We model molecular outflows produced by the time dependent interaction between a stellar wind and a rotating cloud envelope in gravitational collapse, studied by Ulrich. We consider spherical and anisotropic stellar winds. We assume that the bipolar outflow is a thin shocked shell, with axial symmetry around the cloud rotation axis and obtain the mass and momentum fluxes into the shell. We solve numerically a set of partial differential equations in space and time, and obtain the shape of the shell, the mass surface density, the velocity field, and the angular momentum of the material in the shell. We find that there is a critical value of the ratio between the wind and the accretion flow momentum rates $β$ that allows the shell to expand. As expected, the elongation of the shells increase with the stellar wind anisotropy. In our models, the rotation velocity of the shell is the order to 0.1 - 0.2 km s$^{-1}$, a factor of 5-10 lower than the values measured in several sources. We compare our models with those of Wilkin and Stahler for early evolutionary times and find that our shells have the same sizes at the pole, although we use different boundary conditions at the equator.
Recent observations have revealed that the remnants of stellar-coalescence transients are bipolar. This raises the questions of how these bipolar morphologies arise and what they teach us about the mechanisms of mass ejection during stellar mergers and common-envelope phases. In this paper, we analyze hydrodynamic simulations of the lead-in to binary coalescence, a phase of unstable Roche lobe overflow that takes the binary from the Roche limit separation to the engulfment of the more compact accretor within the envelope of the extended donor. As mass transfer runs away at increasing rates, ga…
We present a near-infrared $H$ band polarimetric study toward the S235 e2s3 protostar, obtained using the POLICAN instrument on the 2.1m OAGH telescope. The images reveal a bipolar outflow with a total length of about 0.5pc. The outflow nebulosity presents a high degree of linear polarization ($\sim80\%$) and reveals a centrosymmetric pattern with the polarization position angles. The polarization characteristics suggest their origin to be single scattering associated with dust in the outflow. Using multiwavelength archival data, we performed spectral energy distribution (SED) fitting based on…
3-D modelling of the collimated bipolar outflows of compact planetary nebulae with WR-type central stars
我们提出了高分辨率，长狭缝光谱观测五个紧凑的（$\leq$ 10角秒）行星状星云位于靠近银河系的隆起区域，没有高空间分辨率的图像。这些数据来自圣佩德罗·马尔蒂尔银河系行星状星云运动学目录（López et al. 2012）。其中四个天体（M1 -32、M2 -20、M2 -31和M3 -15）的中心恒星为WR型，第五个天体（M2 -42）的核心为Wels型。这些观测结果揭示了在所有这些存在的密集和厚赤道环面状组件和高速，准直，双极流出。代码SHAPE是用来调查的主要形态运动学特征和再现的3-D结构，这些对象假设一个圆柱形的速度场的双极流出和同源膨胀法的环面/环组件。双极外流的反投影膨胀速度在65至200 km $\rm{s^{-1}}$的范围内，而环面/环组件显示出慢得多的膨胀速度，在15至25 km $\rm{s^{-1}}$的范围内。研究发现，这些行星状星云具有非常相似的结构成分，它们发射谱线的差异主要来自它们在天空中的不同投影。它们的形态运动学特征与WR型核的关系值得进一步研究。
The morphology of bipolar planetary nebulae (PNe) can be attributed to interactions between a fast wind from the central engine and dense toroidal shaped ejecta left over from common envelope (CE) evolution. Here we use the 3-D hydrodynamic AMR code AstroBEAR to study the possibility that bipolar PN outflows can emerge collimated even from an uncollimated spherical wind in the aftermath of a CE event. The output of a single CE simulation via the SPH code PHANTOM serves as the initial conditions. Four cases of winds, all with high enough momenta to account for observed high momenta preplanetary…
We present Caltech Submillimeter Observatory CO (2-1) and Spitzer IRAC observations toward IRAS 22506+5944, which is a 10$^4$ $L_{\odot}$ massive star-forming region. The CO (2-1) maps show an east-west bipolar molecular outflow originating from the 3 mm dust continuum peak. The Spitzer IRAC color-composite image reveals a pair of bow-shaped tips which are prominent in excess 4.5 $μ$m emission and are located to the leading fronts of the bipolar outflow, providing compelling evidence for the existence of bow-shocks as the driving agents of the molecular outflow. By comparing our CO (2-1) obser…
Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12 M$_{\odot}$ object known to power an optical jet. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2-1), CO(3-2), and $^{13}$CO(3-2). Our observations reveal for the first time the base of …
The subclass of bipolar Planetary Nebulae (PN) exhibits well-defined low-power outflows and some show shock-related equatorial spiderweb structures and hourglass structures surrounding these outflows. These structures are distinctly different from the phenomena associated with spherical and elliptical PN and suggest a non-standard way to simultaneously energise both kind of structures. This paper presents evidence from the published literature on bipolar PN Hb\,12 and other sources in support of an alternative scenario for energizing these structures by means of accretion from material shells …
Discovery of collimated bipolar outflows in the planetary nebula Th 2-A
我们提出了一套全面的空间分辨，积分场光谱映射的沃尔夫-拉叶行星状星云Th 2-A，获得使用宽视场光谱仪在澳大利亚国立大学2.3米望远镜。速度分辨H $α$通道地图的分辨率为20公里秒$^{-1}$使我们能够确定不同的运动学成分内的星云。这些信息被用来开发一个三维的星云形态运动学模型，使用交互式运动学建模工具形状。这些结果表明，Th 2-A有一个厚的环形壳的膨胀速度为40 $\pm$ 10 km s $^{-1}$，和一个薄的长椭球体与准直双极流出向其轴达到速度在70-110 km s $^{-1}$的范围内，相对于中央恒星。其形态运动学结构与[WO]型恒星特征之间的关系值得进一步研究。
Kinematic signatures of the jet, winds, multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al.\ (2020), in which an outflow forms by radially directed, wide-angle toroidally magnetized winds interacting with magnetized isothermal toroids, are extracted in the form of position--velocity diagrams. Elongated outflow lobes, driven by magnetized winds and their interplay with the environment, are dominated by extended bubble structures with mixing layers beyond the conventional thin-shell models. The axial cylindrically stratified density jet c…
We present a parsec-scale molecular hydrogen (H$_2$ 1-0 S(1) at 2.12~\micron) outflow discovered from the UKIRT Widefield Infrared Survey for H$_2$. The outflow is located in the infrared dark cloud core MSXDC G053.11+00.05 MM1 at 1.7 kpc and likely associated with two young stellar objects (YSOs) at the center. The overall morphology of the outflow is bipolar along the NE-SW direction with a brighter lobe to the southwest, but the detailed structure consists of several flows and knots. With the total length of $\sim$1 pc, the outflow luminosity is fairly high with $L_{\rm H_{2}} > 6~L_{\sun}$…
One of the outstanding problems in star-formation theory concerns the transfer of angular momentum such that mass can accrete onto a newly born young stellar object (YSO). From a theoretical standpoint, outflows and jets are predicted to play an essential role in angular momentum transfer and their rotation motions have been reported for both low- and high-mass YSOs. However, little quantitative discussion on outflow launching mechanisms have been presented for high-mass YSOs due to a lack of observational data. Here we present a clear signature of rotation in the bipolar outflow driven by Ori…
Context. The bipolar outflows associated with low-mass protostars create cavities in the infalling envelope. These cavities are illuminated by the central protostar and inner disk, creating a bipolar scattered light nebula at near-infrared and mid-infrared wavelengths. The variability of the scattered light nebula in both total intensity and intensity as a function of position in the scattered light nebula can provide important insights into the structure of the inner disk that cannot be spatially resolved. Aims. We aim to determine the likelihood that a warped inner disk is the origin of the …
We have mapped the pre-planetary nebula IRAS 17150-3224 in 350 GHz continuum and CO J=3-2 line at an angular resolution of about 0".09 using the Atacama Large Millimeter/submillimeter Array. A continuum source is detected at the center of the nebula, elongated along the equatorial plane, likely tracing a dusty torus around the central source. Continuum emission is also detected on both sides of the central continuum source in the equatorial plane, probably resulting from interactions of collimated fast winds with envelope material in the equator. CO emission is detected along the optical lobe.…
Massive protostars generate strong radiation feedback, which may help set the mass they achieve by the end of the accretion process. Studying such feedback is therefore crucial for understanding the formation of massive stars. We report the discovery of a photoionized bipolar outflow towards the massive protostar G45.47+0.05 using high-resolution observations at 1.3 mm with the Atacama Large Millimeter/Submillimeter Array (ALMA) and at 7 mm with the Karl G. Jansky Very Large Array (VLA). By modeling the free-free continuum, the ionized outflow is found to be a photoevaporation flow with an ele…
We report the discovery of 11 bipolar outflows within a projected distance of 1pc from Sgr A* based on deep ALMA observations of $^{13}$CO, H30$α$ and SiO (5-4) lines with sub-arcsecond and $\sim1.3$ km/s, resolutions. These unambiguous signatures of young protostars manifest as approaching and receding lobes of dense gas swept up by the jets created during the formation and early evolution of stars. The lobe masses and momentum transfer rates are consistent with young protostellar outflows found throughout the disk of the Galaxy. The mean dynamical age of the outflow population is estimated t…
We explore a new, efficient mechanism that can power toroidally magnetized jets up to two to three times their original terminal velocity after they enter a self-similar phase of magnetic acceleration. Underneath the elongated outflow lobe formed by a magnetized bubble, a wide-angle free wind, through the interplay with its ambient toroid, is compressed and accelerated around its axial jet. The extremely magnetic bubble can inflate over its original size, depending on the initial Alfvén Mach number $M_A$ of the launched flow. The shape-independent slope $\partial{}v_r/\partial{}r=2/3t$ is a sa…
JOYS: JWST MIRI/MRS spectra of the inner 500 au region of the L1527 IRS bipolar outflow
Dublin Institute for Advanced Studies（都柏林高等研究院）；Leiden University（莱顿大学）；INAF-Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；National Radio Astronomy Observatory（美国国家射电天文台）；Maynooth University（梅努斯大学）；Chalmers University of Technology（查尔姆斯理工大学）；University of Virginia（弗吉尼亚大学）；INAF-Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）
We compare multi-epoch sub-arcsecond VLA imaging of the 22 GHz water masers toward the massive protocluster NGC6334I observed before and after the recent outburst of MM1B in (sub)millimeter continuum. Since the outburst, the water maser emission toward MM1 has substantially weakened. Simultaneously, the strong water masers associated with the synchrotron continuum point source CM2 have flared by a mean factor of 6.5 (to 4.2 kJy) with highly-blueshifted features (up to 70 km/s from LSR) becoming more prominent. The strongest flaring water masers reside 3000 au north of MM1B and form a remarkabl…
Stellar feedback plays a fundamental role in shaping the evolution of galaxies. Here we explore the use of ionised gas kinematics in young, bipolar H II regions as a probe of early feedback in these star-forming environments. We have undertaken a multiwavelength study of a young, bipolar H II region in the Galactic disc, G$316.81-0.06$, which lies at the centre of a massive ($\sim10^3$ M$_{\odot}$) infrared-dark cloud filament. It is still accreting molecular gas as well as driving a $\sim 0.2$ pc ionised gas outflow perpendicular to the filament. Intriguingly, we observe a large velocity grad…
We present ALMA continuum and molecular line emission maps at $\sim$1 mm of OH 231.8, a well studied bipolar nebula around an AGB star. The excellent angular resolution of our maps ($\sim$20 mas) allows us to scrutinise the central nebular regions of OH 231.8, which hold the clues to unravel how this iconic object assembled its complex nebular architecture. We report, for the first time in this object and others of its kind, the discovery of a rotating circumbinary disk selectively traced by NaCl, KCl, and H$_2$O emission lines. This represents the first detection of KCl in an oxygen-rich AGB …
The morphologies of planetary nebula have long been believed to be due to wind shaping processes in which a fast wind from the central star impacts a previously ejected envelope. Asymmetries assumed to exist in the slow wind envelope lead to inertial confinement shaping the resulting interacting winds flow. We present new results demonstrating the effectiveness of Common Envelope Evolution (CEE) at producing aspherical envelopes which, when impinged upon by a spherical fast stellar wind, produce highly bipolar, jet-like outflows. We have run two simple cases using the output of a single PHANTO…
The outflows and 3D structure of NGC 6337, a planetary nebula with a close binary nucleus
NGC 6337是一个罕见的行星状星云，其中一个近距离双星核已被确定。星云的形态和发射线轮廓都是不寻常的，特别是后者。我们提出了一个彻底的映射的空间分辨，长缝阶梯光谱获得的星云，允许其复杂的运动学的详细特征。这些信息，连同窄带图像被用来产生一个三维模型的星云使用的代码形状。三维模型产生了一个缓慢膨胀的环形体，在其外围有很大的密度波动，被观察为彗星结。低电离的双极膨胀帽系统位于环形线圈外部。此外，一个扩展的高速和纤细的双极准直流出被发现出现从核心和急剧弯曲在相反的方向，一个行为，不能占纯磁发射和准直，除非流出的源是旋进或旋转，可以预期从一个密切的二元核。
By studying 7 objects in the Lupus clouds we aim to test if a coherence exists between commonly used evolutionary tracers. We present ALMA observations of the continuum and molecular line emission that probe the dense gas and dust of cores and their associated molecular outflows. Our source selection in a common environment allows for a consistent comparison across different evolutionary stages. The quality of the ALMA molecular data allows us to reveal the nature of the molecular outflows by studying their morphology and kinematics. The images in IRAS15398-3359 appear to show that it drives a…
R Aqr is a symbiotic binary system consisting of a Mira variable with a pulsation period of 387 days and a hot companion which is presumably a white dwarf with an accretion disk. This binary system is the source of a prominent bipolar gaseous outflow. We use high spatial resolution and sensitive images from the Hubble Space Telescope to identify and investigate the different structural components that form the complex morphology of the R Aqr jet . Methods. We present new high-resolution HST WFC3/UVIS narrow-band images of the R Aqr jet obtained in 2013/14 in the light of the [OIII] 5007, [OI] …
