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IMAGING THE CIRCUMSTELLAR ENVELOPES AROUND EVOLVED STARS WITH THE SMA
HIRANO NAOMI,CHIU PO-JIAN,MULLER SEBASTIEN,TRUNG DINH-V The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
We present the high-resolution (2"-4") images of the molecular envelopes surrounding the evolved stars, V Hya, VY CMa, and ${\pi}^1$ Gru observed with the Submillimeter Array. The CO J=2-1 and 3-2 images of the carbon star V Hya show that the circumstellar structure of this star consists of three kinematic components; there is a flattened disk-like envelope that is expanding with a velocity of ${\~}16 km\;s^{-1}$, the second component is the medium-velocity wind having a deprojected velocity of 40-120 km $s^{-l}$ moving along the disk plane, and the third one is the bipolar molecular jet having an extreme velocity of 70-185 km $s^{-l}$. The axis of this high velocity jet is perpendicular to the plane of the disk-like envelope. We found that the circumstellar structure of the S-star ${\pi}^1$ Gru traced by the CO J =2-1 resembles that of V Hya quite closely; the star is surrounded by the expanding disk-like envelope and is driving the medium-velocity wind along the disk plane. We also obtained the excellent images of VY CMa with the CO and $^{13}CO$ J=2-1 and $SO\;6_5-5_4$ lines. The maps of three molecular lines show that the envelope has a significant velocity gradient in the east-west direction, suggesting that the envelope surrounding VY CMa is also flattened and expanding along its radial direction. The high-resolution images obtained with the SMA show that some AGB stars are associated with the asymmetric mass loss including the equatorial wind and bipolar jet.
Kim, Hyosun,Liu, Sheng-Yuan,Hirano, Naomi,Zhao-Geisler, Ronny,Trejo, Alfonso,Yen, Hsi-Wei,Taam, Ronald E.,Kemper, Francisca,Kim, Jongsoo,Byun, Do-Young,Liu, Tie IOP Publishing 2015 The Astrophysical journal Vol.814 No.1
<P>CIT 6 is a carbon star in the transitional phase from the asymptotic giant branch (AGB) to the protoplanetary nebulae (pPNs). Observational evidences of two point sources in the optical, circumstellar arc segments in an HC3N line emission, and a bipolar nebula in near-infrared provide strong support for the presence of a binary companion. Hence, CIT 6 is very attractive for studying the role of companions in the AGB-pPN transition. We have carried out high-resolution (CO)-C-12 J = 2-1 and (CO)-C-13 J = 2-1 observations of CIT 6 with the Submillimeter Array combined with the Submillimeter Telescope (single-dish) data. The (CO)-C-12 channel maps reveal a spiral-shell pattern connecting the HC3N segments in a continuous form. and an asymmetric outflow corresponding to the near-infrared bipolar nebula. Rotation of the (CO)-C-12 channel peak position may be related to the inner spiral winding and/or the bipolar outflow. An eccentric orbit binary is suggested for the presence. of an anisotropic mass loss to the west and a double spiral pattern. The lack of interarm emission to the west may indicate a feature corresponding to the periastron passage of a highly eccentric orbit of the binary. Spatially averaged radial and spectral profiles of (CO)-C-12 J = 2-1 and (CO)-C-13 J = 2-1 are compared with simple spherical radiative transfer models, suggesting a change of (CO)-C-12/(CO)-C-13 abundance ratio from similar to 30 to similar to 50 inward in the CSE of CIT 6. The millimeter continuum emission is decomposed into extended dust thermal emission (spectral index similar to -2.4) and compact emission from radio photosphere (spectral index similar to -2.0).</P>
<i>Herschel</i> and SCUBA-2 observations of dust emission in a sample of <i>Planck</i> cold clumps
Juvela, Mika,He, Jinhua,Pattle, Katherine,Liu, Tie,Bendo, George,Eden, David J.,Fehé,r, Orsolya,Michel, Fich,Fuller, Gary,Hirano, Naomi,Kim, Kee-Tae,Li, Di,Liu, Sheng-Yuan,Malinen, Johanna,Marsh Springer-Verlag 2018 Astronomy and astrophysics Vol.612 No.-
<P><I>Context.</I> Analysis of all-sky <I>Planck</I> submillimetre observations and the IRAS 100 <I>μ</I>m data has led to the detection of a population of Galactic cold clumps. The clumps can be used to study star formation and dust properties in a wide range of Galactic environments.</P><P><I>Aims.</I> Our aim is to measure dust spectral energy distribution (SED) variations as a function of the spatial scale and the wavelength.</P><P><I>Methods.</I> We examined the SEDs at large scales using IRAS, <I>Planck</I>, and <I>Herschel</I> data. At smaller scales, we compared JCMT/SCUBA-2 850 <I>μ</I>m maps with <I>Herschel</I> data that were filtered using the SCUBA-2 pipeline. Clumps were extracted using the Fellwalker method, and their spectra were modelled as modified blackbody functions.</P><P><I>Results.</I> According to IRAS and <I>Planck</I> data, most fields have dust colour temperatures <I>T</I>C ~ 14-18 K and opacity spectral index values of <I>β</I> = 1.5-1.9. The clumps and cores identified in SCUBA-2 maps have <I>T</I> ~ 13 K and similar <I>β</I> values. There are some indications of the dust emission spectrum becoming flatter at wavelengths longer than 500 <I>μ</I>m. In fits involving <I>Planck</I> data, the significance is limited by the uncertainty of the corrections for CO line contamination. The fits to the SPIRE data give a median <I>β</I> value that is slightly above 1.8. In the joint SPIRE and SCUBA-2 850 <I>μ</I>m fits, the value decreases to <I>β</I> ~ 1.6. Most of the observed <I>T</I>-<I>β</I> anticorrelation can be explained by noise.</P><P><I>Conclusions.</I> The typical submillimetre opacity spectral index <I>β</I> of cold clumps is found to be ~1.7. This is above the values of diffuse clouds, but lower than in some previous studies of dense clumps. There is only tentative evidence of a <I>T</I>-<I>β</I> anticorrelation and <I>β</I> decreasing at millimetre wavelengths.</P>
Astrochemical Properties of Planck Cold Clumps
Tatematsu, Ken’ichi,Liu, Tie,Ohashi, Satoshi,Sanhueza, Patricio,Nguyê,̃,n Lu’o’, Quang,Hirota, Tomoya,Liu, Sheng-Yuan,Hirano, Naomi,Choi, Minho,Kang, Miju,A.Thompson, Mark,Fuller, Gary,Wu, Y Published by the University of Chicago Press for t 2017 The Astrophysical journal Supplement series Vol.228 No.2
<P>We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N2H+ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, (HNC)-C-13, N2D+, and cyclic-C3H2 toward nine clumps. The detection rate of N2D+ is 50%. Furthermore, we observed the NH3 emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (less than or similar to 20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N2H+ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N2D+. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.</P>