We present wide-field and high-sensitivity CO (1-0) molecular line observations toward the Galactic anticenter region, using the 13.7 m millimeter telescope of the Purple Mountain Observatory. Based on the CO observations, we report the discovery of a giant spiral molecular cloud, which covers the region of 183 .degrees 75 >= l >= 181 .degrees 25 and -2 .degrees 25 <= b <= 0 .degrees 75, and the velocity range from approximately -16 to -8 km s-1. The distance of the cloud is measured to be similar to 1650 pc, while the derived dimension and gas mass of the cloud are similar to 75 pc & times; 90 pc and similar to 8 & times; 104 M circle dot, respectively. Spiral arms and concentric rings are clearly detected in the cloud, which mimics a typical spiral galaxy observed in the local Universe. The oscillation of radial velocities is observed across the cloud, with a spatial wavelength of similar to 4.8-5.3 pc and a velocity amplitude of similar to 0.11-0.13 km s-1. The spiral cloud is undergoing slow rotation with an approximately constant velocity gradient (similar to 2-3 km s-1 deg-1 or similar to 0.07-0.10 km s-1 pc-1). Similar to many spiral galaxies, the observed structure and kinematics of the cloud can be explained by the density wave theory. The discovery provides a unique cloud sample in the solar neighborhood, which may help us to understand the nature of spiral structures in distant galaxies.

Vertical corrugations—wave-like undulations in galactic disks—are potential imprints of past dynamical events that offer key constraints on galaxy evolution. While large-scale corrugations superimposed on the Galactic warp have recently been detected using young stellar tracers, the corresponding widespread structure within the molecular gas remains largely unexplored due to the challenge of disentangling subtle amplitudes from the dominant warp signal. By analysing over 30,000 molecular clouds from the Milky Way Imaging Scroll Painting survey, we systematically characterize widespread corrugations across the outer CO disk. After subtracting a global CO warp model, residual vertical displacements reveal coherent wave-like structures spanning much of the outer disk. Quantitative modelling yields characteristic vertical amplitudes of ~100–200 pc and radial wavelengths of ~3.9–7.9 kpc, and identifies a coherent azimuthal corrugation mode with a 52.6° (~11.6 kpc) wavelength at Galactocentric radius R ≈ 12.7 kpc, extending ~40 kpc. These findings provide direct evidence that vertical corrugations are a common large-scale feature of the outer Galactic molecular disk, offering insights into the three-dimensional structure and dynamics of spiral galaxies. Using more than 30,000 molecular clouds, this study reveals widespread wave-like corrugations superimposed on the warp of the Milky Way’s outer molecular disk, offering insight into its three-dimensional structure and dynamics.

In this article, we find finitely many numerical invariants to classify the diffeomorphism types of three dimensional simply connected Mori fibre spaces with torsion free homology groups.

We show some results of compact K & auml;hler manifolds with elliptic homotopy type. In complex dimension , we list the Hodge diamonds of compact K & auml;hler manifolds with elliptic homotopy type. In general dimension, we obtain a partial characterization of the Hodge diamonds.

We present the first Galactic-scale validation of flux scaling relations among CO isotopologues, using an enlarged sample from the Milky Way Imaging Scroll Painting Phase I survey. We identified 10,843 ^13 CO-emitting clouds and 746 C ^18 O-emitting clouds using a stacking algorithm from the ^12 CO cloud sample of Q.-Z. Yan et al. We obtained flux scaling relations ${F}_{{}^{13}{\rm{CO}}}=0.11\,{F}_{{}^{12}{\rm{CO}}}$ within the ^12 CO-bright region and ${F}_{{}^{13}{\rm{CO}}}=0.16\,{F}_{{}^{12}{\rm{CO}}}$ within the ^13 CO-bright region. Additionally, we found the relation ${F}_{{{\rm{C}}}^{18}{\rm{O}}}\,=\,0.11\,{F}_{{}^{13}{\rm{CO}}}$ in C ^18 O-emitting regions, which indicates their abundance ratio ${X}_{{}^{13}{\rm{CO}}}/{X}_{{{\rm{C}}}^{18}{\rm{O}}}\sim 8.0$ . It suggests large-scale chemical homogeneity in molecular clouds. Flux ratios within individual clouds demonstrate a general pattern that gradually decreases outward. The cumulative distributions of flux in ^12 CO, ^13 CO, and C ^18 O are all close to “top heavy,” suggesting that a small number of high-flux molecular clouds dominate the total flux in the Galaxy.

A giant spiral molecular cloud is recently discovered in the Galactic anticenter, within a wide-field and high-sensitivity CO line survey. We present multiwavelength observational data of this cloud in this work. Radio continuum images find in the geometric center of the spiral molecular cloud a nonthermal bright source, which drives a wiggly radio jet. No optical or X-ray counterparts are found for this radio source. The CO observations reveal a molecular jet from the center of the cloud. The kinematics of the jet lobes suggests that the CO jet is driven by a source located at the cloud geometric center, where no other alternative driving source is found, except the radio source. Based on the multiwavelength images, we suggest that the radio source represents either an active galactic nucleus or a black hole in the Galaxy. Further observations are needed to study the nature of the radio source, including its distance and radial velocity. If the radio source is associated with the spiral molecular cloud, the mass of the candidate black hole is ∼1.5 × 10 ^3 M _⊙ , estimated from the CO gas kinematics and supported by complementary radio and X-ray data. The discovery of the radio source may provide a unique sample in the Galaxy to study the origin of intermediate-mass black holes.

Based on the high-resolution (CO)-C-12, (CO)-C-13 and (CO)-O-18 J = 1 - 0 observations from the Purple Mountain Observatory 13.7 m millimeter telescope, atomic hydrogen (H i) spectral data from the Five-hundred-meter Aperture Spherical radio Telescope, and Herschel far-infrared data, we present a multi-wavelength study toward a giant molecular filament, GMF54.0-52.0 (hereafter G53). We investigated the transition from the cold H i gas, which is associated with the molecular gas of G53, to molecular hydrogen (H-2) gas based on the H i narrow self-absorption (HINSA) feature. The mean/median abundance of HINSA is 3.6/1.4 & times; 10(-3), comparable to that of nearby low-mass star-forming molecular clouds. The abundances present low values in the dense region inside G53 and higher values surrounding it, revealing that the atomic-to-molecular transition is more complete in G53. We derived a chemical age of similar to 2.6 +/- 0.04 to similar to 4.5 +/- 0.1 Myr for the filament, which is comparable to previous studies on the ages of interstellar clouds and clumps. G53 is located at the interaction boundary between two expanding H i bubbles. The dynamical ages of the two bubbles are similar to 6.2-11.7 Myr and similar to 6.6-9.1 Myr, respectively, longer than the chemical age of G53. We suggest that the G53 molecular filament originated from the compression of the cold H i gas at the shared boundary of these bubbles.

Accurate distances to molecular clouds are crucial for determining their physical properties, understanding star formation, and tracing Galactic spiral structure. A total of 103,517 molecular clouds have been identified by the DBSCAN algorithm in the Milky Way Imaging Scroll Painting (MWISP) Phase I CO survey (l = 9 .degrees 75-229 .degrees 75, divided by b divided by <= 5 .degrees 25), most of which lack reliable distances. In this work, we propose three independent methods, all of which match the molecular cloud's velocity-integrated-intensity maps of 12CO lines from the MWISP with the three-dimensional dust extinction maps derived from Gaia, Pan-STARRS 1, and the Two Micron All Sky Survey, to determine molecular cloud distances. We present a catalog of 1573 molecular clouds with robust distances ranging from similar to 150 to similar to 3000 pc, 90% of which are measured for the first time, with typical statistical and systematic uncertainties of similar to 20% and similar to 10%, respectively. We also derive their physical properties, such as their mass and sizes. This publicly available catalog of molecular clouds with distances provides a foundation for testing molecular cloud scaling relations and probing how cloud conditions influence star formation across diverse Galactic environments.

Using CO data from Phase I of the Milky Way Imaging Scroll Painting (MWISP) survey, we present a systematic study of molecular structures with narrow lines. We identify 57 CO structures, most of which exhibit low densities and subsonic/transonic turbulence. Among them, structures with large projected areas and diffuse, sheet-like geometries are identified as veil clouds. The low LSR velocities and the concentration of these CO structures toward both the Galactic center (e.g., Ophiuchus, Aquila) and anticenter (e.g., Cepheus, Taurus) regions suggest a local origin for the sample, as supported by distance measurements of about 200–300pc for a subset with relatively large angular extents. These nearby structures likely arise from large-scale compression driven by past supernova activity within the Local Bubble. The observed low-velocity-dispersion emission may trace quiescent regions where turbulence has decayed due to a lack of sustained energy injection. For diffuse veil clouds with an assumed magnetic field of 10uG, ion-neutral friction may provide an additional mechanism for turbulent dissipation on sub-parsec scales corresponding to their thickness of 0.1–0.3pc. Tracing the atomic-to-molecular transition, veil clouds provide a unique window into the diffuse, quiescent precursor state of dense gas. They likely represent a widespread but previously overlooked component of the Galactic molecular gas reservoir, with significant implications for cloud formation and evolution, the total mass budget and spatial distribution of molecular gas, and the initial conditions of star formation as a related consequence.

We present a comprehensive statistical analysis of molecular cloud (MC) properties using the MWISP survey's 12CO, 13CO, and C18O (J = 1–0) data toward the inner (l = 45^∘–60^∘) and outer (l = 120^∘–130^∘) Galaxy. From a strict selection of 24,724 identified MCs, a final sample of 3,161 well-resolved MCs is established. We investigate the distributions of observational, morphological, and derived physical parameters, as well as their environmental dependencies and intercorrelations. Our analysis reveals that MCs are typically oblate and tend to align with the Galactic disk. A critical evaluation using a nearby subsample confirms significant distance-dependent selection effects for some parameters, nevertheless, the direction of changes in these parameters can indicate distance influence. We also examine several specific subsamples, revealing the distinct characteristics of MCs in the G120 spiral shock region, MCs in the G50 interarm spurs, C18O-bright MCs, and MCs with supra-Larson velocity dispersion. For instance, MCs with supra-Larson velocity dispersion are predominantly small and likely young clouds inheriting turbulence from the diffuse ISM. Notably, a comparison across tracers reveals that typical MCs have a turbulent, diffuse, 12CO-bright gas structure in their outer layers that does not contribute directly to star formation. In contrast, 13CO-bright gas represents a turning point where gravity becomes significant; C18O-bright gas is about gravity-dominated. Comprehensive correlation analysis confirms a flatter σ_v-size relation than classic Larson's law and a strong mass-size relation. Incorporating dimensional analysis, we derive minimal sets of eigenparameters from which most other observational and physical parameters can be estimated. This highlights the underlying scaling relations that governing cloud properties.

Many theories on the evolutionary process of molecular clouds have been proposed, but direct observational evidence remains scarce. The diverse cloud structures may preserve the history of cloud formation and evolution, making the search for critical evidence hidden in cloud structures essential to unraveling the history of clouds. To address this, we analysed the geometric structure of molecular clouds by measuring the fractal dimension (D-H ) across intensity contours of individual clouds and examining its behaviour within cloud samples. For a sample of 10 866 molecular clouds with both (CO)-C-12 and( 13)CO emissions, D-H was measured for 2163 clouds. In general, the D-H distribution peaks at 1.37, with a 95 per cent Highest Density Interval (HDI) of [1.05, 1.54]. Individual molecular clouds exhibit two prominent features: (1) D-H generally decreases linearly with increasing intensity, indicating that molecular clouds are multifractal; (2) D-H undergoes one or more abrupt changes at specific intensity contours. The D-H profiles can be classified into three distinct categories: no jumps (1814 clouds, 84 per cent), one jump (262 clouds, 12 per cent), and two jumps (87 clouds, 4 per cent). The intensity at which these jumps occur is strongly correlated with both the mean and peak temperatures of clouds. Strikingly, these jumps align closely with the breakpoints of recently discovered flux-intensity relations, while the D-H slope exhibits a linear correlation with the exponential flux decay rate. The gradual and abrupt changes in D-H and flux are indicative of historical global events, providing concrete observational evidence for cloud evolution.

Molecular clouds (MCs) are cradles of star and planet formation, thereby playing an important role in the evolution of galaxies. Based on the unbiased Milky Way Imaging Scroll Painting survey data of 12CO, 13CO, and C18O (J = 1-0) line emission in two regions toward the inner and outer Galaxy, i.e., the G50 (44 .degrees 75 <= l <= 60 .degrees 25) and G120 (119 .degrees 75 <= l <= 130 .degrees 25) regions, the distribution of molecular gas is studied. Both regions have Galactic latitudes of divided by b divided by <= 5 .degrees 25. A catalog containing 24,724 MCs is constructed from the data. In our proximity, several molecular structures with large angular scales and small velocity dispersions are discovered, resembling curtains of mist. Beyond the nearby molecular gas, a clear aggregation of MCs along coherent structures in the Galactic plane is visible, sketching spiral arm structures. Nevertheless, the aggregation of MCs is also detected in the inter-arm region between the Perseus and Outer arms in the G50 region. The Galactic molecular disk in this inter-arm region is found to be thinner than that in the adjacent spiral arm region. In addition, the thickness of the Galactic molecular disk examined here is found to be correlated with the warp of it, indicating their homologous origins. The molecular disk has a typical thickness of similar to 220 pc in the inner Galaxy. Moreover, the dispersion of the MC systemic velocity decreases with increasing galactocentric radius, resulting in lower kinematic distance uncertainties at larger radii. However, the Perseus arm segment in the G120 region exhibits a relatively large cloud-to-cloud velocity dispersion and split components in its MC velocity distribution.

We present an analysis of the young stellar moving group ASCC 127 using Gaia DR3 data, significantly expanding its membership to 3971 stars—double the number identified in previous studies. Using kinematic and distance criteria, ASCC 127 is divided into five subgroups (Groups 1−5) with ages spanning from 15 to 32 Myr. Groups 1−5 are spatially linked to the Cepheus Flare star-forming region, revealing potential evidence of four sequential star formation episodes at approximately 32 Myr, 20 Myr, 15 Myr, and 7 Myr. Through dust and gas mapping, we identify a spatial cavity extending several tens of parsecs, which may have resulted from feedback processes such as supernovae associated with earlier generations of stars in the region. This structure, along with the larger Loop III feature, indicates that feedback from massive stars likely influenced the interstellar medium (ISM). By integrating young stellar populations with ISM studies, we provide a detailed picture of the feedback-driven star-formation history in the Cepheus Flare region.

We present the first comprehensive catalogs of ^13 CO clumps from the Milky Way Imaging Scroll Painting (MWISP) project. By developing an equivalent global detection scheme integrated with the FacetClumps algorithm, we successfully extract 71,661 molecular clumps across a high-resolution ^13 CO data cube spanning 2310 deg ^2 from the MWISP Phase I survey. To determine accurate distances, we design an automatic hierarchical distance decision method using signal regions as fundamental objects, effectively resolving the kinematic distance ambiguity problem and obtaining reliable measurements for 97.94% of the sample. Statistical analysis reveals that 65.3% of clumps are gravitationally bound, accounting for approximately 96.3% of the statistical total mass. Scaling relation analysis across multiple surveys reveals universal power-law behaviors in clump populations. Maser-associated clumps exhibit modified parameter distributions and scaling relations, revealing how active star formation alters clump dynamics and structure. These extensive catalogs establish a foundation for investigating molecular clump properties, star formation processes, and Galactic evolution.

A topological space is called self-covering if it is a nontrivial cover of itself. We prove that, under mild assumptions, a closed self-covering manifold with an abelian fundamental group fibers over a torus in various senses. As a corollary, if its dimension is above 5 and its fundamental group is free abelian, then it is a fiber bundle over a circle. We also construct non-fibering examples when these assumptions are not fulfilled. In particular, one class of examples illustrates that the structure of self-covering manifolds is more complicated when the fundamental groups are nonabelian, and the corresponding fibering problem encounters significant difficulties.

Catalytic conversion of bio-ethanol (EtOH) into 1,3-butadiene (1,3-BD, ETB) represents a low-carbon technology contributing to the sustainable production of renewable 1,3-BD. However, the low selectivity towards 1,3-BD and poor stability of catalysts hinder practical applications of the ETB process. In this work, we presented a novel Zn-Zr catalyst supported on dendrite-structured mesoporous silica (DSMS). Compared to the typical meso- or micro- porous materials such as SBA-15, meso-SiO2 and Silicate-1 supported catalysts, the Zn-Zr/DSMS catalysts exhibited outstanding catalytic performance and exceptionally high stability in the ETB reaction. Over the representative 0.5%Zn2%Zr/DSMS catalyst, selectivity of 1,3-BD > 65 % and EtOH conversions of 72 %-100 % were obtained at temperatures in a wide range of 350-400 degrees C. More attractively, the distinguished performance was stable in a long time on stream of 172 h, and able to be effectively restored by calcining the spent catalyst. Systematic characterizations revealed that Zn and Zr species were highly dispersed on the DSMS support nearly at an atomic level, forming abundant Lewis acid sites without Bronsted acidity. This may account for the exceptionally high activity and 1,3-BD selectivity over the 0.5%Zn2%Zr/DSMS catalyst. The unique dendritic structure of the catalyst played important roles in stabilizing the catalytic performance. Correlated to the results of in-situ spectroscopy and conditional experiments, the roles of active sites and the contribution of the catalyst structure were proposed for the ETB process over the Zn-Zr/DSMS catalysts.

We compute the mapping class group of closed simply connected 6-manifolds M which look like complete intersections, that is, H2(M;7) = 7 and x3 0, where x E H2(M;7) is a generator. We determine some algebraic properties of the mapping class group; for example, we compute its abelianization and its center. We show that modulo the center the mapping class group is residually finite and virtually torsion-free. We also study low-dimensional homology groups. The results are very similar to the computation of the mapping class group of Riemann surfaces. We give generators of the mapping class group, and generators and relations for the subgroup acting trivially on n3(M).

Although interstellar dust extinction serves as a powerful distance estimator, the solar system’s location within the Galactic plane complicates distance determinations, especially for molecular clouds (MCs) at varying distances along the line of sight (LoS). The presence of complex extinction patterns along the LoS introduces degeneracies, resulting in less accurate distance measurements to overlapping MCs in crowded regions of the Galactic plane. In this study, we develop the CUSUM-based Jump-point Analysis for Distance Estimation (CU-JADE), a novel method designed to help mitigate these observational challenges. The key strengths of CU-JADE include: (1) sensitivity to detect abrupt jumps in Distance– A _λ ( D – A ) data sets, (2) minimal systematic errors as demonstrated on both mock and observed data, and (3) the ability to combine CUSUM analysis with multiwavelength data to improve the completeness of distance measurements for nearby gas structures, even for extinction values as low as Δ A _V ≳ 0.15 mag. By combining CO survey data with a large sample of stars characterized by high-precision parallaxes and extinctions, we uncovered the multilayered molecular gas distribution in the high-latitude Cepheus region. We also determined accurate distances to MCs beyond the Cygnus Rift by analyzing the intricate structure of gas and extinction within the Galactic plane. Additionally, we constructed a full-sky 3D extinction map extending to 4 kpc, which provides critical insights into dense interstellar medium components dominated by molecular hydrogen. These results advance our understanding of the spatial distribution and physical properties of MCs across the Milky Way.

Dust plays a critical role in the study of the interstellar medium. Extinction maps derived from optical surveys often fail to capture regions with high column density due to the limited photometric depth in optical wavelengths. To address these limitations, we developed the XPNICER method based on near-infrared photometric survey data. This method combines the previously established PNICER and Xpercentile techniques, enabling effective mitigation of foreground contamination and improved handling of complex dust structures in the Galactic plane, which thus can provide more accurate extinction estimates, particularly in highly obscured regions. By applying XPNICER to the Galactic Plane Survey from the UKIRT Infrared Deep Sky Survey, we have generated a series of two-dimensional dust extinction maps that span roughly similar to 1800 deg(2) of the Galactic plane (0 degrees less than or similar to l less than or similar to 110 degrees and 140 degrees less than or similar to l less than or similar to 232 degrees, vertical bar b vertical bar less than or similar to 5 degrees). These maps, with spatial resolutions between 30 and 300 arcsec, can trace extinction up to A(V) similar to 30-40 mag. This new approach offers higher spatial resolution and better detection of high-extinction regions compared to previous large-scale dust-based maps of the Galactic plane, providing an independent and complementary measure of dust column densities.

We determine those (n-1)-connected (2n+1)-manifolds with torsion free homology that admit free circle actions up to almost diffeomorphism, provided that n equivalent to 5, 7 mod 8.