$ flux, and the observed visual or blue magnitude fairly well. The nebulosity of NGC 6537 is likely to be the result of photo-ionization by a very hot star of $T_{eff} \~ 180,000 K$, although the global nebular morphology and kinematics suggest an effect by strong stellar winds and resulting shock heating. NGC 6537 can be classified as a Peimbert Type I planetary nebula. It is extremely young and it may have originated from a star of about 5 $M_{\bigodot}$.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.257-260
• /
• 2005

We have mapped the W 3 giant molecular cloud in the $C^o\;^3P_1-^3 P_o$ ([CI]) line with the Mount Fuji Submillimeter-wave Telescope. The [CI] emission is extended over the molecular cloud, having peaks at three star forming clouds; W 3(Main), W 3(OH), and AFGL 333. The [CI] emission is found to be strong in the AFGL 333 cloud. We have also observed the $C^{18}O,\;CCS,\;N_2H^+$, and $H^{13}CO^+$ lines by using the Nobeyama Radio Observatory 45 m telescope. In the AFGL 333 cloud, we find two massive cores, which are highly gravitationally bound and have no sign of active star formation. The high [$C^o$]/[CO] and [CCS]/[$N_2H^+$] abundance ratios suggest that the AFGL 333 cloud is younger than the W 3(Main) and W 3(OH) clouds.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.215-218
• /
• 2005

An atlas of high resolution (${\lambda}/{\Delta}{\lambda}$=45,000) profiles of interstellar atomic lines of K I (7665, 7699 ${\AA}$), Na I (D 1, D2), Ca II (H, K), Ca I (4227 ${\AA}$), molecular structures of CH, CH+, CN and the major diffuse interstellar bands at 5780 and 5797 ${\AA}$ based on ${\~}$300 echelle spectra of ${\~}$200 OB stars is presented. Relationships between the reddenings, distances and equivalent widths of NaI, CaII, KI, CH, CH+, CN and diffuse bands are discussed. The equivalent width of K I (7699 ${\AA}$) as well as of CH4300 ${\AA}$ / correlate very tightly with E(B- V) in contrast to the features of neutral sodium, ionized calcium and the molecular ion CH+. The equivalent widths of the Hand K lines of Call grow with distance at a rate ${\~}$250m${\AA}$ per 1 kpc. A similar relation for NaI is much less tight. The strengths of neutral potassium lines, molecular features and diffuse interstellar bands do not correlate practically with distance. These facts suggest that ionized calcium fills the interstellar space quite homogeneously while the other carriers mentioned above, especially K I, CH and these of diffuse bands occupy more and more compact volumes, also filled with dust grains. Apparently the carriers of narrow diffuse bands are spatially correlated with simple molecules and dust grains - all abundant in the so-called 'zeta' type clouds. The same environment seems to be hostile to the carriers of broad diffuse interstellar bands (DIEs) (like 5780 or 6284) and -to a certain extent - also to CaII, NaI and CH+.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.253-256
• /
• 2005

We have constructed the Mount Fuji submillimeter-wave telescope at Nishiyasugawara (alt. 3725 m) near the summit of Mt. Fuji (alt. 3774 m). Thanks to the excellent condition of Mt. Fuji, we have successfully carried out the [CI] survey toward more than 40 square degrees of sky, including qrion MC, Taurus MC, Rosetta MC, DR 15, DR 21, NGC 1333, NGC 2264, W 3, W 44, W 51, L 134, p-Oph. Our [CI] survey have revealed that the [CI] 492 GHz emission widely extends to the molecular clouds. The spatial and velocity structures of the [CI] 492 GHz emission resemble those of 13CO J=l-0 in many molecular clouds, implying that [CI] 492 GHz and $^{13}CO$ J=1-0 are emitted from the same gas. The column density of $C^o$ linearly correlates with that of CO up to high Av, suggesting that $C^o$ exist in the deep interior of molecular clouds. In several regions, we have found that the distributions of $C^o$ and CO are different from each other. The $C^o$-rich area is found in the Hieles' cloud 2. The C+/CO/$C^o$ configuration is found in DR 15, p-Oph, M 17, Orion KL, and NGC 1333. These results indicate that an origin of $C^o$ is unrelated with the photodissociation process. We discuss the observed $C^o$ distributions in relation to the non-equilibrium chemistry.

• Publications of The Korean Astronomical Society
• /
• v.25 no.1
• /
• pp.1-13
• /
• 2010

Astrochemistry provides powerful tools to understand various cosmic phenomena, including those in our solar system to the large-scale structure of the universe. In addition, the chemical property of an astronomical body is a crucial factor which governs the evolution of the system. Recent progress in astrophysical theories, computational modelings, and observational techniques requires a detailed understanding of the interactions between the constituents of an astronomical system, which are atoms and molecules within the system. Especially the far-infrared/sub-millimeter wave range, which is called as the last frontier in astronomical observations, contains numerous molecular lines, which may provide a huge amount of new information. However, we need an astrochemical understanding to use this information fully. Although this review is very limited, I would like to stress the importance of astrochemical approach in this overview for the field, which is getting much more attention than ever before.