Peculiar Objects Research Articles

Characterization of semi-volatile compounds in 56 Italian ciders using GC×GC-TOF-MS and multivariate analysis

Fifty-six samples of differently produced commercial Italian ciders were analysed for semi-volatile organic compounds (SVOCs) profiling, using comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-TOF-MS) technique for the very first time. To properly support the compositional investigation of this emerging beverage, a chemometric approach through Principal Component Analysis (PCA) was employed. This revealed a sample distribution in agreement with results of the sensory tasting panel performed on such ciders, highlighting an excellent correlation between variables and perceived odorants. In particular, the positions of peculiar and anomalous objects in the Principal Components (PCs) space are explicitly evaluated, exploring the associated loadings (i.e., the importance of the identified chemical compounds), paying attention to their biochemical origin along the cider-making process and their impact on the sample olfactory analysis. Besides this, the t-distributed Stochastic Neighbor Embedding (t-SNE) method was shown to be an efficient tool for gathering pear ciders from the other samples (apple ciders), better than PCA. This study stands for the first survey on Italian commercial craft cider, and its results are aimed to be a milestone for its characterization and to start and promote cider culture in this country.

Stationary rotating and axially symmetric dust systems as peculiar General Relativistic objects

We study an exact solution of Einstein's equations describing a self-gravitating system, made of dust, distributed with axial symmetry and in stationary rotation, and we prove that this type of system has no Newtonian analogue. In a low-energy limit, its existence depends on the solution of a Grad-Shafranov equation in vacuum which can be interpreted as a Laplace equation for the toroidal component of the gravitomagnetic potential; in particular, in this system the relativistic rotational effects are of the order of magnitude of Newtonian ones. We therefore argue that this exact solution should contain singularities and discuss the possible consequences of using such a system as simplified model for galactic dynamics.

Self-supervised contrastive learning of radio data for source detection, classification and peculiar object discovery

Abstract New advancements in radio data post-processing are underway within the Square Kilometre Array (SKA) precursor community, aiming to facilitate the extraction of scientific results from survey images through a semi-automated approach. Several of these developments leverage deep learning methodologies for diverse tasks, including source detection, object or morphology classification, and anomaly detection. Despite substantial progress, the full potential of these methods often remains untapped due to challenges associated with training large supervised models, particularly in the presence of small and class-unbalanced labelled datasets. Self-supervised learning has recently established itself as a powerful methodology to deal with some of the aforementioned challenges, by directly learning a lower-dimensional representation from large samples of unlabelled data. The resulting model and data representation can then be used for data inspection and various downstream tasks if a small subset of labelled data is available. In this work, we explored contrastive learning methods to learn suitable radio data representations by training the SimCLR model on large collections of unlabelled radio images taken from the ASKAP EMU and SARAO MeerKAT GPS surveys. The resulting models were fine-tuned over smaller labelled datasets, including annotated images from various radio surveys, and evaluated on radio source detection and classification tasks. Additionally, we employed the trained self-supervised models to extract features from radio images, which were used in an unsupervised search for objects with peculiar morphology in the ASKAP EMU pilot survey data. For all considered downstream tasks, we reported the model performance metrics and discussed the benefits brought by self-supervised pre-training, paving the way for building radio foundational models in the SKA era.

Gold Nanoclusters Prepared in the Presence of Adenosine Monophosphate and Citrate: Factorial-Based Synthesis Optimization and Sensing Properties

Gold nanoclusters are peculiar objects promising in view of qualitative and quantitative determination of various species, including heavy metal ions and biological molecules. We have recently discovered that introducing sodium azide in the reaction mixture during gold nanocluster synthesis in the presence of citrate and adenosine monophosphate can tune the product emission from blue to yellow. Taking advantage of the factorial design of the experiment, we have optimized the synthesis conditions to obtain pure blue and yellow emitters and investigate their sensitivity to a series of inorganic salts. The experiments have revealed selective quenching of the nanocluster’s fluorescence in the presence of mercury(II) ions.

Fast and efficient identification of anomalous galaxy spectra with neural density estimation

ABSTRACT Current large-scale astrophysical experiments produce unprecedented amounts of rich and diverse data. This creates a growing need for fast and flexible automated data inspection methods. Deep learning algorithms can capture and pick up subtle variations in rich data sets and are fast to apply once trained. Here, we study the applicability of an unsupervised and probabilistic deep learning framework, the probabilistic auto-encoder, to the detection of peculiar objects in galaxy spectra from the SDSS survey. Different to supervised algorithms, this algorithm is not trained to detect a specific feature or type of anomaly, instead it learns the complex and diverse distribution of galaxy spectra from training data and identifies outliers with respect to the learned distribution. We find that the algorithm assigns consistently lower probabilities (higher anomaly score) to spectra that exhibit unusual features. For example, the majority of outliers among quiescent galaxies are E+A galaxies, whose spectra combine features from old and young stellar population. Other identified outliers include LINERs, supernovae, and overlapping objects. Conditional modelling further allows us to incorporate additional information. Namely, we evaluate the probability of an object being anomalous given a certain spectral class, but other information such as metrics of data quality or estimated redshift could be incorporated as well. We make our code publicly available.

Woodshedding

In the jazz imaginary, taking one’s “axe” to the fictive “woodshed” has long described a solitary and disciplined process of cultivating virtuosic skill in preparation for the competitive arenas of public performance. Despite an abundance of jazz research, the woodshed and its complex social, aesthetic, and political entailments have gone almost entirely unaddressed in the literature. This paper traces the emergence of this peculiar object through a diverse archive of journalistic, critical, and historical sources—in and beyond jazz—to delineate the contours of virtuosity’s everyday reproduction. I argue that the woodshed and woodshedding mark a constitutive ideological moment in the dynamic between private practice and public performance, a moment that uniquely expresses the gendered logic of social reproduction under capitalism. Attention to the woodshed illuminates largely unexplored relations between musical practice, reproductive labor, and aesthetic exemplarity that together constitute a dominant ideology of music-making in the United States.

Detailed equilibrium and dynamical tides: impact on circularization and synchronization in open clusters

ABSTRACT Binary stars evolve into chemically peculiar objects and are a major driver of the galactic enrichment of heavy elements. During their evolution they undergo interactions, including tides, that circularize orbits and synchronize stellar spins, impacting both individual systems and stellar populations. Using Zahn’s tidal theory and mesa main-sequence model grids, we derive the governing parameters λlm and E2, and implement them in the new mint library of the stellar population code binary_c. Our mint equilibrium tides are two to five times more efficient than the ubiquitous bse prescriptions, while the radiative-tide efficiency drops sharply with increasing age. We also implement precise initial distributions based on bias-corrected observations. We assess the impact of tides and initial orbital-parameter distributions on circularization and synchronization in eight open clusters, comparing synthetic populations and observations through a bootstrapping method. We find that changing the tidal prescription yields no statistically significant improvement as both calculations typically lie within 0.5σ. The initial distribution, especially the primordial concentration of systems at log10(P/d) ≈ 0.8, e ≈ 0.05 dominates the statistics even when artificially increasing tidal strength. This confirms the inefficiency of tides on the main sequence and shows that constraining tidal-efficiency parameters using the e − log10(P/d) distribution alone is difficult or impossible. Orbital synchronization carries a more striking age-dependent signature of tidal interactions. In M35 we find twice as many synchronized rotators in our mint calculation as with bse. This measure of tidal efficiency is verifiable with combined measurements of orbital parameters and stellar spins.

Finding Christ in roots and seeds: crucifixes produced by nature in Quaresmio’s Terrae Sanctae Elucidatio

In his Terrae Sanctae Elucidatio (1639), Francesco Quaresmio devotes a digression to three highly peculiar objects: two plant roots grown into the shape of a crucifix (one of them discovered in the vicinity of Jerusalem), and a figure of the crucified Christ sprouted from a nut collected by a pilgrim near the Holy Sepulchre. This article explores the methods employed by Quaresmio in the study of these objects, which belonged to a larger group of images apparently produced by nature discussed in the works of late medieval and early modern travellers, religious writers, natural historians and antiquarians. It examines the use that Quaresmio made of autopsy, visual reproduction, and witness interviews in researching the history of the three crucifixes. At the same time, it shows how his adoption of empirical methods went hand in hand with devotional preoccupations, bringing to the forefront Quaresmio’s conception of the relationship between nature and the divine, as well as his belief in the complementarity of natural evidence, historical knowledge, and biblical exegesis.

SN 2016ije: An SN 2002es-like Type Ia Supernova Exploded in a Metal-poor and Low-surface Brightness Galaxy

We have conducted photometric and spectroscopic observations of the peculiar Type Ia supernova (SN Ia) 2016ije that was discovered through the Tsinghua-NAOC Transient Survey. This peculiar object exploded in the outskirts of a metal-poor, low-surface brightness galaxy (i.e., M g = −14.5 mag). Our photometric analysis reveals that SN 2016ije is subluminous ( = −17.65 ± 0.06 mag) but exhibits relatively broad light curves (Δm 15(B) = 1.35 ± 0.14 mag), similar to the behavior of SN 2002es. Our analysis of the bolometric light curve indicates that only 0.14 ± 0.04 M ⊙ of 56Ni was synthesized in the explosion of SN 2016ije, which suggests a less energetic thermonuclear explosion when compared to normal SNe Ia, and this left a considerable amount of unburned materials in the ejecta. Spectroscopically, SN 2016ije resembles other SN 2002es-like SNe Ia, except that the ejecta velocity inferred from its carbon absorption line (∼4500 km s−1) is much lower than that from silicon lines (∼8300 km s−1) at around the maximum light. Additionally, most of the absorption lines are broader than other 02es-like SNe Ia. These peculiarities suggest the presence of significant unburned carbon in the inner region and a wide line-forming region along the line of sight. These characteristics suggest that SN 2016ije might originate from the violent merger of a white dwarf binary system, when viewed near an orientation along the iron-group-element cavity caused by the companion star.

Self-inflicted penetrating brain injuries with preserved neurological function: a case series

BackgroundPenetrating trauma to the brain is a rare mode of self-harm in individuals with depressive psychosis. It may have variable presentations ranging from intact neurological status to non-survivable damage and the subjects may be surprisingly apathetic to pain. It is even unusual for such an injury to have an excellent prognosis despite coming late to clinical attention.Case presentationsWe report two cases of patients with psychotic depression who attempted suicide by hammering nails into their heads. On imaging, deep penetration within the brain parenchyma was noted; however, neither case had any neurological deficit or symptoms attributable to brain trauma.ConclusionsSelf-inflicted penetrating brain injuries with peculiar objects such as nails are rarely encountered in practice. They need prompt management for their removal and addressing the underlying mental health illnesses.

Pluto orbits in elegant arrangement with the giant planets

Pluto has such a peculiar orbit that people have wondered how it exists. In our new work, we found that the orbital architecture of the giant planets lies in a Goldilock's zone that allows for the survival of Pluto and many other similarly peculiar trans-Neptunian objects. A slightly different arrangement of the giant planets would’ve ejected Pluto long ago from the solar system.

N-enhancement in GN-z11: First evidence for supermassive stars nucleosynthesis in proto-globular clusters-like conditions at high redshift?

Unusually high N/O abundance ratios were recently reported for a very compact, intensively star-forming object GN-z11 at z = 10.6 from JWST/NIRSpec observations. We present an empirical comparison with the C, N, and O abundance ratios in Galactic globular clusters (GCs) over a large metallicity range. We show that hot hydrogen-burning nucleosynthesis within supermassive stars (SMS) formed through runaway collisions can consistently explain the observed abundances ratio in GN-z11 and in GCs. This suggests that a proto-globular cluster hosting a SMS could be at the origin of the strong N-enrichment in GN-z11. Our model predicts the behavior of N/O, C/O, and Ne/O ratios as a function of metallicity, which can be tested if high-z objects similar to GN-z11 are detected with JWST in the future. Further studies and statistics will help differentiate the proto-GC scenario from the Wolf-Rayet scenario that we quantify with a population synthesis model, and shed more light on this peculiar object.

Polarised line shape calculations for conditions encountered in stellar magnetic atmospheres

We present new investigations into spectral line shapes under conditions typical for magnetic stellar atmospheres. Our method for simulating line profiles takes into account the coupled Zeeman and Stark effects. The calculations presented here will ultimately help to correctly model the Stokes parameters of peculiar stellar objects such as the Magnetic White Dwarfs (MWDs), retrieving their magnetic field geometries from spectropolarimetric observations. For the magnetic analysis of this class of stars, in general only Stokes I profiles as a function of rotational phase have been used in the past, in a very few cases, also Stokes V. The present improved simulations of the full Stokes parameters are expected to provide a powerful tool for the analysis of strong magnetic fields like those found in the MWDs.

Dark Matter–admixed Rotating White Dwarfs as Peculiar Compact Objects

Discoveries of anomalous compact objects challenge our understanding of the standard theory of stellar structures and evolution, so they serve as an excellent laboratory for searching for new physics. Earlier studies on spherically symmetric dark matter (DM)–admixed compact stars could explain a handful of anomalies. In this paper, we investigate the observational signatures of DM-admixed rotating white dwarfs, and make connections to observed peculiar compact objects. We compute the equilibrium structures of DM-admixed rotating white dwarfs using a self-consistent, two-fluid method, with the DM component being a nonrotating degenerate Fermi gas. We find that admixing DM to rotating white dwarfs could: (1) account for some peculiar white dwarfs that do not follow their usual mass–radius relation; (2) allow stable rapid-rotating white dwarfs that are free from thermonuclear runaway to exist, which could explain some soft gamma-ray repeaters/anomalous X-ray pulsars; and (3) produce universal I (moment of inertia)–Love (tidal Love number)–Q (quadrupole moment) relations that span bands above those without DM admixture, thus providing an indirect way of searching for DM in white dwarfs through gravitational-wave detection. To conclude, DM-admixed rotating white dwarfs can account for some peculiar compact objects. Our results suggest a systematic approach to accounting for the unusual compact objects that upcoming surveys could discover.

HD 16424: A new weak G-band star with high Li abundance

ABSTRACT The origin of the so-called weak G-band stars constitutes an unsolved problem in stellar astrophysics. In this context, we present a detailed abundance analysis of a new weak G-band star, HD 16424, which stands out with a very low 12C/13C ratio and Li and Na overabundance. Our work is based on the high-resolution échelle spectrum (R ≈ 48 000) and includes photometric and astrometric data from the literature. The analysis adopted in this work is performed under local thermodynamic equilibrium (LTE) approximation; we determine the atmospheric parameters (Teff, $\log \, g$, [Fe/H], and ξ), abundances for proton-capture elements (C, N, O, Li), s-process elements (Y, Zr, La), and mixing tracers such as the 12C/13C isotopic ratio and sodium abundance, following by NLTE corrections applied to Li, O, and Na abundances. Our results show 12C deficiency ([C/Fe] = −0.57) and N enrichment ([N/Fe] = +0.97), that is typical for weak G-band stars. Also, we notice a carbon isotopic ratio characteristic of the CN-cycle equilibrium (〈12C/13C〉 = 4.0) and high lithium-7 abundance ($\log \, \varepsilon$(Li)NLTE = 2.85). In addition, this study shows a low projected rotational velocity ($v\, \sin \, i$ = 2.0 km s−1) and low mass (1.61 M⊙) of HD 16424, which distinguishes this star from the intermediate-mass objects found in this class of peculiar objects.

Discovery of double BSS sequences in the old Galactic open cluster Berkeley 17

ABSTRACT Blue straggler stars (BSS) are peculiar objects which normally appear as a single broad sequence along the extension of the main sequence. Only four globular clusters (GCs) have been observed to have two distinct and parallel BSS sequences. For the first time for any open cluster (OC), we report double BSS sequences in Berkeley 17. Using the machine-learning based membership algorithm ML-MOC on Gaia EDR3 data, we identify 627 cluster members, including 21 BSS candidates out to 15 arcmin from the cluster centre. Both the BSS sequences are almost equally populated and parallel to one another in Gaia as well as in Pan-STARRS colour–magnitude diagram (CMD). We statistically confirm their presence and report that both BSS sequences are highly segregated compared to the reference population out to ∼5.5 arcmin and not segregated thereafter. The lower densities of OCs make BSS formation impossible via the collisional channel. Therefore, mass transfer seems to be the only viable channel for forming candidates of both sequences. The gap between the red and blue BSS sequences, on the other hand, is significant and presents a great opportunity to understand the connection between BSS formation and internal as well as external dynamics of the parent clusters.

Passive spiral galaxies deeply captured by Subaru Hyper Suprime-Cam

Abstract This paper presents a thousand passive spiral galaxy samples at z = 0.01–0.3 based on a combined analysis of the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP PDR3) and the GALEX–SDSS–WISE Legacy Catalog (GSWLC-2). Among 54871 gri galaxy cutouts taken from the HSC-SSP PDR3 over 1072 deg2, we conducted a search with deep-learning morphological classification for candidates of passive spirals below the star-forming main sequence derived by ultraviolet to mid-infrared spectral energy distribution fitting in the GSWLC-2. We then classified the candidates into 1100 passive spirals and 1141 secondary samples based on visual inspections. Most of the latter cases are considered to be passive ringed S0 or pseudo-ringed galaxies. The remaining secondary samples have ambiguous morphologies, including two peculiar objects with diamond-shaped stellar wings. The selected passive spirals have a similar distribution to the general quiescent galaxies on the EWHδ–Dn4000 diagram and concentration indices. Moreover, we detected an enhanced passive fraction of spiral galaxies in X-ray clusters. Passive spirals in galaxy clusters are preferentially located in the midterm or late infall phase on the phase–space diagram, supporting the ram pressure scenario, which has been widely advocated in previous studies. The source catalog and gri-composite images are available on the HSC-SSP PDR3 website 〈https://hsc.mtk.nao.ac.jp/ssp/data-release/〉. Future updates, including integration with a citizen science project dedicated to the HSC data, will achieve more effective and comprehensive classifications.

The Interstellar Medium in the Environment of the Supernova-less Long-duration GRB 111005A

Long (>2 s) gamma-ray bursts (GRBs) are associated with explosions of massive stars, although in three instances, supernovae (SNe) have not been detected, despite deep observations. With new H i line and archival optical integral-field spectroscopy data, we characterize the interstellar medium (ISM) of the host galaxy of one of these events, GRB 111005A, in order to shed light on the unclear nature of these peculiar objects. We found that the atomic gas, radio continuum, and rotational patterns are in general very smooth throughout the galaxy, which does not indicate a recent gas inflow or outflow. There is also no gas concentration around the GRB position. The ISM in this galaxy differs from that in hosts of other GRBs and SNe, which may suggest that the progenitor of GRB 111005A was not an explosion of a very massive star (e.g., a compact object merger). However, there are subtle irregularities of the GRB 111005A host (most at a 2σ level), which may point to a weak gas inflow or interaction. Because in the SE part of the host there is 15% more atomic gas and half the molecular gas than in the NW part, the molecular gas fraction is low. In the SE part there is also a region with a very high Hα equivalent width. There is more continuum 1.4 GHz emission to the SE and an S-shaped warp in the UV. Finally, there is also a low-metallicity region 3.″5 (1 kpc) from the GRB position. Two galaxies within 300 kpc or a past merger can be responsible for these irregularities.

Stellar collisions in globular clusters: the origin of multiple stellar populations

ABSTRACT Two generations of stars, G1 and G2, typically populate Galactic globular clusters (GCs). The origin of G2 stars is unclear. We uncover two empirical dependencies between GC characteristics, which can be explained by the formation of G2 main-sequence (MS) stars due to collision/merging of their primordial counterparts (G1). A similar genesis of both G2 stars and peculiar objects like low-mass X-ray binaries and millisecond pulsars is also implied. Indeed, we find a significant (at a confidence level ${\gt} 99.9{{\ \rm per\ cent}}$) anticorrelation between the fraction of G1 red giants (NG1/Ntot) and stellar encounter rates among 51 GCs. Moreover, a Milky Way-like initial mass function requires at least ∼50 per cent of MS stars located in the mass range [0.1–0.5] M⊙. Unlike cluster mass loss, stellar collisions/merging retain these G1 stars by converting them into more massive G2 ones, with mainly MMS > 0.5 M⊙. This process coupled with a decreasing relative mass loss with increasing GC masses implies a smaller (NG1/Ntot) in more massive GCs with a shallower present-day mass function. From data for 35 GCs, we find that such an anticorrelation is significant at 98.3 per cent confidence level (Spearman’s correlation) for the 12 most massive GCs (MGC > 105.3 M⊙) and it is at a confidence level of 89 per cent for the 12 least massive GCs (MGC < 105.1 M⊙). Other fractions of G1 and G2 stars observed at the bottom of the MS as compared with the red giant branch in a few GCs are consistent with the scenario proposed.

Scope freezing and object shift in Ukrainian: Does Superiority matter?

AbstractThis remark presents novel evidence on Ukrainian specificity‐inducing object shift in its interaction with quantifier scope, evidence suggesting a generalization that whatever scope interpretations are established in the postverbal field will carry over into the preverbal field. We point out that the data present a serious challenge to the Superiority account of scope freezing, since that account predicts that object shift of a QP will always freeze scope with respect to another object QP, contrary to fact. Furthermore, while Ukrainian object shift does not obey Holmberg’s Generalization, we argue that it is nevertheless fully comparable to Scandinavian object shift. We propose to account for the data with a modified version ofcyclic linearization. Cyclic linearization accounts for the crosslinguistic differences with respect to object shift and also derives the peculiar object shift–QP scope interaction patterns we observe, which remain obscure on the Superiority account of scope freezing.