Revista Mexicana de Astronomía y Astrofísica,
Accepted Papers for Volume 61 Number 1 (ADVANCE ACCESS)

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August 2024

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Abstract: In this work we searched for open clusters in the fields of Star-Forming regions in the Galaxy using the HDBSCAN applied on the astrometric data from the Gaia DR3 catalog. It resulted in the identification of 28 new open clusters, of which the real existence is supported by the membership probability determined from astrometric data and by the presence of cluster sequences in their color-magnitude diagrams, which allowed for a reliable isochrone fit. Of the open clusters identified, 3 are younger than 50 Myr, 19 are of intermediate age, and 6 are old clusters. The clusters have apparent radii ranging from 3 to 20 arcmin. For all clusters, we estimate mean proper motion, mean parallax, and fundamental parameters considering the member stars for each cluster. One of the discovered clusters is at a distance of 10 kpc and has a log(age) ≈ 10.1, making it one of the most distant and oldest cataloged open clusters.

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September 2024

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Abstract: New radial velocity (RV) and light curve (LC) data for the near contact eclipsing binary V878 Her have been simultaneously modeled with the Wilson-Devinney code (WD2003). Two distinct LC datasets were investigated: one was from the Transiting Exoplanet Survey Satellite (TESS) while the others were acquired from the ground-based Mountain Ash Observatory (MAO) in British Columbia, Canada. Supporting spectroscopic data were acquired using the 1.83-m Plaskett Telescope at the Dominion Astrophysical Observatory (DAO) between 2009-2020. Preliminary results from our RV investigations produced values for K₁ (−101.7 ± 4.3 km·s⁻¹), K₂ (219.5 ± 2.4 km·s ⁻¹), V_γ (−34.4 ± 5 km·s ⁻¹), and q_sp (0.464 ± 0.040). Potential progenitors of this near contact binary (NCB) were evaluated using an evolutionary model derived from cool close binaries. It is argued that V878 Her is not in the thermal relaxation oscillation (TRO) phase but, instead, it is a first timer, i.e. in a state of contact binary formation. Its most probable ZAMS progenitor had masses equal to about 1.7 and 0.6 M and the orbital period of about 1.6 days.

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October 2024

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Abstract: The bright high-mass X-ray binary GX 301-2 exhibits two periodic flare episodes along its orbit which are produced when the neutron star is close to the apastron and periastron passages. Time-resolved spectra were extracted and several models applied to describe all of them. The best description was obtained with a blackbody continuum modified by the Fe K-shell absorption edge, absorbed by a large column density on the order of 10²³ cm⁻² and, if present, a Fe Kα fluorescent emission line. Three of the nine apastron flares were as bright as the pre-periastron flare and two of them coincided with spin-up episodes of the neutron star. This fact points to the presence of a transient disc around the neutron star as it passes through the apastron that increases the accretion process. The size of emitting region on the neutron star surface showed some variability but quite consistent with a hot spot.

Abstract: The filtered B, V, R and I light curves of four short period (P < 0.25d) eclipsing binary systems are presented and analysed; two having P ≈ 0.22d, close to the short period limit for contact binaries (CBs). New ephemerides are provided. No third light was found necessary in any case, and one or more spots were introduced to account for asymmetries in the light curves. Two systems belong to the W sub-type of the W-UMa CBs and a third one to the A sub-type of the W-UMa type CBs. The last one is a semi-detached binary with a large temperature difference between the components and a low mass ratio q = 0.191. All components of the binaries are of the K spectral type, and the secondary of the semi-detached binary is of the M spectral type. Absolute parameters of the components were calculated using different evolutionary diagrams. Interestingly, two target have estimated total masses that are smaller than the lower mass limit known for CBs.

Abstract: Spectrum analysis at 3 mm of the central ∼800 pc in radius region of NGC 4303 showed molecular gas lines of both dense gas tracers (HCN, HNC, HCO⁺, and C₂H) and diffuse gases (¹³CO and C¹⁸O). Molecular gas parameters were obtained: the central region molecular hydrogen mass M_{H 2} =(1.75±0.32)×10⁸ M; radial velocity V_dense =178±60 km s⁻¹, and V_CO=151±29 km s⁻¹; HCN luminosity L_HCN=(7.38±1.40)×10⁶K km s⁻¹ pc²; dense gas mass M_dense=(4.7±0.3)×10⁷M_☉, indicating that dense gas contributes significantly to the total molecular gas mass. Dense gas tracers abundance was derived to explore the physical processes that prevail in the nuclear region of NGC 4303. To explore the AGN nature and central dusty torus of the galaxy, CIGALE was used to fit the integrated spectral energy distribution from submillimeter to UV frequencies. Large torus properties are estimated, torus luminosity L_TORUS = (7.1±2.8) ×10⁴³ erg s⁻¹ and line of sight inclination of 67±16^°, which is consistent with a Type 2 AGN; total infrared luminosity L_IR=(3.51±0.30)×10⁴⁴ erg s⁻¹; star formation rate SFR=6.0±0.3 M_☉ yr⁻¹; and found that the AGN contribution is marginal at ∼20%.

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November 2024

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Abstract: One long standing tension between theory and observations of Type I X-ray burst is the accretion rate at which the burst disappear due to stabilization of the nuclear burning that powers them. This is observed to happen at roughly one third of the theoretical expectations. Various solutions have been proposed, the most notable of which is the addition of a yet unknown source of heat in the upper layers of the crust, below the burning envelope. In this paper we ran several simulations using the 1D code MESA to explore the impact of opacity on the threshold mass accretion rate after which the bursts disappear, finding that a higher than expected opacity in the less dense layers near the surface has a stabilizing effect.

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January 2025

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Abstract: This study numerically investigates the dynamics of barred spiral galaxies using 3D Ferrers bar response models. A total of 708 models were analyzed, incorporating variations in the axisymmetric potential (nucleus, bulge, disk, halo), bar length, mass, angular velocity, and disk stellar velocity dispersion. Model evaluation employed the Spearman correlation (to assess input-output relationships) and permutation feature importance in a Random Forest Regressor (to measure input variable impacts). Orbital configurations of test particles reveal the critical role of bar dynamics in shaping galaxies’ morphological and kinematic properties. Key findings emphasize how bar potential influences major orbital families, affecting barred galaxies' long-term structure. These results provide deeper insights into galactic component interactions and a robust framework for understanding bar properties.

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February 2025

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Abstract: We present the results of a low resolution optical spectroscopic observation of Near-Earth Asteroid (NEA) 2018 CB during its close approach to Earth, conducted with the 2.1m telescope of the Guillermo Haro Astrophysical Observatory (OAGH), located in Cananea, Sonora, Mexico, using a Boller & Chivens Spectrograph, with a grating of 50 l/mm that covers the interval between 4000Å and 9500Å. The taxonomic classification was performed using the values of the “spectral distance” (D_x), calculated with respect to the mean spectra of the 24 taxonomic classes of DeMeo et al. (2009), and also with respect to individual asteroid spectra from the Phase II of the Small Main-Belt Asteroid Spectroscopy Survey (SMASSII). We determined that 2018 CB is an Xk-class NEA.

Abstract: The evolution of the H₂O maser emission at the S128 source during 1981-2024 is analized, based on long-term regular observations. The emission from −73 to −70 km/s corresponds mainly to source B, while that of velocities < −76 km/s to source A. It was identified that in the time interval 2004-2006, the maser activity gradually shifted from source B to source A. The active phases of masers B and A lasted approximately 23 and 16 years, respectively. It is assumed that the common cause of the variability of the maser emission at both sources (A and B) can be shock waves that occur near the ionization front. When clouds collide, a disturbance propagates along the resulting ionization front, which leads to the appearance of shock waves. It is shown that the disturbance is spreading in the south-north direction. The star formation process occurs in the same direction.

Abstract: Light pollution, a rapidly escalating anthropogenic phenomenon driven by the excessive and often inefficient use of artificial lighting, has profound implications for astronomy, ecology, and human health. This study presents the first comprehensive characterization of night sky quality in Colombia, focusing on sites of astronomical and ecological significance. The selected locations include the Astronomical Observatory of UTP, the Tatacoa Desert, the Bogotá Botanical Garden, and Cerro Guadalupe. Utilizing the Sky Quality Camera, we collected all-sky data to measure surface brightness and correlated color temperature of the night sky. Our findings reveal a significant loss of natural sky visibility in urban areas and demonstrate the detrimental effects of artificial lighting on critical astronomical sites such as La Tatacoa. This study provides a crucial foundation for future research and informs on the development of public policies aimed at preserving the night sky.

Abstract: The Wedge Double Wollaston (WeDoWo) or "double Wollaston" module is a device capable of displaying four images of a single field of view (FOV); each image corresponds to a different polarization angle (0°, 45°, 90°, and 135°), providing enough information for the Stokes I, Q, and U parameters calculation and the linear polarization angle and fraction values retrieved from the source observed, in this case, an astronomical source, in a single exposure (single-shot). In this paper, we present the design of a SiO2 (Crystalline Silica) WeDoWo module, describe the characterization process carried out in the laboratory and the subsequent calibration. Likewise, we show the application of this module for imaging astronomical polarimetry using the 1.0-meter telescope of the National Astronomical Observatory from Tonantzintla, Puebla (OAN-TNT), and illustrate the advantages and limitations of this technique and the optimal performance of this module.