We present a near-infrared study of accretion and outflow activity in 6 Class 0/I proto-brown dwarfs (proto-BDs) using VLT/SINFONI spectroscopy and spectro-imaging observations. The spectra show emission in several [FeII] and H$_{2}$ lines associated with jet/outflow activity, and in the accretion diagnostics of Pa$β$ and Br$γ$ lines. The peak velocities of the [FeII] lines ($>$100 km s$^{-1}$) are higher than the H$_{2}$ lines. The Class 0 proto-BDs show strong emission in the H$_{2}$ lines but the [FeII] lines are undetected, while the Class I objects show emission in both [FeII] and H$_{2}$ lines, suggesting an evolutionary trend in the jets from a molecular to an ionic composition. Extended emission with knots is seen in the [FeII] and H$_{2}$ spectro-images for 3 proto-BDs, while the rest show compact morphologies with a peak on-source. The accretion rates for the proto-BDs span the range of (2$\times$10$^{-6}$ -- 2$\times$10$^{-8}$) Msun yr$^{-1}$, while the mass loss rates are in the range of (4$\times$10$^{-8}$ -- 5$\times$10$^{-9}$) Msun yr$^{-1}$. These rates are within the range measured for low-mass protostars and higher than Class II brown dwarfs. We find a similar range in the jet efficiency for proto-BDs as measured in protostars. We have performed a study of the Brackett decrement from the Br7-Br19 lines detected in the proto-BDs. The upper Brackett lines of Br13-Br19 are only detected in the earlier stage systems. The ratios of the different Brackett lines with respect to the Br$γ$ line intensity are consistent with the ratios expected from Case B recombination.
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.
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…
In this letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A $\sim$ 0\farcs5 blue-shifted outflow is detected in both H$_{2}$ and [Fe II] lines at V$_{sys}$ = (-35~$\pm$ 2)~km~s$^{-1}$ and V$_{sys}$ = (-51~$\pm$ 5)~km~s$^{-1}$ respectively. In addition, slower ($\sim$ $\pm$~10~km~s$^{-1}$) H$_{2}$ emission is detected out to $<$ 5\farcs4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H$_{2}$ emi…
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…
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…
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.
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 present ALMA $^{12}$CO (2-1), $^{13}$CO (2-1), C$^{18}$O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of $\sim$6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that $^{12}$CO emission is tracing an extended ($\sim$1000 au) molecular outflow and a bright shock k…
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…
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…
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 be…
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$^{\cir…
Over the last number of years spectroscopic studies have strongly supported the assertion that protostellar accretion and outflow activity persists to the lowest masses. In this paper we present the results of our latest investigation of brown dwarf (BD) outflow activity and report on the discovery of two new outflows. Here ISO-Oph 32 is shown to drive a blue-shifted outflow with a radial velocity of 10-20 km/s and spectro-astrometric analysis constrains the position angle of this outflow to 240 +/- 7 degrees. The BD candidate ISO-Cha1 217 is found to have a bipolar outflow bright in several k…
We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J=2-1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M_J, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf po…
As the number of observed brown dwarf outflows is growing it is important to investigate how these outflows compare to the well studied jets from young stellar objects. A key point of comparison is the relationship between outflow and accretion activity and in particular the ratio between the mass outflow and accretion rates ($\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…
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…
On the basis of various data such as ALMA, JVLA, Chandra, {\it Herschel}, and {\it Spitzer}, we confirmed that two protostellar candidates in Oph-A are bona fide protostars or proto-brown dwarfs (proto-BDs) in extremely early evolutionary stages. Both objects are barely visible across infrared (IR, i.e., near-IR to far-IR) bands. The physical nature of the cores is very similar to that expected in first hydrostatic cores (FHSCs), objects theoretically predicted in the evolutionary phase prior to stellar core formation with gas densities of $\sim$ 10$^{11-12}$ cm$^{-3}$. This suggests that the …
The evolution of protostellar outflows is investigated under different mass accretion rates in the range $\sim10^{-5}-10^{-2} {\rm M}_\odot$ yr$^{-1}$ with three-dimensional magnetohydrodynamic simulations. A powerful outflow always appears in strongly magnetized clouds with $B_0 \gtrsim B_{\rm 0, cr}$ $=10^{-4} (M_{\rm cl}/100 {\rm M}_\odot){\rm G}$, where $M_{\rm cl}$ is the cloud mass. When a cloud has a weaker magnetic field, the outflow does not evolve promptly with a high mass accretion rate. In some cases with moderate magnetic fields $B_0$ slightly smaller than $B_{\rm 0,cr}$, the outf…
The bipolar outflow associated with the Class 0 low-mass protostellar source (IRAS 18148-0440) in L483 has been studied in the CCH and CS line emission at 245 and 262 GHz, respectively. Sub-arcsecond resolution observations of these lines have been conducted with ALMA. Structures and kinematics of the outflow cavity wall are investigated in the CS line, and are analyzed by using a parabolic model of an outflow. We constrain the inclination angle of the outflow to be from 75 degree to 90 degree, i.e. the outflow is blowing almost perpendicular to the line of sight. Comparing the outflow paramet…
We report on Submillimeter Array observations of the 870 micron continuum and CO(3-2), 13CO(2-1) and C18O(2-1) line emission of a faint object, SMM2E, near the driving source of the HH797 outflow in the IC348 cluster. The continuum emission shows an unresolved source for which we estimate a mass of gas and dust of 30 Mjup, and the CO(3-2) line reveals a compact bipolar outflow centred on SMM2E, and barely seen also in 13CO(2-1). In addition, C18O(2-1) emission reveals hints of a possible rotating envelope/disk perpendicular to the outflow, for which we infer a dynamical mass of ~16 Mjup. In or…
During the early phases of low-mass star formation, episodic accretion causes the ejection of high-velocity outflow bullets, which carry a fossil record of the driving protostar's accretion history. We present 44 SPH simulations of $1\,\mathrm{M}_{\odot}$ cores, covering a wide range of initial conditions, and follow the cores for five free-fall times. Individual protostars are represented by sink particles, and the sink particles launch episodic outflows using a subgrid model. The Optics algorithm is used to identify individual episodic bullets within the outflows. The parameters of the overa…
The accretion history of protostars remains widely mysterious even though it represents one of the best ways to understand the protostellar collapse that leads to the formation of stars. Molecular outflows are here used to characterize the protostellar accretion phase in W43-MM1. The W43-MM1 protocluster host a sufficient number of protostars to statistically investigate molecular outflows in a single, homogeneous region. We used the CO(2-1) and SiO(5-4) line datacubes, taken as part of an ALMA mosaic with a 2000 AU resolution, to search for protostellar outflows, evaluate the influence that t…
Brown dwarf formation and star formation efficiency are studied using a nested grid simulation that covers five orders of magnitude in spatial scale (10^4 - 0.1AU). Starting with a rotating magnetized compact cloud with a mass of 0.22 M_sun, we follow the cloud evolution until the end of main accretion phase. Outflow of about 5 km/s emerges about 100 yr before the protostar formation and does not disappear until the end of the calculation. The mass accretion rate declines from 10^-6 M_sun/yr to 10^-8 - 10^-12 M_sun/yr in a short time (about 10^4 yr) after the protostar formation. This is becau…
This paper presents our observational attempts to precisely measure the central mass of a proto-brown dwarf candidate, L328-IRS, in order to investigate whether L328-IRS is in the substellar mass regime. Observations were made for the central region of L328-IRS with the dust continuum and CO isotopologue line emission at ALMA band 6, discovering the detailed outflow activities and a deconvolved disk structure of a size of $\sim$87 AU $\times$ 37 AU. We investigated the rotational velocities as a function of the disk radius, finding that its motions between 130 AU and 60 AU are partially fitted…
We report the results of spectroscopic mapping observations carried out toward protostellar outflows in the BHR71, L1157, L1448, NGC 2071, and VLA 1623 molecular regions using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope. These observations, covering the 5.2 - 37 micron spectral region, provide detailed maps of the 8 lowest pure rotational lines of molecular hydrogen and of the [SI] 25.25 micron and [FeII] 26.0 micron fine structure lines. The molecular hydrogen lines, believed to account for a large fraction of the radiative cooling from warm molecular gas that has been heat…
We report on an Atacama Large Millimeter/submillimeter Array (ALMA) study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO (J=2-1) images have an angular resolution of ~1'' (~250 au) and show high-velocity blueshifted (>70 km s-1) and redshifted (>50 km s-1) emissions which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow …
We have imaged 15 molecular-line emissions and the dust continuum emission around the Class 0 protostellar source, IRAS 15398-3359, with ALMA. The outflow structure is mainly traced by the H2CO (K_a=0 and 1), CCH, and CS emissions. These lines also trace the disk/envelope structure around the protostar. The H2CO (K_a=2 and 3), CH3OH, and SO emissions are concentrated toward the protostar, while the DCN emission is more extended around the protostar. We have performed the principal component analysis (PCA) for these distributions on the two different scales, the outflow and the disk/envelope st…
Recently it has become apparent that proto-stellar-like outflow activity extends to the brown dwarf (BD) mass regime. While the presence of accretion appears to be the common ingredient in all objects known to drive jets fundamental questions remain unanswered. The more prominent being the exact mechanism by which jets are launched, and whether this mechanism remains universal among such a diversity of sources and scales. To address these questions we have been investigating outflow activity in a sample of protostellar objects that differ considerably in mass and mass accretion rate. Central t…
We study protostellar envelope and outflow evolution using Hubble Space Telescope NICMOS or WFC3 images of 304 protostars in the Orion Molecular clouds. These near-IR images resolve structures in the envelopes delineated by the scattered light of the central protostars with 80 AU resolution and they complement the 1.2-870 micron spectral energy distributions obtained with the Herschel Orion Protostar Survey program (HOPS). Based on their 1.60 micron morphologies, we classify the protostars into five categories: non-detections, point sources without nebulosity, bipolar cavity sources, unipolar …
We investigate the alignment between outflow axes in nine of the youngest binary/multiple systems in the Perseus Molecular Cloud. These systems have typical member spacing larger than 1000 AU. For outflow identification, we use 12CO(2-1) and 12CO(3-2) data from a large survey with the Sub- millimeter Array: Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES). The distribution of outflow orientations in the binary pairs is consistent with random or preferentially anti-aligned distributions, demonstrating that these outflows are misaligned. This result suggests that these …
Observational signatures of infalling envelopes and outflowing material in early stages of protostellar evolution, and at small radii from the protostar, are essential to progress in the understanding of the mass-accretion process in star formation. In this letter, we report a detailed study of the accretion and outflow structure around a protostar in the well-known high-mass star-forming region AFGL 5142. We focus on the mm source MM-1, which exhibits hot-core chemistry, radio continuum emission, and strong water and methanol masers. Remarkably, our Very Long Baseline Interferometry (VLBI) ob…
Emission from protostars at centimeter radio wavelengths has been shown to trace the free-free emission arising from ionizing shocks as a result of jets and outflows driven by protostars. Therefore, measuring properties of protostars at radio frequencies can provide valuable insights into the nature of their outflows and jets. We present a C-band (4.1 cm and 6.4 cm) survey of all known protostars (Class 0 and Class I) in Perseus as part of the VLA Nascent Disk and Multiplicity (VANDAM) Survey. We examine the known correlations between radio flux density and protostellar parameters such as bolo…
The evolution of protostellar outflow is investigated with resistive magneto-hydrodynamic nested-grid simulations that cover a wide range of spatial scales (\sim 1AU - 1pc). We follow cloud evolution from the pre-stellar core stage until the infalling envelope dissipates long after the protostar formation. We also calculate protostellar evolution to derive protostellar luminosity with time-dependent mass accretion through a circumstellar disk. The protostellar outflow is driven by the first core prior to protostar formation and is directly driven by the circumstellar disk after protostar forma…
A Search for Dust in the Outflow of the HH212 Class 0 Protostellar System
U.S. National Science Foundation（美国国家科学基金会）；National Radio Astronomy Observatory（国家射电天文台）；Chalmers University of Technology（查尔姆斯理工大学）；Department of Astronomy, University of Virginia（弗吉尼亚大学天文学系）；Institute of Astronomy, Department of Physics, National Tsing Hua University（国立清华大学物理学院天文学研究所）；Department of Physics, University of Virginia（弗吉尼亚大学物理学系）
The loss of mass from protostars, in the form of a jet or outflow, is a necessary counterpart to protostellar mass accretion. Outflow ejection events probably vary in their velocity and/or in the rate of mass loss. Such `episodic' ejection events have been observed during the Class 0 protostellar phase (the early accretion stage), and continue during the subsequent class I phase that marks the first one million years of star formation. Previously observed episodic-ejection sources were relatively isolated; however, the most common sites of star formation are clusters. Outflows link protostars …
We investigate protostellar outflow evolution, gas entrainment, and star formation efficiency using radiation-hydrodynamic simulations of isolated, turbulent low-mass cores. We adopt an X-wind launching model, in which the outflow rate is coupled to the instantaneous protostellar accretion rate and evolution. We vary the outflow collimation angle from $θ$=0.01-0.1 and find that even well collimated outflows effectively sweep up and entrain significant core mass. The Stage 0 lifetime ranges from 0.14-0.19 Myr, which is similar to the observed Class 0 lifetime. The star formation efficiency of t…
We present SOFIA/FIFI-LS observations of three Class 0 and one Class I outflows (Cep E, HH 1, HH 212, and L1551 IRS5) in the far-infrared [O I]63mum and [O I]145mum transitions. Spectroscopic [O I]63mum maps enabled us to infer the spatial extent of warm, low-excitation atomic gas within these protostellar outflows. If proper shock conditions prevail, the instantaneous mass-ejection rate is directly connected to the [O I]63mum luminosity. In order to unravel evolutionary trends, we analysed a set of 14 Class 0/I outflow sources that were spatially resolved in the [O I]63mum emission. We compar…
We present and discuss \emph{Spitzer} and near-infrared H$_{2}$ observations of a new bi-polar protostellar outflow in the Rosette Molecular Cloud. The outflow is seen in all four IRAC bands and partially as diffuse emission in the MIPS 24 $μ$m band. An embedded MIPS 24 $μ$m source bisects the outflow and appears to be the driving source. This source is coincident with a dark patch seen in absorption in the 8 $μ$m IRAC image. \emph{Spitzer} IRAC color analysis of the shocked emission was performed from which thermal and column density maps of the outflow were constructed. Narrow-band near-infr…
We carry out radiation hydrodynamical simulations of the formation of massive stars in the super-Eddington regime including both their radiative feedback and protostellar outflows. The calculations start from a prestellar core of dusty gas and continue until the star stops growing. The accretion ends when the remnants of the core are ejected, mostly by the force of the direct stellar radiation in the polar direction and elsewhere by the reradiated thermal infrared radiation. How long the accretion persists depends on whether the protostellar outflows are present. We set the mass outflow rate t…
HH 900 is a peculiar protostellar outflow emerging from a small, tadpole-shaped globule in the Carina nebula. Previous Hα imaging with HST/ACS showed an ionized outflow with a wide opening angle that is distinct from the highly collimated structures typically seen in protostellar jets. We present new narrowband near-IR [Fe II] images taken with the Wide Field Camera 3 on the Hubble Space Telescope that reveal a remarkably different structure than Hα. In contrast to the unusual broad Hα outflow, the [Fe II] emission traces a symmetric, collimated bipolar jet with the morphology and kinematics t…
We discover that the very young very low-mass star ISO143 (M5) is driving an outflow based on spectro-astrometry of forbidden [SII] emission lines at 6716A and 6731A observed in UVES/VLT spectra. This adds another object to the handful of brown dwarfs and very low-mass stars (M5-M8) for which an outflow has been confirmed and which show that the T Tauri phase continues at very low masses. We find the outflow of ISO143 to be intrinsically asymmetric and the accretion disk to not obscure the outflow, as only the red outflow component is visible in the [SII] lines. ISO143 is only the third T Taur…
Protostellar outflows provide a means to probe the accretion process of forming stars and their ability to inject energy into their surroundings. However, conclusions based on outflow observations depend upon the degree of accuracy with which their properties can be estimated. We examine the quality of Atacama Large Millimeter/submillimeter Array (ALMA) observations of protostellar outflows by producing synthetic $^{12}$CO(1-0) and $^{13}$CO(1-0) observations of numerical simulations. We use various ALMA configurations, observational parameters, and outflow inclinations to assess how accuratel…
Sub-arcsecond ($0.^{\prime\prime}5$) images of H$_2$CO and CCH line emission have been obtained in the $0.8$ mm band toward the low-mass protostar IRAS 15398-3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about $20^\circ$, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast t…
In star formation, magnetic fields act as a cosmic angular momentum extractor that increases mass accretion rates onto protostars and in the process, creates spectacular outflows. However, recently it has been argued that this magnetic brake is so strong that early protostellar disks -- the cradles of planet formation -- cannot form. Our three-dimensional numerical simulations of the early stages of collapse (\lesssim 10^5 yr) of overdense star--forming clouds form early outflows and have magnetically regulated and rotationally dominated disks (inside 10 AU) with high accretion rates, despite …
Observations of dense molecular gas lie at the basis of our understanding of the density and temperature structure of protostellar envelopes and molecular outflows. We aim to characterize the properties of the protostellar envelope, molecular outflow and surrounding cloud, through observations of high excitation molecular lines within a sample of 16 southern sources presumed to be embedded YSOs. Observations of submillimeter lines of CO, HCO+ and their isotopologues, both single spectra and small maps were taken with the FLASH and APEX-2a instruments mounted on APEX to trace the gas around the…
Protostellar feedback, both radiation and bipolar outflows, dramatically affects the fragmentation and mass accretion from star-forming cores. We use ORION, an adaptive mesh refinement gravito-radiation-hydrodynamics code, to simulate the formation of a cluster of low-mass stars, including both radiative transfer and protostellar outflows. We ran four simulations to isolate the individual effects of radiation feedback and outflow feedback as well as the combination of the two. Outflows reduce protostellar masses and accretion rates each by a factor of three and therefore reduce protostellar lu…
Beyond the main sequence solar type stars undergo extensive mass loss, providing an environment where planet and brown dwarf companions interact with the surrounding material. To examine the interaction of substellar mass objects embedded in the stellar wind of an asymptotic giant branch (AGB) star, three dimensional hydrodynamical simulations at high resolution have been calculated utilizing the FLASH adaptive mesh refinement code. Attention is focused on the perturbation of the substellar mass objects on the morphology of the outflowing circumstellar matter. In particular, we determine the p…
We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si II], [Fe II] and [S I] line emission, and 11 of these in far-infrared [O I] emission. We use the results to derive their mass outflow rates. Thereby we observe a strong correlation of mass outflow rates with bolometric luminosity, and with the inferred mass accretion rates of the central objects, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass-flow rates, the different classes of young stellar objects lie in the sequenc…
We report new results on outflow and infall in the star forming cores W3-SE SMA-1 and SMA-2 based on analysis of $\sim2.5\arcsec$ resolution observations of the molecular lines HCN(3-2), HCO$^+$(3-2), N$_2$H$^+$(3-2) and CH$_3$OH(5$_{2,3}-4_{1,3}$) with the Submillimeter Array. A high-velocity bipolar outflow originating from the proto-stellar core SMA-1 was observed in the HCN(3-2) line, with a projected outflow axis in position angle 48$\arcdeg$. The detection of the outflow is confirmed from other molecular lines. An inverse P-Cygni profile in the HCN(3-2) line toward SMA-1 suggests that at…
The formation and evolution of a circumstellar disk in magnetized cloud cores is investigated from prestellar core stage until sim 10^4 yr after protostar formation. In the circumstellar disk, fragmentation first occurs due to gravitational instability in a magnetically inactive region, and substellar-mass objects appear. The substellar-mass objects lose their orbital angular momenta by gravitational interaction with the massive circumstellar disk and finally fall onto the protostar. After this fall, the circumstellar disk increases its mass by mass accretion and again induces fragmentation. T…
We examine emission from a young protostellar object (YPO) with three-dimensional ideal MHD simulations and three-dimensional non-local thermodynamic equilibrium (non-LTE) line transfer calculations, and show the first results. To calculate the emission field, we employed a snapshot result of an MHD simulation having young bipolar outflows and a dense protostellar disk (a young circumstellar disk) embedded in an infalling envelope. Synthesized line emission of two molecular species (CO and SiO) show that subthermally excited SiO lines as a high density tracer can provide a better probe of the …
We perform a three-dimensional nested-grid radiation magneto-hydrodynamics (RMHD) simulation with self-gravity to study the early phase of the low-mass star formation process from a rotating molecular cloud core to a first adiabatic core just before the second collapse begins. Radiation transfer is handled with the flux-limited diffusion approximation, operator-splitting and implicit time-integrator. In the RMHD simulation, the outer region of the first core attains a higher entropy and the size of first core is larger than that in the magnetohydrodynamics simulations with the barotropic appro…
Forbidden emission lines in protoplanetary disks are a key diagnostic in studies of the evolution of the disk and the host star. We report spatially resolved emission lines, [OI] 6300, 6363, [NII] 6548, 6583, H$α$, and [SII] 6716, 6730 Angstrom that are believed to be associated with jets and magnetically driven winds in the inner disks. Observations were carried out with the optical integral field spectrograph of the Multi Unit Spectroscopic Explorer (MUSE), at the Very Large Telescope (VLT). With a resolution of 0.025 X 0.025 arcsec$^{2}$, we aim to derive the position angle of the outflow/j…
