Architecture of Hierarchical Stellar Systems and Their Formation

Accumulation of new data on stellar hierarchical systems and the progress in numerical simulations of their formation open the door to genetic classification of these systems, where properties of a certain group (family) of objects are tentatively related to their formation mechanisms and early evolution. A short review of the structure and statistical trends of known stellar hierarchies is given. Like binaries, they can be formed by the disk and core fragmentation events happening sequentially or simultaneously and followed by the evolution of masses and orbits driven by continuing accretion of gas and dynamical interactions between stars. Several basic formation scenarios are proposed and associated qualitatively with the architecture of real systems, although quantitative predictions for these scenarios are still pending. The general trend of increasing orbit alignment with decreasing system size points to the critical role of the accretion-driven orbit migration, which also explains the typically comparable masses of stars belonging to the same system. The architecture of some hierarchies bears imprints of chaotic dynamical interactions. Characteristic features of each family are illustrated by several real systems.

From clump to disc scales in W3 IRS4

Context. High-mass star formation typically takes place in a crowded environment, with a higher likelihood of young forming stars affecting and being affected by their surroundings and neighbours, as well as links between different physical scales affecting the outcome. However, observational studies are often focused on either clump or disc scales exclusively. Aims. We explore the physical and chemical links between clump and disc scales in the high-mass star formation region W3 IRS4, a region that contains a number of different evolutionary phases in the high-mass star formation process, as a case-study for what can be achieved as part of the IRAM NOrthern Extended Millimeter Array (NOEMA) large programme named CORE: “Fragmentation and disc formation in high-mass star formation”. Methods. We present 1.4 mm continuum and molecular line observations with the IRAM NOEMA interferometer and 30 m telescope, which together probe spatial scales from ~0.3−20′′ (600−40 000 AU or 0.003−0.2 pc at 2 kpc, the distance to W3). As part of our analysis, we used XCLASS to constrain the temperature, column density, velocity, and line-width of the molecular emission lines. Results. The W3 IRS4 region includes a cold filament and cold cores, a massive young stellar object (MYSO) embedded in a hot core, and a more evolved ultra-compact (UC)H II region, with some degree of interaction between all components of the region that affects their evolution. A large velocity gradient is seen in the filament, suggesting infall of material towards the hot core at a rate of 10−3−10−4 M⊙ yr−1, while the swept up gas ring in the photodissociation region around the UCH II region may be squeezing the hot core from the other side. There are no clear indications of a disc around the MYSO down to the resolution of the observations (600 AU). A total of 21 molecules are detected, with the abundances and abundance ratios indicating that many molecules were formed in the ice mantles of dust grains at cooler temperatures, below the freeze-out temperature of CO (≲35 K). This contrasts with the current bulk temperature of ~50 K, which was obtained from H2CO. Conclusions. CORE observations allow us to comprehensively link the different structures in the W3 IRS4 region for the first time. Our results argue that the dynamics and environment around the MYSO W3 IRS4 have a significant impact on its evolution. This context would be missing if only high resolution or continuum observations were available.

Can You Detect Spread Through Air Spaces (STAS) in Lung Needle Core Biopsies? An Initial Investigation

Objectives The debate of spread through air spaces (STAS) as a newly described pattern of invasion in lung cancer is ongoing. Some authors argue that the inclusion of STAS in the CAP synoptic template is premature and controversial as it is difficult to exclude an artifactual process. However, assessment of STAS in needle core biopsies has not been pursued. Hence, we intended to evaluate STAS in needle core biopsies, with an added emphasis on the specimen requirements for detection. Finally, correlation with the corresponding available resections was performed. Methods Fifty-four needle core biopsies of adenocarcinomas were examined by three pathologists. For each case, the extent of both tumor (1-12 mm) and nonneoplastic alveolated parenchyma (NNT) (2-6 mm) was measured. STAS was defined as presence of only micropapillary clusters, solid nests, and single cells in NNT adjacent to the main tumor. Corresponding lung resections available in 12 cases were also examined. Results Nests highly suspicious for STAS were demonstrated in 4 (7%) cases, predominantly micropapillary clusters and single cells. Of those, only one case had a surgical resection and showed STAS. When the NNT was present, then absence of STAS was determined in 20/54 (37%) tumors, all exhibiting a lepidic/acinar growth pattern. Finally, the presence of STAS could not be evaluated in 30 (55%) cases. This was due to extensive core fragmentation, sampling only from the center of the tumor, with no adjacent NNT, necrosis, or fibrotic background. Conclusion STAS evaluation may be performed in core needle biopsies and depends on the core quality and tumor/NNT content. Despite appropriate material, STAS was not identified in approximately one-third of cases. Rare cases with small groups suspicious for STAS were seen. These findings may provide additional information for further therapeutic/surgical guidance.

Discovery of an equal-mass ‘twin’ binary population reaching 1000 + au separations

ABSTRACT We use a homogeneous catalogue of 42 000 main-sequence wide binaries identified by Gaia to measure the mass ratio distribution, p(q), of binaries with primary masses 0.1 < M1/M⊙ < 2.5, mass ratios 0.1 ≲ q < 1, and separations $50 \lt s/{\rm au} \lt 50\, 000$. A well-understood selection function allows us to constrain p(q) in 35 independent bins of primary mass and separation, with hundreds to thousands of binaries in each bin. Our investigation reveals a sharp excess of equal-mass ‘twin’ binaries that is statistically significant out to separations of 1000–10 000 au, depending on primary mass. The excess is narrow: a steep increase in p(q) at 0.95 ≲ q < 1, with no significant excess at q ≲ 0.95. A range of tests confirm the signal is real, not a data artefact or selection effect. Combining the Gaia constraints with those from close binaries, we show that the twin excess decreases with increasing separation, but its width (q ≳ 0.95) is constant over $0.01 \lt a/{\rm au} \lt 10\, 000$. The wide twin population would be difficult to explain if the components of all wide binaries formed via core fragmentation, which is not expected to produce strongly correlated component masses. We conjecture that wide twins formed at closer separations (a ≲ 100 au), likely via accretion from circumbinary discs, and were subsequently widened by dynamical interactions in their birth environments. The separation-dependence of the twin excess then constrains the efficiency of dynamical widening and disruption of binaries in young clusters. We also constrain p(q) across 0.1 ≲ q < 1. Besides changes in the twin fraction, p(q) is independent of separation at fixed primary mass over $100 \lesssim s/{\rm au} \lt 50\, 000$. It is flatter than expected for random pairings from the initial mass function but more bottom-heavy for wide binaries than for binaries with a ≲100 au.

Core fragmentation and Toomre stability analysis of W3(H2O)

Context. The fragmentation mode of high-mass molecular clumps and the properties of the central rotating structures surrounding the most luminous objects have yet to be comprehensively characterised. Aims. We study the fragmentation and kinematics of the high-mass star-forming region W3(H2O), as part of the IRAM NOrthern Extended Millimeter Array (NOEMA) large programme CORE. Methods. Using the IRAM NOEMA and the IRAM 30 m telescope, the CORE survey has obtained high-resolution observations of 20 well-known highly luminous star-forming regions in the 1.37 mm wavelength regime in both line and dust continuum emission. Results. We present the spectral line setup of the CORE survey and a case study for W3(H2O). At ~0.′′35 (700 AU at 2.0 kpc) resolution, the W3(H2O) clump fragments into two cores (west and east), separated by ~2300 AU. Velocity shifts of a few km s−1 are observed in the dense-gas tracer, CH3CN, across both cores, consistent with rotation and perpendicular to the directions of two bipolar outflows, one emanating from each core. The kinematics of the rotating structure about W3(H2O) W shows signs of differential rotation of material, possibly in a disk-like object. The observed rotational signature around W3(H2O) E may be due to a disk-like object, an unresolved binary (or multiple) system, or a combination of both. We fit the emission of CH3CN (12K−11K), K = 4−6 and derive a gas temperature map with a median temperature of ~165 K across W3(H2O). We create a Toomre Q map to study thestability of the rotating structures against gravitational instability. The rotating structures appear to be Toomre unstable close to their outer boundaries, with a possibility of further fragmentation in the differentially rotating core, W3(H2O) W. Rapid cooling in the Toomre unstable regions supports the fragmentation scenario. Conclusions. Combining millimetre dust continuum and spectral line data toward the famous high-mass star-forming region W3(H2O), we identify core fragmentation on large scales, and indications for possible disk fragmentation on smaller spatial scales.

Contemporary prostate biopsy reporting: insights from a survey of clinicians’ use of pathology data

AimTo determine how clinicians use data in contemporary prostate biopsy reports.MethodsA survey was circulated to members of the British Association of Urological Surgeons and the British Uro-oncology Group.ResultsResponses were received from 114 respondents (88 urologists, 26 oncologists). Ninety-seven (94%) use the number of positive cores from each side and 43 (42%) use the % number of positive cores. When determining the number and percentage of positive cores, 72 (71%) would not differentiate between targeted and non-targeted samples. If multiple Gleason Scores (GS) were included in a report, 77 (78%) would use the worst GS even if present in a core with very little tumour, 12% would use the global GS and 10% the GS in the core most involved by tumour. Fifty-five (55%) either never or rarely used perineural invasion for patient management.ConclusionsThe number of positive cores is an important parameter for patient management but may be difficult to determine in the laboratory due to core fragmentation so the biopsy taker must indicate the number of biopsies obtained. Multiple biopsies taken from a single site are often interpreted by clinicians as separate cores when determining the number of positive cores so pathologists should also report the number of sites positive. Clinicians have a non-uniform approach to the interpretation of multiple GS in prostate biopsy reports so we recommend that pathologists also include a single ‘bottom-line’ GS for each case to direct the clinician’s treatment decision.