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A bstract The chiral worldvolume theory of an M-theory boundary (the so-called M9 brane) is uniquely determined by supersymmetry and anomaly inflow. In this brief note we investigate whether alternative chiral boundary field contents may be allowed by anomaly cancellation once supersymmetry is dropped. Even then, anomaly inflow places stringent constraints on the gauge group G and matter content of the boundary worldvolume theory, which we determine explicitly. We find the most general solution to these constraints in the case where all matter fields are of the same chirality, for all simple Lie algebras except sp 2 , su n ≤ 5 , and so n with 7 ≤ n ≤ 12, and find no solutions other than the supersymmetric E 8 boundary of Hořava and Witten. However, when we extend our search to allow for any chirality in the matter fields, we find one minimal solution with gauge group G 2 , charged matter in the 14, 27 and 77 representations, which satisfies all constraints in a non-trivial way. Therefore, it could in principle describe the low-energy theory of a novel nonsupersymmetric M-theory boundary condition, different from the Hořava-Witten proposal. We briefly discuss some consequences if this was indeed the case, such as the existence of a non-supersymmetric, exotic “ G 2 -string” CFT in 6d, and a novel, non-perturbative, heterotic-like 10d string with gauge group G 2 × G 2 .

Acceleration and manipulation of electron bunches underlie most electron and X-ray devices used for ultrafast imaging and spectroscopy. New terahertz-driven concepts offer orders-of-magnitude improvements in field strengths, field gradients, laser synchronization and compactness relative to conventional radiofrequency devices, enabling shorter electron bunches and higher resolution with less infrastructure while maintaining high charge capacities (pC), repetition rates (kHz) and stability. We present a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the six-dimensional phase space of ultrashort electron bunches. With this single device, powered by few-microjoule, single-cycle, 0.3 THz pulses, we demonstrate record terahertz acceleration of >30 keV, streaking with <10 fs resolution, focusing with >2 kT m–1 strength, compression to ~100 fs as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of terahertz-based electron accelerators, manipulators and diagnostic tools, enabling science beyond current resolution frontiers with transformative impact.

We present high-angular resolution ( ≃0.″06 ) Very Large Array and Atacama Large Millimeter/submillimeter Array observations of Orion South separated by 15.52 yr. The purpose of this study was to search for orbital motions in three close ( ≃0.″1 ) binary systems in the region. We do not detect changes in the position angle of the binaries, but in two of the cases, we detect significant changes in their separation in the plane of the sky. We use these changes to estimate that the total mass of the binaries is in the ≃1–2 M⊙ range. We also estimate the disk masses from the millimeter emission. The disk-to-stellar mass ratio is in the range of 0.04–0.18, values consistent with those expected for very early stellar evolution (Class 0) protostars.

Using James Webb Space Telescope near-infrared data of the inner Orion Nebula, Pearson & McCaughrean detected 40 Jupiter-mass binary objects (JuMBOs). These systems are not associated with stars and their components have masses of giant Jupiter-like planets and separations in the plane of the sky of order ∼100 au. The existence of these wide free-floating planetary-mass binaries was unexpected in our current theories of star and planet formation. Here we report the radio continuum (6.1 and 10.0 GHz) Karl G. Jansky Very Large Array detection of a counterpart to JuMBO 24. The radio emission appears to be steady at a level of ∼50 μJy over timescales of days and years. We set an upper limit of ≃15 km s−1 to the velocity of the radio source in the plane of the sky. As in the near-infrared, the radio emission seems to be coming from both components of the binary.

Using JWST near-infrared data of the inner Orion Nebula, S. G. Pearson & M. J. McCaughrean detected 40 binary systems they proposed to be Jupiter-mass binary objects (JuMBOs)—although their actual nature is still in debate. Only one of the objects, JuMBO 24, was detected in the radio continuum. Here, we report on new radio continuum (10 GHz) Karl G. Jansky Very Large Array (VLA) detections of the radio counterpart to JuMBO 24, and on an unsuccessful search for 5 GHz continuum emission with the High Sensitivity Array (HSA). From our new VLA detections and adopting a distance to the region, we set an upper limit of ≃6 km s−1 to the velocity of the radio source in the plane of the sky. This upper limit favors an origin for this source similar to that of stars, that is, from a stationary contracting core. The nature of the radio emission remains uncertain, but the lack of strong variability (all VLA observations are consistent with a steady flux of ∼50 μJy), of detection on long HSA baselines, and of detectable circular polarization in VLA data do not favor a nonthermal origin.

We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations of the close (0.″3 = 90 au separation) protobinary system SVS 13. We detect two small circumstellar disks (radii ∼12 and ∼9 au in dust, and ∼30 au in gas) with masses of ∼0.004–0.009 M ☉ for VLA 4A (the western component) and ∼0.009–0.030 M ☉ for VLA 4B (the eastern component). A circumbinary disk with prominent spiral arms extending ∼500 au and a mass of ∼0.052 M ☉ appears to be in the earliest stages of formation. The dust emission is more compact and with a very high optical depth toward VLA 4B, while toward VLA 4A the dust column density is lower, allowing the detection of stronger molecular transitions. We infer rotational temperatures of ∼140 K, on scales of ∼30 au, across the whole source, and a rich chemistry. Molecular transitions typical of hot corinos are detected toward both protostars, being stronger toward VLA 4A, with several ethylene glycol transitions detected only toward this source. There are clear velocity gradients, which we interpret in terms of infall plus rotation of the circumbinary disk, and pure rotation of the circumstellar disk of VLA 4A. We measured orbital proper motions and determined a total stellar mass of 1 M ☉. From the molecular kinematics, we infer the geometry and orientation of the system, and stellar masses of ∼0.26 M ☉ for VLA 4A and ∼0.60 M ☉ for VLA 4B.

We present the 12CO (J = 2–1) sensitive molecular line and 1.3 mm continuum observations from the Submillimeter Array (SMA) of the bipolar outflow associated with the young star located in the Bok globule known as CB 26. The SMA observations were carried out in its extended configuration allowing us to study the kinematics and structure of the outflow with about 1″ or 140 au resolution. We find that the dusty and edge-on circumstellar disk related to the outflow has a projected spatial (deconvolved) size of 196 ± 31 × 42 ± 29 au with a total (gas+dust) mass of 0.031 ± 0.015 M ⊙. We estimated a dynamical mass for the central object of 0.66 ± 0.03 M ⊙, and the mass of the molecular outflow of 5 ± 1.5 × 10−5 M ⊙. All these values are consistent with recent estimations. The observations confirm that the outflow rotation has a similar orientation to that of the edge-on disk. For the outflow, we find that the following quantities: the rotation velocity (∼1–3 km s−1), specific angular momentum (∼200–700 au km s−1), and launching radius (∼15–35 au) decrease with the height above the midplane, as observed in other molecular rotating outflows. The radius (∼180–280 au) and expansion velocity (∼2–4 km s−1) also increase with the height above the disk midplane for z < 0 au; however, for z > 0 au these quantities do not exhibit this behavior. Estimations of the outflow linear momentum rate, outflow angular momentum rate, and accretion luminosity seem to be well explained by the presence of a disk wind in CB 26.

We present archival Atacama Large Millimeter/submillimeter Array band 6 observations of the 13CO (J = 2–1) and 12CO (J = 2–1) molecular line emission of the protostellar system associated with HH 30. The 13CO molecular line shows the accretion disk while the molecular outflow is traced by the emission of the 12CO 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 present a high-angular resolution (∼1″) and wide-field ( 2.′9×1.′9 ) image of the 1.3 mm continuum, CO(J = 2–1) and SiO(J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H2 gas number densities are estimated to be 3.8 × 10−5–1.1 × 10−2 M ⊙, 290–2000 au, and 6.4 × 106–3.3 × 108 cm−3, respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO(J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO(J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N2H+ line.

The process of phase separation allows for the establishment and formation of subcompartmentalized structures, thus enabling cells to perform simultaneous processes with precise organization and low energy requirements. Chemical modifications of proteins, RNA, and lipids alter the molecular environment facilitating enzymatic reactions at higher concentrations in particular regions of the cell. In this review, we discuss the nucleolus as an example of the establishment, dynamics, and maintenance of a membraneless organelle with a high level of organization.