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Principal component analysis applied to dendrochronology
(Universidade Federal do Rio Grande do Norte) Silva, Daniela Oliveira da; Klausner, Virginia; Prestes, Alan; Macedo, Humberto Gimenes
This work uses samples of the species Ocotea porosa (Nees & Mart) Barroso (Imbuia), collected in the city of General Carneiro, Southeast region of the State of Paraná (26o24'01 25"S 51o24'03 91"W), Brazil, to generate average chronology (GC index) of this region. The objective of this article is to remove the natural growth trends of trees using a tool that is still little explored for this purpose, Principal Component Analysis (PCA). In each tree sample, the width of each growth ring was measured, obtaining a time series (1 ring per year). The samples were selected using Cluster Analysis, which classifies samples based on their similarities. Once the Principal Components (PCs) were obtained, the dendrochronological series were reconstructed without the first PC. This methodology is an estimate of the trend that best represents the natural growth of all trees on the site. The arithmetic mean of the series without the 1st PC is the GC index. It was found that PCA has three benefits: fast data processing, preservation of low-frequency signals and, when integrated with a powerful tool, the Alternated Least Squares (ALS) method, missing data estimation.
Vaterite microparticle-loaded methylene blue for photodynamic activity in macrophages infected with Leishmania braziliensis
(Springer Nature) Marmo, Vitor Luca Moura; Ambrósio, Jéssica Aparecida Ribeiro; Gonçalves, Érika Peterson; Raniero, Leandro José; Beltrame Junior, Milton; Pinto, Juliana Guerra; Ferreira-Strixino, Juliana; Simioni, Andreza Ribeiro
Calcium carbonate (CaCO3) exhibits a variety of crystalline phases, including the anhydrous crystalline polymorphs calcite, aragonite, and vaterite. Developing porous calcium carbonate microparticles in the vaterite phase for the encapsulation of methylene blue (MB) as a photosensitizer (PS) for use in photodynamic therapy (PDT) was the goal of this investigation. Using an adsorption approach, the PS was integrated into the CaCO3 microparticles. The vaterite microparticles were characterized by scanning electron microscopy (SEM) and steady-state techniques. The trypan blue exclusion method was used to measure the biological activity of macrophages infected with Leishmania braziliensis in vitro. The vaterite microparticles produced are highly porous, non-aggregated, and uniform in size. After encapsulation, the MB-loaded microparticles kept their photophysical characteristics. The carriers that were captured allowed for dye localization inside the cells. The results obtained in this study indicated that the MB-loaded vaterite microparticles show promising photodynamic activity in macrophages infected with Leishmania braziliensis.
Possible relationship of meteor disintegration in the mesosphere and enhancement of sodium atoms: A case study on july 05, 2013
(Elsevier) Pimenta, Alexandre Alvares; Batista, Paulo Prado; Andrioli, Vania Fatima; Fagundes, Paulo Roberto; Batista, Inez Staciarini
Our observations show that on some occasions an influx of meteor ablation possibly contributes to appearance of a sudden enhancement in mesospheric sodium density. On July 05, 2013, all-sky images with a narrow sodium filter in the 589 nm emission, operating at Cachoeira Paulista (22.7 S, 45 W) and lidar observations of the mesospheric sodium layer, operating at Sa˜o Jose´ dos Campos (23.1 S, 45.9 W), both observatories in Brazil, show a possible relationship of meteor disintegration and appearance of sodium enhancements on the background layer. After the meteor impact, the all-sky images showed a sodium cloud that was seen for about 10 min through the images in the NaD 589 nm emission, with initial dimensions of approximately 36 km 9 km and initial speed of about 90 m/s southward. In addition, our observations show that the movement of sodium cloud in the horizontal plane around 90 km is relatively anisotropic and change the dimensions with time
Longitudinal variations of the occurrence of F3 and F4 layers within the southern EIA and their dependence on solar cycle
(Elsevier) Tardelli, Alexandre; Fagundes, Paulo Roberto; Pezzopane, Michael; Pillat, Valdir Gil
This investigation presents for the first time the seasonal and solar cycle variations of the daytime F-layer multiple stratifications (F3 and F4 layers) near the southern crest of the EIA in two different longitudinal sectors of South America. To perform the study, the ionograms recorded from 2007 to 2015 at Sao Jose´ dos Campos (23.2 S, 45.9 W), Brazil (eastern sector), and at Tucuma´n (26.9 S, 65.4 W), Argentina (western sector), are considered. Both sites present a frequency of occurrence of the F3 and F4 layers which is directly proportional to the solar activity, and an annual variation with a maximum in spring/summer and a minimum in autumn/winter. The main result that came out from the analysis is that the frequency of occurrence of the F3 and F4 layers is higher in the western sector than in the eastern sector, and this could be attributed to a different gravity waves activity characterizing the two longitudinal sectors. 2021 COSPAR. Published by Elsevier B.V. All rights reserved.
Ionospheric GPS-TEC responses from equatorial region to the EIA crest in the South American sector under intense space weather conditions
(Elsevier) Abreu, Alessandro José de; Correia, Emilia; Denardini, Clezio Marcos; Jesus, Rodolfo de; Venkatesh, Kavutarapu; Roberto, Marisa; Abalde, José Ricardo; Fagundes, Paulo Roberto; Bolzan, Maurício José Alves; Gende, Maurício Alfredo
We present and discuss the ionospheric F-region observations from equator to the equatorial ionization anomaly (EIA) regions over the South American sector during an intense space weather event occurred between 27 and May 29, 2017. During this geomagnetic storm, the symmetric-H (SYM-H) reached a minimum of − 142 nT at ~0700 UT on May 28, 2017. For this investigation, we analyze the vertical total electron content (VTEC) observations from a chain of nearly 120 Global Positioning System (GPS) stations. Magnetometer measurements obtained at two stations in the low latitude regions are also presented. The observations do not indicate prompt penetration electric field (PPEF) effects in the VTEC variations. Magnetometer’s observations over Cuiaba ´ (CBA) and Cachoeira Paulista (CXP) in central west and south parts of Brazil, respectively, have shown a strong crosscorrelation with SYM-H in the period between 3 and 48 h. The results also show positive ionospheric storm phase during the recovery phase on May 28, 2017. Positive effect during the recovery phase of the geomagnetic storm is possibly associated with effects of disturbances winds. During the recovery phase, a strong intensification of the EIA took place, possibly related to an additional ionization effect. The VTEC values show differences between the west and east sectors. This indicates that the EIA crest is stronger in the east sector than in the west sector, possibly due to the combination of disturbance wind effects and geomagnetic field geometry where in the east sector the field lines are more inclined.
Ionospheric disturbances over the American and African sectors due to the 2019 major Sudden Stratospheric Warming (SSW 2019), under low solar activity conditions
(Elsevier) Vieira, Francisco; Fagundes, Paulo Roberto; Pillat, Valdir Gil; Agyei-Yeboah, Ebenezer; Venkatesh, Kavutarapu; Arcanjo, Mateus de Oliveira
Sudden Stratospheric Warming (SSW) is one of the most spectacular atmospheric large-scale phenomena, which takes place at high latitudes during winter months and is more frequent in the Arctic region than in the Antarctic region. SSWs can change the vertical, latitudinal, and longitudinal distributions of the neutral atmosphere and its dynamics, which in turn affects the ionospheric electrodynamic processes. Simultaneous inferred VTEC from GPS networks over the American and African sectors are used to investigate the ionospheric response due to the SSW 2019 from DOY 356 to DOY 20 (December 22, 2018–January 20, 2019). This study investigates the VTEC and EIA diurnal and day-to-day responses in the American and African sectors during the SSW. It is noted that the VTEC decreased on most of the days at several latitude regions. However, it is also noted that the VTEC increased on some days and in some latitude regions, particularly during the SSW temperature peak. The EIA exhibits significant changes in its shape, intensity, and symmetry during the SSW. This study using simultaneous observations over American and African sectors covering a large geographical extent demonstrates the similarities and differences in ionospheric response to the SSW 2019 event over different regions.
Glycolaldehyde formation mediated by interstellar amorphous ice: a computational study
(Royal Astronomical Society) Paiva, Mateus Augusto Martins; Pilling, Sergio; Mendoza, Edgar; Galvão, Breno Rodrigues Lamaghere; Abreu, Heitor Avelino de
Glycolaldehyde (HOCH2CHO) is the most straightforward sugar detected in the Interstellar Medium (ISM) and participates in the formation pathways of molecules fundamental to life, red such as ribose and derivatives. Although detected in several regions of the ISM, its formation route is still debated and its abundance cannot be explained only by reactions in the gas phase. This work explores a new gas-phase formation mechanism for glycolaldehyde and compares the energy barrier reduction when the same route happens on the surface of amorphous ices. The first step of the mechanism involves the formation of a carbon–carbon bond between formaldehyde (H2CO) and the formyl radical (HCO), with an energy barrier of 27 kJ mol−1 (gas-phase). The second step consists of barrierless hydrogen addition. Density functional calculations under periodic boundary conditions were applied to study this reaction path on 10 different amorphous ice surfaces through an Eley–Rideal type mechanism. It was found that the energy barrier is reduced on average by 49 per cent, leading in some cases to a 100 per cent reduction. The calculated adsorption energy of glycolaldehyde suggests that it can be promptly desorbed to the gas phase after its formation. This work, thus contributes to explaining the detected relative abundances of glycolaldehyde and opens a new methodological framework for studying the formation routes for Complex Organic Molecules (COMs) in interstellar icy grains.
Gas-phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal-poor accretion
(Royal Astronomical Society) Nascimento, Janaína Correa do; Dors Junior, Oli Luiz; Bergmann, Thaisa Storchi; Mallmann, Nícolas Dullius; Riffel, Rogério; Ilha, Gabriele da Silva; Riffel, Rogemar André; Rembold, Sandro Barboza; Deconto-Machado, Alice; Costa, Luiz N. da; Armah, Mark
We derive the metallicity (traced by the O/H abundance) of the narrow-line region (NLR) of 108 Seyfert galaxies as well as radial metallicity gradients along their galaxy discs and of these of a matched control sample of no active galaxies. In view of that, observational data from the SDSS-IV MaNGA survey and strong emission-line calibrations taken from the literature were considered. The metallicity obtained for the NLRs was compared to the value derived from the extrapolation of the radial oxygen abundance gradient, obtained from H II region estimates along the galaxy disc, to the central part of the host galaxies. We find that, for most of the objects (∼ 80 per cent), the NLR metallicity is lower than the extrapolated value, with the average difference (D ) between these estimates ranging from 0.16 to 0.30 dex. We suggest that D is due to the accretion of metal-poor gas to the AGN that feeds the nuclear supermassive black hole (SMBH), which is drawn from a reservoir molecular and/or neutral hydrogen around the SMBH. Additionally, we look for correlations between D and the electron density (Ne), [O III]λ5007, and H α luminosities, extinction coefficient (AV) of the NLRs, as well as the stellar mass (M∗) of the host galaxies. Evidence of an inverse correlation between the D and the parameters Ne, M∗, and Av was found.
Computational simulation of the bombardment of molecular clump by realistic cosmic ray field employing GEANT4 code
(Royal Astronomical Society) Pazianotto, Maurício Tizziani; Pilling, Sergio
Here, we present calculations on the energy delivered (and heating) by realistic cosmic rays (CRs) field at a typical molecular clump. The current model describes, with unprecedented spatial resolution, the energy delivery by a realistic CR field in molecular clumps. The calculations were performed employing the Geant4 code (considering full cascade physical processes and hadron physics) considering the cosmic ray field taken from the Voyager spacecraft measurements in the interstellar medium. The results showed that the total energy deposition rate, considering light particles (protons, electrons and alphas), medium-mass ions and heavy-ions, ranges from 400 MeV/g/s in the outer layer (at 105 AU) to roughly 100 MeV/g/s in the inner layer of the model (below 0.1 AU). The main energy deposition rate is due to the incoming protons. Incoming alphas represent 15–20 per cent of the energy deposition. In the deep core of the cloud, the fraction of energy delivered by medium-mass ions, electrons, and heavy ions are 5 per cent, 2.5 per cent, and 1 per cent, respectively. The heating induced by cosmic rays seems to affect mostly the regions above ∼500 AU. Considering a balanced heat model with warm dust grains (T∼16–18 K), we observe a small bump in temperature at 2000–5000 AU. We suggest this temperature enhancement by CRs might have some affect on the molecular formation or cometary formation in pristine Oort cloud region inside the Solar System.
Climatology of ionospheric amplitude scintillation on GNSS signals at south American sector during solar cycle 24
(Elsevier) Macho, Eduardo Perez; Correia, Emília; Spogli, Luca; Muella, Marcio Tadeu de Assis Honorato
Scintillations are caused by ionospheric irregularities and can affect the propagation of trans-ionospheric radio signals. One way to understand and predict the impact of such irregularities on Global Navigation Satellite System (GNSS) signals is through the spatial/temporal characterization of the scintillation’s climatology during different phases of a solar cycle covering different latitudes and longitudes. This characterization is performed using amplitude scintillation index S4, during the full solar cycle 24, in the South American (SA) sector. The investigation considers the diurnal, daily, and seasonal variation of S4 index for climatological purpose, and the goal of this study is to investigate the scintillations covering a large spatial scale during the full solar cycle 24. The characterization shows a latitudinal asymmetry, whereas at the south, the scintillations were more frequent and their peak was more distant from the magnetic equator, which can be attributed by the South Atlantic Magnetic Anomaly (SAMA), and/or by the transequatorial meridional neutral winds. It also shows a longitudinal asymmetry, where the scintillations at the eastern sector occurred between November and February, while at the western sector, they occurred during the months of October, November, February and March, which can be attributed to the difference between the magnetic and geographic equators. The occurrence of scintillations during two distinct geomagnetic storms with similar storm time in the SA sector is also presented.
Chemical Evolution of CO2 Ices under Processing by Ionizing Radiation: Characterization of Nonobserved Species and Chemical Equilibrium Phase with the Employment of PROCODA Code
(IOP science) Pilling, Sergio; Carvalho, Geanderson Araújo; Rocha, Will Robson Monteiro
Astrophysical ices are being exposed to ionizing radiation in space environments, which trigger new reactions and desorption processes. In the lab, such processing by radiation has revealed the appearance of several new species and complements the study of the chemical evolution of icy astrophysical scenarios. Here, we develop a computational methodology that helps to clarify the chemical evolution of ices investigated experimentally under photolysis/radiolysis processes until reaching chemical equilibrium (CE). Briefly, the code (named PROCODA) solves a system of coupled differential equations and describes the evolution of the molecular abundances with the irradiation time for ices under processing by radiation. Two experimental ice samples containing pure CO2 and irradiated by two ionizing agents (cosmic rays and ultraviolet photons) were considered prototype systems. Here, we considered 11 different chemical species within the ice (four observed: CO2, CO, O3, and CO3; seven nonobserved or unknown: O, O2, C, C2, C2O, C2O2, and C2O3), 100 reaction routes (e.g., direct dissociation reactions, bimolecular and termolecular reactions) and radiation-induced desorption processes. The best-fit models provide the reaction rates, several desorption parameters, as well as the characterization of the CE phase. At CE, the percentage of nonobserved species in the UV model was almost triple the one calculated in the CR model (which also includes a lot of O and C atoms). The determined values can be employed in future astrochemical models to map chemical evolution embedded species in astrophysical regions under the presence of an ionizing radiation field.
Chemical abundances in Seyfert galaxies – IX. Helium abundance estimates
(Royal Astronomical Society) Dors Junior, Oli Luiz; Valerdi, Mabel; Lemes, Priscila Freitas; Krabbe, Angela Cristina; Riffel, Rogemar André; Amôres, Eduardo Brescansin; Riffel, Rogério; Armah, Mark; Monteiro, Adriano Francisco; Oliveira Junior, Celso Benedito de
For the first time, the helium abundance relative to hydrogen (He/H), which relied on direct measurements of the electron temperature, has been derived in the narrow line regions (NLRs) from a local sample of Seyfert 2 nuclei. In view of this, optical emission line intensities [3000 < λ(Å) < 7000] of 65 local Seyfert 2 nuclei (z < 0.2), taken from Sloan Digital Sky Survey Data Release 15 and additional compilation from the literature, were considered. We used photoionization model grid to derive an Ionization Correction Factor (ICF) for the neutral helium. The application of this ICF indicates that the NLRs of Seyfert 2 present a neutral helium fraction of ∼50 per cent in relation to the total helium abundance. We find that Seyfert 2 nuclei present helium abundance ranging from 0.60 to 2.50 times the solar value, while ∼85 per cent of the sample present oversolar abundance values. The derived (He/H)–(O/H) abundance relation from the Seyfert 2 is stepper than that of star-forming regions (SFs) and this difference could be due to excess of helium injected into the interstellar medium by the winds of Wolf–Rayet stars. From a regression to zero metallicity, by using Seyfert 2 estimates combined with SFs estimates, we obtained a primordial helium mass fraction Yp = 0.2441 ± 0.0037, a value in good agreement with the one inferred from the temperature fluctuations of the cosmic microwave background by the Planck Collaboration
Chemical abundance of LINER galaxies – metallicity calibrations based on SDSS-IV MaNGA
(Royal Astronomical Society) Oliveira Junior, Celso Benedito de; Krabbe, Angela Cristina; Hernandez-Jimenez, Jose Andres; Dors Junior, Oli Luiz; Zinchenko, Igor; Hägele, Guilhermo Frederico; Cardaci, Mónica Viviana; Monteiro, Adriano Francisco
The ionizing source of low-ionization nuclear emission-line regions (LINERs) is uncertain. Because of this, an empirical relation to determine the chemical abundances of these objects has not been proposed. In this work, for the first time, we derived two semi-empirical calibrations based on photoionization models to estimate the oxygen abundance of LINERS as a function of the N2 and O3N2 emission-line intensity ratios. These relations were calibrated using oxygen abundance estimations obtained by comparing the observational emission-line ratios of 43 LINER galaxies (taken from the MaNGA survey) and grids of photoionization models built with the cloudy code assuming post-asymptotic giant branch stars with different temperatures. We found that the oxygen abundance of LINERs in our sample is in the range, with a mean value of . We recommend the use of the N2 index to estimate the oxygen abundances of LINERs, since the calibration with this index presented a much smaller dispersion than the O3N2 index. In addition, the estimated metallicities are in good agreement with those derived by extrapolating the disc oxygen abundance gradients to the centre of the galaxies showing that the assumptions of the models are suitable for LINERs. We also obtained a calibration between the logarithm of the ionization parameter and the [O iii]/[O ii] emission-line ratio.
Calibration-based abundances in the interstellar gas of galaxies from slit and IFU spectra
(EDP Sciences) Pilyugin, Leonid; Lara-López, Maritza A.; Vílchez, Jose M.; Duarte Puertas, Salvador; Zinchenko, Igor; Dors Junior, Oli Luiz
In this work, we make use of available integral field unit (IFU) spectroscopy and slit spectra of several nearby galaxies. The pre- existing empirical R and S calibrations for abundance determinations are constructed using a sample of H ii regions with high- quality slit spectra. In this paper, we test the applicability of those calibrations to the IFU spectra. We estimate the calibration-based abundances obtained using both the IFU and the slit spectroscopy for eight nearby galaxies. The median values of the slit and IFU spectra-based abundances in bins of 0.1 in fractional radius Rg (normalised to the optical radius R25) of a galaxy are determined and compared. We find that the IFU and the slit spectra-based abundances obtained through the R calibration are close to each other; the mean value of the differences of abundances is 0.005 dex, and the scatter in the differences is 0.037 dex for 38 datapoints. The S calibration can produce systematically underestimated values of the IFU spectra-based abundances at high metallicities (12 + log(O/H) 􏰅8.55); the mean value of the differences is −0.059 dex for 21 datapoints, while at lower metallicities the mean value of the differences is −0.018 dex and the scatter is 0.045 dex for 36 data points. This provides evidence that the R calibration produces more consistent abundance estimations between the slit and the IFU spectra than the S calibration. We find that the same calibration can produce close estimations of the abundances using IFU spectra obtained with different spatial resolution and different spatial samplings. This is in line with the recent finding that the contribution of the diffuse ionised gas to the large-aperture spectra of H ii regions has a secondary effect.
Analysis of Y-component of geomagnetic field and SYM-H Index using wavelet multiresolution analysis
(Springer Nature Link) Sapkota, Santosh; Saurav, Sarup Khadka; Gautam, Sabin; Karki, Monika; Adhikari, Binod; Mishra, Roshan Kumar; Oliveira, Virgínia Klausner de; Dhungana, Beni Madhav
Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere cre- ates geomagnetic disturbances recorded on the ground. This work analyzes the Y-component of the geomag- netic field during two geomagnetic storms and compares it to the solar quiet days. The magnetogram data recorded on low latitude stations are used for the study. We investigated the correlation of the Y-component with geomagnetic index SYM-H using wavelet multiresolution analysis. We have used solar wind velocity, pressure, and interplanetary magnetic fields (By and Bz) to know the interplanetary structure for the selected duration. We found a positive correlation between Y-component and the SYM-H index for both events. The magnitude of the Y-component was significantly reduced during the main phase in comparison to the quiet days. Further, variation of solar wind parameters indicated geomagnetic storms are guided by the prolonged southward IMF-Bz component and highly fluctuated IMF-By component. This work connects the inter- planetary plasma parameters to the storm-time geomagnetic variations.
Ahead-of-Tsunami magnetic disturbance detection using intrinsic mode functions: Tohoku-Oki earthquake case study
(Springer Nature Link) Oliveira, Virgínia Klausner de; Macedo, Humberto Gimenes; Prestes, Alan
We document magnetic disturbances that occurred during the Tohoku-Oki tsunami of 11 March 2011 using empirical mode decomposition (EMD) in a dataset derived from a network of ground-based magnetometers (INTERMAGNET and GIS). The disturbances, obtained by filtering the magnetic field data using the first intrinsic mode function (IMF1) of EMD, propagate ahead of the tsunami at a speed in the range of 600–1.6 km/s. They also appear 3 min (near-field) to 2 h (far-field) earlier than the tsunami arrival at the magnetic observatories. We refer to these distur- bances as ahead-of-tsunami magnetic disturbances (ATMDs). A comparison with seismometer data shows them arriving 10 min after the arrival of Rayleigh waves. Their association with both seismogenic and tsunamigenic processes is discussed, and it is argued that the tsunamigenic process can well explain the magnetic disturbance propagation characteristics at the far-field. At near- field, the ATMDs are the coseismic magnetic signatures mainly driven by surface Rayleigh waves. Monitoring these ATMDs can be extremely useful for the early warning of the tsunami.
Freya: an educational MATLAB GUI-based tool for generalized Fourier series
(Research, Society and Development) Macedo, Humberto Gimenes; Oliveira, Virgínia Klausner de; Gomes, Anna Karina Fontes; Fernandes, Francisco Carlos Rocha
The Fourier analysis is a very powerful mathematical tool to decompose functions into their frequency components. Due to this, it has applications in a wide variety of fields inside the realm of science and engineering. As usual, this theory starts with a discussion about the trigonometric Fourier series, the expansion of a function in terms of sines and cosines, and then is generalized in the sense that other functions rather than the trigonometric ones can be used as an orthogonal basis, as the eigenfunctions of some specific Sturm-Liouville problems, such as Bessel functions and Legendre polynomials. In this direction, we present the so- called Freya, an educational graphical user interface (GUI) for the generalized Fourier series developed using the interactive MATLAB (MATrix Laboratory) App Designer environment. We aim to provide a user-friendly tool as a learning aid system for students to gain a comprehensive understanding of the subject as well as for teaching.
The contact binary system TYC 7275-1968-1 as seen by optical, UV and X-ray observations
(Elsevier) Lima, Isabel de Jesus; Mattiuci, Ana Carolina; Luna, Gerardo Juan Manuel; Oliveira, Alexandre Soares de; Rodrigues, Claudia Vilega; Palivanas, Natália; Nuñez, Natalia Edith
We present an analysis of publicly available X-ray and optical observations of TYC 7275-1968-1, a contact binary, red nova progenitor candidate. The long optical time series of ASAS-3, SuperWASP, CRTS, Gaia, ASASSN, and TESS enabled us to improve its orbital period to 0.3828071 ± 0.0000026 d. We show the presence of an X-ray and UV source associated with TYC 7275-1968-1 from Neil Gehrels Swift Observatory, that was previously assumed to be the counterpart of CD -36 8436 (V1044 Cen), a symbiotic star located 22 arcsec from the red nova candidate. The X-ray data indicate the presence of a region with a temperature of 𝑘𝑇 = 0.8+0.9 −0.1 keV and a luminosity of 1.4+0.1 −0.2 × 1031 erg s−1 in the range 0.3 – 10 keV. The detection of X-rays and modulated UV emission suggests that both components of the binary are chromospherically active.
Diagnostic diagrams for ram pressure stripped candidates
(Royal Astronomical Society) Krabbe, Angela Cristina; Hernandez-Jimenez, José Andrés; Oliveira, Claudia Mendes de; Jaffe, Yara L.; Oliveira Junior, Celso Benedito de; Cardoso, Nathalia Machado; Castelli, Analía V Smith; Dors Junior, Oli Luiz; Cortesi, Arianna; Crossett, Jacob P.
This paper presents a method for finding ram pressure stripped (RPS) galaxy candidates by performing a morphological analysis of galaxy images obtained from the Legacy survey. We consider a sample of about 600 galaxies located in different environments such as groups and clusters, tidally interacting pairs and the field. The sample includes 160 RPS previously classified in the literature into classes from J1 to J5, based on the increasing level of disturbances. Our morphological analysis was done using the ASTROMORPHLIB software followed by the inspection of diagnostic diagrams involving combinations of different parameters like the asymmetry (A), concentration (C), Sersic ´ index (n), and bulge strength parameters F(G, M20). We found that some of those diagrams display a distinct region in which galaxies classified as J3, J4, and J5 decouples from isolated galaxies. We call this region as the morphological transition zone and we also found that tidally interacting galaxies in pairs are predominant within this zone. Nevertheless, after visually inspecting the objects in the morphological transition zone to discard obvious contaminants, we ended up with 33 bona fide new RPS candidates in the studied nearby groups and clusters (Hydra, Fornax, and CLoGS sample), of which one-third show clear evidence of unwinding arms. Future works may potentially further increase significantly the samples of known RPS using such method.
Understanding the Molecular Kinetics and Chemical Equilibrium Phase of Frozen CO during Bombardment by Cosmic Rays by Employing the PROCODA Code
(IOP science) Pilling, Sergio; Carvalho, Geanderson Araújo; Abreu, Heitor Avelino de; Galvão, Breno Rodrigues Lamaghere; Silveira, Carolina Hahn da; Mateus, Marcelo Silva
Within the cold regions of space, ices that are enriched with carbon monoxide (CO) molecules are exposed to ionizing radiation, which triggers new reactions and desorption processes. Laboratory studies on astrochemical ices employing different projectiles have revealed the appearance of several new species. In this study, we employed the upgraded PROCODA code, which involves a calculation phase utilizing thermochemistry data, to map the chemical evolution of pure CO ice irradiated by cosmic-ray analogs. In the model, we have considered 18 different chemical species (six observed: CO, CO2, C3, O3, C2O, and C5O3; 12 unobserved: C, O, C2, O2, CO3, C3O, C4O, C5O, C2O2, C2O3, C3O2, and C4O2) coupled at 156 reaction routes. Our best-fit model provides effective reaction rates (effective rate constants, (ERCs)), branching ratios for reactions within reaction groups, several desorption parameters, and the characterization of molecular abundances at the chemical equilibrium (CE) phase. The most abundant species within the ice at the CE phase were atomic oxygen (68.2%) and atomic carbon (18.2%), followed by CO (11.8%) and CO2 (1.6%). The averaged modeled desorption yield and rate were 1.3e5 molecules ion−1 and 7.4e13 molecules s−1, respectively, while the average value of ERCs in the radiation-induced dissociation reactions was 2.4e-1 s−1 and for the bimolecular reactions it was 4.4e-24 cm3 molecule−1 s−1. We believe that the current kinetics study can be used in future astrochemical models to better understand the chemical evolution of embedded species within astrophysical ices under the presence of an ionizing radiation field.

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