Spatio-kinematical model of the collimated molecular outflow in the water-fountain nebula IRAS 16342-3814 | |
Tafoya, D.1,2; Orosz, G.3,4; Vlemmings, W. H. T.2; Sahai, R.5; Perez-Sanchez, A. F.6 | |
刊名 | ASTRONOMY & ASTROPHYSICS |
2019-08-22 | |
卷号 | 629页码:A8 |
关键词 | stars: AGB and post-AGB stars: jets stars: mass-loss stars: winds, outflows submillimeter: stars |
ISSN号 | 1432-0746 |
DOI | 10.1051/0004-6361/201834632 |
产权排序 | 4 |
英文摘要 | Context. Water-fountain nebulae are asymptotic giant branch (AGB) and post-AGB objects that exhibit high-velocity outflows traced by water-maser emission. Their study is important for understanding the interaction between collimated jets and the circumstellar material that leads to the formation of bipolar and/or multi-polar morphologies in evolved stars. Aims. The aim of this paper is to describe the three-dimensional morphology and kinematics of the molecular gas of the water-fountain nebula IRAS 16342-3814. Methods. Data was retrieved from the ALMA archive for analysis using a simple spatio-kinematical model. The software SHAPE was employed to construct a three-dimensional, spatio-kinematical model of the molecular gas in IRAS 16342-3814, and to then reproduce the intensity distribution and position-velocity diagram of the CO emission from the ALMA observations to derive the morphology and velocity field of the gas. Data from CO(J = 1 -> 0) supported the physical interpretation of the model. Results. A spatio-kinematical model that includes a high-velocity collimated outflow embedded within material expanding at relatively lower velocity reproduces the images and position-velocity diagrams from the observations. The derived morphology is in good agreement with previous results from IR and water-maser emission observations. The high-velocity collimated outflow exhibits deceleration across its length, while the velocity of the surrounding component increases with distance. The morphology of the emitting region, the velocity field, and the mass of the gas as function of velocity are in excellent agreement with the properties predicted for a molecular outflow driven by a jet. The timescale of the molecular outflow is estimated to be similar to 70-100 yr. The scalar momentum carried by the outflow is much larger than it can be provided by the radiation of the central star. An oscillating pattern was found associated with the high-velocity collimated outflow. The oscillation period of the pattern is T approximate to 60-90 yr and its opening angle is theta(op) approximate to 2 degrees. Conclusions. The CO (J= 3 -> 2) emission in IRAS 16342-3814 is interpreted in terms of a jet-driven molecular outflow expanding along an elongated region. The position-velocity diagram and the mass spectrum reveal a feature due to entrained material that is associated with the driving jet. This feature is not seen in other more evolved objects that exhibit more developed bipolar morphologies. It is likely that the jet in those objects has already disappeared since it is expected to last only for a couple hundred years. This strengthens the idea that water fountain nebulae are undergoing a very short transition during which they develop the collimated outflows that shape the circumstellar envelopes. The oscillating pattern seen in the CO high-velocity outflow is interpreted as due to precession with a relatively small opening angle. The precession period is compatible with the period of the corkscrew pattern seen at IR wavelengths. We propose that the high-velocity molecular outflow traces the underlying primary jet that produces such a pattern. |
资助项目 | National Key R&D Program of China[2018YFA0404602] ; NSFC[11503072] ; ERC[614264] ; Youth Innovation Promotion Association of the CAS |
WOS关键词 | PREPLANETARY NEBULA ; BIPOLAR OUTFLOW ; MASS ; JET ; MOMENTUM |
WOS研究方向 | Astronomy & Astrophysics |
语种 | 英语 |
出版者 | EDP SCIENCES S A |
WOS记录号 | WOS:000482762800001 |
内容类型 | 期刊论文 |
源URL | [http://ir.xao.ac.cn/handle/45760611-7/3021] |
专题 | 研究单元未命名 |
通讯作者 | Tafoya, D. |
作者单位 | 1.Natl Inst Nat Sci, Natl Astron Observ Japan, Chile Observ, 2-21-1 Osawa, Mitaka, Tokyo 1818588, Japan 2.Chalmers Univ Technol, Onsala Space Observ, Dept Space Earth & Environm, S-43992 Onsala, Sweden 3.Univ Tasmania, Sch Nat Sci, Private Bag 37, Hobart, Tas 7001, Australia 4.Chinese Acad Sci, Xinjiang Astron Observ, 150 Sci 1 St, Urumqi 830011, Xinjiang, Peoples R China 5.CALTECH, Jet Prop Lab, MS 183-900, Pasadena, CA 91109 USA 6.European Southern Observ, Alonso Cordova 3107,Casilla 19001, Santiago 19001, Chile |
推荐引用方式 GB/T 7714 | Tafoya, D.,Orosz, G.,Vlemmings, W. H. T.,et al. Spatio-kinematical model of the collimated molecular outflow in the water-fountain nebula IRAS 16342-3814[J]. ASTRONOMY & ASTROPHYSICS,2019,629:A8. |
APA | Tafoya, D.,Orosz, G.,Vlemmings, W. H. T.,Sahai, R.,&Perez-Sanchez, A. F..(2019).Spatio-kinematical model of the collimated molecular outflow in the water-fountain nebula IRAS 16342-3814.ASTRONOMY & ASTROPHYSICS,629,A8. |
MLA | Tafoya, D.,et al."Spatio-kinematical model of the collimated molecular outflow in the water-fountain nebula IRAS 16342-3814".ASTRONOMY & ASTROPHYSICS 629(2019):A8. |
个性服务 |
查看访问统计 |
相关权益政策 |
暂无数据 |
收藏/分享 |
除非特别说明,本系统中所有内容都受版权保护,并保留所有权利。
修改评论