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题名: CEN34-high-mass YSO in M17 or background post-AGB star?
作者: Chen, Zhiwei1, 2, 3; Nuernberger, Dieter E. A.2; Chini, Rolf2, 4; Liu Yao(刘尧)1; Fang Min(房敏)1; Jiang ZhiBo(江治波)1
刊名: ASTRONOMY & ASTROPHYSICS
出版日期: 2013-09-01
卷号: 557
关键词: stars: late-type ; stars: AGB and post-AGB ; stars: formation ; stars: pre-main sequence
DOI: 10.1051/0004-6361/201321694
文章类型: Article
英文摘要: We investigate the proposed high-mass young stellar object (YSO) candidate CEN34, thought to be associated with the star-forming region M17. Its optical to near-infrared (550-2500 nm) spectrum reveals several photospheric absorption features, such as H alpha, the Ca II triplet, and the CO bandhead, but lacks emission lines. The spectral features in the range 8375-8770 angstrom are used to constrain an effective temperature T-eff = 5250 +/- 250K (early-/mid-G) and a log g = 2.0 +/- 0.3 (supergiant). The spectral energy distribution (SED) displays a faint infrared excess that resembles that of a high-mass YSO or an evolved star of intermediate mass. Moreover, the observed temperature and surface gravity are identical for high-mass YSOs and evolved stars. The radial velocity of CEN34 relative to the local standard of rest (V-LSR) as obtained from various photospheric lines is of the order of -60 km s(-1) and thus distinct from the +25 km s (1) found for several OB stars in the cluster and for the associated molecular cloud. The SED modeling yields similar to 10 (4) M-circle dot of circumstellar material, which contributes only a tiny fraction to the total visual extinction (11 mag). The distance of CEN34 is between 2.0 kpc and 4.5 kpc. In the case of a YSO, a dynamical ejection process is proposed to explain the VLSR difference between CEN34 and M17. Additionally, to match the temperature and luminosity, we speculate that CEN34 had accumulated the bulk of its mass with an accretion rate >4 x 10(-3) M-circle dot/yr over a very short time span (similar to 10(3) yrs), and it is currently undergoing a phase of gravitational contraction without any further mass gain. However, all the aforementioned characteristics of CEN34 are compatible with an evolved star of 5-7 M-circle dot and an age of 50-100 Myr, so it is most likely a background post-AGB star with a distance between 2.0 kpc and 4.5 kpc. We consider the latter classification as the more likely interpretation. Further discrimination of the two possible scenarios should come from the stricter confinement of CEN34's distance.
WOS标题词: Science & Technology ; Physical Sciences
类目[WOS]: Astronomy & Astrophysics
研究领域[WOS]: Astronomy & Astrophysics
关键词[WOS]: RADIAL-VELOCITIES ; DISK ACCRETION ; TRIGONOMETRIC PARALLAXES ; MASSIVE PROTOSTAR ; STELLAR OBJECTS ; X-SHOOTER ; M-17 ; SPECTRA ; CATALOG ; REGION
收录类别: SCI
语种: 英语
WOS记录号: WOS:000325211900095
Citation statistics:
内容类型: 期刊论文
URI标识: http://libir.pmo.ac.cn/handle/332002/15515
Appears in Collections:分子云与恒星形成研究团组_期刊论文

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作者单位: 1.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Jiangsu, Peoples R China
2.Ruhr Univ Bochum, Astronom Inst, D-44801 Bochum, Germany
3.Univ Chinese Acad Sci, Beijing 100039, Peoples R China
4.Univ Catolica Norte, Inst Astron, Antofagasta, Chile
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