National Astronomical Research Institute of Thailand

Abstract The Massive and Distant Clusters of Wide-field Infrared Survey Explorer (WISE) Survey 2 (MaDCoWS2) is a WISE-selected catalog of galaxy clusters at 0.1 &lt; z &lt; 2 covering an effective area of &gt;6000 deg 2 . In this paper, we derive splashback radii for this cluster ensemble from galaxy density profiles and constrain the mass threshold of the survey as a function of redshift. We use MaDCoWS2 cluster candidates at 0.4 ≤ z ≤ 1.65 divided into subsamples with different Poissonian signal-to-noise ratios (S/N P s) and redshifts, cross correlated with galaxies from the CatWISE2020 catalog, to obtain average surface density profiles. We perform a Markov Chain Monte Carlo analysis to derive parameter estimates for theoretical models consisting of orbiting and infalling terms. A distinct splashback feature is detected in all subsamples. The measured splashback radii span from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.8</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.02</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.02</mml:mn> </mml:mrow> </mml:msubsup> <mml:msup> <mml:mrow> <mml:mi>h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> cMpc ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.6</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.02</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.02</mml:mn> </mml:mrow> </mml:msubsup> <mml:msup> <mml:mrow> <mml:mi>h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> pMpc) at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="true">¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>0.45</mml:mn> </mml:math> to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1.2</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> </mml:msubsup> <mml:msup> <mml:mrow> <mml:mi>h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> cMpc ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.5</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> </mml:msubsup> <mml:msup> <mml:mrow> <mml:mi>h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> pMpc) at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="true">¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>1.54</mml:mn> </mml:math> . We also find that the splashback radii increase with S/N P at fixed redshift. The resultant splashback radii constrain the redshift dependence of the mass of MaDCoWS2 clusters at fixed S/N P . We calculate M 200m from the radii using a relation based on a cosmological simulation. MaDCoWS2 M 200m values derived from the simulation-based relation are lower than the expected values based on weak-lensing observations. More robust mass constraints will come from calibrating splashback radii derived from galaxy density profiles with weak-lensing shear profiles from facilities such as Euclid, the Vera C. Rubin Observatory, and the Nancy Grace Roman Space Telescope.

Abstract We present and analyze panchromatic (0.35–14 μ m) spectroscopy of the Type II supernova 2023ixf, including near- and mid-infrared spectra obtained 33.6 days after explosion during the plateau phase, with the James Webb Space Telescope (JWST). This is the first in a series of papers examining the evolution of SN 2023ixf with JWST during the initial 1000 days after explosion and monitoring the formation and growth of molecules and dust in ejecta and the surrounding environment. The JWST infrared spectra are overwhelmingly dominated by H lines, whose profiles reveal ejecta structures, including flat tops, blue notches, and red shoulders, unseen in the optical spectra. We characterize the nature of these structures, concluding that they likely result from a combination of ejecta geometry, viewing angle, and opacity effects. We find no evidence for the formation of dust precursor molecules such as carbon monoxide (CO), nor do we observe an infrared excess attributable to dust. These observations imply that the detections of molecules and dust in SN 2023ixf at later epochs arise either from freshly synthesized material within the ejecta or circumstellar material at radii not yet heated by the supernova at this epoch.

Abstract SN 2025coe is a calcium-strong transient located at an extremely large projected offset ∼39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of ∼25.5 Mpc. In this paper, we present multiband photometric and spectroscopic observations spanning ∼100 days postdiscovery. Its multiband light curves display multiple distinct peaks: (1) an initial peak at t ≈ 1.6 day attributed to shock cooling emission, (2) a secondary peak of M R , peak ≈ −15.8 mag at t ≈ 10.2 days powered by radioactive decay, and (3) a possible late-time bump at t ≈ 42.8 days likely caused by ejecta–circumstellar material/clump interaction. Spectral evolution of SN 2025coe reveals a fast transition to the nebular phase within 2 months, where it exhibits an exceptionally high [Ca II ]/[O I ] ratio larger than 6. Modeling of the bolometric light curve suggests an ejecta mass of M ej = 0.2 9 − 0.15 + 0.14 M ⊙ , a 56 Ni mass of M 56 Ni = 2 . 4 − 0.05 + 0.06 × 1 0 − 2 M ⊙ , and a progenitor envelope with mass M e = 1 . 4 − 1.2 + 6.9 × 1 0 − 3 M ⊙ and radius R e = 13 . 5 − 11.1 + 64.1 R ⊙ . The tidal disruption of a hybrid HeCO white dwarf (WD) by a low-mass CO WD provides a natural explanation for the low ejecta mass, the small fraction of 56 Ni, and the presence of an extended, low-mass envelope.

Effective temperature, surface gravity, and metallicity are important fundamental parameters for the study of stars. The established approach to determine these parameters is by analyzing data collected from time-consuming spectroscopy. Recently, photometry emerged as a cheaper alternative to spectroscopy to obtain stellar data, and though less accurate, it provides a cost-effective alternative for large-scale observations. This raises an important research question about how accurately and extensively photometric data can be used to predict the spectroscopic parameters across large stellar populations.In this paper, we present a stacking ensemble regression model for predicting the effective temperature, surface gravity, and metallicity of M dwarf stars from photometric data. Our method combines a non-linear global function approximator, as instantiated by a neural network model, and a local approximator, as instantiated by a tree-based gradient boosting model, to capture the regularities in the data. We evaluated our approach on a dataset constructed by cross-matching LAMOST DR8 spectroscopic parameters with multi-wavelength photometric data from the SDSS, 2MASS, and WISE surveys. The experimental results demonstrated the potential of the proposed stacking ensemble compared to the baselines.

This study presents an integrated and reproducible framework for within-tier screening of potential healthcare accessibility in Bangkok. Facilities in three service tiers (primary 294 units, regular 75, referral 29) are analyzed using point-pattern diagnostics, Voronoi geometric partitions, population-weighted allocation from subdistrict controls, and cumulative network travel-time isochrones. Spatial diagnostics indicate clustering among primary care units, a near-random configuration for regular units, and modest dispersion for referral hospitals, summarized by observed-to-expected nearest-neighbor ratios of approximately 0.77, 1.05, and 1.19, respectively. Voronoi partitions translate these distributions into geometric units that enlarge with increasing inter-facility spacing, while population-weighted assignments reveal higher population-per-partition-area burdens in the outer east and southwest. Isochrone maps (5–60 min rings) show central corridors with short travel times and peripheral areas where potential access declines. Interpreted against statutory planning intent, the maps indicate broad consistency of siting with high-intensity zones, alongside residual gaps at residential fringes. Framed as repeatable indicators of access and coverage, the workflow contributes to measuring and monitoring urban health sustainability under universal health coverage and routine planning cycles. The framework yields transparent indicators that support monitoring, priority setting, and incremental adjustments within each tier. Limitations include planar proximity assumptions, uniform areal weighting, single-mode modeled travel times without temporal variation, and the absence of capacity measures, motivating future work on capacity-weighted partitions, minimal dasymetric refinements, and time-dependent multimodal scenarios.

Abstract The FIRESTORM project–Feedback-Induced Regions and Emission from Star-forming Tracers of ObseRvable Molecular Gas–has targeted four star-forming regions to quantify the impact of stellar feedback on star formation. In this paper, we present multiwavelength results for one of the targets, the nearby high-mass star-forming region W40. Using dense-gas tracers C18O(1–0) and H13CO+(1–0), we identified six velocity-coherent filaments: five at VLSR∼ 7.5 km s−1 and one at VLSR∼ 5 km s−1. Four of these converge towards an infrared-bright cluster hosting the most massive star of the region (IRS 1A South, O9.5V), forming a hub-filament system (HFS). Key physical parameters, including filament lengths, widths, masses, velocity dispersions, and line masses, are derived. Five dense clumps traced by N2H+(1–0) exhibit subsonic to transonic turbulence, contrasting with the supersonic motions of their parental filaments, indicating turbulence dissipation. A deficit of emission at VLSR∼ 7 km s−1 in several molecular lines, along with a blueshifted absorption dip in the HCN(1–0) profile, suggests that emission from OB-heated gas is being absorbed by a cold foreground cloud. A bridge-like feature in position-velocity space connects the VLSR∼ 5 and ∼ 7.5 km s−1 filaments, and spatially coinciding with dense condensations and radio continuum peaks. These findings suggest that a past interaction–likely a cloud-cloud collision–triggered the formation of HFS and ultimately the central massive cluster.

Abstract We present panchromatic 0.4–21 μ m observations of the nearby (∼7.2 Mpc) Type II supernova (SN) 2024ggi, obtained during the plateau phase at ∼55 days past explosion. Our data set includes JWST spectra spanning 1.7–14 μ m, mid-infrared (MIR) imaging at 7.7 and 21 μ m, and near-simultaneous ground-based optical and near-infrared (NIR) spectra covering 0.32−1.8 μ m. The NIR and MIR spectral features of SN 2024ggi are dominated by H i emission. We present line IDs and a toy PHOENIX/1D model that reproduces the observations well, especially the continuum redward of 0.9 μ m. We compare SN 2024ggi to SN 2022acko and SN 2023ixf, two other Type II SNe that were also observed by JWST, and highlight key similarities and differences in their spectral features. No evidence for a MIR excess or dust is found at these epochs, with the model matching the observed flux out to 21 μ m. We discuss the model’s shortcomings, focusing on the density profile, which suppresses line blanketing and produces features in the optical that are too narrow. Our results show the power of panchromatic studies in both exploring the nature of the SN ejecta and constraining detailed models of SNe.

A checklist of the West Malaysian fauna is provided with information on local and world distribution, host trees, biology and taxonomy. Three hundred seventy-six species are recorded from Malaya, 33 for the first time. Five new species are described: Asiophilus bukiticola Smith, Beaver &amp; Cognato sp. nov., Cyclorhipidion brownei Smith, Beaver &amp; Cognato sp. nov., Euwallacea frimensis Smith, Beaver &amp; Cognato sp. nov., Euwallacea phrixosoma Smith, Beaver &amp; Cognato sp. nov., and Microperus pasohanthus Smith, Beaver &amp; Cognato sp. nov. Three species are removed from synonymy and reinstated as valid species: Euwallacea barbatus (Hagedorn, 1910), Euwallacea pseudobarbatus (Schedl, 1942), Euwallacea rudis (Eggers, 1930). Two new combinations are proposed: Ancipitis scabrior (Schedl) comb. nov. from Leptoxyleborus Wood, 1980; Xylosandrus mascareniformis (Eggers, 1972) comb. nov. from Xyleborus Eichhoff, 1864. Two new synonyms are proposed: Coccotrypes gedeanus (Eggers, 1936) (= Xyleborus despectus Schedl, 1975 syn. nov.) and Arixyleborus scapularis (Schedl, 1942) (=Xyleborus magnus Browne, 1985 syn. nov.).

We present the first dark-sky map of Thailand, derived from calibrated Visible Infrared Imaging Radiometer Suite (VIIRS) satellite data spanning 2012–2023. Artificial night-sky brightness was classified into 14 levels, with Classes 1–9 defined as potential dark-sky areas where the Milky Way remains visible. International comparisons with the United Kingdom, Chile, and Botswana reveal that Thailand has undergone the steepest decline, losing 15.4% of pristine skies since 2012, while the UK remained stable (+0.8%), Botswana nearly unchanged (−0.7%), and Chile moderately degraded (−5.3%). A correlation analysis shows strong negative associations between potential dark-sky area and both GDP (r=−0.65) and population (r=−0.68), while inflation (r=0.26) and unemployment (r=0.24) exhibit weak influence. Five algorithms, including GLM and machine learning models, were tested; among them, the Decision Tree achieved the lowest relative error (0.4%±0.3%), with ensemble methods and GLM performing comparably and Deep Learning being less accurate. By 2023, over 60% of Thais lived under skies too bright to observe the Milky Way by naked eye, and one-fifth were exposed to intensities preventing dark adaptation. Thailand’s rapid transition to LED street lighting after 2015, while energy-efficient, has intensified skyglow. Protecting remaining dark-sky areas requires urgent policies, linking conservation to human health, biodiversity, cultural heritage, and sustainable development.