Revista Mexicana de Astronomía y Astrofísica
The Revista Mexicana de Astronomía y Astrofísica, founded in 1974, publishes original research papers in all branches of astronomy, astrophysics and closely related fields. It is a digital journal, with open access. The editorial process is free of charge for all authors. Our journal has two main publications, the main journal RMxAA and the Conference Series, RMxAC.
Obituary: Francisco Sánchez Martínez (1936-2025)
Obituary: Francisco Sánchez Martínez (1936-2025) by José Franco.
Copyright (c) 2025 Universidad Nacional Autónoma de México https://creativecommons.org/licenses/by-nc/4.0/
Obituary: Julieta Fierro (1948 - 2025) by Silvia Torres-Peimbert.
Obituary: George F. Smoot (1945-2025) by Omar López-Cruz.
The first 10 years of the HAWC Gamma-Ray Observatory: science results
The High-Altitude Water Cherenkov (HAWC) Observatory, located on the slopes of the Sierra Negra volcano in Mexico, began operations in March 2015. Over the past decade, HAWC has enabled the exploration of a broad range of topics in high-energy astrophysics and particle physics, resulting in more than 90 peer-reviewed publications. These studies have significantly advanced our understanding of several previously unexplored and poorly understood phenomena in the TeV energy regime. The present work provides an overview of the key scientific contributions of HAWC during its first ten years of operation.
Characterization and First Analysis of Three Shallow-Contact Binary Systems
We present a photometric study and characterization of three contact eclipsing binary systems, analyzed using the Wilson-Devinney code in its Python implementation (PyWD2015). Analysis of the CCD-filtered and TESS light curves reveals that two of these systems are totally eclipsing, display starspots and belong to the W-subtype. These systems exhibit good thermal contact with a low degree of overcontact, and their components are consistent with late-type stars. The remaining system is an A-subtype W UMa binary, characterized by a considerable temperature difference between the components (∆T ~2200K) despite a low mass ratio (q = M2/M1). The times of minima derived from our observations, as well as from optical sky surveys, cover sufficient orbital cycles, allowing us to refine their ephemerides and present O-C diagrams fitted with polynomial functions. Additionally, the orbital angular momentum ( J0 ) of each system was calculated, and their positions were plotted on the logM-logL and Temperature-Period diagrams for further comparison.
High-Energy Neutron Enhancements Not Classified as GLEs: A Case Study Using Ground-Based Neutron Monitor Data
During their propagation through the interplanetary medium, cosmic rays interact with solar and interplanetary structures, which can cause fluctuations in their intensity observed at ground level. In this work, we apply a statistical method of overlapping epochs to analyze the effect of solar flares and energetic particle events on the intensity of cosmic radiation, considering periods of low geomagnetic activity and a 24-hour interval before and after the onset of the events. Our objective is to identify possible variations of tiny amplitude, observable simultaneously at different monitoring stations. The results indicate that solar flares, whether accompanied by energetic particle events or not, are not associated with noticeable increases in the cosmic ray intensity. This suggests that small increases may go undetected without specific treatment to highlight subtle variations.
Spectral and Dynamical Study of 12p/Pons-Brooks
We present a spectral and dynamical study of the Halley-type comet 12P/Pons-Brooks (~ 71 year period), confirming its intense cometary activity. We performed an N-body simulation, integrating its orbit for 2×105 years, to analyze its chaoticity and close encounters with Venus, Earth, Mars, Jupiter, and Saturn. The orbit becomes highly chaotic for t < 20×103 years, with significant instabilities arising between 15-20×103 years. We calculate a Lyapunov time of ~ 200 yr.
Theory of Functional Connections Applied to the Temporary Gravitational Capture Problem
This paper presents applications of the Theory of Functional Connections (TFC) for solving problems in celestial mechanics, with a focus on temporary gravitational capture. The univariate TFC framework is employed to solve second-order differential equations. The mathematical formulation for the solution of the two-body problem and the circular restricted three-body problem (CR3BP) through TFC is presented and some differences between the circular and elliptic problems are discussed. The application of TFC to solve the temporary gravitational capture based on the CR3BP, considering backward integration, is presented under different formulations, including inertial and rotating frames, as well as initial and boundary value problems. Error comparisons among these cases are provided and the best strategies for solving the capture problem, depending on the need, are discussed.
Collisions in a System of Conical Jet/Counterjet Outflows
Stars predominantly form in compact, non-hierarchical clusters. The gas outflows ejected by protostars can intersect and interact with each other, resulting in complex interactions that affect the dynamics, morphology, and evolution of these outflows. Determining the probability of an encounter between them requires a Bayesian approach that considers the collimation, length (or age), and separation between young stellar objects in clusters. In this study, we employed a Monte Carlo approach to estimate this probability as a function of the jet opening angle and the ratio between the jet length and separation between stars. We propose a function that predicts the number of interactions within a cluster based on the opening angle of the gas outflows ejected by protostars.
Blade Antenna-SDR System Prototype for the CANTAR Global 21-cm Experiment: Simulations, Measurements, and In-Situ Results
We present the design and initial testing of a low-frequency radio telescope prototype developed for the Colombian Antarctic Telescope for 21-cm Absorption during Reionization (CANTAR) experiment. Operating from 100 to 200 MHz, the system integrates a blade dipole antenna inspired by the EDGES high-band design with a software-defined radio (SDR) receiver. We report simulations of antenna impedance and beam chromaticity, along with SDR performance tests (Limenet Mini, Ettus E310, and USRP2920). A dual-stage low-noise amplifier reduces the system temperature, enabling foreground-sensitive observations. Radiometric estimates suggest that sub-mK sensitivity is achievable with 1000 h of integration. This prototype is part of Colombia's emerging infrastructure for 21-cm cosmology, with deployments planned at low-RFI sites in the Colombian Andes and Antarctica.
Analysis of Spatio-Temporal Changes in Future Artificial Light Pollution and Projections Until 2029 and 2041: A Case Study in the Brazilian States of Roraima, Amazonas, Acre, and Rondônia
This study presents an integrated spatial and temporal analysis of night sky brightness transitions, classified into Bortle classes using the MOLUSCE plugin. Future projections for 2029 and 2041 were generated based on remote sensing data from 2017 and 2020. The results indicate that the “Excellent Sky” and “Typical Dark Sky” classes may decrease by 100% and 56%, respectively, while the “Rural Sky” class could lose approximately 284,679 km2. In contrast, the “Rural-suburban Transition” class is projected to grow by 73%, with smaller increases in the “Suburban”, “Bright Suburban”, “Suburban/urban Transition”, and “Urban Center” classes. The “Urban Center” class shows a steady growth rate of 0.004%. These trends suggest a continued spread of light pollution into rural areas. The results provide valuable input for national and local authorities to anticipate future light-pollution patterns and develop effective mitigation strategies.
Astronomical Site Selection Scenarios for Asia
This study aimed to identify and evaluate suitable areas for astronomical observations in Asia using Geographic Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) methods. Our study provides spatial coverage with satellite-based datasets to determine the ideal astronomical areas in Asia for future telescope construction. These datasets were created by adding a digital elevation model (DEM) and artificial light (AL), along with atmospheric data such as cloud cover (CC), precipitation water vapor content (PWV), aerosol optical density (AOD), and wind speed (WS). The dataset was analyzed using a combination of MCDA and GIS techniques. On the continent, the Tibetan Plateau and its surroundings (except the area around 90° E–35° N) in northern China were identified as the most suitable areas for astronomical studies with radio telescopes. Suitable areas for infrared and optical telescopes are mainly found in the southeast of the Tibetan Plateau (around 83° E–31° N). According to the analysis, an area of 369,096 km2, which corresponds to approximately 0.83% of the continent, is best suited for infrared observations. Approximately 3.87% of the continent, that is, about 1,725,246 km2, is best suited for radio telescopes, while 0.8%, that is, 355,842 km2, is best suited for observations with optical telescopes. The Corona-Borealis Observatory (Ngari) is located in the most ideal location for all three scenarios. The findings of this study are of great importance for future plans for astronomical sites on the continent.
Gaseous Disks in White Dwarfs: Properties of the Current Sample
In recent years, the number of white dwarfs (WDs) known to feature infrared (IR) excesses attributed to circumstellar dust disks has grown significantly. Gaseous disks have also been detected in some WDs with dust. We obtained optical spectra with Gemini/GMOS for 13 WDs exhibiting IR excesses to search for gaseous components. No Ca II emission was detected, suggesting that the gas phase may be short-lived compared to the dusty stage. By combining our data with those from the literature, we compiled the largest sample (to date) of WDs with and without gaseous disks. We found no significant differences in stellar properties between the two groups, although disks with gas may be, on average, brighter. The detection rate of Ca II emission supports the idea that the gas phase persists for only a fraction of the total disk lifetime. A more definitive assessment will likely require dedicated searches for both gas and dust across large WD samples.
Analysis of Telescope-Detector Coupling for a Mid-Infrared Solar Flare Observations Telescope
This study analyzes various optical couplings between an RC telescope and an MIR detector to develop a portable instrument for solar observation. The coupling systems included lenses or mirrors –custom-made and catalog types–, as well as direct coupling analysis. Simulations of the couplings were performed using the Zemax package to estimate the ray dispersion, Airy disk diameter, and PSF. Coupling with catalog lenses shows better performance, and their FOV allows the observation of a region as wide as the solar diameter. Direct coupling provides a higher spatial resolution for resolving smaller solar active regions, although it has a smaller FOV than indirect coupling. Therefore, depending on the observation goal on the Sun, the telescope can operate with either optical coupling configuration to cover a larger or smaller area on the solar disk.
A New Set of Classical-Like Mass Assignment Schemes for Power Spectrum Estimation
In this study, we present the impact of the mass-assignment scheme (MAS) on the estimation of the power spectrum and bispectrum in simulations of structure formation. We used numerical simulations to study the aliasing effect for both power spectrum and bispectrum estimation using the classical MAS, such as Nearest Grid Point, Cloud In Cell, and Triangular Shaped Cloud, to estimate, which of them suffers from a smaller aliasing effect for both small and large scales. We propose a new set of MAS, the NJ1, NJ2, and NJ3 functions, and study its aliasing effect, obtaining an improvement with respect to the classical schemes without the need for additional computational resources. We show that with the newly proposed MAS, we achieve comparable or even better performance in the aliasing of the power spectrum and bispectrum at the expense of a lower computational cost compared to high-order interpolation schemes such as PCS, resulting in an effective improvement in the estimation of the power spectrum and bispectrum.
We present the 2025 release of the spectral synthesis code CLOUDY, highlighting the significant enhancements in the scope and accuracy of the physics that have been made since the previous release. This key development resolves the Lyman-alpha line into j-resolved fine-structure doublets, thereby making CLOUDY useful to the X-ray community. We also updated the inner-shell ionization line energies and incorporated the 1 keV feature that is commonly observed in X-ray binaries. In addition, we updated the Stout database for the carbon isoelectronic sequence, improving the CLOUDY microphysical calculations for all wavelengths. The molecular network has also been extended with new silicon-bearing species, titanium-related reactions, and phosphorus-containing molecules, enhancing CLOUDY’s ability to model the complex chemistry relevant to exoplanet atmospheres. Finally, we outline future developments aimed at maximizing scientific returns from current and upcoming generations of observatories.
Physical Properties of Hii Regions at Sub-kpc Scales Using Integral Field Spectroscopy on IC 342
In this study, we use Integral Field Spectroscopic (IFS) observations for one of the closest galaxies to us, the grand design spiral IC342, to derive the physical properties of Hii regions at sub-kpc scales. To our knowledge, the IFS data represent the most comprehensive observational effort in the optical range for this galaxy. The final IFS datacube consists of 349 individual pointings using IFS instrumentation from the SDSS-IV MaNGA survey. Using a prototype of the data analysis pipeline that will be devoted to the SDSS-V Local Volume Mapper (LVM) survey, we measured different observables from the optical emission line. In particular, using the flux map of the Halpha emission line, we derived the location and size of Hii region candidates for IC342. Using the integrated flux for different emission lines within each region, we derived the radial distribution of different physical properties from the ionized gas (e.g., optical extinction, Halpha luminosity, oxygen abundance, etc.). Compared with larger samples of galaxies with IFS data, our results suggest that the physical properties of the ionized gas of IC342\ are similar to those of galaxies with similar stellar masses in the nearby universe.
We determined the surface lithium abundance of the eclipsing binary components in V 505 Per (HIP 10961) to be $A(Li)$=2.65$\pm$0.07 and 2.35$\pm$0.1, which supports the rather unexpected conclusion that their surface Li abundances differ. We find effective temperatures of 6600 K + 6550 K ($\sim$150 K higher than previously reported), which places the stars at the hot limit of the Lithium Dip, thus alleviating the previously suggested discrepancy with cluster stars of similar ages and temperatures. These temperatures are also more consistent with the system's {\it Gaia} spectral energy distribution. Our iron abundances, $[Fe/H]=-0.15\pm 0.07$ and $-0.25\pm 0.1$, agree with the predictions of the higher temperatures deduced from our spectra and from the evolutionary tracks. The rotation rate implied by our line profiles, 12.5$\pm$1 km\,s$^{-1}$, is smaller than the synchronous rotation rate, which is a curious result given the circular orbit and the age of the system.
Spectroscopic Study of Blue Straggler Stars in the Globular Cluster NGC 3201
We conducted a spectroscopic study of 39 blue straggler stars in the globular cluster NGC~3201. The spectra of these stars have been previously reported. We determined the radial velocity, atmospheric parameters (T$_{eff}$, log $g$), Mg abundance, and metallicity ([Fe/H]) for all sources in the sample. The mean radial velocity and [Fe/H] were determined to be 498.0$\pm$5.3 km/s and -1.42$\pm$0.27, respectively. The derived [Fe/H] is consistent, within uncertainties, with the cluster's [Fe/H] of -1.59 dex. The mean [Mg/Fe] for the sample was estimated to be 0.36$\pm$0.73. Importantly, this study is the first to estimate [Mg/Fe] for blue straggler stars in the cluster NGC~3201.
Espartaco 2, a New Stellar Spectrograph at Universidad de los Andes
We present the construction and early results of ESPARTACO 2, a new stellar spectrograph built for research and education at the Astronomical Observatory of the Universidad de los Andes in Bogotá, Colombia. This instrument offers several resolution modes, from 20,000 in the first order using a 50 $\mu$m fiber, to 100,000 in the second order in the near-infrared. Precise radial-velocity measurements were made possible by simultaneous wavelength calibration. Combined with the 40-cm Meade telescope located at our facilities, a limiting magnitude of 6 was achieved. This instrument represents a significant improvement over its predecessor in terms of throughput, reliability, and ease of use.
Confirmation and Characterization of Galactic Planetary Nebulae: Insights from a Spectroscopic Study
We present a spectroscopic investigation of 25 objects previously reported as possible Planetary Nebulae (PNe) in recent catalogs to obtain their physical properties and establish their true nature. We found 11 objects showing intense emission lines, 11 objects where it was not possible to measure $\mathrm{H{\beta}}$, and 3 objects where no lines were present. We used diagnostic diagrams to confirm the true PN nature of the eight objects. We obtained elemental abundances for the three objects, the values of which are in agreement with the mean PNe values for our Galaxy. Four objects show [\ion{N}{II}] $\lambda$6583 being more intense than $\mathrm{H{\alpha}}$, and for two of them, this can be explained by the presence of shocks in the gas. Finally, we report angular sizes based on $\mathrm{H{\alpha}}$ and [\ion{O}{III}] $\lambda$5007 emission.
Investigating Open Cluster KING 6: Detection of Three New Variables
This study presents a photometric analysis of the intermediate-age open cluster King 6, utilizing photometric data in UBV(RI)c passbands and JHKs from the 2MASS mission. Gaia DR3 kinematic data were used to estimate the membership probabilities, and TESS data were employed to search for variable stars within the cluster. The cluster's radius is estimated to be 9’.0 based on the stellar density profile, while optical and near-infrared color-color diagrams revealed color excesses of E(B-V) = 0.58 +/- 0.03, E(J-K) = 0.24 +/- 0.03, and E(V-K) = 1.53 +/- 0.01 mag. The interstellar extinction law is normal in the direction of the cluster. The cluster$^\prime$s estimated age is $\sim$ 251~Myr and the distance is \(724 +/- 5\) pc. The mass function slope was found to be $x$ = $0.57 +/- 0.28$ by considering stars $\geq$ 1 M$_\odot$. Our analysis indicates that the cluster was dynamically relaxed. Furthermore, we identified three new variable stars for the first time in the cluster region using TESS data. These variables belong to the category of slow-pulsating B-type variables with periods of 46.70, 47.92, and 37.56 h.
Deep-TAO: The Deep Learning Transient Astronomical Object data set for Astronomical Transient Event Classification
We present the Deep-learning Transient Astronomical Object (Deep-TAO), a dataset of 1,249,079 annotated images from the Catalina Real-time Transient Survey, including 3,807 transient and 12,500 non-transient sequences. Deep-TAO has been curated to provide a clean, open-access, and user-friendly resource for benchmarking deep learning models. Deep-TAO covers transient classes such as blazars, active galactic nuclei, cataclysmic variables, supernovae, and events of an indeterminate nature. The dataset is publicly available in FITS format, with Python routines and Jupyter notebooks for easy data manipulation. Using Deep-TAO, a baseline Convolutional Neural Network outperformed traditional random forest classifiers trained on light curves, demonstrating its potential for advancing transient classification.
Asymmetry and Concentration Parameters for Dwarf Late-Type Spiral Galaxies
We analyzed the asymmetry and concentration parameters in a sample of late-type spiral galaxies using V and R broadband images. Asymmetry values were computed for different rotation angles and radii, revealing low asymmetry overall, with smaller values in the inner regions. No preferred angle significantly affected the asymmetry measurements. The concentration indices lie between those of large spirals and irregular galaxies. We compared our sample distribution in the $C{\rm -}A$ plane with other late-type systems (dwarfs and normal spirals). Additionally, we explored the correlations between asymmetry and star formation rate and between concentration and stellar mass, contrasting our results with those of prior studies.
An Oscillating Rastall Universe Crossing the Phantom Divide Line
A cyclic flat universe with Quintom behavior and a future Big Rip as presented in the framework of Rastall gravity, which is an extension of the standard $\Lambda$CDM model. The Hubble parameter oscillates periodically between positive and negative values in each cycle. Cosmic transit has been simulated through an oscillating time-dependent deceleration parameter and is expected to occur at approximately 8.7~Gyr. Causality is satisfied at all times, except near the initial singularity and the future Big Rip singularity. The apparent horizon, entropy, and other thermodynamic quantities associated with the current model were analyzed. The energy conditions were investigated.
Copyright (c) 2025 RMxAA https://creativecommons.org/licenses/by-nc/4.0/
Proper motions of L1551 IRS 5 binary system using 7 mm VLA observations
We analyzed high angular resolution observations of the Very Large Array archive at a wavelength of 7 mm made for the L1551 IRS 5 binary system. Six sets of observations, five with the A configuration and one with the B configuration, were used, covering a time span of about 15 years. With these multi-epoch data, we estimated the absolute and relative proper motions of the binary system, which are about 25.1 mas yr-1 (≈ 16.7 km s-1 considering a distance of 140 pc) and 4.2 mas yr-1, respectively. Finally, based on the relative proper motion, we estimated a total mass for the L1551 IRS 5 binary system of 1.7 M⊙ and an orbital period of 246 years.
Astrophysics - Solar and Stellar Astrophysics
On the Longevity of current epoch Compact Group-like Associations in a ΛCDM Cosmology
The survival time of initially compact associations of galaxy-size dark matter halos, obtained at the present epoch from a series of ΛCDM cosmological simulations, is studied by means of dynamical N-body simulations. The time evolution of such systems from the present epoch up to 5 Gyr into the future is followed. We find that out of 14 initial compact associations only 1 (≈ 10%) suffers a full merger, and the others still have at least two discernible members in such a time span, although they have suffered multiple mergers. Our results support the hypothesis that the majority of current compact galaxy groups will not suffer a complete merger within the next few gigayears, and that some of them (≈ 10%) may even evolve without a single merger. We conclude that no overmerging problem exists in compact groups.
Infrared characteristics of the BIS catalog objects
We studied several color-color infrared diagrams of the 276 late type stars of the BIS catalog. For 95 of these stars we derived spectral classification from our slit spectroscopy. From the 2MASS color diagram we concluded that none of the sample stars is a dwarf. The WISE 3.4-12 vs 12-22 plot is the best to discriminate the variability type (Mira, irregular and not-variable), as well as carbon stars. IRAS colors are less useful due to the poor quality of the data for most of the BIS stars. Mixed plots involving 2MASS, AKARI and WISE were also explored: the 2MASS-AKARI J-[S09] vs [S09]-[L18] plot is efficient to discriminate carbon and Mira stars. From the color plots and our spectroscopy we can statistically predict that in the whole BIS catalog no other dusty carbon star is present, while a few Miras and CH or R carbon stars could be discovered. Only about 15% of the BIS stars are of early M type.
CANICA: The Cananea Near-Infrared Camera at the 2.1 m OAGH Telescope
The Cananea near-infrared camera (CANICA) is an instrument commissioned at the 2.12 m telescope of the Guillermo Haro Astrophysical Observatory (OAGH) located in Cananea, Sonora, México. CANICA operates in the near-infrared at multiple bands including J(1.24 μm), H(1.63 μm) and K' (2.12 μm) broad-bands. CANICA in located at the Ritchey-Chrétien focal plane of the telescope, reimaging the f/12 beam into f/6 beam. The detector is a 1024 × 1024 HgCdTe HAWAII array of 18.5 μm pixel size, covering a field of view of 5.5 × 5.5 arcmin2, for a plate scale of 0.32 arcsec/pixel. The camera is enclosed in a cryostat, cooled with liquid nitrogen to 77 K. The cryostat contains the collimator, two 15-position filter wheels, single fixed reimaging optics and the detector.
We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S II] HST images of the HH 1 jet (covering a period of ≈20 yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in ≈450 yr and at a distance of ≈80'' from the outflow source, close to the present-day position of HH 1.