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HOPS 87 is a Class 0 protostellar core known to harbor an extremely young bipolar outflow and a hot corino. We report the discovery of localized, chemically rich regions near the bases of the two-lobe bipolar molecular outflow in HOPS 87 containing molecules such as H2CO, 13CS, H2S, OCS, and CH3OH, the simplest complex organic molecule (COM). The locations and kinematics suggest that these localized features are due to jet-driven shocks rather than being part of the hot-corino region encasing the protostar. The COM compositions of the molecular gas in these jet-localized regions are relatively simpler than those in the hot-corino zone. We speculate that this simplicity is due to either the liberation of ice with a less complex chemical history or the effects of shock chemistry. Our study highlights the dynamic interplay between the protostellar bipolar outflow, disk, inner-core environment, and the surrounding medium, contributing to our understanding of molecular complexity in solar-like young stellar objects. [ABSTRACT FROM AUTHOR]

We present Atacama Large Millimeter/submillimeter Array CO (J = 2–1) and 1.3 mm continuum observations of the high-velocity jet associated with the FIR 6b protostar located in the Orion Molecular Cloud-2. We detect a velocity gradient along the short axis of the jet in both the red- and blueshifted components. The position–velocity diagrams along the short axis of the redshifted jet show a typical characteristic of a rotating cylinder. We attribute the velocity gradient in the redshifted component to rotation of the jet. The rotation velocity (>20 km s−1) and specific angular momentum (>1022 cm2 s−1) of the jet around FIR 6b are the largest among all jets in which rotation has been observed. By combining disk wind theory with our observations, the jet launching radius is estimated to be in the range of 2.18–2.96 au. The rapid rotation, large specific angular momentum, and a launching radius far from the central protostar can be explained by a magnetohydrodynamic disk wind that contributes to the angular momentum transfer in the late stages of protostellar accretion. [ABSTRACT FROM AUTHOR]

Using the Atacama Large Millimeter/submillimeter Array (ALMA), we investigated the peculiar millimeter source MMS 3 located in the Orion Molecular Cloud 3 (OMC-3) region in the 1.3 mm continuum, CO (J = 2–1), SiO (J = 5–4), C18O (J = 2–1), N2D+ (J = 3–2), and DCN (J = 3–2) emissions. With the ALMA high angular resolution (∼0.″2), we detected a very compact and highly centrally condensed continuum emission with a size of 0.″45 × 0.″32 (P.A. = 0.°22). The peak position coincides with the locations of previously reported Spitzer/IRAC and X-ray sources within their positional uncertainties. We also detected an envelope with a diameter of ∼6800 au (P.A. = 75°) in the C18O (J = 2–1) emission. Moreover, a bipolar outflow was detected in the CO (J = 2–1) emission for the first time. The outflow is elongated roughly perpendicular to the long axis of the envelope detected in the C18O (J = 2–1) emission. Compact high-velocity CO gas in the (redshifted) velocity range of 22–30 km s−1, presumably tracing a jet, was detected near the 1.3 mm continuum peak. A compact and faint redshifted SiO emission was marginally detected in the CO outflow lobe. The physical quantities of the outflow in MMS 3 are somewhat smaller than those in other sources in the OMC-3 region. The centrally condensed object associated with the near-infrared and X-ray sources, the flattened envelope, and the faint outflow indicate that MMS 3 harbors a low-mass protostar with an age of ∼103 yr. [ABSTRACT FROM AUTHOR]

Studying the physical conditions of very low luminosity objects (VeLLOs; Lbol < 0.1 Lʘ) is important for understanding the earliest evolutionary stage of protostars and brown dwarfs. We report interferometric observations of the VeLLO L1521F-IRS, in 12CO (2-1) line emission and the 1.3 mm continuum emission, using the Submillimeter Array. With the 12CO (2-1) high-resolution observations, we have spatially resolved a compact but poorly collimated molecular outflow associated with L1521F-IRS for the first time. The blueshifted and redshifted lobes are aligned along the east and west side of L1521F-IRS with a lobe size of ≈1000 AU. The estimated outflow mass, maximum outflow velocity, and outflow force are (9.0-80) × 10-4Mʘ, 7.2 kms-1, and (7.4-66) × 10-7Mʘ km s-1 yr-1, respectively. The estimated outflow parameters such as size, mass, and momentum rate are similar to values derived for other VeLLOs, and are located at the lower end of values compared to previously studied outflows associated with low- to high-mass star-forming regions. Low-velocity less collimated (1.5 km s-1/ 1200 AU) and higher-velocity compact (4.0 km s?1/920 AU) outflow components are suggested by the data. These velocity structures are not consistent with those expected in the jet-driven or wind-driven outflow models, perhaps suggesting a remnant outflow from the first hydrostatic core as well as an undeveloped outflow from the protostar. Detection of an infrared source and compact millimeter continuum emission suggests the presence of the protostar, while its low bolometric luminosity (0.034-0.07 Lʘ) and small outflow suggests that L1521F is in the earliest protostellar stage (<104 yr) and contains a substellar mass object. The bolometric (or internal) luminosity of L1521F-IRS suggests that the current mass accretion rate is an order of magnitude lower than expected in the standard mass accretion model (≈10-6Mʘ yr-1), which may imply that L1521F-IRS is currently in a low activity phase. [ABSTRACT FROM AUTHOR]

We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of keV and an equivalent isotropic energy of Eiso as erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo – αX = –1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array. [ABSTRACT FROM AUTHOR]

We report on high-sensitivity and high angular resolution archival Submillimeter Array observations of the large (∼15,000 AU) putative circumstellar disk associated with the O-type protostar NGC 7538 S. Observations of the continuum resolve this putative circumstellar disk into five compact sources, with sizes ∼3000 AU and masses ∼10 M☼. This confirms the results of recent millimeter observations made with CARMA/BIMA toward this object. However, we find that most of these compact sources eject collimated bipolar outflows, revealed by our silicon monoxide (SiO J = 5-4) observations, and confirm that these sources have a (proto)stellar nature. All outflows are perpendicular to the large and rotating dusty structure. We propose therefore that, rather than being a single massive circumstellar disk, NGC 7538 S could instead be a large and massive contracting or rotating filament that is fragmenting at scales of 0.1-0.01 pc to form several B-type stars, via the standard process involving outflows and disks. As in recent high spatial resolution studies of dusty filaments, our observations also suggest that thermal pressure does not seem to be sufficient to support the filament, so that either additional support needs to be invoked or else the filament must be in the process of collapsing. A smoothed particle hydrodynamics numerical simulation of the formation of a molecular cloud by converging warm neutral medium flows produces contracting filaments whose dimensions and spacings between the stars forming within them, as well as their column densities, strongly resemble those observed in the filament reported here. [ABSTRACT FROM AUTHOR]

With the Submillimeter Array, the brightest (sub)millimeter continuum source in the Orion Molecular Cloud-2/3 region, MMS 6, has been observed in the 850 μm continuum emission with approximately 10 times better angular resolution than previous studies (≈0.″3, ≈120 AU at Orion). The deconvolved size, the mass, and the column density of MMS 6-main are estimated to be 0.″32 × 0.″29 (132 AU × 120 AU), 0.29 M☼, and 2.1 × 1025 cm–2, respectively. The estimated extremely high mean number density, 1.5 × 1010 cm–3, suggests that MMS 6-main is likely optically thick at 850 μm. We compare our observational data with three theoretical core models: prestellar core, protostellar core + disk-like structure, and first adiabatic core. These comparisons clearly show that the observational data cannot be modeled as a simple prestellar core with a gas temperature of 20 K. A self-luminous source is necessary to explain the observed flux density in the (sub)millimeter wavelengths. Our recent detection of a very compact and energetic outflow in the CO (3-2) and HCN (4-3) lines supports the presence of a protostar. We suggest that MMS 6 is one of the first cases of an intermediate-mass protostellar core at an extremely young stage. In addition to the MMS 6-main peak, we have also spatially resolved a number of spiky structures and sub-clumps, distributed over the central 1000 AU. The masses of these sub-clumps are estimated to be 0.066-0.073 M☼, which are on the order of brown dwarf masses. Higher angular resolution and higher sensitivity observations with ALMA and EVLA will reveal the origin and nature of these structures such as whether they are originated from fragmentations, spiral arms, or inhomogeneity within the disk-like structures/envelope. [ABSTRACT FROM AUTHOR]