We show that the very young brown dwarf candidate ISO217 (M6.25) is driving an intrinsically asymmetric bipolar outflow with a stronger and slightly faster red-shifted component based on spectro-astrometry of forbidden [SII] emission lines observed in UVES/VLT spectra taken in 2009. ISO217 is only one of a handful of brown dwarfs and VLMS (M5-M8) for which an outflow has been detected and that show that the T Tauri phase continues at the substellar limit. We measure a spatial extension of the outflow of +/-190mas (+/-30AU) and velocities of +/-40-50kms/s. We show that the velocity asymmetry between both lobes is variable on timescales of a few years and that the strong asymmetry of a factor of 2 found in 2007 might be smaller than originally anticipated when using a more realistic stellar rest-velocity. We also detect forbidden [FeII]7155 emission, for which we propose as potential origin the hot inner regions of the outflow. To understand the ISO217 system, we determine the disk properties based on radiative transfer modeling of the SED. This disk model agrees very well with Herschel/PACS data at 70mu. We find that the disk is flared and intermediately inclined (~45deg). The total disk mass (4e-6 Msun) is small compared to the accretion and outflow rate of ISO217 (~1e-10 Msun/yr). We propose that this discrepancy can be explained by either a higher disk mass than inferred from the model (strong undetected grain growth) and/or by an on average lower accretion and outflow rate than the determined values. We show that a disk inclination significantly exceeding 45deg, as suggested from Halpha modeling and from both lobes of the outflow being visible, is inconsistent with the SED data. Thus, despite its intermediate inclination angle, the disk of this brown dwarf does not appear to obscure the red outflow component, which is very rarely seen for T Tauri objects (only one other case).
We report the discovery based on GLIMPSE data of a proto-stellar system driving a bipolar outflow . The bipolar outflow closely resembles the shape of an hourglass in the infrared. The total luminosity of L_total=5507 L_sun, derived from IRAS fluxes, indicates the ongoing formation of a massive star in this region. The spectral energy distribution (SED) of the driving source is fitted with an online SED fitting tool, which results in a spectral index of about 1.2. This, along with the presence of a bipolar outflow, suggests the detection of a Class I protostar. The driving source indicates pro…
The origin of bipolar outflow asymmetry in young stellar objects (YSOs) remains poorly understood. It may be due to an intrinsically asymmetric outflow launch mechanism, or it may be caused by the effects of the ambient medium surrounding the YSO. Answering this question is an important step in understanding outflow launching. We have investigated the bipolar outflows driven by the T Tauri star DG Tauri on scales of hundreds of AU, using the Near-infrared Integral Field Spectrograph (NIFS) on Gemini North. The approaching outflow consists of a well-collimated jet, nested within a lower-velocit…
IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar lobes, one in the east-west (E-W) direction and one in the southeast-northwest (SE-NW) direction. We have observed it in CO J=2-1 with the Submillimeter Array at ~ 1" resolution. The E-W bipolar lobe is known to trace a bipolar outflow and it is detected at high velocity. The SE-NW bipolar lobe appears at low velocity, and could trace a bipolar outflow moving in the plane of the sky. Two compact clumps are seen at low velocity around the common waist of the two bipolar lobes, spatially coincident with the two emissio…
Some evolved stars in the pre-planetary nebula phase produce highly-collimated molecular outflows that resemble the accretion-driven jets and outflows from pre-main sequence stars. We show that IRAS 16342-3814 (the Water Fountain Nebula) is such an object and present K-band integral field spectroscopy revealing a fast (> 150 km/s) bipolar H2 outflow. The H2 emission is shock excited and may arise in fast-moving clumps, accelerated by the previously observed precessing jet. The total luminosity in H2 is 0.37 L$_{\odot}$ which is comparable with that of accretion-powered outflows from Class 0 pr…
Carbon monoxide is an excellent tracer of the physical conditions of gas in molecular outflows from young stars. To understand the outflow mechanism we need to investigate the origin of the molecular emission and the structure and interaction of the outflowing molecular gas. Deriving the physical parameters of the gas will help us to trace and understand the various gas components in the flow. We observed CO(12-11) line emission at various positions along the L1157 bipolar outflow with GREAT aboard SOFIA. Comparing these new data with CO(2-1), we find basically constant line ratios along the o…
We present high resolution images of the bipolar outflow from W51e2, which are produced from the Submillimeter Array archival data observed for CO(3-2) and HCN(4-3) lines with angular resolutions of 0.8" x 0.6" and 0.3" x 0.2", respectively. The images show that the powerful outflow originates from the protostellar core W51e2-E rather than from the ultracompact HII region W51e2-W. The kinematic timescale of the outflow from W51e2-E is about 1000 yr, younger than the age (~5000 yr) of the ultracompact HII region W51e2-W. A large mass loss rate of ~1 x 10^{-3} M_sun yr^{-1} and a high mechanical…
The multiple protostellar system L1551 IRS5 exhibits a large-scale bipolar molecular outflow. We have studied this outflow within ~4000 AU of its driving source(s) with the SubMillimeter Array. Our CO(2-1) image at ~4" (~560 AU) resolution reveals three distinct components: 1) an X-shaped structure spanning ~20" from center with a similar symmetry axis and velocity pattern as the large-scale outflow; 2) an S-shaped structure spanning ~10" from center also with an opposite velocity pattern to the large-scale outflow; and 3) a compact central component spanning ~1.4" from center again with a sim…
We present high-resolution, long-slit spectroscopic observations of five compact ($\leq$ 10 arcsec) planetary nebulae located close to the galactic bulge region and for which no high spatial resolution images are available. The data have been drawn from the San Pedro Mártir kinematic catalogue of galactic planetary nebulae (López et al. 2012). The central star in four of these objects (M 1-32, M 2-20, M 2-31 and M 3-15) is of WR-type and the fifth object (M 2-42) has a wels type nucleus. These observations reveal the presence in all of them of a dense and thick equatorial torus-like component …
We present the results of multi-epoch very long baseline interferometry (VLBI) water (H2O) maser observations carried out with the VLBI Exploration of Radio Astrometry (VERA) toward the Cepheus A HW3d object. We measured for the first time relative proper motions of the H2O maser features, whose spatio-kinematics traces a compact bipolar outflow. This outflow looks highly collimated and expanding through ~ 280 AU (400 mas) at a mean velocity of ~ 21 km/s (~ 6 mas/yr) without taking into account the turbulent central maser cluster. The opening angle of the outflow is estimated to be ~ 30{\circ}…
Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M$_{JUP}$ BD, 2MASSJ12073347-3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [OI]$λ$6300 emission line. Follow-up observations consisting of spectra and [SII], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow PA at $\sim$ 65$^{\cir…
We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 with an angular-resolution of ~1"-5", using the Submillimeter Array (SMA), in the 12CO J=2-1, 3-2, 13CO J=2-1 and SiO J=5-4 (v=0) lines. Single-dish observations, using the SMT 10-m, were made in these lines as well as in the CO J=4-3 and SiO J-6-5 (v=0) lines. The lines profiles are very broad, showing the presence of a massive (>0.1 Msun), extreme high-velocity outflow (V~200 km/s) directed along the nebular symmetry axis derived from the HST imaging of this object. The outflow's scalar momentum far exceeds…
We present high angular resolution Submillimeter Array (SMA) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of two GLIMPSE Extended Green Objects (EGOs)--massive young stellar object (MYSO) outflow candidates identified based on their extended 4.5 micron emission in Spitzer images. The mm observations reveal bipolar molecular outflows, traced by high-velocity 12CO(2-1) and HCO+(1-0) emission, coincident with the 4.5 micron lobes in both sources. SiO(2-1) emission confirms that the extended 4.5 micron emission traces active outflows. A single dominant outflow …
A massive envelope and a strong bipolar outflow are the two main structures characterizing the youngest protostellar systems. In order to understand the physical properties of a bipolar outflow and the relationship with those of the envelope, we obtained a mosaic map covering the whole bipolar outflow of the youngest protostellar system L1157 with about $5"$ angular resolution in CO J=2-1 using the Combined Array for Research in Millimeter-wave Astronomy. By utilizing these observations of the whole bipolar outflow, we estimate its physical properties and show that they are consistent with mul…
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…
We present high spatial resolution mid-IR images of the ring of UCHII regions in W49A obtained at Gemini North, allowing us to identify the driving source of its powerful H2O maser outflow. These data also confirm our previous report that several radio sources in the ring are undetected in the mid-IR because they are embedded deep inside the cloud core. We locate the source of the water maser outflow at the position of the compact mid-IR peak of source G (source G:IRS1). This IR source is not coincident with any identified compact radio continuum source, but is coincident with a hot molecular …
CIT 6 is a carbon star in the transitional phase from the asymptotic giant branch (AGB) to the protoplanetary nebulae (pPN). Observational evidences of two point sources in the optical, circumstellar arc segments in an HC$_3$N 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 $^{12}$CO $J=2-1$ and $^{13}$CO $J=2-1$ observations of CIT 6 with the Submillimeter Array combined with the Submillimeter Tel…
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 …
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…
As outflow activity in low mass protostars is strongly connected to ac- cretion it is reasonable to expect accreting brown dwarfs to also be driving out- flows. In the last three years we have searched for brown dwarf outflows using high quality optical spectra obtained with UVES on the VLT and the technique of spectro-astrometry. To date five brown dwarf outflows have been discovered. Here the method is discussed and the results to date outlined.
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…
We present results of a series of magnetohydrodynamic (MHD) and hydro- dynamic (HD) 2.5D simulations of the morphology of outflows driven by nested wide-angle winds - i.e. winds which eminate from a central star as well as from an orbiting accretion disk. While our results are broadly relevent to nested wind systems we have tuned the parameters of the simulations to touch on issues in both Young Stellar Objects and Planetary Nebula studies. In particular our studies connect to open issues in the early evolution of Planetary Nebulae. We find that nested MHD winds exhibit marked morphological di…
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 …
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…
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 …
It is now apparent that classical T Tauri-like outflows commonly accompany the formation of young brown dwarfs. To date two optical outflows have been discovered and results presented in this paper increase this number to three. Using spectro-astrometry the origin of the LS-RCrA 1 forbidden emission lines in a blue-shifted outflow is confirmed. The non-detection of the red-shifted component of the outflow in forbidden lines, along with evidence for some separation between low and high velocity outflow components, do not support the hypothesis that LS-RCrA 1 has an edge-on accretion disk. The k…
Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle ($\sim$180$\arcdeg$) bipolar outflow ("EWBO") in a cluster forming region AFGL 5142 from low-velocity emission of the HCN (3-2) and HCO$^{+}$ (3-2) lines. This bipolar outflow is along a north-west to south-east direction with a line-of-sight flow velocity of about 3 km~s$^{-1}$ and is spatially connected to the high-velocity jet-like outflows. It seems to be a collection of low-velocity material entrained by the high-velocity outflow…
We present a comprehensive set of spatially resolved, integral field spectroscopic mapping of the Wolf-Rayet planetary nebula Th 2-A, obtained using the Wide Field Spectrograph on the Australian National University 2.3-m telescope. Velocity-resolved H$α$ channel maps with a resolution of 20 km s$^{-1}$ allow us to identify different kinematic components within the nebula. This information is used to develop a three-dimensional morpho-kinematic model of the nebula using the interactive kinematic modeling tool SHAPE. These results suggest that Th 2-A has a thick toroidal shell with an expansion …
We present ALMA follow-up observations of two massive, early-stage core candidates, C1-N & C1-S, in Infrared Dark Cloud (IRDC) G028.37+00.07, which were previously identified by their N2D+(3-2) emission and show high levels of deuteration of this species. The cores are also dark at far infrared wavelengths up to ~100 microns. We detect 12CO(2-1) from a narrow, highly-collimated bipolar outflow that is being launched from near the center of the C1-S core, which is also the location of the peak 1.3mm dust continuum emission. This protostar, C1-Sa, has associated dense gas traced by C18O(2-1) and…
Context. The previously identified source SSTB213 J041757 is a proto brown dwarf candidate in Taurus, which has two possible components A and B. It was found that component B is probably a class 0/I proto brown dwarf associated with an extended envelope. Aims. Studying molecular outflows from young brown dwarfs provides important insight into brown dwarf formation mechanisms, particularly brown dwarfs at the earliest stages such as class 0, I. We therefore conducted a search for molecular outflows from SSTB213 J041757. Methods. We observed SSTB213 J041757 with the Submillimeter Array to search…
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 $L_{\rm H_{2}} > 6~L_{\sun}$…
Characterization of the properties of young brown dwarfs are important to constraining the formation of objects at the extreme low-mass end of the IMF. While young brown dwarfs share many properties with solar-mass T Tauri stars, differences may be used as tests of how the physics of accretion/outflow and disk chemistry/dissipation depend on the mass of the central object. This article summarizes the presentations and discussions during the splinter session on 'Disks, accretion and outflows of brown dwarfs' held at the CoolStars17 conference in Barcelona in June 2012. Recent results in the fie…
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…
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 s…
We present the results of new spectral diagnostic investigations applied to high-resolution long-slit spectra of the RW Aur bipolar jet obtained with HST/STIS. The spectra include the forbidden doublets [O I] 6300,6363 Å, [S II] 6716,6731 Å, and [N II] 6548, 6583 Åthat we utilized to determine electron density, electron temperature, hydrogen ionisation fraction, total hydrogen density, radial velocity and the mass outflow rate. We were able to extract the parameters as far as 3".9 in the red- and 2".1 in the blueshifted beam. The RW Aur jet appears to be the second densest outflow from a T Tau…
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 discuss accretion and outflow properties of three very low-mass young stellar objects based on broad-band mid-resolution X-Shooter/VLT spectra. Our targets (FU TauA, 2M 1207-39, and Par-Lup3-4) have spectral types between M5 and M8, ages between 1 Myr and ~10 Myr, and are known to be accreting from previous studies. The final objective of our project is the determination of mass outflow to accretion rate for objects near or within the substellar regime as a probe for the T Tauri phase of brown dwarfs and the investigation of variability in the accretion and outflow processes.
We present Submillimeter Array (SMA) 1.35 mm subarcsecond angular resolution observations toward the LkHα 234 intermediate-mass star-forming region. The dust emission arises from a filamentary structure of $\sim$5 arcsec ($\sim$4500 au) enclosing VLA 1-3 and MM 1, perpendicular to the different outflows detected in the region. The most evolved objects are located at the southeastern edge of the dust filamentary structure and the youngest ones at the northeastern edge. The circumstellar structures around VLA 1, VLA 3, and MM 1 have radii between $\sim$200 and $\sim$375 au and masses in the $\si…
We have mapped the pre-planetary nebula IRAS 17150-3224 in 350 GHz continuum and CO J=3-2 line at an angular resolution of about 0".09 using the Atacama Large Millimeter/submillimeter Array. A continuum source is detected at the center of the nebula, elongated along the equatorial plane, likely tracing a dusty torus around the central source. Continuum emission is also detected on both sides of the central continuum source in the equatorial plane, probably resulting from interactions of collimated fast winds with envelope material in the equator. CO emission is detected along the optical lobe.…
Massive protostars generate strong radiation feedback, which may help set the mass they achieve by the end of the accretion process. Studying such feedback is therefore crucial for understanding the formation of massive stars. We report the discovery of a photoionized bipolar outflow towards the massive protostar G45.47+0.05 using high-resolution observations at 1.3 mm with the Atacama Large Millimeter/Submillimeter Array (ALMA) and at 7 mm with the Karl G. Jansky Very Large Array (VLA). By modeling the free-free continuum, the ionized outflow is found to be a photoevaporation flow with an ele…
We report multi-epoch VLBI H$_2$O maser observations towards the compact cluster of YSOs close to the Herbig Be star LkH$α$ 234. This cluster includes LkH$α$ 234 and at least nine more YSOs that are formed within projected distances of $\sim$10 arcsec ($\sim$9,000 au). We detect H$_2$O maser emission towards four of these YSOs. In particular, our VLBI observations (including proper motion measurements) reveal a remarkable very compact ($\sim$0.2 arcsec = $\sim$180 au), bipolar H$_2$O maser outflow emerging from the embedded YSO VLA 2. We estimate a kinematic age of $\sim$40 yr for this bipolar…
The protostellar outflow mechanism operates for a significant fraction of the pre-main sequence phase of a solar mass star and is thought to have a key role in star and perhaps even planet formation. This energetic mechanism manifests itself in several different forms and on many scales. Thus outflow activity can be probed in numerous different regimes from radio to X-ray wavelengths. Recent discoveries have shown that it is not only solar mass stars that launch outflows during their formation but also the sub-stellar brown dwarfs. In this article what is currently known about jets from young …
We have performed an unbiased search for outflows from young stars in Cygnus-X using 42 deg$^2$ of data from the UKIRT Widefield Infrared Survey for H$_2$ (UWISH2 survey), to identify shock-excited near-IR H$_2$ emission in the 1$-$0 S(1) 2.122 $μ$m line. We uncovered 572 outflows, of which 465 are new discoveries, increasing the number of known objects by more than 430%. This large and unbiased sample allows us to statistically determine the typical properties of outflows from young stars. We found 261 bipolar outflows and 16% of these are parsec-scale. The typical bipolar outflow is 0.45pc i…
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…
From multi-epoch adaptive optics imaging and integral field unit spectroscopy we report the discovery of an expanding and narrowly confined bipolar shell surrounding the helium nova V445 Puppis (Nova Puppis 2000). An equatorial dust disc obscures the nova remnant, and the outflow is characterised by a large polar outflow velocity of 6720 +/- 650 km/s and knots moving at even larger velocities of 8450 +/- 570 km/s. We derive an expansion parallax distance of 8.2 +/- 0.5 kpc and deduce a pre-outburst luminosity of the underlying binary of log L/L_Sun = 4.34 +/- 0.36. The derived luminosity sugge…
We present narrow-band optical and near-IR imaging and optical long-slit spectroscopic observations of Hu1-2, a Galactic planetary nebula (PN) with a pair of [N II]-bright, fast-moving (> 340 km/s) bipolar knots. Intermediate-dispersion spectra are used to derive physical conditions and abundances across the nebula, and high-dispersion spectra to study the spatio-kinematical structure. Generally Hu1-2 has high He/H (~0.14) and N/O ratios (~0.9), typical of Type I PNe. On the other hand, its abundances of O, Ne, S, and Ar are low as compared with the average abundances of Galactic bulge and dis…
An investigation of the magnetospheric accretion and outflow signatures in sub-stellar objects is a natural extension of similar studies conducted on classical T Tauri stars (CTTS), and helps understand if brown dwarfs (BDs) follow the same formation mechanism as stars. Over the past decade, evidence for accretion in very low-mass stars (VLMs) and BDs has been accumulated using various techniques, which indicates that the overall accretion characteristics are continuous across the sub-stellar boundary. Outflow activity in VLMs and BDs has been confirmed based on spectro-astrometry of forbidden…
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…
We report the detection of a molecular outflow driven by the brown dwarf binary FU Tau. Using the IRAM 30 m telescope we observed the $^{12}$CO(2-1) (CO) emission in the vicinity of FU Tau and detected a bipolar outflow by examining the wings of the CO(2-1) line as we moved away from the source position. An integrated map of the wing emission between 3 kms$^{-1}$ and 5 kms$^{-1}$ reveals a blue-shifted lobe at a position of $\sim$ 20 \arcsec\ from the FU Tau system and at a position angle of $\sim$ 20$^{\circ}$. The beam size of the observations is $11\arcsec$\ hence it is not possible to dist…
NGC 6337 is a member of the rare group of planetary nebulae where a close binary nucleus has been identified. The nebula's morphology and emission line profiles are both unusual, particularly the latter. We present a thorough mapping of spatially resolved, long-slit echelle spectra obtained over the nebula that allows a detailed characterization of its complex kinematics. This information, together with narrow band imagery is used to produce a three dimensional model of the nebula using the code SHAPE. The 3-D model yields a slowly expanding toroid with large density fluctuations in its periph…
We perform two-dimensional axially symmetric radiation-hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, the ratio of ejection to accretion rates, and the strength of the wide angle disk wind component. The star formation efficiency, i.e. the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects: First, the protostar grows slower with a lower luminosity at any given time, l…
Over the last number of years spectroscopic studies have strongly supported the assertion that protostellar accretion and outflow activity persists to the lowest masses. In this paper we present the results of our latest investigation of brown dwarf (BD) outflow activity and report on the discovery of two new outflows. Here ISO-Oph 32 is shown to drive a blue-shifted outflow with a radial velocity of 10-20 km/s and spectro-astrometric analysis constrains the position angle of this outflow to 240 +/- 7 degrees. The BD candidate ISO-Cha1 217 is found to have a bipolar outflow bright in several k…
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）
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 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…
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$O emission lines. This represents the first detection of KCl in an oxygen-rich AGB …
We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J=2-1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M_J, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf po…
Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry, as well as the kinematical information allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. We aim at determining the spatial distribution of different species, of different chemical origin. This is to examine the physical processes in play in the observed reg…
As the number of observed brown dwarf outflows is growing it is important to investigate how these outflows compare to the well studied jets from young stellar objects. A key point of comparison is the relationship between outflow and accretion activity and in particular the ratio between the mass outflow and accretion rates ($\dot{M}_{out}$/$\dot{M}_{acc}$). The brown dwarf candidate ISO-ChaI 217 was discovered by our group, as part of a spectro-astrometric study of brown dwarfs, to be driving an asymmetric outflow with the blue-shifted lobe having a position angle of $\sim$ 20$^{\circ}$. The…
Ou4 is a recently discovered bipolar outflow with a projected size of more than one degree in the plane of the sky. It is apparently centred on the young stellar cluster -whose most massive representative is the triple system HR8119- inside the HII region Sh 2-129. The driving source, the nature, and the distance of Ou4 are not known. Deep narrow-band imagery of the whole nebula at arcsec resolution was obtained to study its morphology. Long-slit spectroscopy of the tips of the bipolar lobes was secured to determine the gas ionization mechanism, physical conditions, and line-of-sight velocitie…
