http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
NEAR-INFRARED PAH FEATURES IN GALACTIC PLANETARY NEBULAE
R. Ohsawa,O.ONAKA,I.SAKON,T.I. MORI,H.KANEDA,M.MATSUURA 한국천문학회 2017 天文學論叢 Vol.32 No.1
Polycyclic aromatic hydrocarbons (PAHs) are considered to be carriers of the unidentified infrared bands, which are ubiquitously observed in the Universe. PAHs are mainly formed around evolved carbon-rich stars and injected into interstellar space. Planetary nebulae (PNe), a late stage of low- and intermediate stellar mass evolution, are suitable objects to investigate the formation and evolution of PAHs. The shortest PAH feature is located in 3.3$\,\mu$m, which is important to examine the excitation and size distribution of PAHs. While the number of samples had been limited before, the high sensitivity of \textit{AKARI}/IRC has drastically increased the number of samples. We obtained the 2--5$\,\mu$m spectra of Galactic PNe with \textit{AKARI}/IRC and compiled a near-infrared spectral catalog, containing 73 PNe. We investigate the detection rate and the evolution of the PAH features. The characteristics of the catalog are illustrated and the origin of the evolution of the PAH features is discussed.
INVESTIGATION OF PAHs IN GALACTIC PLANETARY NEBULAE WITH THE AKARI/IRC AND THE SPITZER/IRS
Ohsawa, R.,Onaka, T.,Sakon, I.,Mori, T.I.,Yamamura, I.,Matsuura, M.,Kaneda, H.,Bernard-Salas, J.,Berne, O.,Joblin, C. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
Polycyclic aromatic hydrocarbons (PAHs) in Galactic planetary nebulae (PNe) are investigated by means of the unidentified infrared (UIR) bands. Continuous near- to mid-infrared spectra of PNe are obtained with the AKARI/IRC and the Spitzer/IRS. All 19 PNe in the present study show prominent dust emissions and we investigate the variation in the intensity ratios among the UIR bands. The ionization fraction and the size distribution of PAHs in PNe are derived using the UIR band ratios. We find that the ionization fraction of PAHs in PNe is around 0.0-0.6 and that small PAHs are scarce. The present result indicates a systematic trend of the $3.4{\mu}m$ aliphatic feature to become weak as the PAH ionization fraction increases.
Planck Collaboration, Planck Collaboration,Giard, M.,Berne, O.,Doi, Y.,Ishihara, D.,Joblin, Ch.,Kaneda, I.,Marshall, D.,Nakagawa, T.,Ohsawa, R.,Onaka, T.,Sakon, I.,Shibai, H.,Ysard, N. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We show how the rotation emission from isolated interstellar Polycyclic Aromatic Hydrocarbons (PAHs) can explain the so-called anomalous microwave emission (AME). AME has been discovered in the last decade as microwave interstellar emission (10 to 70 GHz) that is in excess compared to the classical emission processes: thermal dust, free-free and synchrotron. The PAHs are the interstellar planar nano-carbons responsible for the near infrared emission bands in the 3 to 15 micron range. Theoretical studies show that under the physical conditions of the interstellar medium (radiation and density) the PAHs adopt supra-thermal rotation velocities, and consequently they are responsible for emission in the microwave range. The first results from the PLANCK mission unexpectedly showed that the AME is not only emitted by specific galactic interstellar clouds, but it is present throughout the galactic plane, and is particularly strong in the cold molecular gas. The comparison of theory and observations shows that the measured emission is fully consistent with rotation emission from interstellar PAHs. We draw the main lines of our PLANCK-AKARI collaborative program which intends to progress on this question by direct comparison of the near infrared (AKARI) and microwave (PLANCK) emissions of the galactic plane.