Using three-dimensional magnetohydrodynamics simulations, the driving of protostellar jets is investigated in different star-forming cores with the parameters of magnetic field strength and mass accretion rate. Powerful high-velocity jets appear in strongly magnetized clouds when the mass accretion rate onto the protostellar system is lower than $\dot{M} \lesssim 10^{-3}\,{\rm M}_\odot$ yr$^{-1}$. On the other hand, even at this mass accretion rate range, no jets appear for magnetic fields of prestellar clouds as weak as $μ_0 \gtrsim 5$--$10$, where $μ_0$ is the mass-to-flux ratio normalized by the critical value $(2πG^{1/2})^{-1}$. For $\dot{M}\gtrsim 10^{-3}\,{\rm M}_\odot$ yr$^{-1}$, although jets usually appear just after protostar formation independent of the magnetic field strength, they soon weaken and finally disappear. Thus, they cannot help drive the low-velocity outflow when there is no low-velocity flow just before protostar formation. As a result, no significant mass ejection occurs during the early mass accretion phase either when the prestellar cloud is weaky magnetized or when the mass accretion rate is very high. Thus, protostars formed in such environments would trace different evolutionary paths from the normal star formation process.
The formation of stars is usually accompanied by the launching of protostellar outflows. Observations with the Atacama Large Millimetre/sub-millimetre Array (ALMA) will soon revolutionalise our understanding of the morphologies and kinematics of these objects. In this paper, we present synthetic ALMA observations of protostellar outflows based on numerical magnetohydrodynamic collapse simulations. We find significant velocity gradients in our outflow models and a very prominent helical structure within the outflows. We speculate that the disk wind found in the ALMA Science Verification Data of…
Young stars are associated with prominent outflows of molecular gas. The ejection of gas via these outflows is believed to remove angular momentum from the protostellar system, thus permitting young stars to grow by accretion of material from the protostellar disk. The underlying mechanism for outflow ejection is not yet understood, but is believed to be closely linked to the protostellar disk. Assorted scenarios have been proposed to explain protostellar outflows; the main difference between these models is the region where acceleration of material takes place: close to the protostar itself (…
We identify 45 protostellar outflows in CO maps of the Orion A giant molecular cloud from the CARMA-NRO Orion survey. Our sample includes 11 newly detected outflows. We measure the mass and energetics of the outflows, including material at low-velocities by correcting for cloud contributions. The total momentum and kinetic energy injection rates of outflows is comparable to the turbulent dissipation rate of the cloud. We also compare the outflow position angles to the orientation of C$^{18}$O filaments. We find that the full sample of outflows is consistent with being randomly oriented with re…
Protostellar outflow is a prominent process that accompanies the formation of stars. It is generally agreed that wide-angled protostellar outflows come from the interaction between the wind from a forming star and the ambient gas. However, it is still unclear how the interaction takes place. In this work, we theoretically investigate the possibility that the outflow results from interaction between the wind and the ambient gas in the form of turbulent entrainment. In contrast to the previous models, turbulent motion of the ambient gas around the protostar is taken into account. In our model, t…
The star-forming efficiency of dense gas is thought to be set within cores by outflow and radiative feedback. We use magneto-hydrodynamic simulations to investigate the relation between protostellar outflow evolution, turbulence and star formation efficiency. We model the collapse and evolution of isolated dense cores for $\gtrsim$ 0.5 Myr including the effects of turbulence, radiation transfer, and both radiation and outflow feedback from forming protostars. We show that outflows drive and maintain turbulence in the core environment even with strong initial fields. The star-formation efficien…
We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects sign…
We present the first 2.5-D MHD simulations of protostellar jets that include both the region in which the jet is launched magnetocentrifugally at scale lengths $<0.1$ AU, and where the propagating jet is observed at scale lengths $>10^3$ AU. These simulations, performed with the new AMR-MHD code AZEuS, reveal interesting relationships between conditions at the disc surface, such as the magnetic field strength, and direct observables such as proper motion, jet rotation, jet radius, and mass flux. By comparing these quantities with observed values, we present direct numerical evidence that the m…
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…
With the recent recognition of a second, distinctive class of molecular outflows, namely the explosive ones not directly connected to the accretion-ejection process in the star formation, a juxtaposition of the morphological and kinematic properties of both classes is warranted. By applying the same method used in Zapata et al. (2009), and using $^{12}$CO(J=2-1) archival data from the Submillimeter Array (SMA), we contrast two well known explosive objects, Orion KL and DR21, to HH211 and DG Tau B, two flows representative of classical low-mass protostellar outflows. At the moment there are onl…
The dense molecular clump P1 in the infrared dark cloud (IRDC) complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array (SMA) observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here we present the Expanded Very Large Array (EVLA) spectral line observations toward P1 in the NH3 (J,K) = (1,1), (2,2), (3,3) lines, as well as H2O and class I CH3OH masers. Multiple NH3 transitions reveal the heated gas widely spread in the 1 …
For a binary protostellar outflow system in which its members are located so close to each other (the separation being smaller than the addition of the widths of the flows) and with large opening angles, the collision seems unavoidable regardless of the orientation of the outflows. This is in contrast to the current observational evidence of just a few regions with indications of colliding outflows. Here, using sensitive observations of the Atacama Large Millimeter/Submillimeter Array (ALMA), we report resolved images of carbon monoxide (CO) towards the binary flows associated with the BHR71 p…
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…
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 present results of 1.3 mm dust polarization observations toward 16 nearby, low-mass protostars, mapped with ~2.5" resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotation axes of circumstellar disks, and that the outflows have not disrupted the fields in the surrounding m…
Molecular outflows driven by protostellar cluster members likely impact their surroundings and contribute to turbulence, affecting subsequent star formation. The very young Serpens South cluster consists of a particularly high density and fraction of protostars, yielding a relevant case study for protostellar outflows and their impact on the cluster environment. We combined CO $J=1-0$ observations of this region using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Institut de Radioastronomie Millimétrique (IRAM) 30 m single dish telescope. The combined map allows …
Molecular outflows are often detected originating from both protostellar and extragalactic sources. Studies of low-mass, isolated high-mass, and extragalactic sources reveal scaling relations connecting the force carried by an outflow and the properties of the source that drives it. The aim of this work is to examine the effects of clustered star formation on the protostellar outflows and their scaling relations and to explore the possibility that outflows varying greatly scale and energetics are consistent with being launched by the same physical processes. High-angular resolution CO J = 3-2 …
We present new Submillimeter Array (SMA) observations of CO(2-1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orientation of the local filaments as derived from $Herschel$ observations. We find that the relative angles between outflows and filaments are inconsistent with purely parallel or purely perpendicular distributions. Instead, the observed distribution of o…
We present sub-arcsecond resolution HCN (4-3) and CO (3-2) observations made with the Submillimeter Array (SMA), toward an extremely young intermediate-mass protostellar core, MMS 6-main, located in the Orion Molecular Cloud 3 region (OMC-3). We have successfully imaged a compact molecular outflow lobe (~1500 AU) associated with MMS6-main, which is also the smallest molecular outflow ever found in the intermediate-mass protostellar cores. The dynamical time scale of this outflow is estimated to be <100 yr. The line width dramatically increases downstream at the end of the molecular outflow (Δv…
Protostellar Outflows Shed Light on the Dominant Close Companion Star Formation Pathways
University of Illinois（伊利诺伊大学）；National Radio Astronomy Observatory（国家射电天文台）；Yale University（耶鲁大学）；NSF-Simons AI Institute for the Sky (SkAI)（NSF-Simons天空人工智能研究所）；Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)（天体物理跨学科探索与研究中心）；NRC Herzberg Astronomy and Astrophysics（NRC赫茨伯格天文学与天体物理学研究所）；University of Victoria（维多利亚大学）；Space Science Institute（太空科学研究所）；University of Virginia（弗吉尼亚大学）
The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momenta. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce $^{12}$CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. T…
The proper motions of the three stars ejected from Orion's OMC1 cloud core are combined with the requirement that their center of mass is gravitationally bound to OMC1 to show that radio source I (Src I) is likely to have a mass around 15 Solar masses consistent with recent measurements. Src I, the star with the smallest proper motion, is suspected to be either an AU-scale binary or a protostellar merger remnant produced by a dynamic interaction ~550 years ago. Near-infrared 2.2 um images spanning ~21 years confirm the ~55 km/s motion of `source x' (Src x) away from the site of stellar ejectio…
We present results of hydrodynamic simulations of massive star forming regions with and without protostellar jets. We show that jets change the normalization of the stellar mass accretion rate, but do not strongly affect the dynamics of star formation. In particular, $M_*(t) \propto f^2 (t-t_*)^2$ where $f = 1 - f_{\rm jet}$ is the fraction of mass accreted onto the protostar, $f_{\rm jet}$ is the fraction ejected by the jet, and $(t-t_*)^2$ is the time elapsed since the formation of the first star. The star formation efficiency is nonlinear in time. We find that jets have only a small effect …
The initial mass function (IMF) of stars is a key quantity affecting almost every field of astrophysics, yet it remains unclear what physical mechanisms determine it. We present the first runs of the STARFORGE project, using a new numerical framework to follow the formation of individual stars in giant molecular clouds (GMCs) using the GIZMO code. Our suite include runs with increasingly complex physics, starting with isothermal ideal magnetohydrodynamic (MHD) and then adding non-isothermal thermodynamics and protostellar outflows. We show that without protostellar outflows the resulting stell…
G351.16+0.70 is a relatively well-studied High Mass Star Forming Region with at least two main bipolar outflow structures originating from an OB embedded star and multiple IR cores. Using high-resolution and large bandwidth SMA observations, we studied its molecular content to probe the emission of iCOMs which could be related to the bipolar outflows or their jets. We analyzed the emission spectra in the 1mm band within 8 GHz bandwidth coverage, from 216.75 to 220.75 GHz, and from 228.75 to 232.75 GHz. Employing the LTE approximation using the XCLASS software, we identified 260 emission lines …
Context. Understanding the conditions in which stars and stellar clusters form is of great importance. In particular the role that stellar feedback may have is still hampered by large uncertainties. Aims. We investigate the role played by ionising radiation and protostellar outflows during the formation and evolution of a stellar cluster. To self-consistently take into account gas accretion, we start with clumps of tens of parsecs in size. Methods. Using an adaptive mesh refinement code, we run magneto-hydrodynamical numerical simulations aiming at describing the collapse of massive clumps wit…
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…
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…
We report ALMA observations of a one-sided, high-velocity ($\sim$80 km s$^{-1}$) CO($J = 2 \rightarrow 1$) jet powered by the intermediate-mass protostellar source Serpens SMM1-a. The highly collimated molecular jet is flanked at the base by a wide-angle cavity; the walls of the cavity can be seen in both 4 cm free-free emission detected by the VLA and 1.3 mm thermal dust emission detected by ALMA. This is the first time that ionization of an outflow cavity has been directly detected via free-free emission in a very young, embedded Class 0 protostellar source that is still powering a molecular…
We present Submillimeter Array (SMA) polarization observations of the CO $J$ = 3--2 line toward the NGC1333 IRAS 4A. The CO Stokes $I$ maps at an angular resolution of $\sim$1$\arcsec$ reveal two bipolar outflows from the binary sources of the NGC 1333 IRAS 4A. The kinematic features of the CO emission can be modeled by wind-driven outflows at $\sim$ 20$\arcdeg$ inclined from the plane of the sky. Close to the protostars the CO polarization, at an angular resolution of $\sim$$2\farcs3$, has a position angle approximately parallel to the magnetic field direction inferred from the dust polarizat…
Protostellar outflows are one of the most outstanding features of star formation. Observational studies over the last several decades have successfully demonstrated that outflows are ubiquitously associated with low- and high-mass protostars in the solar-metallicity Galactic conditions. However, the environmental dependence of protostellar outflow properties is still poorly understood, particularly in the low-metallicity regime. Here we report the first detection of a molecular outflow in the Small Magellanic Cloud with 0.2 $Z_{\odot}$, using Atacama Large Millimeter/submillimeter Array observ…
Young low-mass protostars undergo short phases of high accretion and outburst activity leading to lumpy outflows. Recent observations have shown that the position-velocity and mass-velocity diagrams of such outflows exhibit individual bullet-like features; some of these bullets subscribe to a `Hubble Law' velocity relation, and others are manifest as `Hubble wedges'. In order to explore the origin of these features, we have developed a new episodic outflow model for the SPH code {\sc gandalf}, which mimics the accretion and ejection behaviour of FU Ori type stars. We apply this model to simula…
Context. To investigate the dynamical properties of protostellar jets. Aims. Determine the proper motion of protostellar jets around Class 0 and Class I sources in an active star forming region in Serpens. Methods. Multi-epoch deep images in the 2.122 $μ$m line of molecular hydrogen, v=1-0 S(1), obtained with the near-infrared instrument NOTCam over a time-scale of 10 years, are used to determine proper motion of knots and jets. K-band spectroscopy of the brighter knots is used to supply radial velocities, estimate extinction, excitation temperature, and H$_2$ column densities towards these kn…
The role of magnetic fields in the early stages of star formation is not well constrained. In order to discriminate between different star formation models, we analyze 3D magnetohydrodynamic simulations of low-mass cores and explore the correlation between magnetic field orientation and outflow orientation over time. We produce synthetic observations of dust polarization at resolutions comparable to millimeter-wave dust polarization maps observed by CARMA and compare these with 2D visualizations of projected magnetic field and column density. Cumulative distribution functions of the projected …
Magnetic fields are known to play a crucial role in the star formation process, particularly in the formation of jets and outflows from protostellar discs. The magnetic field structure in star forming regions is not always uniform and ordered, often containing regions of magnetic turbulence. We present grid-based, magneto-hydrodynamical simulations of the collapse of a 1$\,\mathrm{M}_{\odot}$ cloud core, to investigate the influence of complex magnetic field structures on outflow formation, morphology and efficiency. We compare three cases: a uniform field, a partially turbulent field and a fu…
Through the magnetic braking and the launching of protostellar outflows, magnetic fields play a major role in the regulation of angular momentum in star formation, which directly impacts the formation and evolution of protoplanetary disks and binary systems. The aim of this paper is to quantify those phenomena in the presence of non-ideal magnetohydrodynamics effects, namely the Ohmic and ambipola r diffusion. We perform three-dimensional simulations of protostellar collapses varying the mass of the prestellar dense core, the thermal support (the $α$ ratio) and the dust grain size-distribu tio…
We present the first Spitzer-IRS spectral maps of the Herbig-Haro flow GGD 37 detected in lines of [Ne III], [O IV], [Ar III], and [Ne V]. The detection of extended [O IV] (55 eV) and some extended emission in [Ne V] (97 eV) indicates a shock temperature in excess of 100,000 K, in agreement with X-ray observations, and a shock speed in excess of 200 km s-1. The presence of an extended pho- toionization or collisional ionization region indicates that GGD 37 is a highly unusual protostellar outflow.
We observe 1.3~mm spectral lines at 2000~AU resolution toward four massive molecular clouds in the Central Molecular Zone of the Galaxy to investigate their star formation activities. We focus on several potential shock tracers that are usually abundant in protostellar outflows, including SiO, SO, CH$_3$OH, H$_2$CO, HC$_3$N, and HNCO. We identify 43 protostellar outflows, including 37 highly likely ones and 6 candidates. The outflows are found toward both known high-mass star forming cores and less massive, seemingly quiescent cores, while 791 out of the 834 cores identified based on the conti…
Ten protostellar outflows in the Orion molecular clouds were mapped in the $^{12}$CO/$^{13}$CO ${J=6\rightarrow5}$ and $^{12}$CO ${J=7\rightarrow6}$ lines. The maps of these mid-$J$ CO lines have an angular resolution of about 10$''$ and a typical field size of about 100$''$. Physical parameters of the molecular outflows were derived, including mass transfer rates, kinetic luminosities, and outflow forces. The outflow sample was expanded by re-analyzing archival data of nearby low-luminosity protostars, to cover a wide range of bolometric luminosities. Outflow parameters derived from other tra…
It is not well known what drives the chemistry of a protostellar envelope, in particular the role of the stellar mass and the outflows on its chemical enrichment. We study the chemical structure of NGC 1333 IRAS 4A in order to (i) investigate the influence of the outflows on the chemistry, (ii) constrain the age of our object, (iii) compare it with a typical high-mass protostellar envelope. In our analysis we use JCMT line mapping and HIFI pointed spectra. To study the influence of the outflow on the degree of deuteration, we compare JCMT maps of HCO+ and DCO+ with non-LTE (RADEX) models in a …
We have selected six sources (G209.55-19.68S2, G205.46-14.56S1$_{-}$A, G203.21-11.20W2, G191.90-11.21S, G205.46-14.56S3, and G206.93-16.61W2) from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP), in which these sources have been mapped in the CO (J=2-1), SiO (J=5-4), and C$^{18}$O (J=2-1) lines. These sources have high-velocity SiO jets surrounded by low-velocity CO outflows. The SiO jets consist of a chain of knots. These knots have been thought to be produced by semi-periodical variations in jet velocity. Therefore, we adopt a shock-form…
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…
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）
We aim at studying the causal link between the knotty jet structure in CARMA 7, a young Class 0 protostar in the Serpens South cluster, and episodic accretion in young protostellar disks. We used numerical hydrodynamics simulations to derive the protostellar accretion history in gravitationally unstable disks around solar-mass protostars. We compared the time spacing between luminosity bursts Δτ_mod, caused by dense clumps spiralling on the protostar, with the differences of dynamical timescales between the knots Δτ_obs in CARMA 7. We found that the time spacing between the bursts have a bi-mo…
We adopt the deep learning method CASI-3D (Convolutional Approach to Structure Identification-3D) to systemically identify protostellar outflows in 12CO and 13CO observations of the nearby molecular clouds, Ophiuchus, Taurus, Perseus and Orion. The total outflow masses are 267 Msun, 795 Msun, 1305 Msun and 6332 Msun for Ophiuchus, Taurus, Perseus and Orion, respectively. We show the outflow mass in each cloud is linearly proportional to the total number of young stellar objects. The estimated total 3D deprojected outflow energies are 9e45 ergs, 6e46 ergs, 1.2e47 ergs and 6e47 ergs for Ophiuchu…
With the aim of characterizing the dynamical processes involved in the formation of young protostars, we present high angular resolution ALMA dust polarization observations of the Class 0 protostellar cores Serpens SMM1, Emb 8(N), and Emb 8. With spatial resolutions ranging from 150 to 40 au at 870 μm, we find unexpectedly high values of the polarization fraction along the outflow cavity walls in Serpens Emb8(N). We use 3 mm and 1 mm molecular tracers to investigate outflow and dense gas properties and their correlation with the polarization. These observations allow us to investigate the phys…
The role played by protostellar feedback in clustered star formation is still a matter of debate. In particular, protostellar outflows have been proposed as a source of turbulence in cluster-forming clumps, which may provide support against global collapse for several free-fall times. Here, we seek to test the above hypothesis in the case of the well-documented NGC 2264-C protocluster, byquantifying the amount of turbulence and support injected in the surrounding medium by protostellar outflows. Using the HERA heterodyne array on the IRAM 30m telescope, we carried out an extensive mapping of N…
The evolution of collapsing clouds embedded in different star-forming environments is investigated using three-dimensional non-ideal magnetohydrodynamics simulations considering different cloud metallicities ($Z/\thinspace Z_\odot$ = 0, 10$^{-5}$, 10$^{-4}$, 10$^{-3}$, 10$^{-2}$, 10$^{-1}$ and 1) and ionisation strengths ($C_ζ$=0, 0.01, 1 and 10, where $C_ζ$ is a coefficient controlling the ionisation intensity and $C_ζ=1$ corresponds to the ionisation strength of nearby star-forming regions). With all combinations of these considered values of $Z/\thinspace Z_\odot$ and $C_ζ$, 28 different st…
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 …
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…
