arXiv subjects

A. Rodríguez-González

Publications and source records attributed to A. Rodríguez-González.

13 recordsLinked to original sources

arXiv2026

Characterization of molecular outflows at core-scale in the massive clump AGAL G345.0029-0.224

High-mass stars, with their powerful winds and intense radiation fields, are fundamental in regulating galactic dynamics and evolution; however, despite their great relevance, the mechanisms involved in their formation are still not fully understood. In this context, molecular outflows, which are essential for removing angular momentum and allowing accretion onto the central object, are a crucial phenomenon for characterizing their formation. Previous studies reveal a discrepancy in the masses of outflows associated with high-mass clumps between works conducted at the clump scale ($\sim$ pc) and those at the core scale ($\sim$ subpc). This suggests that the high-mass outflow activity observed at the clump scale might be the result of the contribution from several lower-mass outflows linked to individual molecular cores. This work presents a study of the molecular gas toward a high-mass clump associated with an Extended Green Object (EGO). EGOs are indicators of jets associated with high-mass protostars. Employing high angular resolution data from the Atacama Large Millimeter/submillimeter Array (ALMA), the presence of several hot cores with outflow activity was observed in the source. A characterization of the outflows at the core scale is presented within the context of the physical parameters of the molecular clumps.

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arXiv2025

Outflow Interaction in Cep-E: Numerical Simulation and Observational Manifestation

There is clear observational evidence that the main Class 0/I stages of the star formation process are associated with powerful collimated outflows (jets), which sometimes propagate up to distances as large as $10^{4-5}$ au scales in molecular clouds. Additionally, intermediate high-mass and low-mass protostars have often been observed to form in crowded clusters, where the typical separation distance between any two cluster members is of the same order or smaller than the scale of the outflow length. Therefore, there must be an interaction between the molecular outflows of different protostars within the protostellar association. A good example of this is the case of Cepheus E-mm, which is a protostellar outflow extending over a few dozen au. At its core is a binary system consisting of two protostars, Cep E-A and Cep E-B, separated by about 1000 au. Both protostars eject molecular jets at velocities of ~100 km/s. The interaction between these molecular outflows provides an opportunity to study the effects of jet collisions in a clustered star-forming environment, as they may leave detectable imprints on the morphology of the main envelope of the system. Our work aims to study the effects of the collision of molecular jets associated with the components of the binary system Cep-A and Cep-E, analyzing the disruption or reduction of molecular emission in the main envelope of the system, which the molecular outflow { launched} by Cep-A presumably pushes. If we characterize the collision in this system, we can provide insights into the expected morphology and molecular emissions in collisions of molecular outflows { associated to star forming process.

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arXiv2025

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 the clusters. In this study, we employ a Monte Carlo approach to estimate this probability as a function of the jet opening angle and the ratio between the jet length and the 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.

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arXiv2025

A ring-shaped starburst as a galactic wind-generating mechanism: Morphology, emission, and mass ejection

Star formation bursts promote the ejection of material from the hosting galaxies due to the momentum and energy injected by winds from massive stars and supernova explosions. Numerical or analytical models generally consider that the mass, momentum, and energy injections result from bursts in a nuclear star formation region. However, star formation bursts have recently been observed in ring-like regions in the nuclear part of the galaxies. One example is NGC 253, which has shown a central toroidal burst and an asymmetric galactic wind observed in thermal X-ray emission. The general aim of this work is to study the effect of mechanical energy injection from stellar winds and supernova explosions in star-forming bursts distributed in rings around the nucleus of the galaxy NGC 253. Additionally, these partial objectives allow us to analyze the asymmetry of the outflows due to the bursts position as well as to study the formation of filaments with optical emission and make comparisons with recent observations of galaxies with these types of star-forming bursts. We used the hydrodynamic code AMRVAC to simulate galactic wind ejection coming from a central ring-like starburst located at different vertical positions. We showed that including a ring-shaped starburst (RSS) generates a more complex structured wind than what would be expected for a spherical starburst injection. Besides the interaction between the wind generated by the RSS and the host galaxy, it can generate dense filamentary structures with H alpha emission. The mass flux analysis of our models shows that the variation in the vertical position of the starburst can generate a variation in the mass flux of each lobe of the wind up to an order of magnitude. However, this difference is sustained only for a short period, with the flux tending to be symmetrical once it enters into a free-wind solution.

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arXiv2025

Unveiling the collision between molecular outflows: observational evidence and hydrodynamic simulations

We present an unexplored scenario for interpreting the outflows in the EGO G338.92+0.55 (b) region (hereafter, EGO G338). Within this framework, we investigate the hypothesis that the interaction between two outflows is responsible for the observed morphology and kinematics of this astrophysical object. To explore this possibility, we reanalyse the region using observational molecular line data. We base our analysis on maps of moments 0, 1, and 2 of the CO emission associated with the molecular outflows. Additionally, we conduct three-dimensional hydrodynamic simulations to examine the presence or absence of a collision between two jets. From our numerical results, we produce synthetic CO images to facilitate a direct comparison with observations. The findings of this study provide compelling evidence that the observed morphology and kinematics in the EGO G338 region are the result of a likely collision between two molecular outflows.

astro-ph.GA↗

arXiv2021

Two-wind interactions in binaries with two orbiting giant stars

Some red giant envelopes present spiral structures (seen either in dust scattered stellar continuum or in molecular line emission), the most striking example probably being AFGL 3068. This object has been modeled (both analytically and numerically) in terms of a wind ejected from a star in orbit around a binary companion. We revisit both analytical models and 3D simulations of a wind from an orbiting red giant star, and extend the numerical simulations to the case of a binary with two red giants with strong winds. We find that most two-wind models on the orbital plane show a "double spiral" structure close to the binary source, and that these two arms merge into a single spiral structure at larger distances. However, for the case of a binary with two identical winds the two spiral arms are still present at large distances from the binary source. We also find that for models of two (not identical) dynamically important winds, a region close to the orbital plane has material from both winds. Also, an approximately conical region centered on the orbital axis is filled exclusively by the wind with larger momentum rate. These two structures lead to morphologies reminiscent of the so-called "hour glass" planetary nebulae. Finally, we find that increasing wind velocity disparities lead to the formation of clumpy structures along the spiral amrs. Observations of "clumpy spirals" are therefore likely to indicate the presence of two strong winds from the stars in the central binary system.

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arXiv2021

Estimating the propagation of a uniformly accelerated jet

We study the problem of a Herbig-Haro jet with a uniformly accelerating ejection velocity, travelling into a uniform environment. For the ejection density we consider two cases: a time-independent density, and a time-independent mass loss rate. For these two cases, we obtain analytic solutions for the motion of the jet head using a ram-pressure balance and a center of mass equation of motion. We also compute axisymmetric numerical simulations of the same flow, and compare the time-dependent positions of the leading working surface shocks with the predictions of the two analytic models. We find that if the jet is over-dense and over-pressured (with respect to the environment) during its evolution, a good agreement is obtained with the analytic models, with the flow initially following the center of mass analytic solution, and (for the constant ejection density case) at later times approaching the ram-pressure balance solution.

astro-ph.SR↗

arXiv2021

Velocity segregation in a clump-like outflow with a non-top hat velocity cross-section

High velocity clumps joined to the outflow source by emission with a "Hubble law" ramp of linearly increasing radial velocity vs. distance are observed in some planetary nebulae and in some outflows in star formation regions. We propose a simple model in which a "clump" is ejected from a source over a period $τ_0$, with a strong axis to edge velocity stratification. This non-top hat cross section results in the production of a highly curved working surface (initially being pushed by the ejected material, and later coasting along due to its inertia). From both analytic models and numerical simulations we find that this working surface has a linear velocity vs. position ramp, and therefore reproduces in a qualitative way the "Hubble law clumps" in planetary nebulae and outflows from young stars.

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arXiv2019

Numerical models for the dust in RCW 120

The interstellar bubble RCW 120 seen around a type O runaway star is driven by the stellar wind and the ionising radiation emitted by the star. The boundary between the stellar wind and interstellar medium (ISM) is associated with the arc-shaped mid-infrared dust emission around the star within the HII region.

astro-ph.GA↗

arXiv2016

The metallic winds in dwarf galaxies

We present results from models of galactic winds driven by energy injected from nuclear (at the galactic center) and non-nuclear starbursts. The total energy of the starburst is provided by very massive young stellar clusters,which can push the galactic interstellar medium and produce an important outflow. Such outflow can be a well, or partially mixed wind, or a highly metallic wind. We have performed adiabatic 3D N-Body/Smooth Particle Hydrodynamics simulations of galactic winds using the GADGET-2 code. The numerical models cover a wide range of parameters, varying the galaxy concentration index, gas fraction of the galactic disk, and radial distance of the starburst. We show that an off-center starburst in dwarf galaxies is the most effective mechanism to produce a significant loss of metals (material from the starburst itself). At the same time a non-nuclear starburst produce a high efficiency of metal loss, in spite of having a moderate to low mass loss rate.

astro-ph.GA↗

arXiv2014

A two-mode planetary nebula luminosity function

We propose a new Planetary Nebula Luminosity Function (PNLF) that includes two populations in the distribution. Our PNLF is a direct extension of the canonical function proposed by Jacoby et al. (1987), in order to avoid problems related with the histogram construction, it is cast in terms of cumulative functions. We are interested in recovering the shape of the faint part of the PNLF in a consistent manner, for galaxies with and without a dip in their PN luminosity functions. The parameters for the two mode PNLF are obtained with a genetic algorithm, which obtains a best fit to the PNLF varying all of the parameters simultaneously in a broad parameter space. We explore a sample of 9 galaxies with various Hubble types and construct their PNLF. All of the irregular galaxies, except one, are found to be consistent with a two-mode population, while the situation is less clear for ellipticals and spirals.For the case of NGC\, 6822, we show that the two-mode PNLF is consistent with previous studies of the star formation history within that galaxy. Our results support two episodes of star formation, in which the latter is significantly stronger.

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arXiv2011

The cometary cavity created by an aligned streaming environment/collimated outflow interaction

We present a "thin shell" model of the interaction of a biconical outflow and a streaming environment (aligned with the direction of the flow), as well as numerical (axisymmetric) simulations of such an interaction. A similar situation, although in a more complex setup, takes place at the head of the cometary structure of Mira. Thus, for most of the numerical simulations we explore parameters consistent with the observed bipolar outflow from Mira B. For these parameters, the interaction is non-radiative, so that a rather broad jet/streaming environment interaction region is formed. In spite of this, a reasonable agreement between the thin-shell analytic model and the numerical simulations is obtained.

astro-ph.HE↗

arXiv2008

A latitude-dependent wind model for Mira's cometary head

We present a 3D numerical simulation of the recently discovered cometary structure produced as Mira travels through the galactic ISM. In our simulation, we consider that Mira ejects a steady, latitude-dependent wind, which interacts with a homogeneous, streaming environment. The axisymmetry of the problem is broken by the lack of alignment between the direction of the relative motion of the environment and the polar axis of the latitude-dependent wind. With this model, we are able to produce a cometary head with a ``double bow shock'' which agrees well with the structure of the head of Mira's comet. We therefore conclude that a time-dependence in the ejected wind is not required for reproducing the observed double bow shock.

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