Search

We continue to present the results of a Byurakan Narrow Band Imaging Survey (BNBIS). In this work, we present the results of the search and further detailed investigation of the objects, found in the course of the BNBIS survey in the southern part of the Mon R2 (Monoceros R2) association. For the search of Herbig–Haro (HH) objects, the narrow-band images, obtained with the 1 m Schmidt telescope of the Byurakan Observatory, were used. Newly found objects were imaged in optical and near-infrared (IR) range with the Apache Point Observatory 3.5 m telescope, and observed spectrally with a long-slit spectrograph and scanning Fabry–Perot interferometer on a 6 m telescope of Special Astrophysical Observatory of the Russian Academy of Sciences using SCORPIO-2 (Spectral Camera with Optical Reducer for Photometrical and Interferometrical Observations – 2). We found three new HH groups: HH 1233, HH 1234, and HH 1235, two of them represent extended collimated flows. HH 1233 is the C-shape bipolar outflow system associated with the 2MASS 06084223−0657385 source star. HH 1234 is the helical chain of HH knots near the star V963 Mon. HH 1235 is a separate compact knot, connected with the visible only in mid- and far-IR source WISE J060856.57−070103.5. We also found several molecular hydrogen outflows, one of which coincides with HH 1233 and two other are associated with the deeply embedded IR sources in the same field. One more probable bipolar H2 outflow is related to WISE J060856.57−070103.5. The emission spectra and spectral energy distributions of the source stars were analysed. According to them they should be under a rather early evolutional stage. [ABSTRACT FROM AUTHOR]

Context. Due to the high visual extinction and lack of sensitive mid-infrared (MIR) telescopes, the origin and properties of outflows and jets from embedded Class 0 protostars are still poorly constrained. Aims. We aim to characterise the physical, kinematic, and dynamical properties of the HH 211 jet and outflow, one of the youngest protostellar flows. Methods. We used the James Webb Space Telescope (JWST) and its Mid-InfraRed Instrument (MIRI) in the 5–28 µm range to study the embedded HH 211 flow. We mapped a 0′.95 × 0′.22 region, covering the full extent of the blueshifted lobe, the central protostellar region, and a small portion of the redshifted lobe. We extracted spectra along the jet and outflow and constructed line and excitation maps of both atomic and molecular lines. Additional JWST NIRCam H2 narrow-band images (at 2.122 and 3.235 µm) provide a visualextinction map of the whole flow, and are used to deredden our data. Results. The jet-driving source is not detected even at the longest MIR wavelengths. The overall morphology of the flow consists of a highly collimated jet, which is mostly molecular (H2, HD) with an inner atomic ([Fe I], [Fe II], [S I], [Ni II]) structure. The jet shocks the ambient medium, producing several large bow shocks (BSs) that are rich in forbidden atomic ([Fe II], [S I], [Ni II], [Cl I], [Cl II], [Ar II], [Co II], [Ne II], [S III]) and molecular lines (H2, HD, CO, OH, H2O, CO2, HCO+), and is driving an H2 molecular outflow that is mostly traced by low- J, v = 0 transitions. Moreover, H2 0-0 S(1) uncollimated emission is also detected down to 2″-3″ (~650–1000 au) from the source, tracing a cold (T=200–400 K), less dense, and poorly collimated molecular wind. Two H2 components (warm, T =300–1000 K, and hot, T =1000–3500 K) are detected along the jet and outflow. The atomic jet ([Fe II] at 26 µm) is detected down to ~130 au from the source, whereas the lack of H2 emission (at 17 µm) close to the source is likely due to the large visual extinction (AV > 80 mag). Dust-continuum emission is detected at the terminal BSs and in the blue- and redshifted jet, and is likely attributable to dust lifted from the disc. Conclusions. The jet shows an onion-like structure, with layers of different size, velocity, temperature, and chemical composition. Moreover, moving from the inner jet to the outer BSs, different physical, kinematic, and excitation conditions for both molecular and atomic gas are observed. The mass-flux rate and momentum of the jet, as well as the momentum flux of the warm H2 component, are up to one order of magnitude higher than those inferred from the atomic jet component. Our findings indicate that the warm H2 red component is the main driver of the outflow, that is to say it is the most significant dynamical component of the jet, in contrast to jets from more evolved YSOs, where the atomic component is dominant. [ABSTRACT FROM AUTHOR]

We continue to present the results of the Byurakan Narrow Band Imaging Survey (BNBIS). The main goal of this survey is to search for Herbig–Haro (HH) objects and jets in Galactic dark clouds. In this work we present the results of the search in the vicinity of infrared sources that are bright in the WISE survey and embedded in the dark clouds. The survey is performed with the 1-m Schmidt telescope of Byurakan Observatory, lately equipped with a new CCD detector, which allows to obtain one square degree images of the sky in various filters. Narrow-band filters were used to obtain H α and [S  ii ] images, and a medium-width filter was used for the continuum imaging. New HH flows and knots were found near six embedded IR sources, which constitutes a significant proportion of the objects observed. At least two of the newly found HH flows (HH 1226 and HH 1227) lie in isolated dark clouds, thus pointing to active star formation in these regions. Other flows are also located in detached and dense globules or filaments. The length of the HH 1228 flow is about 1 pc; it has also a molecular hydrogen counterpart of the same extension. Coordinates, charts, detailed descriptions and distance estimates are provided. The lower limits of bolometric luminosities of the source stars are typical for low-mass young stellar objects. [ABSTRACT FROM AUTHOR]

We report on the results of a simulation-based study of colliding magnetized plasma flows. Our set-up mimics pulsed power laboratory astrophysical experiments but, with an appropriate frame change, is relevant to astrophysical jets with internal velocity variations. We track the evolution of the interaction region where the two flows collide. Cooling via radiative losses is included in the calculation. We systematically vary plasma beta (βm) in the flows, the strength of the cooling (Λ0), and the exponent (α) of temperature dependence of the cooling function. We find that for strong magnetic fields a counter-propagating jet called a 'spine' is driven by pressure from shocked toroidal fields. The spines eventually become unstable and break apart. We demonstrate how formation and evolution of the spines depend on initial flow parameters and provide a simple analytical model that captures the basic features of the flow. [ABSTRACT FROM AUTHOR]

Protostellar jets and outflows are signposts of active star formation. In H  ii regions, molecular tracers like CO only reveal embedded portions of the outflow. Outside the natal cloud, outflows are dissociated, ionized, and eventually completely ablated, leaving behind only the high-density jet core. Before this process is complete, there should be a phase where the outflow is partially molecular and partially ionized. In this paper, we capture the HH 900 outflow while this process is in action. New observations from the Enhanced Resolution Imager and Spectrograph/SPIFFIER near-infrared (IR) integral field unit spectrograph using the K-middle filter (λ = 2.06–2.34 μ m) reveal H2 emission from the dissociating outflow and Br-γ tracing its ionized skin. Both lines trace the wide-angle outflow morphology but H2 only extends ∼5000 au into the H  ii region while Br-γ extends the full length of the outflow (∼12 650 au), indicating rapid dissociation of the molecules. H2 has higher velocities further from the driving source, consistent with a jet-driven outflow. Diagnostic line ratios indicate that photoexcitation, not just shocks, contributes to the excitation in the outflow. We argue that HH 900 is the first clear example of an evaporating molecular outflow and predict that a large column of neutral material that may be detectable with Atacama Large Millimeter Array accompanies the dissociating molecules. Results from this study will help guide the interpretation of near-IR images of externally irradiated jets and outflows such as those obtained with the JWST in high-mass star-forming regions where these conditions may be common. [ABSTRACT FROM AUTHOR]

We present new observations of the Mystic Mountains cloud complex in the Carina Nebula using the ALMA Atacama Compact Array (ACA) to quantify the impact of strong UV radiation on the structure and kinematics of the gas. Our Band 6 observations target CO, 13CO, and C18O; we also detect DCN J=3–2 and 13CS J=5–4. A dendrogram analysis reveals that the Mystic Mountains are a coherent structure, with continuous emission over −10.5 km s−1 < v < −2 km s−1. We perform multiple analyses to isolate non-thermal motions in the Mystic Mountains including computing the turbulent driving parameter, b , which indicates whether compressive or solenoidal modes dominate. Each analysis yields values similar to other pillars in Carina that have been observed in a similar way but are subject to an order of magnitude less intense ionizing radiation. We find no clear correlation between the velocity or turbulent structure of the gas and the incident radiation, in contrast to other studies targeting different regions of Carina. This may reflect differences in the initial densities of regions that go on to collapse into pillars and those that still look like clouds or walls in the present day. Pre-existing over-densities that enable pillar formation may also explain why star formation in the pillars appears more evolved (from the presence of jets) than in other heavily irradiated but non-pillar-like regions. High resolution observations of regions subject to an array of incident radiation are required to test this hypothesis. [ABSTRACT FROM AUTHOR]

Two new Herbig-Haro flows were found in a study of the isolated Dobashi 5006 dark cloud (l = 216°.7, b = –13°.9): one certain (HH 1179) and one presumable, associated with the infrared sources 2MASS 06082284-0936139 and 2MASS 06081525-0933490, correspondingly. Judging from their spectral energy distributions, these sources may be Class 1 objects with luminosities of order 23 L⨀ and 3.6 L⨀, respectively. They are part of the poor star cluster MWSC 0739, study of which based on data from the Gaia DR3 survey has made it possible to detect 17 stars which are probably members of it. A list of them and their main parameters is given. The distance of the cluster is estimated to be 820 pc and the color excess on the path to the cluster is E(BP - RP) ≈ 1.05 mag. All of these stars are PMS-objects and most of them are optically variable. It is concluded that the newly discovered compact star-formation zone in the Dobashi 5006 cloud has an age of no more than a few million years and this process continues up to the present time. [ABSTRACT FROM AUTHOR]

We present the Atacama Large Millimeter/submillimeter Array Band 7 observations of the CO ( J = 3−2) line emission of the protostellar system HH 212 at ∼24 au spatial resolution and compare them to those of the SiO ( J = 8−7) and SO ( J = 8−7) line emission reported in the literature. We find that the CO line traces four distinct regions: (1) an outer outflow shell, (2) a rotating wind region between the SiO and CO shells, (3) the shocked and wide-angle inner X-wind inside a SiO shell, and (4) the jet. The origin of the CO outer outflow shell could be associated with the entrained material of the envelope, or an extended disk wind. The rotating wind, which is shocked, is launched from a radius of 9–15 au, slightly exterior to that of the previously detected SO shell, which marks the boundary where the wide-angle X-wind is interacting with and shocking the disk wind. Additionally, the SO is found to be mixed with the CO emission within the thick and extended rotating wind region. The large-scale CO-shocked wind coexists with the SO emission near the upper portion of the inner shocked region converged on top of the inner SiO knots. The CO jet is traced by a chain of knots with roughly equal intervals, exhibiting quasiperiodicity, as reported in other jets in the literature.

We present archival Atacama Large Millimeter/submillimeter Array band 6 observations of the ^13 CO ( J = 2–1) and ^12 CO ( J = 2–1) molecular line emission of the protostellar system associated with HH 30. The ^13 CO molecular line shows the accretion disk while the molecular outflow is traced by the emission of the ^12 CO molecular line. We estimated a dynamical mass for the central object of 0.45 ± 0.14 M _⊙ , and a mass for the molecular outflow of (1.83 ± 0.19) × 10 ^−4 M _⊙ . The molecular outflow presents an internal cavity as well as multiple outflowing shell structures. We distinguish three different shells with constant expansion (∼4–6 km s ^−1 ) and possible rotation signatures (≤0.5 km s ^−1 ). We find that the shells can be explained by magnetocentrifugal disk winds with launching radii R _launch ≲ 4 au and a small magnetic lever arm λ ∼ 1.6–1.9. The multiple shell structure may be the result of episodic ejections of the material from the accretion disk associated with three different epochs with dynamical ages of 497 ± 15 yr, 310 ± 9 yr, and 262 ± 11 yr for the first, second, and third shells, respectively. The outermost shell was ejected 187 ± 17 yr before the middle shell, while the middle shell was launched 48 ± 14 yr before the innermost shell. Our estimations of the linear and angular momentum rates of the outflow as well as the accretion luminosity are consistent with the values expected if the outflow of HH 30 is produced by a wide-angle disk wind.

We aim to clarify the link between mass accretion and ejection by analyzing DG Tau’s jet observations from optical and near-infrared data spanning 1984–2019, alongside photometric variations between 1983 and 2015. We classified 12 moving knot groups among 17 total knot groups based on their constant proper motions and comparable radial velocities. A strong correlation emerges between the deprojected flow velocities of the knots and the photometric magnitudes of DG Tau. From 1983 to 1995, as the deprojected ejection velocities surged from ∼273 ± 15 to ∼427 ± 16 km s ^−1 , the photometric magnitudes ( V ) concurrently brightened from 12.3 to 11.4. Notably, when DG Tau became brighter than 12.2 in the V band, its ( B − V ) color shifted bluer than its intrinsic color range of K5–M0. During this period, the launching point of the jet in the protoplanetary disk moved closer to 0.06 au from the star in 1995. Following a V magnitude drop from 11.7 to 13.4 in 1998, the star may have experienced significant extinction due to a dust wall created by the disk wind during the ejection of the high-velocity knot in 1999. Since then, the magnitude became fainter than 12.2, the ( B − V ) and ( V − R ) colors became redder, and the deprojected velocities consistently remained below 200 km s ^−1 . The launching point of the jet then moved away to ∼0.45 au by 2008. The prevailing factor influencing photometric magnitude appears to be the active mass accretion causing the variable mass ejection velocities.

We present a combined Stratospheric Observatory for Infrared Astronomy (SOFIA) and two-epoch Hubble Space Telescope (HST) study of the region NGC 2071 IR containing the outflow from the protostar HOPS 361-A (NGC 2071 IRS 1). New [O i ] 63 μ m spectra, taken with the German REciever for Astronomy at Terahertz frequencies (GREAT) instrument aboard SOFIA, trace the outflow, spectrally resolve line profiles, and give radial velocities of the far-IR emission to yield 3D kinematics, shock properties, and feedback properties. Proper motions and extinction values from HST give a more complete quasi-3D picture that we use to model shock speeds and densities. We identify 14 distinct features that show proper motions. Combined with the GREAT data, we estimate that HOPS 361-A has a mass outflow rate of 3.16 × 10 ^−6 M _⊙ yr ^−1 with shock speeds up to 51 km s ^−1 . The outflow force summed over all knots per area is measured to be 1.45 × 10 ^−4 M _⊙ km ^−1 s ^−1 yr ^−1 and a power summed over all knotsper area of 2.37 × 10 ^−2 M _⊙ s ^−3 dissipated assuming constant $\dot{M}$ , with large uncertainties on the feedback values. The total [O i ] luminosity using all SOFIA apertures encompassing the HOPS 361 clump is 0.7 L _⊙ , corresponding to a mass outflow rate of 7 × 10 ^−5 M _⊙ yr ^−1 . This is the second 3D kinematic study of an outflow in NGC 2071 IR in the near- and far-IR regimes following Rubinstein et al. ( 2023 ). The SOFIA [O i ] spectra add unique focus to the entrained gas connecting the recent episode of outflows from HOPS 361-A to the outflow cavity and the surrounding NGC 2071 IR star-forming environment.

We present a detailed analysis of the protostellar outflow activity in the massive star-forming region NGC 3324, as revealed by new Early Release Observations (EROs) from the James Webb Space Telescope (JWST). Emission from numerous outflows is revealed in narrow-band images of hydrogen Paschen α (Paα) and molecular hydrogen. In particular, we report the discovery of 24 previously unknown outflows based on their H2 emission. We find three candidate driving sources for these H2 flows in published catalogues of young stellar objects (YSOs), and we identify 15 infrared point sources in the new JWST images as potential driving protostars. We also identify several Herbig–Haro (HH) objects in Paα images from JWST ; most are confirmed as jets based on their proper motions measured in a comparison with previous Hubble Space Telescope (HST) Hα images. This confirmed all previous HST -identified HH jets and candidate jets, and revealed seven new HH objects. The unprecedented capabilities of JWST allow the direct comparison of atomic and molecular outflow components at comparable angular resolution. Future observations will allow quantitative analysis of the excitation, mass-loss rates, and velocities of these new flows. As a relatively modest region of massive star formation (larger than Orion but smaller than starburst clusters), NGC 3324 offers a preview of what star formation studies with JWST may provide. [ABSTRACT FROM AUTHOR]

4FGL J0822.8–4207 is a point source found in the 4FGL-DR2 catalogue by the gamma-ray observatory Fermi -LAT and has no known association. We carry out X-ray observations of 4FGL J0822.8–4207 to help understand its nature. We explore two scenarios for the origin of 4FGL J0822.8–4207 . In the first case, we study the possibility that cosmic rays from the supernova remnant (SNR) Puppis A, seen nearby in the sky, reach the dense gas at the location of the source and produce the gamma-rays through inelastic proton–proton collisions. We apply a standard model for particle diffusion in the interstellar medium and derive the required physical parameters. We find that this scenario for the gamma-rays is possible if the gas is located at a distance that is not higher than ∼40 pc from Puppis A, unless the SNR is older than 7 kyr or the diffusion coefficient is higher than typical Galactic values, and relatively low-energy cosmic rays are currently escaping from the SNR. In the second scenario, we consider the protostellar jet HH219 as the origin of the GeV source and find the very interesting possibility that particles could be accelerated up to energies of at least several TeV in HH219. This would make this system the first known of its kind to produce gamma-ray emission extending up to hundreds of GeV without any apparent cut-off and an excellent laboratory to study the process of particle acceleration. [ABSTRACT FROM AUTHOR]

Collisional self-interactions occurring in protostellar jets give rise to strong shocks, the structure of which can be affected by radiative cooling within the flow. To study such colliding flows, we use the AstroBEAR AMR code to conduct hydrodynamic simulations in both one and three dimensions with a power-law cooling function. The characteristic length and time-scales for cooling are temperature dependent and thus may vary as shocked gas cools. When the cooling length decreases sufficiently and rapidly, the system becomes unstable to the radiative shock instability, which produces oscillations in the position of the shock front; these oscillations can be seen in both the one- and three-dimensional cases. Our simulations show no evidence of the density clumping characteristic of a thermal instability, even when the cooling function meets the expected criteria. In the three-dimensional case, the nonlinear thin shell instability (NTSI) is found to dominate when the cooling length is sufficiently small. When the flows are subjected to the radiative shock instability, oscillations in the size of the cooling region allow NTSI to occur at larger cooling lengths, though larger cooling lengths delay the onset of NTSI by increasing the oscillation period. [ABSTRACT FROM AUTHOR]

The HH 24 complex harbors five collimated jets emanating from a small protostellar multiple system. We have carried out a multiwavelength study of the jets, their driving sources, and the cloud core hosting the embedded stellar system, based on data from the Hubble Space Telescope, Gemini, Subaru, Apache Point Observatory 3.5 m, Karl G. Jansky Very Large Array, and Atacama Large Millimeter/submillimeter Array (ALMA) telescopes. The data show that the multiple system, SSV 63, contains at least 7 sources, ranging in mass from the hydrogen-burning limit to proto-Herbig Ae stars. The stars are in an unstable nonhierarchical configuration, and one member, a borderline brown dwarf, is moving away from the protostellar system with 25 km s ^−1 , after being ejected ∼5800 yr ago as an orphaned protostar. Five of the embedded sources are surrounded by small, possibly truncated, disks resolved at 1.3 mm with ALMA. Proper motions and radial velocities imply jet speeds of 200–300 km s ^−1 . The two main HH 24 jets, E and C, form a bipolar jet system that traces the innermost portions of parsec-scale chains of Herbig–Haro and H _2 shocks with a total extent of at least 3 pc. H _2 CO and C ^18 O observations show that the core has been churned and continuously fed by an infalling streamer. ^13 CO and ^12 CO trace compact, low-velocity, cavity walls carved by the jets and an ultracompact molecular outflow from the most embedded object. Chaotic N -body dynamics likely will eject several more of these objects. The ejection of stars from their feeding zones sets their masses. Dynamical decay of nonhierarchical systems can thus be a major contributor to establishing the initial mass function.

The HH80-81 system is one of the most powerful jets driven by a massive protostar. We present new near-infrared (NIR) line imaging observations of the HH80-81 jet in the H _2 (2.122 μ m) and [Fe ii ] (1.644 μ m) lines. These lines trace not only the jet close to the exciting source but also the knots located farther away. We have detected nine groups of knot-like structures in the jet including HH80 and HH81 spaced 0.2–0.9 pc apart. The knots in the northern arm of the jet show only [Fe ii ] emission closer to the exciting source, a combination of [Fe ii ] and H _2 at intermediate distances, and solely H _2 emission farther outwards. Toward the southern arm, all the knots exhibit both H _2 and [Fe ii ] emission. The nature of the shocks is inferred by combining the NIR observations with radio and X-ray observations from the literature. In the northern arm, we infer the presence of strong dissociative shocks, in the knots located close to the exciting source. The knots in the southern arm that include HH80 and HH81 are explicable as a combination of strong and weak shocks. The mass-loss rates of the knots determined from [Fe ii ] luminosities are in the range ∼3.0 × 10 ^−7 –5.2 × 10 ^−5 M _⊙ yr ^−1 , consistent with those from massive protostars. Toward the central region, close to the driving source of the jet, we have observed various arcs in H _2 emission that resemble bow shocks, and strings of H _2 knots that reveal traces of multiple outflows.

We present a study of six dusty and gaseous pillars (containing the Herbig–Haro (HH) objects HH 1004 and HH 1010) and globules (that contain the HH 666, HH 900, HH 1006, and HH 1066 objects) localized in the Carina Nebula using sensitive and high-angular-resolution (∼0.″3) Atacama Large Millimeter/submillimeter Array observations. This is a more extensive study that the one presented in Cortes-Rangel et al. As in this former study, we also analyzed the 1.3 mm continuum emission and C ^18 O(2−1), N _2 D ^+ (3−2), and ^12 CO(2−1) spectral lines. These new observations revealed the molecular outflows emanating from the pillars, the dusty envelopes+disks that are exciting them, and the extended HH objects far from their respective pillars. We reveal that the masses of the disks+envelopes are in the range of 0.02–0.38 M _⊙ , and those for the molecular outflows are of the order of 10 ^−3 M _⊙ , which suggest that their exciting sources might be low- or intermediate-mass protostars as already revealed in recent studies at infrared and submillimeter bands. In the regions associated with the objects HH 900 and HH 1004, we report multiple millimeter continuum sources, from where several molecular outflows emanate.

We present the analysis of physical conditions, chemical composition, and kinematic properties of two bow shocks – HH 529 II and HH 529 III – of the fully photoionized Herbig–Haro object HH 529 in the Orion Nebula. The data were obtained with the Ultraviolet and Visual Echelle Spectrograph at the 8.2m Very Large Telescope and 20 yr of Hubble Space Telescope imaging. We separate the emission of the high-velocity components of HH 529 II and III from the nebular one, determining n e and T e in all components through multiple diagnostics, including some based on recombination lines (RLs). We derive ionic abundances of several ions, based on collisionally excited lines and RLs. We find a good agreement between the predictions of the temperature fluctuation paradigm (t 2) and the abundance discrepancy factor (ADF) in the main emission of the Orion Nebula. However, t 2 cannot account for the higher ADF found in HH 529 II and III. We estimate 6 per cent of Fe in the gas phase of the Orion Nebula, while this value increases to 14 per cent in HH 529 II and between 10 and 25 per cent in HH 529 III. We find that such increase is probably due to the destruction of dust grains in the bow shocks. We find an overabundance of C, O, Ne, S, Cl, and Ar of about 0.1 dex in HH 529 II and III that might be related to the inclusion of H-deficient material from the source of the HH 529 flow. We determine the proper motions of HH 529 finding multiple discrete features. We estimate a flow angle with respect to the sky plane of 58° ± 4° for HH 529. [ABSTRACT FROM AUTHOR]

HH 175 is an isolated Herbig–Haro object seen towards the B35 cloud in the λ Ori region. We use deep Subaru 8 m interference filter images and Spitzer images to show that HH 175 is a terminal shock in a large collimated outflow from the nearby embedded source IRAS 05417+0907. The body of the eastern outflow lobe is hidden by a dense ridge of gas. The western outflow breaks out of the front of the cometary-shaped B35 cloud, carrying cloud fragments along, which are optically visible due to photoionization by the massive λ Ori stars. The total extent of the bipolar outflow is 13.7 arcmin, which at the adopted distance of 415 pc corresponds to a projected dimension of 1.65 pc. The embedded source IRAS 05417+0907 is located on the flow axis approximately midway between the two lobes, and near-infrared images show it to be a multiple system of six sources, with a total luminosity of 31 L⊙. Millimeter maps in CO, 13CO, and C18O show that the B35 cloud is highly structured with multiple cores, of which the one that spawned IRAS 05417+0907 is located at the apex of B35. It is likely that the embedded source is the result of compression by an ionization-shock front driven by the λ Ori OB stars. [ABSTRACT FROM AUTHOR]

We present the results of a narrow-band Hα and [S  ii ] imaging survey of the Mon R1 association performed with the 1-m Schmidt telescope at Byurakan Observatory. Our observations covered a 1° field near the centre of the association. As a result of this study, 20 new Herbig–Haro knots were discovered, some of which form collimated outflows. Among the most extended ones are HH 1203 and HH 1196, which have a length of 1 pc or even more. During the search for the probable sources of HH objects, several new nebulous stars were found. A list of all nebulous stellar objects in the Mon R1 area under study is presented, with detailed descriptions of the most interesting ones. The near-infrared data from the GLIMPSE360 and WISE surveys revealed several more objects related to Mon R1, some of which had optical counterparts, as well as helped to identify at least three probable H2 collimated flows from the deeply embedded pre-main-sequence objects. The probable members of Mon R1 were selected by their distances; their bolometric luminosities and extinctions were estimated. Among the outflow sources, three embedded objects with luminosities greater than 10 L⊙ were found. The mean distance to the Mon R1 complex is estimated as 715 pc. [ABSTRACT FROM AUTHOR]

Looking for evidence of recent star formation, we have studied a small comet-shaped reflection nebula, known as BBWo 192E (GM 1–23), which is located in the dark cloud SL 4 in the Vela Molecular Ridge cloud C, and a young infrared cluster embedded into the nebula. We obtained the images of BBWo 192E in Hα and [S  ii ] lines and in a Sloan Digital Sky Survey i  ′ filter with the Blanco telescope at the Cerro Tololo Inter-American Observatory in order to discover new Herbig–Haro (HH) flows. We used the Two-Micron All-Sky Survey and the Wide-field Infrared Survey Explorer to search for additional member stars of the cluster. We also studied the proper motions and parallaxes of the cluster members using GAIA Data Release 2. Five new groups containing at least nine HH objects, tracing several distinct outflows, were revealed. A previously unreported reflection nebula and a number of probable outflow sources were found in the infrared range. The proper motions allowed us to select eight probable member stars in the visual range. Their parallaxes correspond to a mean distance 800 ± 100 pc for this cluster. The bolometric luminosities of the brightest cluster members are 1010 L⊙ (IRAS 08513−4201, the strong source in the centre of the cluster) and 2–6 L⊙ for the five other stars. The existence of optical HH flows around the infrared cluster of young stellar objects suggests that star formation in this cloud is ongoing around the more massive Herbig Ae/Be star. Considering its morphology and other features, this star-forming region is similar to the zone of star formation near CPM 19. [ABSTRACT FROM AUTHOR]

Context. We present SOFIA/FIFI-LS observations of five prototypical, low-mass Class I outflows (HH111, SVS13, HH26, HH34, HH30) in the far-infrared [O I]63μm and [O I]145μm transitions. Aims. Spectroscopic [O I]63μm,145μm maps enable us to study the spatial extent of warm, low-excitation atomic gas within outflows driven by Class I protostars. These [O I] maps may potentially allow us to measure the mass-loss rates (Ṁjet) of this warm component of the atomic jet. Methods. A fundamental tracer of warm (i.e. T ~ 500–1500 K), low-excitation atomic gas is the [O I]63μm emission line, which is predicted to be the main coolant of dense dissociative J-type shocks caused by decelerated wind or jet shocks associated with protostellar outflows. Under these conditions, the [O I]63μm line can be directly connected to the instantaneous mass ejection rate. Thus, by utilising spectroscopic [O I]63μm maps, we wish to determine the atomic mass flux rate Ṁjet ejected from our target outflows. Results. Strong [O I]63μm emission is detected at the driving sources HH111IRS, HH34IRS, SVS13, as well as at the bow shock region, HH7. The detection of the [O I]63μm line at HH26A and HH8/HH10 can be attributed to jet deflection regions. The far-infrared counterpart of the optical jet is detected in [O I]63μm only for HH111, but not for HH34. We interpret the [O I]63μm emission at HH111IRS, HH34IRS, and SVS13 to be coming primarily from a decelerated wind shock, whereas multiple internal shocks within the HH111 jet may cause most of the [O I]63μm emission seen there. At HH30, no [O I]63μm,145μm was detected. The [O I]145μm line detection is at noise level almost everywhere in our obtained maps. The observed outflow rates of our Class I sample are to the order of Ṁjet ~ 10−6M⊙ yr−1, if proper shock conditions prevail. Independent calculations connecting the [O I]63μm line luminosity and observable jet parameters with the mass -loss rate are consistent with the applied shock model and lead to similar mass-loss rates. We discuss applicability and caveats of both methods. Conclusions. High-quality spectroscopic [O I]63μm maps of protostellar outflows at the jet driving source potentially allow a clear determination of the mass ejection rate. [ABSTRACT FROM AUTHOR]

The massive star-forming region W75N (B) is thought to host a cluster of massive protostars (VLA 1, VLA 2, and VLA 3) undergoing different evolutionary stages. In this work, we present radio continuum data with the highest sensitivity and angular resolution obtained to date in this region, using the VLA-A and covering a wide range of frequencies (4–48 GHz), which allowed us to study the morphology and the nature of the emission of the different radio continuum sources. We also performed complementary studies with multi-epoch Very Large Array (VLA) data and Atacama Large Millimeter Array (ALMA) archive data at 1.3 mm wavelength. We find that VLA 1 is driving a thermal radio jet at scales of ≈0.1 arcsec (≈130 au), but also shows signs of an incipient hypercompact H  ii region at scales of ≲1 arcsec (≲1300 au). VLA 3 is also driving a thermal radio jet at scales of a few tenths of arcsec (few hundred of au). We conclude that this jet is shock exciting the radio continuum sources Bc and VLA 4 (obscured Herbig–Haro objects), which show proper motions moving outward from VLA 3 at velocities of ≈112–118 km s−1. We have also detected three new weak radio continuum sources, two of them associated with millimetre continuum cores observed with ALMA, suggesting that these two sources are also embedded young stellar objects in this massive star-forming region. [ABSTRACT FROM AUTHOR]

'Orion fingers' are a system of dozens of bow shocks, with the wings of shocks pointing to a common system of origin, which is centred on a dynamically disintegrating system of several massive stars. The shock heads propagate with velocities of up to 300–400 km s−1, but the formation and physical properties of the 'bullets' leading the shocks are not known. Here, we summarize two possible scenarios for the formation of the 'bullets' and the resulting bow shocks ('fingers'). In the first scenario, bullets are self-gravitating, Jupiter-mass objects that were formed rapidly and then ejected during the strong dynamical interactions of massive stars and their discs. This scenario naturally explains the similar time-scales for the outflow of bullets and for the dynamical interaction of the massive stars, but has some difficulty explaining the observed high velocities of the bullets. In the second scenario, bullets are formed via hydrodynamic instabilities in a massive, infrared-driven wind, naturally explaining the high velocities and the morphology of outflow, but the bullets are not required to be self-gravitating. The processes that created the Orion fingers are likely not unique to this particular star-forming region and may result in free-floating, high-velocity, core-less planets. [ABSTRACT FROM AUTHOR]

Context. We present the very first wide-field, 110 by 110, optical spectral mapping ofM16, one of the most famous star-forming regions in the Galaxy. The data were acquired with the new imaging Fourier transform spectrograph SITELLE mounted on the Canada-France- Hawaii Telescope (CFHT). We obtained three spectral cubes with a resolving power of 10 000 (SN1 filter), 1500 (SN2 filter) and 600 (SN3 filter), centered on the iconic Pillars of Creation and the HH 216 flow, covering the main optical nebular emission lines, namely [O II]λ3726,29 (SN1), Hα, [O III]λ4959,5007 (SN2), [N II]λ6548,84, Hβ, and [S II]λ6717,31 (SN3). Aims. We validate the performance, calibration, and data reduction of SITELLE, and analyze the structures in the large field-of-view in terms of their kinematics and nebular emission. Methods. We compared the SITELLE data to MUSE integral field observations and other spectroscopic and narrow-band imaging data to validate the performance of SITELLE. We computed gas-phase metallicities via the strong-line method, performed a pixelby- pixel fit to the main emission lines to derive kinematics of the ionized gas, computed the mass-loss rate of the Eastern pillar (also known as the Spire), and combined the SITELLE data with near-infrared narrow-band imaging to characterize the HH 216 flow. Results. The comparison with previously published fluxes demonstrates very good agreement. We disentangle the dependence of the gas-phase metallicities (derived via abundance-tracing line ratios) on the degree of ionization and obtain metallicities that are in excellent agreement with the literature. We confirm the bipolar structure of HH 216, find evidence for episodic accretion from the source of the flow, and identify its likely driving source. We compute the mass-loss rate M of the Spire pillar on the East side of the H II region and find excellent agreement with the correlation between the mass-loss rate and the ionizing photon flux from the nearby cluster NGC 6611. [ABSTRACT FROM AUTHOR]

This is a study of several new star-formation regions in the southern sky. Jets, Herbig-Hero objects, compact HII regions, and IR stars exist in these regions. The star-formation regions lie in giant molecular clouds, with one cloud containing several regions that have a radial system of dark globules in the cloud itself. Many of the stars have dust disks. There is also a group of two pairs of stars, in which the stars are joined by two bright filaments in each pair. [ABSTRACT FROM AUTHOR]

Context. Herbig–Haro (HH) flows exhibit a large variety of morphological and kinematical structures such as bow shocks, Mach disks, and deflection shocks. Both proper motion (PM) and radial velocity investigations are essential to understand the physical nature of such structures. Aims. We investigate the kinematics and PM of spectrally separated structures in the FS Tau B HH flow. Collating these data makes it possible to understand the origin of these structures and to explain the unusual behavior of the jet. Besides, the study of emission profiles in the associated reflection nebulae allows us to consider the source of the outflow both from edge-on and pole-on points of view. Methods. We present the data obtained with the 6 m telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences using the SCORPIO multimode focal reducer with a scanning Fabry–Perot interferometer. Two epochs of the observations of the FS Tau B region in Hα emission (2001 and 2012) allowed us to measure the PM of the spectrally separated inner structures of the jet. Results. In addition to already known emission structures in the FS Tau B system, we discover new features in the extended part of the jet and in the counter-jet. Moreover, we reveal a new HH knot in the HH 276 independent outflow system and point out its presumable source. In the terminal working surface of the jet, structures with different radial velocities have PMs of the same value. This result can be interpreted as the direct observation of bow-shock and Mach disk regions. A bar-like structure, located southwest from the source demonstrates zero PM and can be considered as one more example of deflection shock. An analysis of Hα profiles in the reflection nebulae R1 and R3 indicates the uniqueness of this object, which can be studied in pole-on and edge-on directions simultaneously. [ABSTRACT FROM AUTHOR]

We studied the Class I protostar 2MASS 22352345 + 7517076 whose dramatic brightening between the IRAS, Akari, and WISE surveys was reported by Onozato et al. 2MASS 22352345+7517076 is a member of a small group of low-mass young stellar objects, associated with IRAS 22343 + 7501 in the molecular cloud Lynds 1251. The IRAS, ISO, Spitzer, Akari, Herschel, and WISE missions observed different stages of its outburst. Supplemented these data with archival and our own near-infrared observations, and considering the contributions of neighbouring sources to the mid-infrared fluxes we studied the nature and environment of the outbursting object, and its photometric variations from 1983 to 2017. The low-state bolometric luminosity L bol≈32 L |$\odot$| is indicative of a 1.6–1.8 M |$\odot$| , 1–2 × 105-yr old protostar. Its 2- |$\mu$| m brightness started rising between 1993 and 1998, reached a peak in 2009–2011, and started declining in 2015. Changes in the spectral energy distribution suggest that the outburst was preceded by a decade-long, slow brightening in the near-infrared. The actual accretion burst occurred between 2004 and 2007. We fitted the spectral energy distribution in the bright phases with simple accretion disc models. The modelling suggested an increase of the disc accretion rate from ∼3.5 × 10−7 M |$\odot$|  yr−1 to ∼1.1 × 10−4 M |$\odot$|  yr−1. The central star accreted nearly 10−3 M |$\odot$| , about a Jupiter mass during the 10 yr of the outburst. We observed H2 emission lines in the K -band spectrum during the fading phase in 2017. The associated optical nebulosity RNO 144 and the Herbig–Haro object HH 149 have not exhibited significant variation in shape and brightness during the outburst. [ABSTRACT FROM AUTHOR]

Here, we analyse the character of the turbulence of the Huygens region in the Orion Nebula (M 42) using structure functions. We compute the second-order structure function of a high-resolution velocity map in H α obtained through the MUSE instrument. Ours is one of the few works that follows a mathematically sound methodology for calculating the second-order structure function of astronomical velocity fields. Because of that, our results will be useful for future comparisons with other studies of M 42 or other regions. We first analyse the probability distribution function and found it consistent with those resulting from numerical simulations of solenoidal turbulence. After a further analysis of the data, we found two possible separate motions or at least regimes in the region. This is confirmed later through the calculation of several filtered structure functions. We found that the turbulence in the Huygens region is between the Kolmogorov regime (S 2 ∝ δ r 2/3) and the Burgers regime (S 2 ∝ δ r). We found that the turbulence in the region consists of two flow regimes that reproduce a generalized Larson's Law, S 2 ∼ δ r 0.74−0.76. [ABSTRACT FROM AUTHOR]

We present an analysis of radio (Karl G. Jansky Very Large Array (VLA)), optical (Hubble Space Telescope (HST)), and X-ray (Chandra and XMM–Newton) observations and archival data of the Herbig–Haro objects HH 80 and HH 81 in the context of jet–cloud interactions. Our radio images are the highest angular resolution to date of these objects, allowing to spatially resolve the knots and compare the regions emitting in the different spectral ranges. We found that soft X-ray thermal emission is located ahead of the non-thermal radio peak. This result is consistent with a radiative forward shock that heats the shocked gas up to 106 K, and an adiabatic reverse shock able to accelerate particles and produce synchrotron radiation detectable at radio frequencies. These high angular resolution radio images also reveal a bow shock structure in the case of HH 80N, with it being the first time this morphology is detected in a Herbig–Haro object at these frequencies. [ABSTRACT FROM AUTHOR]

Context. The molecular richness of fast protostellar jets within 20–100 au of their source, despite strong ultraviolet irradiation, remains a challenge for the models investigated so far. Aim.We aim to investigate the effect of interaction between a time-variable jet and a surrounding steady disk wind, to assess the possibility of jet chemical enrichement by the wind, and the characteristic signatures of such a configuration. Methods. We have constructed an analytic model of a jet bow shock driven into a surrounding slower disk wind in the thin shell approximation. The refilling of the post bow shock cavity from below by the disk wind is also studied. An extension of the model to the case of two or more successive internal working surfaces (IWS) is made. We then compared this analytic model with numerical simulations with and without a surrounding disk wind. Results. We find that at early times (of order the variability period), jet bow shocks travel in refilled pristine disk wind material, before interacting with the cocoon of older bow shocks. This opens the possibility of bow shock chemical enrichment (if the disk wind is molecular and dusty) and of probing the unperturbed disk wind structure near the jet base. Several distinctive signatures of the presence of a surrounding disk wind are identified, in the bow shock morphology and kinematics. Numerical simulations validate our analytical approach and further show that at large scale, the passage of many jet IWS inside a disk wind produces a stationary V-shaped cavity, closing down onto the axis at a finite distance from the source. [ABSTRACT FROM AUTHOR]

HH212, a nearby (400 pc) object in Orion, is a class 0 protostellar system with a Keplerian disc and collimated bipolar SiO jets. Deuterated water, HDO, and a deuterated complex molecule, methanol (CH2DOH), have been reported in the source. Here, we report the HDCO (deuterated formaldehyde) line observation from Atacama Large Millimeter Array data to probe the inner region of HH212. We compare HDCO line with other molecular lines to understand the possible chemistry and physics of the source. The distribution of HDCO emission suggests that it may be associated with the base of the outflow. The emission also shows a rotation but it is not associated with the Keplerian rotation of disc or the rotating infalling envelope, rather it is associated with the outflow as previously seen in C34S. From the possible deuterium fractionation, we speculate that the gas phase formation of deuterated formaldehyde is active in the central hot region of the low-mass protostar system, HH212. [ABSTRACT FROM AUTHOR]