Collimated Jet Research Articles

Illuminating the Tadpole’s metamorphosis – I. MUSE observations of a small globule in a sea of ionizing photons

ABSTRACT We present new MUSE/VLT observations of a small globule in the Carina H ii region that hosts the HH 900 jet+outflow system. Data were obtained with the GALACSI ground-layer adaptive optics system in wide-field mode, providing spatially resolved maps of diagnostic emission lines. These allow us to measure the variation of the physical properties in the globule and jet+outflow system. We find high temperatures (Te ≈ 104 K), modest extinction (AV ≈ 2.5 mag), and modest electron densities (ne ≈ 200 cm−3) in the ionized gas. Higher excitation lines trace the ionized outflow; both the excitation and ionization in the outflow increase with distance from the opaque globule. In contrast, lower excitation lines that are collisionally de-excited at densities ≳104 cm−3 trace the highly collimated protostellar jet. Assuming the globule is an isothermal sphere confined by the pressure of the ionization front, we compute a Bonnor–Ebert mass of ∼3.7 M⊙. This is two orders of magnitude higher than previous mass estimates, calling into question whether small globules like the Tadpole contribute to the bottom of the initial mass function. The derived globule properties are consistent with a cloud that has been and/or will be compressed by the ionization front on its surface. At the estimated globule photoevaporation rate of ∼5 × 10−7 M⊙ yr−1, the globule will be completely ablated in ∼7 Myr. Stars that form in globules like the Tadpole will emerge into the H ii later and may help resolve some of the temporal tension between disc survival and enrichment.

Collimated radiation in SS 433

Context. The microquasar SS 433 is well known for its precessing, relativistic, and highly collimated baryonic jets, which manifest in its optical spectrum as pairs of hydrogen and helium emission lines moving with large Doppler shifts. Depending on their heating mechanism, the optical jet bullets may serve as a probe of the collimated radiation coming from the inner region close to the compact object, and which is not directly visible to observers on Earth. Aims. We aim to better understand the baryonic jet phenomenon in SS 433, in particular the properties of the optical bullets and their interaction with the ionizing collimated radiation. Methods. The optical interferometer VLTI/GRAVITY has allowed us to spatially resolve the optical jets in SS 433 for the first time. We present here the second such observation taken over three nights in July 2017. In addition, we used the X-shooter spectrograph at VLT to study the optical bullets in SS 433 in detail. Over the full wavelength range 0.3−2.5 μm, we identified up to twenty pairs of jet lines observed simultaneously, which we modeled with the spectral synthesis code Cloudy. Results. GRAVITY reveals elongated exponential-like radial spatial profiles for the optical jets on scales ≲1−10 mas, suggestive of a heating mechanism acting throughout a long portion of the jet and naturally explained by photoionization by the collimated radiation. We also spatially resolve the movement of the optical bullets for the first time, detecting more extended jet components corresponding to previous ejections. Cloudy photoionization models can explain the spatial intensity profiles measured with GRAVITY and the emission line ratios from X-shooter, and constrain the properties of the optical bullets and the ionizing radiation. We find that the latter must peak in the UV with an isotropic luminosity (as inferred by a face-on observer) ∼1041 erg s−1. Provided that the X-ray spectral energy distribution is sufficiently hard, the collimated X-ray luminosity could still be high enough so that the face-on observer would see SS 433 as ultraluminous X-ray source and it would still be compatible with the H/He/He+ ionization balance of the optical bullets. The kinetic power in the optical jets is constrained to 2−20 × 1038 erg s−1, and the extinction in the optical jets to AV = 6.7 ± 0.1. We suggest there may be substantial AV ≳ 1 and structured circumstellar extinction in SS 433, likely arising from dust formed in equatorial outflows.

An Ordered Envelope–Disk Transition in the Massive Protostellar Source G339.88-1.26

Abstract We report molecular line observations of the massive protostellar source G339.88-1.26 with the Atacama Large Millimeter/Submillimeter Array. The observations reveal a highly collimated SiO jet extending from the 1.3 mm continuum source, which connects to a slightly wider but still highly collimated CO outflow. Rotational features perpendicular to the outflow axis are detected in various molecular emissions, including SiO, SO2, H2S, CH3OH, and H2CO emissions. Based on their spatial distributions and kinematics, we find that they trace different parts of the envelope–disk system. The SiO emission traces the disk and inner envelope in addition to the jet. The CH3OH and H2CO emissions mostly trace the infalling-rotating envelope and are enhanced around the transition region between envelope and disk, i.e., the centrifugal barrier. The SO2 and H2S emissions are enhanced around the centrifugal barrier and also trace the outer part of the disk. Envelope kinematics are consistent with rotating-infalling motion, while those of the disk are consistent with Keplerian rotation. The radius and velocity of the centrifugal barrier are estimated to be about 530 au and 6 , respectively, leading to a central mass of about 11 M ⊙, consistent with estimates based on spectral energy distribution fitting. These results indicate that an ordered transition from an infalling-rotating envelope to a Keplerian disk through a centrifugal barrier, accompanied by changes of types of molecular line emissions, is a valid description of this massive protostellar source. This implies that at least some massive stars form in a similar way to low-mass stars via core accretion.

The MRI Imprint on the Short-GRB Jets

Abstract Short gamma-ray bursts (GRBs) are presumably results of binary neutron star mergers, which lead to the formation of a stellar mass black hole, surrounded by remnant matter. The strong magnetic fields help collimate jets of plasma, launched along the axis of the black hole rotation. We study the structure and evolution of the accreting plasma in the short GRBs and we model the formation of the base of relativistic, Poynting-dominated jets. Our numerical models are based on general relativistic MHD, axisymmetric simulations. We discuss the origin of variability in the GRB jet emission, the timescales of which are related to the action of the magnetorotational instability in the accreting plasma. We also estimate the value of a maximum achievable Lorentz factor in the jets produced by our simulations and reached at large distances, where the gamma-ray emission is produced.

Numerical simulation of magnetized jet creation using a hollow ring of laser beams

Three dimensional FLASH magneto-hydrodynamic modeling is carried out to interpret the OMEGA laser experiments of strongly magnetized, highly collimated jets driven by a ring of 20 OMEGA beams. The predicted optical Thomson scattering spectra and proton images are in good agreement with a subset of the experimental data. Magnetic fields generated via the Biermann battery term are amplified at the boundary between the core and the surrounding of the jet. The simulation predicts multiple axially aligned magnetic flux ropes with an alternating poloidal component. Future applications of the hollow ring configuration in laboratory astrophysics are discussed.

A highly collimated jet from the Red Square nebula MWC 922

Deep, narrow-band \Ha\ and 6584 \AA\ [\Nii ] CCD images of the peculiar, infrared excess B[e] star MWC~922 reveal a collimated, bipolar jet orthogonal to the previously detected extended nebula. The jet consists of a pair of $\sim$0.15 pc segments on either side of MWC~922 separated by gaps. The most distant jet segments disappear $\sim$0.6 pc from the star. The northwest beam points to a faint emission-line feature 1.65 pc from MWC~922 that may be a terminal bow shock where the jet rams the ambient medium. The narrow opening-angle of the jet combined with an estimated internal sound speed of $\sim$10 \kms\ implies a jet speed $\sim$500 \kms . The previously detected nebula extends up to 0.6~pc to the southwest of MWC~922 at right angles to the jet and appears to be an extension of the compact, edge-on disk surrounding the star. It points toward the HII region Messier 16 located $\sim$1\degr\ ($\sim$30 pc in projection) to the southwest. This nebula and jet appear to be externally ionized by the ambient Lyman continuum radiation field and have electron densities of n$_e \sim$ 50 to 100 cm$^{-3}$. The southwest nebula and jet have similar surface brightness in \Ha\ and [\Nii ]. Faint 70 $\mu$m emission traces the southwest ejecta that likely originates from $\sim$50 K dust embedded in the photo-ionized plasma which may shadow the dimmer ejecta northeast of MWC~922. MWC~922 may be a massive member of the Serpens OB1 or OB2 associations surrounding Messier 16 and Sh2-54.

UV Monochromatic Imaging of the Protoplanetary Nebula Hen 3-1475 Using HST STIS

Collimated outflows and jets play a critical role in shaping planetary nebulae (PNe), especially in the brief transition from a spherical AGB envelope to an aspherical PN, which is called the protoplanetary nebula (pPN) phase. We present UV observations of Hen 3-1475, a bipolar pPN with fast, highly collimated jets, obtained with STIS on board the Hubble Space Telescope (HST). The deep, low-dispersion spectroscopy enabled monochromatic imaging of Hen 3-1475 in different UV nebular emission lines; this is the first of such attempt ever conducted for a pPN. The northwest inner knot (NW1) is resolved into four components in Mg ii λ 2800. Through comparison analysis with the HST optical narrowband images obtained 6 yr earlier, we found that these components of NW1 hardly move, despite of a negative gradient of high radial velocities, from −1550 km s - 1 on the innermost component to ∼−300 km s - 1 on the outermost. These NW1 knot components might thus be quasi-stationary shocks near the tip of the conical outflow of Hen 3-1475.

Constraining the Outflow Structure of the Binary Neutron Star Merger Event GW170817/GRB170817A with a Markov Chain Monte Carlo Analysis

Abstract The multiwavelength nonthermal emission from the binary neutron star merger event GW170817/GRB170817A has raised a heated debate concerning the post-merger outflow structure. Both a relativistic structured jet viewed off-axis and a mildly relativistic quasi-spherical outflow can explain the observational data up to ∼260 days. We utilize a physically motivated analytic two-parameter model called the “boosted fireball,” for the outflow structure after it has expanded far from the merger site. This model consists of a family of outflows with structures varying smoothly between a highly collimated ultra-relativistic jet and an isotropic outflow. We simulate the dynamical evolution of 240 “boosted fireball” outflows using the moving-mesh relativistic hydrodynamics code JET following their evolution through the full afterglow phase. We compute ∼2,000,000 synchrotron spectra from the hydrodynamic simulations. Using scaling relations for the hydrodynamic and radiation equations, we develop a synthetic light-curve generator with efficient sampling speed. This allows the observational data to be fit using Markov Chain Monte Carlo analysis in an eight-dimensional parameter space of hydrodynamic, radiation, and observational parameters. Our results favor the relativistic structured jet, with an opening angle θ 0 ≈ 5° and Lorentz factor Γ ≈ 175, viewed from off-axis angle degrees. Due to parameter degeneracies, we find broad distributions for the explosion energy E 0, the circumburst density n 0, and the electron and magnetic energy fractions ϵ e and ϵ B . High n 0 and low ϵ B can also produce a good fit, indicating that very low n 0 may not be required for GW170817/GRB170817A.

Jets and outflows of massive protostars

Context. Massive stars live short but intense lives. While less numerous than low-mass stars, they enormously impact their surroundings by several feedback mechanisms. They form in opaque and far-away regions of the galaxy, such that one of these feedback mechanisms also becomes a record of their evolution: their bright large-scale jets and outflows. Aims. In a comprehensive convergence study, we investigate the computational conditions necessary to resolve (pseudo-) disk formation and jet-launching processes, and analyze possible caveats. We explore the magneto-hydrodynamic (MHD) processes of the collapse of massive prestellar cores in detail, including an analysis of the forces involved and their temporal evolution for up to two free-fall times. Methods. We conduct MHD simulations using the state-of-the-art code PLUTO, combining nonideal MHD, self-gravity, and very high resolutions as they have never been achieved before. Our setup includes a 100 M⊙ cloud core that collapses under its own self-gravity to self-consistently form a dense disk structure and launch tightly collimated magneto-centrifugal jets and wide-angle tower flows. Results. We show a comprehensive evolutionary picture of the collapse of a massive prestellar core with a detailed analysis of the physical processes involved and our high-resolution simulations can resolve a magneto-centrifugal jet and a magnetic pressure-driven outflow, separately. The nature of the outflows depends critically on spatial resolution. Only high-resolution simulations are able to differentiate a magneto-centrifugally launched, highly collimated jet from a slow wide-angle magnetic-pressure-driven tower flow. Of these two outflow components, the tower flow dominates angular-momentum transport. The mass outflow rate is dominated by the entrained material from the interaction of the jet with the stellar environment and only part of the ejected medium is directly launched from the accretion disk. A tower flow can only develop to its full extent when much of the original envelope has already dispersed. Taking into account both the mass launched from the surface of the disk and the entrained material from the envelope, we find an ejection-to-accretion efficiency of 10%. Nonideal MHD is required to form centrifugally supported accretion disks and the disk size is strongly dependent on spatial resolution. A converged result for disk and both outflow components requires a spatial resolution of Δx ≤ 0.17 au at 1 au and sink-cell sizes ≤3.1 au. Conclusions. Massive stars not only possess slow wide-angle tower flows, but also produce magneto-centrifugal jets, just as their low-mass counterparts. The actual difference between low-mass and high-mass star formation lies in the “embeddedness” of the high-mass star which implies that the jet and tower flow interact with the infalling large-scale stellar environment, potentially resulting in entrainment.

Zooming in on a neutron-star merger jet

Observations with a continent-wide array of radio telescopes show that the merger of two neutron stars, which produced gravitational waves, successfully launched a very fast and highly collimated jet.

Laboratory Investigation of Astrophysical Collimated Jets with Intense Lasers

Abstract One of the remarkable dynamic features of the Herbig–Haro (HH) object is its highly collimated propagation far away from the accretion disk. Different factors are proposed to give us a clearly physical explanation behind these fascinating phenomena, including magnetic field, radiation cooling, surrounding medium, and so on. Laboratory astrophysics, as a new complementary method of studying astrophysical issues, can provide an insight into these behaviors in a similar and controllable laboratory environment. Here we report the scaled laboratory experiments that a well-collimated radiative jet with high Mach number is successfully created to mimic the evolution of HH objects. According to our results, we find that the radiation cooling effect within the jet and the outer rare surrounding plasmas from the X-ray (>keV) photoionized target contribute to the jet collimation. The local nonuniform density structures along the collimated radiative jet axis are caused by the pressure competition between the inner jet and the outer plasmas. The corresponding simulations performed with radiation-hydrodynamic codes FLASH reveal how the radiative jet evolves.

Late Time Afterglow Observations Reveal a Collimated Relativistic Jet in the Ejecta of the Binary Neutron Star Merger GW170817.

The binary neutron star (BNS) merger GW170817 was the first astrophysical source detected in gravitational waves and multiwavelength electromagnetic radiation. The almost simultaneous observation of a pulse of gamma rays proved that BNS mergers are associated with at least some short gamma-ray bursts (GRBs). However, the gamma-ray pulse was faint, casting doubt on the association of BNS mergers with the luminous, highly relativistic outflows of canonical short GRBs. Here we show that structured jets with a relativistic, energetic core surrounded by slower and less energetic wings produce afterglow emission that brightens characteristically with time, as recently seen in the afterglow of GW170817. Initially, we only see the relatively slow material moving towards us. As time passes, larger and larger sections of the outflow become visible, increasing the luminosity of the afterglow. The late appearance and increasing brightness of the multiwavelength afterglow of GW170817 allow us to constrain the geometry of its ejecta and thus reveal the presence of an off-axis jet pointing about 30° away from Earth. Our results confirm a single origin for BNS mergers and short GRBs: GW170817 produced a structured outflow with a highly relativistic core and a canonical short GRB. We did not see the bright burst because it was beamed away from Earth. However, approximately one in 20 mergers detected in gravitational waves will be accompanied by a bright, canonical short GRB.

The correlation between the total jet power and the Poynting flux at the jet base

AbstractThe magneto hydrodynamic models of relativistic jets from active galactic nuclei predict the jet power transported by the Poynting flux at the jet base, setting the correlation between the jet power and the total magnetic flux. For highly collimated jets taking the transversal structure into account allows to rewrite this correlation through the observed jet properties such as spectral flux and core shift. Applying this method we find that, for the sample of 48 sources, their jet power distribution is well peaked at the theoretically predicted level.

The bipolar jet of the symbiotic star R Aquarii: A study of its morphology using the high-resolution HST WFC3/UVIS camera

Context. R Aqr is a symbiotic binary system consisting of a Mira variable with a pulsation period of 387 days and a hot companion which is presumably a white dwarf with an accretion disk. This binary system is the source of a prominent bipolar gaseous outflow. Aims. We use high spatial resolution and sensitive images from the Hubble Space Telescope (HST) to identify and investigate the different structural components that form the complex morphology of the R Aqr jet. Methods. We present new high-resolution HST WFC3/UVIS narrow-band images of the R Aqr jet obtained in 2013/14 using the [OIII]λ5007, [OI]λ6300, [NII]λ6583, and Hα emission lines. These images also allow us to produce detailed maps of the jet flow in several line ratios such as [OIII]λ5007/[OI]λ6300 and [NII]λ6583/[OI]λ6300 which are sensitive to the outflow temperature and its hydrogen ionisation fraction. The new emission maps together with archival HST data are used to derive and analyse the proper motion of prominent emitting features which can be traced over 20 years with the HST observations. Results. The images reveal the fine gas structure of the jet out to distances of a few tens of arcseconds from the central region, as well as in the innermost region, within a few arcseconds around the stellar source. They reveal for the first time the straight, highly collimated jet component which can be traced to up to ~900 AU in the NE direction. Images in [OIII]λ5007, [OI]λ6300, and [NII]λ6583 clearly show a helical pattern in the jet beams which may derive from the small-scale precession of the jet. The highly collimated jet is accompanied by a wide opening angle outflow which is filled by low excitation gas. The position angles of the jet structures as well as their opening angles are calculated. Our measurements of the proper motions of some prominent emission knots confirm the scenario of gas acceleration during the propagation of the outflow. Finally, we produce several detailed line ratio maps which present a mosaic combined from the large field and the PSF-subtracted inner region. Conclusions. The high signal-to-noise HST WFC3/UVIS images provide powerful tools for the study of the jet morphology and also bring detailed information about the physical jet gas conditions. The simultaneous observations of [OIII], [OI], [NII], and [SII] would allow us to measure basic parameters of the ionised gas in the R Aqr outflow such as electron density, electron temperature and hydrogen ionisation fraction, and compare them with other stellar jets.

Precessing Jet and Large Dust Grains in the V380 Ori NE Star-forming Region

The V380 Ori NE bipolar outflow was imaged in the SiO and CO lines, and dense cores in L1641 were observed in the 2.0–0.89 mm continuum. The highly collimated SiO jet shows point-symmetric oscillation patterns in both position and velocity, which suggests that the jet axis is precessing and the driving source may belong to a non-coplanar binary system. By considering the position and velocity variabilities together, accurate jet parameters were derived. The protostellar system is viewed nearly edge-on, and the jet has a flow speed of ∼35 km s−1 and a precession period of ∼1600 years. The CO outflow length gives a dynamical timescale of ∼6300 years, and the protostar must be extremely young. The inferred binary separation of 6–70 au implies that this protobinary system may have been formed through the disk instability process. The continuum spectra of L1641 dense cores indicate that the emission comes from dust, and the fits with modified blackbody functions give emissivity power indices of β = 0.3–2.2. The emissivity index shows a positive correlation with the molecular line width, but no strong correlation with bolometric luminosity or temperature. V380 Ori NE has a particularly low value of β = 0.3, which tentatively suggests the presence of millimeter-sized dust grains. Because the dust growth takes millions of years, much longer than the protostellar age, this core may have produced large grains in the starless core stage. HH 34 MMS and HH 147 MMS also have low emissivity indices.

A rotating protostellar jet launched from the innermost disk of HH 212

The central problem in forming a star is the angular momentum in the circumstellar disk which prevents material from falling into the central stellar core. An attractive solution to the "angular momentum problem" appears to be the ubiquitous (low-velocity and poorly-collimated) molecular outflows and (high-velocity and highly-collimated) protostellar jets accompanying the earliest phase of star formation that remove angular momentum at a range of disk radii. Previous observations suggested that outflowing material carries away the excess angular momentum via magneto-centrifugally driven winds from the surfaces of circumstellar disks down to ~ 10 AU scales, allowing the material in the outer disk to transport to the inner disk. Here we show that highly collimated protostellar jets remove the residual angular momenta at the ~ 0.05 AU scale, enabling the material in the innermost region of the disk to accrete toward the central protostar. This is supported by the rotation of the jet measured down to ~ 10 AU from the protostar in the HH 212 protostellar system. The measurement implies a jet launching radius of ~ 0.05_{-0.02}^{+0.05} AU on the disk, based on the magneto-centrifugal theory of jet production, which connects the properties of the jet measured at large distances to those at its base through energy and angular momentum conservation.

The dusty silhouette jet HH 1019 in the Carina Nebula

We report the discovery in Hubble Space Telescope (HST) images of the new Herbig-Haro jet, HH 1019, located near the Tr 14 cluster in the Carina Nebula. Like other HH jets in the region, this bipolar collimated flow emerges from the head of a dark dust pillar. However, HH 1019 is unique because -- unlike all other HH jets known to date -- it is identified by a linear chain of dark, dusty knots that are seen primarily in silhouette against the background screen of the H II region. Proper motions confirm that these dark condensations move along the jet axis at high speed. [S II] emission traces a highly collimated jet that is spatially coincident with these dust knots. The high extinction in the body of the jet suggests that this outflow has lifted a large amount of dust directly from the disk, although it is possible that it has entrained dust from its surrounding protostellar envelope before exiting the dust pillar. If dust in HH 1019 originates from the circumstellar disk, this provides further evidence for a jet launched from a range of radii in the disk, including those outside the dust sublimation radius. HH 1019 may be the prototype for a new subclass of dusty HH objects seen primarily in extinction against the background screen of a bright H II region. Such jets may be common, but difficult to observe because they require the special condition of a very bright background in order to be seen in silhouette.

Protostellar Outflows

Outflows from accreting, rotating, and magnetized systems are ubiquitous. Protostellar outflows can be observed from radio to X-ray wavelengths in the continuum and a multitude of spectral lines that probe a wide range of physical conditions, chemical phases, radial velocities, and proper motions. Wide-field visual and near-IR data, mid-IR observations from space, and aperture synthesis with centimeter- and millimeterwave interferometers are revolutionizing outflow studies. Many outflows originate in multiple systems and clusters. Although most flows are bipolar and some contain highly collimated jets, others are wide-angle winds, and a few are nearly isotropic and exhibit explosive behavior. Morphologies and velocity fields indicate variations in ejection velocity, mass-loss rate, and in some cases, flow orientation and degree of collimation. These trends indicate that stellar accretion is episodic and often occurs in a complex dynamical environment. Outflow power increases with source luminosity but decreases with evolutionary stage. The youngest outflows are small and best traced by molecules such as CO, SiO, H2O, and H2. Older outflows can grow to parsec scales and are best traced by shock-excited atoms and ions such as hydrogen-recombination lines, [Sii], and [Oii]. Outflows inject momentum and energy into their surroundings and provide an important mechanism in the self-regulation of star formation. However, momentum injection rates remain uncertain with estimates providing lower bounds.

Variable X-Ray and UV emission from AGB stars: Accretion activity associated with binarity

Almost all of our current understanding of the late evolutionary stages of (1 — 8) Mʘ stars is based on single-star models. However, binarity can drastically affect late stellar evolution, producing dramatic changes in the history and geometry of mass loss that occurs in stars as they evolve off the AGB to become planetary nebulae (PNe). A variety of binary models have been proposed, which can lead to the generation of accretion disks and magnetic fields, which in turn produce the highly collimated jets that have been proposed as the primary agents for the formation of bipolar and multipolar PNe. However, observational evidence of binarity in AGB stars is sorely lacking simply these stars are very luminous and variable, invalidating standard techniques for binary detection. Using an innovative technique of searching for UV emission from AGB stars with GALEX, we have identified a class of AGB stars with far- ultraviolet excesses (fuvAGB stars), that are likely candidates for active accretion associated with a binary companion. We have carried out a pilot survey for X-ray emission from fuvAGB stars. The X-ray fluxes are found to vary in a stochastic or quasi-periodic manner on roughly hour-long times-scales, and simultaneous UV observations show similar variations in the UV fluxes. We discuss several models for the X-ray emission and its variability and find that the most likely scenario for the origin of the X-ray (and FUV) emission involves accretion activity around a main-sequence companion star, with confinement by strong magnetic fields associated with the companion and/or an accretion disk around it.

AN EXTREMELY HIGH VELOCITY MOLECULAR JET SURROUNDED BY AN IONIZED CAVITY IN THE PROTOSTELLAR SOURCE SERPENS SMM1

ABSTRACT We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of a one-sided, high-velocity (∼80 km s−1) CO(J = 2 → 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 Very Large Array 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 jet. The cavity walls are ionized either by UV photons escaping from the accreting protostellar source or by the precessing molecular jet impacting the walls. These observations suggest that ionized outflow cavities may be common in Class 0 protostellar sources, shedding further light on the radiation, outflow, and jet environments in the youngest, most embedded forming stars.