• Title/Summary/Keyword: Nebula

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EXPANSION VELOCITY INVESTIGATION OF THE ELLIPTICAL PLANETARY NEBULA NGC 6803

  • Choi, Youn-Su;Lee, Seong-Jae;Hyung, Siek
    • Journal of The Korean Astronomical Society
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    • v.41 no.6
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    • pp.163-172
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    • 2008

  • Using the spectral data in the 3700 to $10050{\AA}$ wavelength range secured with the Hamilton Echelle Spectrograph (HES) at the Lick observatory, we have investigated the expansion velocities and the physical conditions of the elliptical planetary nebula NGC 6803. Various forbidden and permitted lines, e.g. HI, HeI, HeII, [OIII], [NII], [ArIII], and [SII], indicate complicated but systematic physical conditions variation: electron temperatures $T_{\varepsilon}\;{\sim}\;9000$ - 11000 K and electron number densities $N_{\varepsilon}\;{\sim}\;2000$ - $9000\;cm^{-3}$. The line profile analysis of these ions also indicates the systematic change or the acceleration of the expansion velocities in the range of 10 - $22\;km\;s^{-1}$. We show that the velocity gradient and physical condition found in various ions are closely related to the prolate ellipsoidal structure of NGC 6803. The expansion velocity and the ionic abundance of $O^{2+}$ were derived based on the OII and [OIII] lines. In spite of the discrepancy of ionic abundances derived by the two cases and their line profiles, the expansion velocities of them agree well. We find that the ratios of the red to blue line component of the HeII & OII lines are different from those of the [OIII] or other forbidden lines that indicates a possible involvement of emission of HeII & OII lines. This subtle difference and the different physical condition of the lines are likely to be caused by the elongated geometry and the latitude dependence of the emission zone.

  • https://doi.org/10.5303/JKAS.2008.41.6.163 인용 PDF KSCI

[Fe II] 1.64 ${\mu}m$ images of Jets and Outflows from Young Stellar Objects in the Carina Nebula

  • Shinn, Jong-Ho;Pyo, Tae-Soo;Lee, Jae-Joon;Lee, Ho-Gyu;Koo, Bon-Chul;Sung, Hwan-Kyung;Moon, Dae-Sik;Kyeong, Jae-Mann;Park, Byeong-Gon
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.74.2-74.2
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    • 2012

  • We present [Fe II] 1.64 ${\mu}m$ imaging observations for jets and outflows from young stellar objects over the northern part (-24'${\times}$45') of the Carina Nebula, a typical evolved massive star forming region. The observations were performed with IRIS2 of Anglo-Autralian Telescope and the seeing was -1.5". Several jets and outflows features are detected at seven different regions, and one new Herbig-Haro Object is identified. The [Fe II] features have knotty and elongated shapes, and distribute around the triangular area formed by the star clusters Tr 14, Tr 15, and Tr 16, which contain many massive stars. The [Fe II] feature shows a highest detection rate (3.2 %) for the earliest stage YSOs, and the rate decreases as the stage evolves. The low detection rate (1.5 %) of [Fe II] features from the numerous YSOs seem to be related with the severe radiation environment of the Carina Nebula. The outflow rate shows reasonable relations with the physical parameters of the corresponding YSOs-derived from the SED fitting-such as the accretion luminosity, the stellar mass, the stellar age, the disk accretion rate, etc.

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