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Hyperreduced-order modeling of thermally coupled flows
(ELSEVIER SCIENCE INC, 01-01-2024) Espinoza-Contreras Nicolas, Bayona-Roa Camilo, Castillo Ernesto, Gandara Tomas, Moraga Nelson O.
This article presents a full and reduced-order methodology based on the finite element method that allows the characterization of convective-dominant conjugate heat transfer flows. Reduced-order modeling (ROM) allows the description of several degrees of freedom problems, referred to as full-order modeling (FOM), through a reduced-order surrogate representation based on a Petrov-Galerkin projection onto a reduced subspace. The FOM and ROM problems are stabilized through the Variational Multi-Scale (VMS) method, which ensures stability in dominant convective problems and allows equal interpolation spaces for the pressure, velocity, and temperature. The proposed methodology is validated solving natural heat convection in a differentially heated square cavity, considering air as the working fluid and Rayleigh numbers in the interval 10(4) <= Ra <= 10(8). In this problem, the benefit of using a ROM approximation for the three unknown fields, i.e., velocity, pressure, and temperature, is compared against ROM approximation only in the velocity and pressure fields and a FOM type approximation for temperature. The benefit of using mesh-based hyperreduction and its computational performance and precision are also analyzed. Subsequently, the method simulates a conjugate heat transfer problem that includes natural heat convection, allowing the inclusion of different rheologies between the working fluids. The results verify the precision and speed up of the calculations by more than three hundred times with respect to the time necessary to solve a full-order formulation, emerging it as a great potential tool in the resolution of thermally coupled flows.
ALUMINUM RECOVERY FROM MINE TAILINGS, APPLYING INNOVATIVE CHEMICAL AND BIOLOGICAL PROCESSES
(EXECUTIVE BUSINESS SCH-EXEBS, 01-06-2023) Zamarreno-Bastias Ricardo, Espinoza-Barrera Javiera
An investigation was carried out, at the chemical -metallurgical laboratory level, evaluating two methods in the recovery of aluminum, present in an abandoned mining tailing. In order to find a new source of recovery for this element. Aluminum is found in the form of aluminosilicates in the tailings. Two methods were used, a biological process and a chemical one. In the biological one, bioleaching was carried out with cultivated Aspergillus niger fungi, which produces organic acids, which can extract aluminum from the tailings. The chemical method consisted of leaching with two organic acids, citric acid and oxalic acid with the addition of oxidizing agents such as hydrogen peroxide and a strong base. According to the results, the methods that had the highest extraction were chemical, specifically leaching with the mixture of oxalic acid and hydrogen peroxide. In the case of bioleaching, no significant results were obtained in the extraction of aluminum.
Analytical Hierarchical Process to Establish the Criteria for Choosing Explosives Suppliers in Small and Medium Mining Companies
(MDPI, 01-09-2023) Ramirez Olivares Edison, Castillo-Vergara Mauricio
Mining plays a pivotal role in economies worldwide, contributing to employment, infrastructure, and the supply of essential raw materials. Chile's global mining powerhouse, particularly in copper production, exemplifies this industry's economic significance. The supplier selection process in the mining industry, a complex and multifaceted task, is explored in detail, specifically focusing on explosives procurement, a critical component for mineral extraction. The paper underscores the importance of informed supplier selection decisions, especially for SMEs, which often need more resources and capabilities for efficient management. To address these challenges, the study proposes applying the Analytic Hierarchical Process (AHP), a multi-criteria decision-making methodology, to identify and prioritize the criteria and sub-criteria pertinent to choosing explosives suppliers. A case study in the Coquimbo Region, Chile, involving SMEs in the mining sector is the empirical foundation for this research. Our research highlights that the foremost criterion for SMEs in the Coquimbo Region's mining sector is relationship with the environment and communities. This reflects the national context of mining community tensions and the rising environmental standards and social expectations, which can profoundly impact mining operations. Quality of products and services is the second most crucial criterion, underscoring SMEs' drive to enhance productivity and efficiency. Contractual compliance follows closely, signifying the integration of SMEs into broader social and environmental sustainability efforts. Conversely, innovation ranks as the least relevant criterion, indicating that SMEs prioritize traditional processes due to limited resources and cost constraints. These insights are valuable for mining supplier company managers, emphasizing the need for sustainability, corporate social responsibility, and management control systems.
Augmented reality and education in electronics: Relationship between usability, academic performance, and emotions experienced in learning
(WILEY, 01-11-2023) Alvarez-Marin Alejandro, Paredes-Velasco Maximiliano, Velazquez-Iturbide J. Angel, Poblete-Castro Julio C. C.
Students often find difficult to understand the concepts and working details of electricity because its mechanisms of operation are invisible. The visualization of electricity through an augmented reality (AR) app could assist students in understanding these concepts more intuitively and in improving their academic achievement. Due to the lack of studies on AR apps for electricity education, this study aimed to investigate the effects of an interactive AR app designed for teaching electrical circuits on students. The study investigates its impact on students' academic performance, explores its influence on their emotions, and examines the relationship between the perceived usability of the app and the student's learning outcomes and emotional experiences. The study was conducted in an electromagnetism laboratory with the participation of 28 engineering students. The findings revealed that the students who used the augmented reality application presented a better academic performance than those who participated in the traditional laboratory. Except for the students in the experimental group feeling less shame, there were no discernible variations between the students' feelings in the two groups. Anxiety increases in both groups. The AR application proved to have usability rated as good, but it was not evident that it correlated with academic performance, or the emotions students experienced. Only one relationship was determined between the perceived consistency of the system and hopelessness.
Álgebras y fibrados de Clifford con aplicaciones
(Universidad de La Serena, 2012) Notte-Cuello, Eduardo
Preservice Teacher Professional Identity: Influence of the Teacher Educator and the Teacher Education Model
(ARIZONA STATE UNIV, MARY LOU FULTON TEACHERS COLL, 2023) Cuadra-Martinez David, Castro-Carrasco Pablo, Oyanadel-Veliz Cristian, Gonzalez-Palta Ingrid, Zivkovic Predrag, Sandoval-Diaz Jose, Perez-Zapata Daniel
The objective of this study is to estimate the association between the following variables: teacher professional identity, the teacher education model adopted, the type of teacher educator, and academic progression of teacher education students. A purposive and convenience sampling process was used to recruit 662 preservice teachers attending teacher education programs at three Chilean universities. A sociodemographic survey and teacher professional identity scale were administered to these preservice students. Data were analysed using Spearman correlation, the Kruskal-Wallis test, and multiple linear regression. Results how different types of teacher educator profiles and teacher education models positively correlate with professional identity; furthermore, levels of professional identity were found to differ in connection with students' level (year) within their teacher education program. It was also found that the profile of teacher trainers, who are also schoolteachers, and the critical-intellectual educational model are predictors of teacher professional identity. In the discussion, these results are analysed based on the literature.
Towards a comprehensive musical education: analysis of a proposal from traditional music in four Chilean schools
(UNIV RIOJA, DEPT EXPRESION ARTISTICA, 2023) Valverde Ximena, Rossel Raul Jorquera, Casals Albert
Music education in Chile has yet to focus and deepen the possibilities that the use of traditional music can have as an interdisciplinary learning resource. As a result of this problem, this research focused on the relevance and value that traditional music can have as a comprehensive and interdisciplinary learning tool in formal music education. The research analyzed the implementation and results of a proposal for the sixth year of basic education with a pedagogical approach based on the idea that the music that we transfer to formal education cannot be separated from the experiences, activities, knowledge and socio-cultural implications that give them meaning in their contexts of origin. Through collaborative action research, the proposal was carried out in four centers and the perceptions of the collaborating teaching staff were analyzed. The results show that the inclusion of these types of music can enrich the learning process from an integrating conception of knowledge, considering the indivisibility of the musiccontext-society triad.
Remote teaching and pandemic: perceptions of university professors from the Coquimbo region, Chile
(UNIV REPUBLICA, COMISION SECTORIAL ENSENANZA, 2023) Dibona Paula, Miranda Florencia, Mondaca Gabriel, Matamoros Scarlet, Marin Fernanda
The main aim of this phenomenological study was to understand the perceptions of academics from the Faculty of Humanities of a state university in relation to remote teaching. The findings show that the restrictive measures of the pandemic affected teachers' mental health more than factors related to remote teaching. They were also affected by the lack of interaction with their students, who keep their cameras turned off. Teachers showed good adaptability to changes in this context, and applied methodological changes and self-care strategies. Despite the fact that more time is required to prepare teaching material, most of them indicate that there are no problems in the distribution of time. It is concluded that the objectives of the research have been achieved, however, the conclusions could be limited. It is recommended that further studies address teachers' perceptions of the future of higher education and conduct less structured interviews that consider gender and age.
Self-regulation of Learning in First Year Law Students: A preexperimental design
(UNIV CHILE, FAC DERECHO, 2023) Apablaza Carmen Gloria Covarrubias, Alfaro Maribel Veas, Marino Israel Gonzalez
The objective of this study was to analyze the effect on the self -regula-tion of learning in a group of first-year university students, after completing the subject Workshop on Study Techniques and Methodologies of the Law degree at the Central University of Chile, Coquimbo Region. The methodology is quantitative, with a pre -ex-perimental pretest-posttest design with a group, and cross-sectional data collection. The non-probabilistic and intentional sample consisted of 59 students for the pretest and 59 for the posttest, who answered the Inventory of self-regulation strategies in univer-sity students by Cleary and Platten at the beginning and end of the course. The results of both measurements revealed few differences for the actions of the students in the information search dimension, while in the organization of the task it is possible to appreciate increases. The need to strengthen the self-regulation of learning in first-year law students with systematic and intentional actions emanating from the institution and teaching is concluded.
Framing Teacher Identity in an Era of Accountability: Media and Teachers' Narratives in Chile
(ARIZONA STATE UNIV, MARY LOU FULTON TEACHERS COLL, 2023) Cabalin Cristian, Andrada Pablo
This article presents the main results of a research project that aims to analyze teachers' perceptions of media discourses and how those discourses influence their teacher identity. Based on focus groups with teachers from public, charter, and private schools in the Metropolitan Region of Chile, this study shows that teachers' identities are results of their experiences, the audit culture context, and media discourses. However, in order to combat negative media discourse representations, teachers need to re-frame the conversation by becoming aware of media discourses and creating counternarratives to reposition themselves in society.
On monotone pseudocontractive operators and Krasnoselskij iterations in an ordered Hilbert space
(Springer Open, 2023-02-22) Jorquera Alvarez, Eduardo Daniel
The aim of this work is to establish fixed point results in ordered Hilbert spaces for monotone operators with a pseudocontractive property. We state monotone versions of Theorem 12 in [F. E. Browder, W. V. Petryshyn, Construction of fixed points of nonlinear mappings in Hilbert space, J. Math. Anal. Appl. 20 (1967), 197–228] and Theorem 2.1 in [Berinde, Vasile. Weak and strong convergence theorems for the Krasnoselskij iterative algorithm in the class of enriched strictly pseudocontractive operators, Annals of West University of Timisoara-Mathematics and Computer Science, vol. 56, no. 2, 2018, pp. 13–27], as well as, several related results. Further results, in Hilbert spaces without a partial order, are stated too.
Fear-Avoidance Beliefs Are Associated with Pain Intensity and Shoulder Disability in Adults with Chronic Shoulder Pain: A Cross-Sectional Study
(Journal of Clinical Medicine, 2023-05-10) González-Aroca, Joaquín; Puelles-Díaz, Alvaro; Navarrete, Carlos; Albarnez, Loreto
Shoulder pain is one of the most common musculoskeletal conditions, and for people over 40 years old, it represents the musculoskeletal pain with the greatest impact on quality of life. Psychological factors, such as fear-avoidance beliefs, are associated with musculoskeletal pain, and several studies suggest that they can influence various treatment outcomes. Our objective was to explore the cross-sectional association between fear-avoidance beliefs and shoulder pain intensity and disability in subjects with chronic shoulder pain. A cross-sectional study was conducted, and 208 participants with chronic unilateral subacromial shoulder pain were recruited. The shoulder pain and disability index assessed pain intensity and disability. The Spanish fear-avoidance components scale assessed the presence of fear-avoidance beliefs. The association between fear-avoidance beliefs and pain intensity and disability was analyzed by means of multiple linear regression models and proportional odds models, reporting odds ratios and 95% confidence intervals. Shoulder and pain disability scores were significantly associated with fear-avoidance beliefs (p < 0.0001, adjusted R-square 0.93, multiple linear regression). There was no evidence of an association between sex and age in this study. The regression coefficient for shoulder pain intensity and disability score was 0.67446. The proportional odds model showed an odds ratio of 1.39 (1.29-1.50) for shoulder pain intensity and disability total score. This study suggests that greater levels of fear-avoidance beliefs are associated with greater levels of shoulder pain and disability in adults with chronic shoulder pain.
CAPOS: the bulge Cluster APOgee Survey IV elemental abundances of the bulge globular cluster NGC 6558
(MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2023-10-20) González-Díaz, D.; Fernández-Trincado, J. G.; Villanova, S.; Geisler, D.; Barbuy, B.; Minniti, D.; Beers, T. C.; Bidin, C. M.; Mauro, F.; Muñoz, C.; Tang, B. T.; Soto, M.; Monachesi, A.; Lane, R. R.; Frelijj, H.
This study presents the results concerning six red giant stars members of the globular cluster NGC 6558. Our analysis utilized high-resolution near-infrared spectra obtained through the CAPOS initiative (the APOgee Surv e y of Clusters in the Galactic Bulge), which focuses on surv e ying clusters within the Galactic Bulge, as a component of the Apache Point Observatory Galactic Evolution Experiment II surv e y (APOGEE-2). We employ the Brussels Automatic Code for Characterizing High accUracy Spectra ( BACCHUS ) code to provide line-by-line elemental-abundances for Fe-peak (Fe, Ni), alpha-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z (Al), and the s-process element (Ce) for the four stars with high-signal-to-noise ratios. This is the first reliable measure of the CNO abundances for NGC 6558. Our analysis yields a mean metallicity for NGC 6558 of ([Fe/H]) = -1.15 +/- 0.08, with no evidence for a metallicity spread. We find a Solar Ni abundance, ([Ni/Fe]) similar to + 0.01, and a moderate enhancement of alpha-elements, ranging between + 0.16 and < + 0.42, and a slight enhancement of the s-process element ([Ce/Fe]) similar to + 0.19. We also found low levels of ([Al/Fe]) similar to + 0.09, but with a strong enrichment of nitrogen, [N/Fe] > + 0.99, along with a low level of carbon, [C/Fe] < -0.12. This behaviour of Nitrogen-Carbon is a typical chemical signature for the presence of multiple stellar populations in virtually all GCs; this is the first time that it is reported in NGC 6558. We also observed a remarkable consistency in the behaviour of all the chemical species compared to the other CAPOS bulge GCs of the same metallicity.
The moderating role of aesthetics and information quality for acceptance of augmented reality
(Taylor&Francis, 2023-10-22) Alvarez-Marin, Alejandro; Velazquez-Iturbide, J. Angel; Castillo-Vergara, Mauricio; Acuna-Opazo, Christian
This study explores the moderating role of aesthetics and information quality on the technological acceptance of augmented reality. A technology acceptance model with the following variables was used: perceived ease of use, perceived usefulness, attitude towards using, and behavioural intention to use. Analysis was conducted by using structural equation modelling and a participation of 90 engineering students. Participants used an augmented-reality app for electrical resistive circuits, which works as a virtual laboratory. The app allows manipulating circuit elements and computing voltage and amperage values using the loop method, applying Kirchhoff's voltage law. The results suggest that aesthetics and information quality influence attitudes towards use. These findings show the importance of aesthetics and information quality in accepting augmented reality apps; therefore, designers and developers should consider these factors. This type of study has not been investigated previously.
Integrated global assessment of the natural forest carbon potential
(2023-12-07) Mo, Lidong
Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2-5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellite-derived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151-363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.
Analysis of ground-sourced and satellite-derived models reveals a global forest carbon potential of 226 Gt outside agricultural and urban lands, with a difference of only 12% across these modelling approaches.
Pegasus IV: Discovery and Spectroscopic Confirmation of an Ultra-faint Dwarf Galaxy in the Constellation Pegasus
(IOP Publishing Ltd, 2023/01/01) Cerny, W., Simon, J. D., Li, T. S., Drlica-Wagner, A., Pace, A. B., Martinez-Vazquez, C. E., Riley, A. H., Mutlu-Pakdil, B., Mau, S., Ferguson, P. S., Erkal, D., Munoz, R. R., Bom, C. R., Carlin, J. L., Carollo, D., Choi, Y., Ji, A. P., Manwadkar, V., Martinez-Delgado, D., Miller, A. E., Noel, N. E. D., Sakowska, J. D., Sand, D. J., Stringfellow, G. S., Tollerud, E. J., Vivas, A. K., Carballo-Bello, J. A., Hernandez-Lang, D., James, D. J., Nidever, D. L., Castellon, J. L. Nilo, Olsen, K. A. G., Zenteno, A.
We report the discovery of Pegasus IV, an ultra-faint dwarf galaxy found in archival data from the Dark Energy Camera processed by the DECam Local Volume Exploration Survey. Pegasus IV is a compact, ultra-faint stellar system ( = -r(1/2) 41(-6)(+8) pc, M-V = -4.25 +/- 0.2 mag) located at a heliocentric distance of 90(-6)(+4) kpc. Based on spectra of seven nonvariable member stars observed with Magellan/IMACS, we confidently resolve Pegasus IV's velocity dispersion, measuring s = sigma(v) 3.3(-1.1)(+1.7) km s(-1) (after excluding three velocity outliers), this implies a mass-to-light ratio of M1/2LV ,(1/2)=167(-99)(+224) M-?/L-? for the system. From the five stars with the highest signal-to-noise spectra, we also measure a systemic metallicity of [Fe/H] = -2.63(-0.30)(+0.26) dex, making Pegasus IV one of the most metal-poor ultra-faint dwarfs. We tentatively resolve a nonzero metallicity dispersion for the system. These measurements provide strong evidence that Pegasus IV is a dark-matter-dominated dwarf galaxy, rather than a star cluster. We measure Pegasus IV's proper motion using data from Gaia Early Data Release 3, finding (mu(alpha*, mu delta)) = (0.33 +/- 0.07, -0.21 +/- 0.08) mas yr(-1). When combined with our measured systemic velocity, this proper motion suggests that Pegasus IV is on an elliptical, retrograde orbit, and is currently near its orbital apocenter. Lastly, we identify three potential RR Lyrae variable stars within Pegasus IV, including one candidate member located more than 10 half-light radii away from the system's centroid. The discovery of yet another ultra-faint dwarf galaxy strongly suggests that the census of Milky Way satellites is still incomplete, even within 100 kpc.
Bulge-disc decomposition of the Hydra cluster galaxies in 12 bands
(OXFORD UNIV PRESS, 2023/01/01) Lima-Dias, Ciria, Monachesi, Antonela, Torres-Flores, Sergio, Cortesi, Arianna, Hernandez-Lang, Daniel, P. Montaguth, Gissel, Jimenez-Teja, Yolanda, Panda, Swayamtrupta, Menendez-Delmestre, Karin, Goncalves, Thiago S., Mendez-Hernandez, Hugo, Telles, Eduardo, Dimauro, Paola, Bom, Clecio R., de Oliveira, Claudia Mendes, Kanaan, Antonio, Ribeiro, Tiago, Schoenell, William
When a galaxy falls into a cluster, its outermost parts are the most affected by the environment. In this paper, we are interested in studying the influence of a dense environment on different galaxy's components to better understand how this affects the evolution of galaxies. We use, as laboratory for this study, the Hydra cluster which is close to virialization, yet it still shows evidence of substructures. We present a multiwavelength bulge-disc decomposition performed simultaneously in 12 bands from S-PLUS (Southern Photometric Local Universe Survey) data for 52 galaxies brighter than m(r) = 16. We model the galaxies with a Sersic profile for the bulge and an exponential profile for the disc. We find that the smaller, more compact, and bulge-dominated galaxies tend to exhibit a redder colour at a fixed stellar mass. This suggests that the same mechanisms (ram-pressure and tidal stripping) that are causing the compaction in these galaxies are also causing them to stop forming stars. The bulge size is unrelated to the galaxy's stellar mass, while the disc size increases with greater stellar mass, indicating the dominant role of the disc in the overall galaxy mass-size relation found. Furthermore, our analysis of the environment unveils that quenched galaxies are prevalent in regions likely associated with substructures. However, these areas also harbour a minority of star-forming galaxies, primarily resulting from galaxy interactions. Lastly, we find that similar to 37 per cent of the galaxies exhibit bulges that are bluer than their discs, indicative of an outside-in quenching process in this type of dense environments.
Pre-main-sequence Brackett Emitters in the APOGEE DR17 Catalog: Line Strengths and Physical Properties of Accretion Columns
(IOP Publishing Ltd, 2023/01/01) Campbell, Hunter, Khilfeh, Elliott, Covey, Kevin R., Kounkel, Marina, Ballantyne, Richard, Corey, Sabrina, Roman-Zuniga, Carlos G., Hernandez, Jesus, Martinez, Ezequiel Manzo, Ramirez, Karla Pena, Roman-Lopes, Alexandre, Stassun, Keivan G., Stringfellow, Guy S., Borissova, Jura, Chojnowski, S. Drew, Ramirez-Preciado, Valeria, Kim, Jinyoung Serena, Serna, Javier, Stutz, Amelia M., Lopez-Valdivia, Ricardo, Suarez, Genaro, Ybarra, Jason E., Longa-Pena, Penelope, Fernandez-Trincado, Jose G.
Very young (t less than or similar to 10 Myr) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar disks to the surface of the star. Upon impacting the stellar surface, the shocked gas recombines and emits hydrogen spectral lines. To characterize the density and temperature of the gas within these accretion streams, we measure equivalent widths of Brackett (Br) 11-20 emission lines detected in 1101 APOGEE spectra of 326 likely pre-main-sequence accretors. For sources with multiple observations, we measure median epoch-to-epoch line strength variations of 10% in Br11 and 20% in Br20. We also fit the measured line ratios to predictions of radiative transfer models by Kwan & Fischer. We find characteristic best-fit electron densities of n ( e ) = 10(11)-10(12) cm(-3), and excitation temperatures that are inversely correlated with electron density (from T similar to 5000 K for n ( e ) similar to 10(12) cm(-3) to T similar to 12,500 K at n ( e ) similar to 10(11) cm(-3)). These physical parameters are in good agreement with predictions from modeling of accretion streams that account for the hydrodynamics and radiative transfer within the accretion stream. We also present a supplementary catalog of line measurements from 9733 spectra of 4255 Brackett emission-line sources in the APOGEE Data Release 17 data set.
The isolated elliptical galaxy NGC 5812-MOND or dark matter?
(WILEY-V C H VERLAG GMBH, 2023/01/01) Richtler, Tom, Salinas, Ricardo, Lane, Richard, Hilker, Michael
There exist isolated elliptical galaxies, whose dynamics can be modeled without resorting to dark matter or MOND, for example, NGC 7507. Such objects lack understanding within the current framework of galaxy formation. The isolated elliptical NGC 5812 is another object to investigate a possible role of isolation. We use globular clusters (GCs) and the galaxy light itself as dynamical tracers to constrain its mass profile. We employ Gemini/GMOS mask spectroscopy, apply the GMOS reduction procedures provided within IRAF, measure GC velocities by cross correlation methods and extract the line-of-sight kinematics of galaxy spectra using the tool pPXF. We identify 28 GCs with an outermost galactocentric distance of 20 kpc, for which velocities could be obtained. Furthermore, 16 spectra of the integrated galaxy light out to 6 kpc have been used to model the central kinematics. These spectra provide evidence for a disturbed velocity field, which is plausible given the disturbed morphology of the galaxy. We construct spherical Jeans models for the galaxy light and apply tracer mass estimators for the globular clusters. With the assumptions inherent to the mass estimators, MOND is compatible with the mass out to 20 kpc. However, a dark matter free galaxy is not excluded, given the uncertainties related to a possible nonsphericity and a possible nonequilibrium state. We find one globular cluster with an estimated mass of 1.6x107M circle dot$$ 1.6times 1{0}<^>7{M}_{odot } $$, the first Ultra Compact Dwarf in an isolated elliptical. We put NGC 5812 into the general context of dark matter or alternative ideas in elliptical galaxies. The case for a MONDian phenomenology also among early-type galaxies has become so strong that deviating cases appear astrophysically more interesting than agreements. The baryonic Tully Fisher relation (BTFR) as predicted by MOND is observed in some samples of early-type galaxies, in others not. However, in cases of galaxies that deviate from the MONDian prediction, data quality and data completeness are often problematic.
Colour and infall time distributions of satellite galaxies in simulated Milky-Way analogues
(OXFORD UNIV PRESS, 2023/01/09) Pan, Yue, Simpson, Christine M., Kravtsov, Andrey, Gomez, Facundo A., Grand, Robert J. J., Marinacci, Federico, Pakmor, Rudiger, Manwadkar, Viraj, Esmerian, Clarke J.
We use the Auriga simulations to probe different satellite quenching mechanisms operating at different mass scales (10(5) M-theta ? M * < 10(11) M ((R))) in Milky Way-like hosts. Our goal is to understand the origin of the satellite colour distribution and star-forming properties in both observations and simulations. We find that the satellite populations in the Auriga simulations, which was originally designed to model Milky Way-like host galaxies, resemble the populations in the Exploration of Local VolumE Satellites (ELVES) Surv e y and the Satellites Around Galactic Analogs (SAGA) survey in their luminosity function in the luminosity range -12 ? M-V ? -15 and resemble ELVES in their quenched fraction and colour-magnitude distribution in the luminosity range -12 ? M-g ? -15. We find that satellites transition from blue colours to red colours at the luminosity range -15 ? Mg ? -12 in both the simulations and observations and we show that this shift is driven by environmental effects in the simulations. We demonstrate also that the colour distribution in both simulations and observations can be decomposed into two statistically distinct populations based on their morphological type or star-forming status that are statistically distinct. In the simulations, these two populations also have statistically distinct infall time distributions. The comparison presented here seems to indicate that this tension is resolved by the impro v ed target selection of ELVES, but there are still tensions in understanding the colours of faint galaxies, of which ELVES appears to have a significant population of faint blue satellites not reco v ered in Auriga.