Solar Neighborhood Research Articles

The Global Patterns of Instantaneous CO2 Forcing at the Top of the Atmosphere and the Surface

Abstract The radiative forcing of carbon dioxide (CO2) at the top of the atmosphere (TOA) has a rich spatial structure and has implications for large-scale climate changes, such as poleward energy transport and tropical circulation change. Beyond the TOA, additional CO2 increases downwelling longwave at the surface, and this change in flux is the surface CO2 forcing. Here we thoroughly evaluate the spatiotemporal variation of the instantaneous, longwave CO2 radiative forcing at both the TOA and surface. The instantaneous forcing is calculated with a radiative transfer model using ERA5 reanalysis fields. Multivariate regression models show that the broadband forcing at the TOA and surface are well predicted by local temperatures, humidity, and cloud radiative effects. The difference between the TOA and surface forcing, the atmospheric forcing, can be either positive or negative and is mostly controlled by the column water vapor, with little explicit dependence on the surface temperature. The role of local variables on the TOA forcing is also assessed by partitioning the change in radiative flux to the component emitted by the surface versus that emitted by the atmosphere. In cold, dry regions, the surface and atmospheric contribution partially cancel out, leading to locally weak or even negative TOA forcing. In contrast, in the warm, moist regions, the surface and atmospheric components strengthen each other, resulting in overall larger TOA forcing. The relative contributions of surface and atmosphere to the TOA forcing depend on the optical thickness in the current climate, which in turn is controlled by the column water vapor.

The kinematic structure of magnetically aligned H i filaments

ABSTRACT We characterize the kinematic and magnetic properties of H i filaments located in a high Galactic latitude region (165° < α < 195° and 12° < δ < 24°). We extract three-dimensional filamentary structures using fil3d from the Galactic Arecibo L-Band Feed Array H i (GALFA-H i) survey 21-cm emission data. Our algorithm identifies coherent emission structures in neighbouring velocity channels. Based on the mean velocity, we identify a population of local and intermediate velocity cloud (IVC) filaments. We find the orientations of the local (but not the IVC) H i filaments are aligned with the magnetic field orientations inferred from Planck 353 GHz polarized dust emission. We analyse position–velocity diagrams of the velocity-coherent filaments, and find that only 15 per cent of filaments demonstrate significant major-axis velocity gradients with a median magnitude of 0.5 km s−1 pc−1, assuming a fiducial filament distance of 100 pc. We conclude that the typical diffuse H i filament does not exhibit a simple velocity gradient. The reported filament properties constrain future theoretical models of filament formation.

Dynamical charging of interstellar dust particles in the heliosphere

Interstellar dust (ISD) particles penetrate the solar system due to the relative motion of the Sun and the local interstellar cloud. Before entering the heliosphere, they pass through the heliospheric interface – the region of the solar wind interaction with the interstellar plasma. The size distribution and number density of dust grains are modified in the interface essentially. The modification depends on the charging of the dust particles along their trajectories. In this paper, we present modeling results of the charging of ISD particles passing through the heliospheric interface. The main physical processes responsible for the charging within the heliospheric conditions are the sticking of primary plasma particles, secondary electron emission, photoemission, and the effects of cosmic ray electrons. We consider two methods to calculate the electric charge of ISD particles based on (1) the classic steady-state assumption that the charge depends only on local plasma and radiation conditions and (2) the dynamical computation of charge along the particle trajectory. We demonstrate that the steady-state assumption is quite justified to model trajectories and number density distributions of relatively big ISD grains (radius of 100 nm and larger) penetrating the heliosphere. The estimates show that ISD grains of these sizes require less than 0.25 years (distance of ≈1 au) after transition from the LISM into the heliosphere to reach an equilibrium. For small particles ( radius of 10 nm), the dynamical computation of charge influences the trajectories and modifies the number density substantially. The dust density accumulations are distributed within a more elongated region along the heliopause in case of dynamically changed charge as compared with the use of a steady-state charge approximation. As a result, the magnitudes of number density at the points of density features differ several times between the results obtained by the two considered approaches.

Resonant Effects of a Bar on the Galactic Disk Kinematics Perpendicular to Its Plane

Detailed analysis of kinematics of the Milky Way disk in the solar neighborhood based on the GAIA DR3 catalog reveals the existence of peculiarities in the stellar velocity distribution perpendicular to the galactic plane. We study the influence of resonances—the outer Lindblad resonance and the outer vertical Lindblad resonance—of a rotating bar with stellar oscillations perpendicular to the plane of the disk, and their role in shaping the spatial and the velocity distributions of stars. We find that the Z and VZ distributions of stars with respect to LZ are affected by the outer Lindblad resonance. The existence of bar resonance with stellar oscillations perpendicular to the plane of the disk is demonstrated for a long (large semi-axis 5 kpc) and fast rotating bar with Ωb=60.0kms−1kpc−1. We show also that, in the model with the long and fast rotating bar, some stars in the 2:1 OLR region deviate far from their original places, entering the bar region. A combination of resonance excitation of stellar motions at the 2:1 OLR region together with strong interaction of the stars with the bar potential leads to the formation of the group of ‘escapees’, i.e., stars that deviate in R and Z—directions at large distances from the resonance region. Simulations, however, do not demonstrate any noticeable effect on VZ-distribution of stars in the solar neighborhood.

ESCARGOT: Mapping Vertical Phase Spiral Characteristics Throughout the Real and Simulated Milky Way

The recent discovery of a spiral pattern in the vertical kinematic structure in the solar neighborhood provides a prime opportunity to study nonequilibrium dynamics in the Milky Way from local stellar kinematics. Furthermore, results from simulations indicate that even in a limited volume, differences in stellar orbital histories allow us to trace variations in the initial perturbation across large regions of the disk. We present ESCARGOT, a novel algorithm for studying these variations in both simulated and observed data sets. ESCARGOT automatically extracts key quantities from the structure of a given phase spiral, including the time since perturbation and the perturbation mode. We test ESCARGOT on simulated data and show that it is capable of accurately recovering information about the time since the perturbation occurred as well as subtle differences in phase spiral morphology due to stellar locations in the disk at the time of perturbation. We apply ESCARGOT to kinematic data from data release 3 of the Gaia mission in bins of guiding radius. We show that similar structural differences in morphology occur in the Gaia phase spirals as a function of stellar orbital history. These results indicate that the phase spirals are the product of a complex dynamical response in the disk with large-scale coupling between different regions of phase space.

The Orion-Taurus ridge: A synchrotron radio loop at the edge of the Orion-Eridanus superbubble

Large-scale synchrotron loops are recognized as the main source of diffuse radio-continuum emission in the Galaxy at intermediate and high Galactic latitudes, yet their origin remain unexplained. For the first time, using a combination of multi-frequency data in the radio band of total and polarized intensities, we were able to associate one arc, hereafter, the Orion-Taurus ridge, with the wall of the most prominent stellar-feedback blown shell in the Solar neighborhood, namely, the Orion-Eridanus superbubble. We traced the Orion-Taurus ridge using 3D maps of interstellar dust extinction and column-density maps of molecular gas,NH2. We found the Orion-Taurus ridge at a distance of 400 pc, with a plane-of-the-sky extent of 180 pc. Its medianNH2value is (1.4−0.6+2.6) × 1021cm−2. Thanks to the broadband observations below 100 MHz of the Long Wavelength Array (LWA), we were also able to compute the low-frequency spectral-index map of synchrotron emissivity,β, in the Orion-Taurus ridge. We found a flat distribution ofβwith a median value of −2.24−0.02+0.03, which we interpreted in terms of depletion of low-energy (< GeV) cosmic-ray electrons in recent supernova remnants (105–106yr). Our results are consistent with plane-of-the-sky magnetic-field strengths in the Orion-Taurus ridge greater than a few tens of μG (> 30 − 40 μG). We report the first detection of diffuse synchrotron emission from cold-neutral, partly molecular gas in the surroundings of the Orion-Eridanus superbubble. This observation opens a new perspective for studies of the multiphase and magnetized interstellar medium with the advent of future high-sensitivity radio facilities, such as theC-Band All-Sky Survey (C-BASS) and the Square Kilometre Array (SKA).

Neutral Atomic and Molecular Clouds and Star Formation in the Outer Carina Arm

We present a comprehensive investigation of H i (super)clouds, molecular clouds (MCs), and star formation in the Carina spiral arm of the outer Galaxy. Utilizing HI4PI and CfA CO survey data, we identify H i clouds and MCs based on the (l, v LSR) locations of the Carina arm. We analyzed 26 H i clouds and 48 MCs. Most of the identified H i clouds are superclouds, with masses exceeding 106 M ⊙. We find that 15 of these superclouds have associated MC(s) with M H I ≳ 106 M ⊙ and 50 M ⊙ pc−2. Our virial equilibrium analysis suggests that these CO-bright H i clouds are gravitationally bound or marginally bound. We report an anticorrelation between molecular mass fractions and Galactocentric distances, and a correlation with total gas surface densities. Nine CO-bright H i superclouds are associated with H ii regions, indicating ongoing star formation. We confirm the regular spacing of H i superclouds along the spiral arm, which is likely due to some underlying physical process, such as gravitational instabilities. We observe a strong spatial correlation between H ii regions and MCs, with some offsets between MCs and local H i column density peaks. Our study reveals that, in the context of H i superclouds, the star formation rate surface density is independent of H i and total gas surface densities but positively correlates with molecular gas surface density. This finding is consistent with both extragalactic studies of the resolved Kennicutt–Schmidt relation and local giant molecular clouds study of Lada et al. (2013), emphasizing the crucial role of molecular gas in regulating star formation processes.

Collaborative 3D Object Detection for Autonomous Vehicles via Learnable Communications

3D object detection from LiDAR point cloud is a challenging task in autonomous driving systems. Collaborative perception can incorporate information from spatially diverse sensors and provide significant benefits for accurate 3D object detection from point clouds. In this work, we consider that the autonomous vehicle uses local point cloud data and combines information from neighboring infrastructures through wireless links for cooperative 3D object detection. However, information sharing among vehicles and infrastructures in predefined communication schemes may result in communication congestion and/or bring limited performance improvement. To this end, we propose a novel collaborative 3D object detection framework using an encoder-decoder network architecture and an attention-based learnable communications scheme. It consists of three components: a feature encoder network that maps point clouds into feature maps; an attention-based communication module that propagates compact and fine-grained query feature maps from the vehicle to support infrastructures, and optimizes attention weights between query and key to refine support feature maps; a region proposal network that fuses local feature maps and weighted support feature maps for 3D object detection. We evaluate the performance of the proposed framework on CARLA-3D, a new dataset that we synthesized using CARLA for 3D cooperative object detection. Experimental results and bandwidth consumption analysis show that the proposed collaborative 3D object detection framework achieves a better detection performance and communication bandwidth trade-off than five baseline 3D object detection models under different detection difficulties.

Binary star population of the Sculptor dwarf galaxy

Aims. We aim to compute the binary fraction of “classical” dwarf spheroidal galaxies (dSphs) that are satellites of the Milky Way (MW). This value can offer insights into the binary fraction in environments that are less dense and more metal-poor than our own galaxy. Additionally, knowledge of the binary fraction in dwarf galaxies is important with respect to avoiding overestimations of their dark matter content, inferred from stellar kinematics. Methods. We refined an existing method from the literature, placing an emphasis on providing robust uncertainties on the value of the binary fraction. We applied this modified method to a VLT/FLAMES dataset for Sculptor, specifically acquired for the purpose of velocity monitoring of individual stars, as well as to literature datasets for other six MW “classical” dSphs. In all cases, the targeted stars were mainly red giant branch stars, with expected masses of around 0.8 M⊙. The VLT/FLAMES dataset offers the most precise binary fractions compared to literature datasets, due to its time baseline of 12 yr, along with at least nine repeated observations for each star. Results. We found that the binary fraction of Sculptor is 0.55−0.19+0.17. We find that it is important to take into account the Roche lobe overflow for constraining the period distribution of binary stars. In contrast to what has recently been proposed in the literature, our analysis indicates that there is no evidence to support varying the properties of the binary stellar population or their deviations from those established for the solar neighborhood, based on the sample of MW dSphs analyzed here.

Fast Radio Bursts as Probes of Magnetic Fields in Galaxies at z < 0.5

We present a sample of nine fast radio bursts (FRBs) from which we derive magnetic field strengths of the host galaxies represented by normal, z < 0.5 star-forming galaxies with stellar masses M * ≈ 108–1010.5 M ⊙. We find no correlation between the FRB rotation measure (RM) and redshift, which indicates that the RM values are due mostly to the FRB host contribution. This assertion is further supported by a significant positive correlation (Spearman test probability P S < 0.05) found between the RM and the estimated host dispersion measure (DMhost; with Spearman rank correlation coefficient r S = +0.75). For these nine galaxies, we estimate their magnetic field strengths projected along the sight line ∣B ∥∣, finding a low median value of 0.5 μG. This implies the magnetic fields of our sample of hosts are weaker than those characteristic of the solar neighborhood (≈6 μG), but relatively consistent with a lower limit on the observed range of ≈2–10 μG for star-forming disk galaxies, especially as we consider reversals in the B-field, and that we are only probing B∥. We compare to RMs from simulated galaxies of the Auriga project—magneto-hydrodynamic cosmological zoom simulations—and find that the simulations predict the observed values to within a 95% confidence interval. Upcoming FRB surveys will provide hundreds of new FRBs with high-precision localizations, RMs, and imaging follow-up to support further investigation into the magnetic fields of a diverse population of z < 1 galaxies.

Important non-local effects of deforestation on cloud cover changes in CMIP6 models

Recent satellite and in-situ measurements show that forests can influence regional and global cloud cover through biophysical processes. However, forest’s possible local and non-local impacts on clouds remain unclear. By analyzing the model simulations from the Coupled Model Intercomparison Project Phase 6, here we show that deforestation-induced cloud cover changes have a strong latitudinal dependence, with decreased cloudiness in the tropics but increased cloudiness in the temperate and boreal regions. We further disentangle the local and non-local effects in influencing the cloudiness changes in model simulations. Results show that deforestation leads to a local cloud reduction in the tropics and a non-local cloud enhancement in the temperate and boreal regions. We demonstrate that the relationship between changes in cloud cover and deforestation would be misinterpreted without considering the non-local signals. Furthermore, our modeling results are inconsistent with recent observational studies, with enhanced clouds in model simulations but reduced clouds in observations in the temperate and boreal regions. Further efforts to explore the non-local effect and to reduce the model uncertainty could help advance our understanding of the biophysical effects of deforestation.

Analisis Citra Satelit Himawari-8 Terkait Kejadian Puting Beliung Di Kabupaten Bogor (Studi Kasus 02 November 2021)

&#x0D; Puting Beliung is a strong-rotating wind originating from Cumulonimbus clouds with a speed of more than 34.8 knots or 64.4 km/hour that occurs short time. Puting Beliung occurred on November 2, 2021, at 2 pm in the Kampung Dukuh area, Pasirmukti Village, Citeureup District, Bogor Regency (106° 53' 47.99"E and 6° 31' 5.2"S). The research data are surface air observation data from Bogor Climatology Station, Himawari-8 satellite data, and Copernicus CDS reanalysis data. This study aims to analyze the dynamics of the atmosphere during the occurrence of wind phenomena in a tornado in the Kampung Dukuh area, Pasirmukti Village, Citeureup District, Bogor Regency. This study method is a descriptive analysis of Himawari-8 satellite imagery using SATAID software. The results of this study indicate that tornadoes occur due to shear lines and strong-atmospheric lability in the Bogor and surrounding areas, thus triggering the formation of local convective clouds characterized by cloud peak temperatures reaching -69oC.&#x0D;

Tracing dense gas in six resolved GMCs of the Andromeda Galaxy

ABSTRACT We present dense-gas-tracing molecular observations of six resolved Giant Molecular Clouds (GMCs) in the Andromeda Galaxy (M31). Using the NOEMA interferometer, we observed the transitions of HCN(1–0), HCO+(1–0), and HNC(1–0), as well as 13CO(1–0) and 100 GHz continuum emission. This complements our earlier work with the Submillimetre Array, including resolved dust continuum detections of these clouds at 230 GHz. In this work, we first compare different continuum measurements to conclude that the average free–free contamination of the observed flux is 71 per cent at 3 mm but only 13 per cent at 1 mm, confirming that emission at 3 mm is less reliable than that at 1 mm for calculating dust masses of star-forming clouds. While the 13CO emission is more extended than both HCN and HCO+ emission, which in turn is more extended than HNC emission, we find that both HCN and HCO+ are spatially coincident with, and similarly extended as, the 230 GHz dust emission. This suggests that both the 230 GHz dust continuum and most importantly the HCN emission traces the dense gas component of these GMCs. From comparison of the molecular emission with dust masses derived from the 230 GHz continuum emission, we obtain the first direct measurements of the dust-mass-to-light ratios ($\alpha ^\prime _{\rm HCN}$ and $\alpha ^\prime _{\rm HCO^+}$) in GMCs of an external galaxy. For HCN, the result is broadly similar to a measurement in the local Perseus cloud suggesting that these are indeed dense gas conversion factors. A larger cloud sample will be required to assess whether HCN is tracing comparable cloud-scale density regimes across the environments of M31.

SPYGLASS. IV. New Stellar Survey of Recent Star Formation within 1 kpc

Young stellar populations provide a powerful record that traces millions of years of star formation history in the solar neighborhood. Using a revised form of the SPYGLASS young star identification methodology, we produce an expanded census of nearby young stars (age < 50 Myr). We then use the HDBSCAN clustering algorithm to produce a new SPYGLASS Catalog of Young Associations, which reveals 116 young associations within 1 kpc. More than 25% of these groups are largely new discoveries, as 20 are substantively different from any previous definition, and 10 have no equivalent in the literature. The new associations reveal a yet undiscovered demographic of small associations with little connection to larger structures. Some of the groups we identify are especially unique for their high transverse velocities, which can differ from the solar velocity by 30–50 km s−1, and for their positions, which can reach up to 300 pc above the galactic plane. These features may suggest a unique origin, matching existing evidence of infalling gas parcels interacting with the disk interstellar medium. Our clustering also suggests links between often-separated populations, hinting to direct structural connections between Orion Complex and Perseus OB2, and between the subregions of Vela. The ∼30 Myr old Cepheus-Hercules association is another emerging large-scale structure, with a size and population comparable to Sco-Cen. Cep-Her and other similarly aged structures are also found clustered along extended structures perpendicular to known spiral arm structure, suggesting that arm-aligned star formation patterns have only recently become dominant in the solar neighborhood.

A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE

We present new maps of the Milky Way disk showing the distribution of metallicity ([Fe/H]), α-element abundances ([Mg/Fe]), and stellar age, using a sample of 66,496 red giant stars from the final data release (DR17) of the Apache Point Observatory Galactic Evolution Experiment survey. We measure radial and vertical gradients, quantify the distribution functions for age and metallicity, and explore chemical clock relations across the Milky Way for the low-α disk, high-α disk, and total population independently. The low-α disk exhibits a negative radial metallicity gradient of −0.06 ± 0.001 dex kpc−1, which flattens with distance from the midplane. The high-α disk shows a flat radial gradient in metallicity and age across nearly all locations of the disk. The age and metallicity distribution functions shift from negatively skewed in the inner Galaxy to positively skewed at large radius. Significant bimodality in the [Mg/Fe]–[Fe/H] plane and in the [Mg/Fe]–age relation persist across the entire disk. The age estimates have typical uncertainties of ∼0.15 in log(age) and may be subject to additional systematic errors, which impose limitations on conclusions drawn from this sample. Nevertheless, these results act as critical constraints on galactic evolution models, constraining which physical processes played a dominant role in the formation of the Milky Way disk. We discuss how radial migration predicts many of the observed trends near the solar neighborhood and in the outer disk, but an additional more dramatic evolution history, such as the multi-infall model or a merger event, is needed to explain the chemical and age bimodality elsewhere in the Galaxy.

A Design for a Lithium-Ion Battery Pack Monitoring System Based on NB-IoT-ZigBee

With environmental issues arising from the excessive use of fossil fuels, clean energy has gained widespread attention, particularly the application of lithium-ion batteries. Lithium-ion batteries are integrated into various industrial products, which necessitates higher safety requirements. Narrowband Internet of Things (NB-IoT) is an LPWA (Low Power Wide Area Network) technology that provides IoT devices with low-power, low-cost, long-endurance, and wide-coverage wireless connectivity. This study addresses the shortcomings of existing lithium-ion battery pack detection systems and proposes a lithium-ion battery monitoring system based on NB-IoT-ZigBee technology. The system operates in a master-slave mode, with the subordinate module collecting and fusing multi-source sensor data, while the master control module uploads the data to local monitoring centers and cloud platforms via TCP and NB-IoT. Experimental validation demonstrates that the design functions effectively, accomplishing the monitoring and protection of lithium-ion battery packs in energy storage power stations.

Big Data for Beginners

With the increasing amount of datasets being published and made available through global aggregators, such as the Global Biodiversity Information Facility (GBIF), new opportunities have opened to answer research questions that previously could not be considered. Techniques for large scale data integration offer benefits for the biodiversity research community (Heberling et al. 2021, Kays et al. 2020), profiting from the great and continuing efforts in data mobilisation and standardisation (such as Darwin Core, Wieczorek et al. 2012). These benefits include integrating several large data sources or enriching existing occurrence data with other information. Several commonly encountered barriers to large-scale use of biodiversity occurrence data exist. These include the lack of facilities for local storage of large and rapidly changing datasets, the computational power required for processing, unfamiliarity with existing toolsets, and insufficient resources to maintain big data infrastructure. These challenges are well documented in the context of high-throughput genomics (Marx 2013), and more recently in occurrence-based biodiversity research (for example Thessen et al. 2018). However, while these hurdles and bottlenecks are very real, several of them have low cost of entry solutions. The aim of this presentation is to encourage the community to explore ambitious queries, to combine and examine all available data in its totality and to break down specific technical barriers, by providing a practical overview for researchers to maximise the power of large-scale data processing in their work. While big data processing may seem daunting, tools accessible to users without a background in big data are available for both local workstations and cloud computing services that allow for scalable data processing at low cost, for instance Databricks Community Edition or Apache Arrow. Using these resources, researchers can incorporate larger datasets into existing protocols, and by doing so, uncover patterns and insights that would be otherwise impossible to acquire using smaller subsets of the ever-expanding complex set that biodiversity occurrence data presents.

Detection of Alzheimer's Disease Based on Cloud-Based Deep Learning Paradigm.

Deep learning is playing a major role in identifying complicated structure, and it outperforms in term of training and classification tasks in comparison to traditional algorithms. In this work, a local cloud-based solution is developed for classification of Alzheimer's disease (AD) as MRI scans as input modality. The multi-classification is used for AD variety and is classified into four stages. In order to leverage the capabilities of the pre-trained GoogLeNet model, transfer learning is employed. The GoogLeNet model, which is pre-trained for image classification tasks, is fine-tuned for the specific purpose of multi-class AD classification. Through this process, a better accuracy of 98% is achieved. As a result, a local cloud web application for Alzheimer's prediction is developed using the proposed architectures of GoogLeNet. This application enables doctors to remotely check for the presence of AD in patients.

The Relationship Between the Present‐Day Seasonal Cycles of Clouds in the Mid‐Latitudes and Cloud‐Radiative Feedback

AbstractWe show that the seasonal cycles of clouds over the mid‐latitude oceans in the Northern Hemisphere are predictors of the responses of clouds to increasing sea‐surface temperatures globally. These regions are therefore “natural laboratories” in which the processes responsible for low‐cloud feedbacks on global scales are observed as seasonal changes in local cloud properties. We use an ensemble of configurations of a global‐climate model to show that the sensitivities of cloud‐radiative anomalies to surface temperature and lower‐tropospheric stability in the “laboratory” regions predict the models' global cloud‐radiative feedbacks. Models with greater changes in low‐clouds between seasons are shown to have stronger negative feedbacks in the mid‐latitudes, and stronger positive feedbacks from the subtropical stratocumulus. The biases in the simulated seasonal cycles, compared to observations, imply that both feedbacks are too weak in the model. The consequences of this for configuring our model to have a lower climate sensitivity are discussed.

Constraining gas metal mixing strength in simulations using observations of the Milky Way’s disc

ABSTRACT This work explores the mixing rate of metals in the interstellar medium (ISM), comparing observational constraints from our solar neighbourhood to high resolution cosmological hydrodynamical simulations of Milky Way (MW)-like galaxies. The mixing rate, described by the coefficient C, is varied in simulations between 0 and 0.05, with resultant simulated galaxies compared to observations of metallicity dispersion in young star clusters, H ii regions and neutral gas in the disc of the MW. A value of C between 0.003125 and 0.0125 is found to self-consistently match a range of observables, with a best estimate of C = 0.0064 ± 0.0004. We demonstrate that the relationship between metal dispersion in young stars, H ii regions and neutral gas, versus the coefficient C, can be described by a power law. These constrained mixing rates infer a comparatively well-mixed ISM in the solar neighbourhood, at odds with some recent observations that have reported a highly inhomogeneous ISM. The degree of mixing suggested by this work is lower than what often employed in many hydrodynamical simulations. Our results have implications for studying the metallicity distribution of stars as well as of gas in the interstellar and circum-galactic media.