Showing papers in "Revista Mexicana De Astronomia Y Astrofisica in 2019"
TL;DR: In this article, the authors present a new database of fully radiative shock models calculated with the shock and photoionization code MAPPINGS V. The database architecture is built to contain diverse shock grids comprising of multiple shock parameters.
Abstract: We present a new database of fully radiative shock models calculated with the shock and photoionization code MAPPINGS V. The database architecture is built to contain diverse shock grids comprising of multiple shock parameters. It can be easily accessible through the MySQL protocol. Intensities of spectral lines from infrared to X-rays are stored along with other useful outputs such as the ionic fractions/temperature, integrated densities, etc. A web page was created in other to explore interactively the database as it evolves with time. Examples of its usage is given using the Python language.
12 citations
TL;DR: In this article, the authors compared the metallicity gradients derived from planetary nebulae (PNe) using O, Ne, and Ar abundances and compared to those from H ii regions in the galaxies M 31, M 33, NGC 300 and the Milky Way.
Abstract: Metallicity gradients derived from planetary nebulae (PNe) using O, Ne, and Ar abundances are studied and compared to those from H ii regions in the galaxies M 31, M 33, NGC 300 and the Milky Way. Galactocentric radii and chemical abundances were collected from the literature, carefully selecting a homogeneous sample for each galaxy. Metallicity gradients shown by PNe are flatter than those of H ii regions in all cases. The extreme case is M 31 where PN abundances are not related to galactocentric distances and the gradients are consistent with zero. To analyze the evolution of gradients with time we build gradients for Peimbert Type I and non-Type I PNe finding that Type I PNe show steeper gradients than non-Type I PNe and more similar to the ones of H ii regions indicating that the chemical gradients might steepen with time. Alternatively, the flat gradients for old PNe show that radial migration could have an important role in the evolution of galaxies.
6 citations
6 citations
TL;DR: In this article, the relative importance of the relativistic beaming model (RBM) and the density variation model (DVM) in the understanding of asymmetries in double radio sources, using their lobe separation ratio (Q) and flux density ratio (F).
Abstract: We have studied the comparative importance of the relativistic beaming model (RBM) and the density variation model (DVM) in our understanding of asymmetries in double radio sources, using their lobe separation ratio (Q) and flux density ratio (F). Our result shows an F − Q correlation in the sense expected for the RBM but contrary to the DVM. We attributed the result for the DVM to varying beam power, as its efficiency is density profile-dependent. From the coredominant parameter-linear size R − D relation for the RBM subsample, we found that sources in this subsample are beamed within an optimum cone angle Phi_c≈8°. We posit that relativistic beaming is largely accountable for the observed structural asymmetries in radio sources, though other effects cannot be ruled out.
6 citations
TL;DR: In this article, the authors report the development of a high-time resolution, 3-colour, simultaneous optical imaging system for the 2.1 m telescope in San Pedro M\'artir Observatory, M\'exico.
Abstract: We report the development of a high-time resolution, 3-colour, simultaneous optical imaging system for the 2.1 m telescope in San Pedro M\'artir Observatory, M\'exico. OPTICAM will be equipped with three Andor Zyla 4.2-Plus sCMOS cameras and a set of SDSS filters allowing optical coverage in the 320-1,100 nm range. OPTICAM will nominally allow sub-second exposures. Given its instrumental design, a wide range of fast-variability astrophysical sources can be targeted with OPTICAM including X-ray binaries, pulsating white dwarfs, accreting compact objects, eclipsing binaries and exoplanets. OPTICAM observations will be proprietary for only six months and will then be made publicly available for the astronomical community.
4 citations
TL;DR: In this article, a search and study of IS features in the observed spectra of two novae is presented, and the column densities of Ca II, K I and hydrogen in the direction of Nova V5668 Sgr (log NCa II = 12.50, log NK I = 11.55, log NH = 18.5).
Abstract: We present a search and study of interstellar (IS) absorption features in the observed spectra of two Novae V339 Del and V5668 Sgr. We obtained high resolution spectra (R ≈ 20, 000) in the wavelength range between 3800 and 8800 Å of both novae with the TIGRE telescope. Common IS features of Na I and Ca II were identified in both novae, and the Ca II H and K features of Nova V339 Del show substructures, while a blueshifted absorption feature was found in the spectra of Nova V5668 Sgr. Absorption of K I was identified only in the spectra of Nova V5668 Sgr. The DIBs 6196, 6203, 6379, 6614 and 7562 were found in both novae, and in the spectra of Nova V5668 Sgr we could also identify the DIBs 5780, 5797 and 6660. We present the equivalent widths of all features and determined the column densities of Ca II, K I and hydrogen in the direction of Nova V5668 Sgr (log NCa II = 12.50, log NK I = 11.55, log NH = 18.5).
4 citations
TL;DR: In this paper, a method for the suppression of OH emission lines at near-infrared (NIR) wavelengths by actively adjusting the aperiodic fiber optic Bragg gratings tension was presented.
Abstract: This paper presents the conceptual design for a new method for the suppression of OH emission lines at near-infrared (NIR) wavelengths by actively adjusting the aperiodic fiber optic Bragg gratings tension. First, we prepared an experimental study in which we simulated an OH emission line using a semiconductor laser at 1548.43 nm and a commercial FBG, with a Bragg wavelength of 1547.76 nm. We demonstrated that the grating Bragg wavelength can be adjusted by controlling the linear deformation of the fiber with a force in the range of 0 to 53.88 gf (0.528 N) that provides a sensitivity of 0.014 nm g −1 . Second, we proposed the design of a system connected to the telescope instrumentation, with the different stages that would allow monitoring the suppression of emission lines.
3 citations
TL;DR: In this paper, the authors presented the results of a fourth order perturbation analysis of the metric theory of gravity, where the mass of the system is included into the gravitational field's action.
Abstract: In this article, we present the results of a fourth order perturbation analysis of the metric theory of gravity $f(\chi) = \chi^{3/2}$, with $\chi$ a suitable dimensionless Ricci scalar. Such model corresponds to a specific $f(R)$ metric theory of gravity, where the mass of the system is included into the gravitational field's action. In previous works we have shown that, up to the second order in perturbations, this theory reproduces flat rotation curves of galaxies and the details of the gravitational lensing in individual, groups and clusters of galaxies. Here, leaving fixed the results from our previous works, we show that the theory reproduces the dynamical masses of 12 Chandra X-ray galaxy clusters, without the need of dark matter, through the metric coefficients up to the fourth order of approximation. In this sense, we calculate the first relativistic correction of the $f(\chi)$ metric theory and apply it to fit the dynamical masses of the clusters of galaxies.
3 citations
TL;DR: An exact solution for the spatially flat scale-invariant cosmology, recently proposed by Maeder (2017), was deduced in this article, which yields transparency for the dynamical equations and faster cosmological constraints may be performed.
Abstract: An exact solution for the spatially flat scale-invariant Cosmology, recently proposed by Maeder (2017) is deduced. No deviation from the numerical solution was detected. The exact solution yields transparency for the dynamical equations and faster cosmological constraints may be performed.
3 citations
TL;DR: The first multicolor observations, and light curve solutions, of the eclipsing binary systems V1009~Per and CRTS~J031642.2+332639 are presented in this article.
Abstract: The first multicolor observations, and light curve solutions, of the eclipsing binary systems V1009~Per and CRTS~J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact binaries. V1009~Per has a mass ratio of $q = 0.362 \pm 0.002$ and a shallow fill out parameter of $f = 11.8 \pm 0.6\%$ while CRTS~J031642.2+332639 has a mass ratio of $q=2.507 \pm0.006$ and a fill out of $f= 13.6 \pm0.4\%$. High orbital inclinations, $i = 85^\circ.9$ for V1009 Per and $i = 83^\circ.2$ for CRTS~J031642.2+332639, implies that both systems are total eclipsing binaries and that the photometric parameters here obtained are reliable. Based on 16 times of minimum, the orbital period variations of V1009~Per are discussed.
%The estimated physical parameters of V1009 Per are $M_1 = 0.874M_\odot, M_2 = 0.317M_\odot, R_1 = 0.865R_\odot, R_2 = 0.474R_\odot, L_1 = 0.521L_\odot, L_2 = 0.153L_\odot$. For CRTS J031642.2+332639, the physical parameters are $M_1 = 1.037M_\odot, M_2 = 0.414M_\odot, R_1 = 1.002R_\odot, R_2 = 0.661R_\odot, L_1 = 0.770L_\odot, L_2 = 0.370L_\odot$.
The absolute dimensions of the systems are estimated and, from the logM-logL diagram, it is found that both components of the systems follow the general pattern of the W subtype W Ursae Majoris systems.
3 citations
TL;DR: Using uvby − β photoelectric photometry obtained with the 0.84 m telescope of the Observatorio Astro-nomico Nacional de San Pedro Mañrtir, Mexico as mentioned in this paper, the authors determined some of the physical characteristics of the high amplitude Delta Scuti star V2455 Cyg (HD 204615).
Abstract: Using uvby − β photoelectric photometry obtained with the 0.84 m telescope of the Observatorio Astrónomico Nacional de San Pedro Mártir, México, we determined some of the physical characteristics, such as effective temperature and surface gravity of the high amplitude Delta Scuti star V2455 Cyg (=HD 204615). Newly determined times of maximum light gathered at the Observatorio Astrónomico Nacional de Tonantzintla, México with small 10 inch telescopes equipped with CCD cameras were combined with times of maxima in the literature, and used to study the secular variation of the pulsational period of the star.
TL;DR: In this article, the authors carried out multi-wavelength followup observations of a blue optical transient during its 2017 outburst using Swift and RATIR and found that the source was ∼>4.4 mag above its quiescent level during the peak of the outburst and the outburst lasted ∼>19 days.
Abstract: MASTER OT 075353.88+174907.6 was a blue optical transient reported by the MASTER-Net project on 2017 Oct 31. We carried out multiwavelength followup observations of this source during its 2017 outburst using Swift and RATIR. The source was found to be ∼>4.4 mag above its quiescent level during the peak of the outburst and the outburst lasted ∼>19 days. Our observations suggest that it was a superoutburst of a long period U Geminorum type dwarf nova system. The spectral energy distribution during the initial slow decay phase of the outburst was consistent with a disk-dominated spectrum (with spectral indices Γ ≈1.5–2.3). Afterwards, the UV flux decreased slowlier than the optical and the spectral energy distribution was very steep with indices Γ ≈3.7 ±0.7. This slow UV decay may be the emission from a cooling white dwarf heated during the outburst. No X-ray emission was detected from the source since it is likely located at a large distance >2.3 kpc.
TL;DR: In this paper, the enhancement function of the gravitational lensing of gravitational waves by galactic dark matter halos was studied and compared with an isothermal sphere with an NFW type density distribution, both of which are assumed to be spherically symmetric.
Abstract: The recent success of the dark matter model has proven to be an invaluable tool for describing the formation, evolution and stability of galaxies. In this work we study the enhancement function, F , of the gravitational lensing of gravitational waves by galactic dark matter halos and show how this function may be used to distinguish between halo models. In particular we compare an isothermal sphere with an NFW type density distribution, both of which are assumed to be spherically symmetric, and find that our technique clearly distinguishes between the models.
TL;DR: Vazzano et al. as mentioned in this paper presented the work of the Instituto Argentino de Radioastronomia (IRA) and the Consejo Nacional de Investigaciones Cientificas y Tecnicas.
Abstract: Fil: Vazzano, Maria Mercedes. Provincia de Buenos Aires. Gobernacion. Comision de Investigaciones Cientificas. Instituto Argentino de Radioastronomia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina
TL;DR: Iturbide et al. this article presented Reyes Iturbide, J. et al., this article, who presented a method for the identification of the structure of the human brain.
Abstract: Fil: Reyes Iturbide, J.. Universidad Nacional Autonoma de Mexico. Instituto de Ciencias Nucleares; Mexico. Tecnologico de Estudios Superiores de Tianguistenco; Mexico
TL;DR: In this paper, the authors presented spectroscopic orbits of three binary stars, HD 121212, HD 148434 and HD 148912, with evolved primaries and periods of order a year, found in a survey of late-type stars listed in the Supplement to the Yale Bright Star Catalog.
Abstract: This paper presents spectroscopic orbits of three binaries, HD 121212, HD 148434 and HD 148912, with evolved primaries and periods of order a year, found in a survey of late-type stars listed in the Supplement to the Yale Bright Star Catalog. All the orbits were determined from observations made with the DAO 1.2-m telescope and coudé spectrograph. Observations were obtained using the radial velocity spectrometer until it was decommissioned in 2004, and since then using a CCD detector and cross-correlating the spectra with those of standard stars.
TL;DR: In this paper, an in-depth photometric study of the 2013 superoutburst of the recently discovered cataclysmic variable V1838 Aql and subsequent photometry near its quiescent state is presented.
Abstract: We present an in-depth photometric study of the 2013 superoutburst of the recently discovered cataclysmic variable V1838 Aql and subsequent photometry near its quiescent state. A careful examination of the development of the superhumps is presented. Our best determination of the orbital period is Porb=0.05698(9) days, based on the periodicity of early superhumps. Comparing the superhump periods at stages A and B with the early superhump value we derive a period excess of ɛ=0.024(2) and a mass ratio of q=0.10(1). We suggest that V1838 Aql is approaching the orbital period minimum and thus has a low-mass star as a donor instead of a substellar object.
TL;DR: In this paper, the authors presented two methods of immediate transfer and another with wait time to minimize the fuel consumption in orbit transfers, where a spacecraft performs a change from an orbit around the Earth to another one around a different celestial body.
Abstract: Minimizing fuel consumption in space travels is becoming increasingly important for spatial development. In the present paper, the fuel consumption in orbit transfers (without gravitational assistance) is minimized, where a spacecraft performs a change from an orbit around the Earth to another one around a different celestial body. Two methods are presented: one of immediate transfer and another with wait time. Minimizing is done by solving a nonlinear system, obtained by applying Lagrange multipliers to the equation modelling the keplerian system, and using the seeds coming from the particle swarm algorithm to execute the Newton’s method. Numerical simulations with real values were made to compare these methods with the Hohmann transfer and data from the specialized literature.
TL;DR: In this article, the authors search for transfers from the Earth to three of the Kuiper Belt Objects (KBO): Haumea, Makemake, and Quaoar) by searching for the minimum total ∆V transfer for a given launch window.
Abstract: The present paper searches for transfers from the Earth to three of the Kuiper Belt Objects (KBO): Haumea, Makemake, and Quaoar. These trajectories are obtained considering different possibilities of intermediate planet gravity assists. The model is based on the “patched-conics” approach. The best trajectories are found by searching for the minimum total ∆V transfer for a given launch window, inside the 2023-2034 interval, and disregarding the ∆V required for the capture at the target object. The results show transfers with duration below 20 years that spend a total ∆ V under 10 km/s. There is also one trajectory for each of the KBOs with ∆V under 10 km/s and duration below 10 years, using the Jupiter swingby. For the 20-year trajectories, there are also asteroids in the main belt that could be encountered with low additional ∆V , so increasing the scientific return of the mission.
TL;DR: In this article, the authors explore the impact of extreme red supergiant mass-loss on stellar evolution and on their circumstellar medium, and find that stars with extreme mass loss in the RSG phase behave as larger mass stars.
Abstract: In this work, we present models of massive stars between 15 and 23 M⊙ , with enhanced mass loss rates during the red supergiant phase. Our aim is to explore the impact of extreme red supergiant mass-loss on stellar evolution and on their circumstellar medium. We computed a set of numerical experiments, on the evolution of single stars with initial masses of 15, 18, 20 and, 23 M⊙ , and solar composition (Z = 0.014), using the numerical stellar code BEC. From these evolutionary models, we obtained time-dependent stellar wind parameters, that were used explicitly as inner boundary conditions in the hydrodynamical code ZEUS-3D, which simulates the gas dynamics in the circumstellar medium (CSM), thus coupling the stellar evolution to the dynamics of the CSM. We found that stars with extreme mass loss in the RSG phase behave as a larger mass stars.
TL;DR: In this article, the photometry obtained in the present work has been combined with data from previous studies to examine the brightest stars in the direction of the cluster, and they found that all the stars are of late spectral types.
Abstract: The open cluster Upgren 1 presents peculiar features that in the past led to divergent opinions about its existence. In previous studies of other clusters, uvby − β photoelectric photometry has shown results in agreement with other techniques; therefore, the photometry obtained in the present work has been combined with data from previous studies to examine the brightest stars in the direction of the cluster. Analyzing the unreddened indexes, we found that all the stars are of late spectral types. Applying the empirical relations of Nissen (1987) to determine the reddening and, consequently, the unreddened indexes, we found that all but three are located at a distance of 123 ± 17 pc. The assigned membership in this study is in concordance with that of Upgren, Philip and Beaver (1982) obtained through radial velocities.
TL;DR: In this paper, a numerical search is performed to find and classify mid-range natural orbits around Deimos that are dominated by Mars, using the idea of quasi satellite orbits (QSO).
Abstract: In this paper we search for mid-range planar orbits for a spacecraft traveling in the neighborhood of Deimos. The first task is to perform a numerical search to find and classify mid-range natural orbits around Deimos that are dominated by Mars, using the idea of “Quasi Satellite Orbits” (QSO). The influence of the eccentricity of the orbit of Deimos around Mars and the irregular shape of Mars are considered in the mathematical model, allowing an assessment of their importance. Our approach uses two different initial positions for Deimos in its orbit around Mars, at apoapsis and periapsis. The minimum, maximum, and average Deimos-spacecraft distances are also obtained.
TL;DR: In this paper, the authors explore the idea that substructures like stellar clusters could be formed from the tidal stream produced in galactic minor mergers, and they use N -body and SPH simulations of satellite galaxies interacting with a larger galaxy.
Abstract: In this work, we explore the idea that substructures like stellar clusters could be formed from the tidal stream produced in galactic minor mergers. We use N -body and SPH simulations of satellite galaxies interacting with a larger galaxy. We study the distribution of mass in streams to identify overdensity regions in which a substructure could be formed. We find that without gas, no substructure forms as none of the overdensities shows a definite morphology nor dynamical stability. Including gas we find that several clumps appear and prove to be real long standing physical structures (t ≥ 1 Gyr). We analyze the orbits, ages and masses of these structures, finding their correspondence with the halo subsystems. We conclude that it is possible to form cluster-like structures from the material in tidal streams and find evidence in favour of the presence of dark matter in these systems.
TL;DR: In this paper, the projected linear size, (D) as an orientation parameter, the armlength ratio, (Q) and the lobe-luminosity ratio (R) as asymmetry parameters were used to test the FR-II galaxies (Gs) and radio-loud quasar (Qs) unification scheme.
Abstract: Using the projected linear size, (D) as an orientation parameter, the armlength ratio, (Q) and the lobe-luminosity ratio, (R) as asymmetry parameters, we test the FR-II galaxies (Gs) and radio-loud quasar (Qs) unification scheme. Using the median values of our binned sample, our results, generally indicate that the D of the radio sources are smaller at higher redshifts z and at larger Q values, with the D of Qs smaller than those of Gs across all Q, z and R bins. Also, the D of Gs appear smaller for lower values of Q, if R ≤ 1.0 but become larger at higher values of Q if R > 1.0. For Qs, the D decreases with increasing Q, R and z. These results imply that the beaming effect is more important in Qs than in Gs. The D − R regression analyses for different Q and z subsamples suggest the importance of factors other than beaming and orientation in the interpretation of the evolution of these radio sources.
TL;DR: In this article, the authors constructed a LRG (Luminous Red Galaxy) sample with redshifts 0.6 ≤ z ≤ 0.75 from the Sloan Digital Sky Survey Data Release 15 (SDSS DR15), which contains 184172 CMASS LRGs and 27158 eBOSS LRGs, and examined the environmental dependence of galaxy age and stellar mass in this galaxy sample.
Abstract: In this work, I construct a LRG (Luminous Red Galaxy) sample with redshifts 0.6 ≤ z ≤ 0.75 from the Sloan Digital Sky Survey Data Release 15 (SDSS DR15), which contains 184172 CMASS LRGs and 27158 eBOSS LRGs, and examine the environmental dependence of galaxy age and stellar mass in this galaxy sample. I divide this LRG sample into subsamples with a redshift binning size of ∆z = 0.01, and analyze the environmental dependence of galaxy age and stellar mass for these subsamples in each redshift bin. Overall, galaxy age and stellar mass in the LRG sample with redshift 0.6 ≤ z ≤ 0.75 are very weakly correlated with the local environment, which shows that minimal environmental dependence of galaxy parameters can continue to larger redshifts.
TL;DR: In this paper, the influence of the bar, its pattern speed (Ω_b) and its rate of growth on the stability of the orbits in gravitational potentials was investigated.
Abstract: This paper aims to verify the influence of the bar, its pattern speed (Ω_b) and its rate of growth on the stability of the orbits in gravitational potentials. We studied the nature of the orbits in potentials representing galaxies with growing bars, where a linear growth was assumed. In order to study the stability of the orbits we applied SALI. We studied six models in which the bar dimensions were fixed, but we varied their pattern speed and time of bar growth. We found that when the bar growth is faster, more chaos is generated and we also noted that the higher the Ω_b, the greater its influence on the system dynamics. The initial positions of the orbits that became chaotic were located in a well-defined ring-like region, confined between the ILR and CR resonances. There was also an indication that the retrograde orbits, although much scarcer, are more conductive to chaos when they do exist.
TL;DR: In this paper, the authors derived recombination line profile shapes for ionized spherical stellar winds at radio wavelengths, assuming that the free-free photosphere forms in the outer, constant expansion portion of the wind.
Abstract: Recombination line profile shapes are derived for ionized spherical stellar winds at radio wavelengths. It is assumed that the wind is optically thick owing to free-free opacity. Emission lines of arbitrary optical depth are obtained assuming that the free-free photosphere forms in the outer, constant expansion portion of the wind. Previous works have derived analytic results for isothermal winds when the line and continuum source functions are equal. Here, semi-analytic results are derived for when the source functions are not equal to reveal that line shapes can be asymmetric about line center. A parameter study is presented and applications discussed.
TL;DR: In this paper, a mid infrared (MIR) solar telescope, centered at 10 µm, was developed based on computer simulations and a RitcheyChretien 6-inches telescope was selected with a plate scale of 2.5′/mm using a pyroelectric 4 × 16 pixels detector.
Abstract: We developed a mid infrared (MIR) solar telescope, centered at 10 µm. Various optical layouts were analyzed based on computer simulations and a RitcheyChretien 6-inches telescope was selected with a plate scale of 2.5′′/mm using a pyroelectric 4 × 16 pixels detector. The angular resolution is 36′′/pixel with a field of view of 9.6′×2.4′. Two germanium filters are used, one at the aperture of thetelescope and another near its focal plane. The detector was characterized with alaboratory black-body. The count values follow a linear relation with the blackbody temperature. The control systems for both the telescope and the detectorwere developed. Proper mechanical supports were designed for the filters, detectorand electronics. The system has been integrated and a user interface was developed. Preliminary observations have been made giving a signal-to-noise ratio of ≈ 1000.
TL;DR: In this paper, the spectral types of the stars in the direction of the open cluster NGC 1528 were determined from the uvby − β photoelectric photometry of sixty-five stars.
Abstract: uvby − β photoelectric photometry of sixty-five stars in the direction of the open cluster NGC 1528 is presented. From the uvby − β photometry of the cluster we classified the spectral types of the stars which allowed us to determine the reddening (E(b-y) of 0.196 ± 0.054) and hence, their distance, in parsecs, of (954 ± 154). We determined membership of the stars to the cluster and the age (Log age equal 8.04) of the cluster. A metallicity [Fe/H] of −0.31 ± 0.08 was calculated.