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1. CMZoom III: Spectral line data release

   https://doi.org/10.1093/mnras/stad388  

   Callanan, Daniel; Longmore, Steven N; Battersby, Cara; Hatchfield, H Perry; Walker, Daniel L; Henshaw, Jonathan; Keto, Eric; Barnes, Ashley; Ginsburg, Adam; Kauffmann, Jens; et al (February 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We present an overview and data release of the spectral line component of the SMA Large Program, CMZoom. CMZoom observed 12CO (2–1), 13CO (2–1), and C18O (2–1), three transitions of H2CO, several transitions of CH3OH, two transitions of OCS, and single transitions of SiO and SO within gas above a column density of N(H2) ≥ 1023 cm−2 in the Central Molecular Zone (CMZ; inner few hundred pc of the Galaxy). We extract spectra from all compact 1.3 mm CMZoom continuum sources and fit line profiles to the spectra. We use the fit results from the H2CO 3(0, 3)–2(0, 2) transition to determine the source kinematic properties. We find ∼90 per cent of the total mass of CMZoom sources have reliable kinematics. Only four compact continuum sources are formally self-gravitating. The remainder are consistent with being in hydrostatic equilibrium assuming that they are confined by the high external pressure in the CMZ. We find only two convincing proto-stellar outflows, ruling out a previously undetected population of very massive, actively accreting YSOs with strong outflows. Finally, despite having sufficient sensitivity and resolution to detect high-velocity compact clouds (HVCCs), which have been claimed as evidence for intermediate mass black holes interacting with molecular gas clouds, we find no such objects across the large survey area. 

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2. Early Planet Formation in Embedded Disks. XI. A High-resolution View Toward the BHR 71 Class 0 Protostellar Wide Binary

   https://doi.org/10.3847/1538-4357/ad655e  

   Gavino, Sacha; Jørgensen, Jes K; Sharma, Rajeeb; Yang, Yao-Lun; Li, Zhi-Yun; Tobin, John J; Ohashi, Nagayoshi; Takakuwa, Shigehisa; Plunkett, Adele L; Kwon, Woojin; et al (October 2024, The Astrophysical Journal)

   Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the binary Class 0 protostellar system BHR 71 IRS1 and IRS2 as part of the Early Planet Formation in Embedded Disks (eDisk) ALMA Large Program. We describe the¹²CO (J= 2–1),¹³CO (J= 2–1), C¹⁸O (J= 2–1), H₂CO (J= 3_2,1–2_2,0), and SiO (J= 5–4) molecular lines along with the 1.3 mm continuum at high spatial resolution (∼0.″08 or ∼5 au). Dust continuum emission is detected toward BHR 71 IRS1 and IRS2, with a central compact component and extended continuum emission. The compact components are smooth and show no sign of substructures such as spirals, rings, or gaps. However, there is a brightness asymmetry along the minor axis of the presumed disk in IRS1, possibly indicative of an inclined geometrically and optically thick disk-like component. Using a position–velocity diagram analysis of the C¹⁸O line, clear Keplerian motions were not detected toward either source. If Keplerian rotationally supported disks are present, they are likely deeply embedded in their envelope. However, we can set upper limits of the central protostellar mass of 0.46M_⊙and 0.26M_⊙for BHR 71 IRS1 and BHR 71 IRS2, respectively. Outflows traced by¹²CO and SiO are detected in both sources. The outflows can be divided into two components, a wide-angle outflow and a jet. In IRS1, the jet exhibits a double helical structure, reflecting the removal of angular momentum from the system. In IRS2, the jet is very collimated and shows a chain of knots, suggesting episodic accretion events. 

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3. Unveiling the 3D structure of the central molecular zone from stellar kinematics and photometry: The 50 and 20 km/s clouds

   https://doi.org/10.1051/0004-6361/202556047  

   Nogueras-Lara, Francisco; Barnes, Ashley T; Henshaw, Jonathan D; Fiteni, Karl; Sofue, Yoshiaki; Schödel, Rainer; Martínez-Arranz, Álvaro; Sormani, Mattia C; Armijos-Abendaño, Jairo; Colzi, Laura; et al (February 2026, Astronomy & Astrophysics)

   Context. The central molecular zone (CMZ), surrounding the Galactic centre, is the largest reservoir of dense molecular gas in the Galaxy. Despite its relative proximity, the 3D structure of the CMZ remains poorly constrained, primarily due to projection effects. Aims. We aim to constrain the line-of-sight location of two molecular clouds in the CMZ - the 50 and 20 km/s clouds - and to investigate their possible physical connection using stellar kinematics and photometry. This study serves as a pilot for future applications across the full CMZ. Methods. We estimated the line-of-sight position of the clouds by analysing stellar kinematics, stellar densities, and stellar populations towards the cloud regions and a control field. Results. We find an absence of westward moving stars in the cloud regions, which indicates that they lie on the near side of the CMZ. This interpretation is supported by the stellar density distributions. The similar behaviour observed in the two clouds, as well as in the region between them (the ridge), suggests that they are located at comparable distances and are physically linked. We also identified an intermediate-age stellar population (2-7 Gyr) in both regions, consistent with that observed on the near side of the CMZ. We estimated the line-of-sight distances at which the clouds and the ridge become kinematically detectable (i.e. where the proper motion component parallel to the Galactic plane differs from that of the control field at the 3σ level) by converting their measured proper motions parallel to the Galactic plane using a theoretical model of the stellar distribution. We find that the 50 and 20 km/s clouds are located at 43 ± 8 pc and 56 ± 11 pc from Sgr A^*, respectively, and that the ridge lies at 56 ± 11 pc; this supports the idea that the clouds are physically connected through the ridge. 

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4. 3D MC. II. X-Ray Echoes Reveal a Clumpy Molecular Cloud in the CMZ

   https://doi.org/10.3847/1538-3881/adbaf3  

   Alboslani, Danya; Battersby, Cara; Brunker, Samantha W; Clavel, Maïca; Lipman, Dani; Walker, Daniel L (March 2025, The Astronomical Journal)

   Abstract X-ray observations collected over the past decades have revealed a strongly variable X-ray signal within the Milky Way’s Galactic center, interpreted as X-ray echoes from its supermassive black hole, Sgr A*. These echoes are traced by the strong Fe Kαfluorescent line at 6.4 keV, the intensity of which is proportional to the density of the illuminated molecular gas. Over time, the echo scans through molecular clouds (MCs) in our Galactic center, revealing their 3D structure and highlighting their densest parts. While previous studies have utilized spectral line Doppler shifts along with kinematic models to constrain the geometry of the Central Molecular Zone (CMZ) or to study the structure of individual clouds, these methods have limitations, particularly in the turbulent region of the CMZ. We use archival Chandra X-ray data to construct one of the first 3D representations of one prominent MC, the Stone cloud, located at (ℓ= 0 $\stackrel{\text{°}}{.}$068,b= –0 $\stackrel{\text{°}}{.}$076) at a distance of ∼20 pc from Sgr A* in projection. Using the Chandra X-ray Observatory, we followed the X-ray echo in this cloud from 2008 to 2017. We combine these data with 1.3 mm dust continuum emission observed with the Submillimeter Array (SMA) and the Herschel Space Observatory to reconstruct the 3D structure of the cloud and estimate the column densities for each year’s observed slice. The analysis of the X-ray echoes, along with velocities from SMA molecular line data, indicates that the structure of the Stone cloud can be described as a very diffuse background with multiple dense clumps throughout. 

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5. The JWST-NIRCam View of Sagittarius C. I. Massive Star Formation and Protostellar Outflows

   https://doi.org/10.3847/1538-4357/ad8889  

   Crowe, Samuel; Fedriani, Rubén; Tan, Jonathan C; Kinman, Alva; Zhang, Yichen; Andersen, Morten; Bravo_Ferres, Lucía; Nogueras-Lara, Francisco; Schödel, Rainer; Bally, John; et al (April 2025, The Astrophysical Journal)

   Abstract We present James Webb Space Telescope (JWST) Near Infrared Camera observations of the massive star-forming molecular cloud Sagittarius C (Sgr C) in the Central Molecular Zone (CMZ). In conjunction with ancillary mid-IR and far-IR data, we characterize the two most massive protostars in Sgr C via spectral energy distribution (SED) fitting, estimating that they each have current masses ofm_*∼ 20M_⊙and surrounding envelope masses of ∼100M_⊙. We report a census of lower-mass protostars in Sgr C via a search for infrared counterparts to millimeter continuum dust cores found with the Atacama Large Millimeter/submillimeter Array (ALMA). We identify 88 molecular hydrogen outflow knot candidates originating from outflows from protostars in Sgr C, the first such unambiguous detections in the infrared in the CMZ. About a quarter of these are associated with flows from the two massive protostars in Sgr C; these extend for over 1 pc and are associated with outflows detected in ALMA SiO line data. An additional ∼40 features likely trace shocks in outflows powered by lower-mass protostars throughout the cloud. We report the discovery of a new star-forming region hosting two prominent bow shocks and several other line-emitting features driven by at least two protostars. We infer that one of these is forming a high-mass star given an SED-derived mass ofm_*∼ 9M_⊙and associated massive (∼90M_⊙) millimeter core and water maser. Finally, we identify a population of miscellaneous molecular hydrogen objects that do not appear to be associated with protostellar outflows. 

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