Colour-Magnitude Diagrams of candidate age-gap filling LMC clusters

The LMC has a rich star cluster system spanning a wide range of ages and masses. One striking feature of the LMC cluster system is the existence of an age gap between 3-10 Gyrs. Four LMC clusters whose integrated colours are consistent with those of intermediate age simple stellar populations have been imaged with the Optical Imager (SOI) at the Southern Telescope for Astrophysical Research (SOAR). Their colour-magnitude diagrams (CMDs) reach V ~ 24. Isochrone fits, based on Padova evolutionary models, were carried out to these CMDs, after subtraction of field contamination. The preliminary results are as follows: KMK88-38 has an age of ~ 1.3 Gyr, assuming typical LMC metallicity and distance modulus, and a very low redenning. For OGLE-LMC0531, the best eye fits to isochrones yield an age ~ 1.6 Gyr and E(B-V)=0.03. BSDL917 is younger, ~ 150 yrs, and subjected to larger extinction (E(B-V)=0.08). The remaining cluster is currently under analysis. Therefore, we conclude that these clusers are unlikely to fill in the LMC cluster age gap, even when fitting uncertainties in the parameters are considered.Comment: 4 pages, 5 figures, compact form of the poster published online in the proceedings of IAUS256: The Magellanic System: Stars, Gas, and Galaxie

Self-consistent physical parameters for MC clusters from CMD modelling: application to SMC clusters observed with the SOAR telescope

The Magellanic Clouds (MCs) present a rich system of stellar clusters that can be used to probe the dynamical and chemical evolution of these neighboring and interacting irregular galaxies. In particular, these stellar clusters (SCs) present combinations of age and metallicity that are not found for this class of objects in the Milky Way, being therefore very useful templates to test and to calibrate integrated light simple stellar population (SSP) models applied to unresolved distance galaxies. On its turn, the age and metallicity for a cluster can be determined spatially resolving its stars, by means of analysis of its colour-magnitude diagrams (CMDs). In this work we present our method to determine self-consistent physical parameters (age, metallicity, distance modulus and reddening) for a stellar cluster, from CMDs modelling of relatively unstudied SCs in the Small Magellanic Cloud (SMC) imaged in the BVI filters with the 4.1 m SOAR telescope. Our preliminary results confirm our expectations that come from a previous integrated spectra and colour analysis: at least one of them (Lindsay 2) is an intermediate-age stellar cluster with ~ 2.6 Gyr and [Fe/H] ~ -1.3, being therefore a new interesting witness regarding the reactivation of the star formation in the MCs in the last 4 Gyr.Comment: 4 pages, 2 figures. To be published in the proceedings of IAUS256: The Magellanic System: Stars, Gas, and Galaxie

Mass models of NGC 6624 without an intermediate-mass black hole

An intermediate-mass black hole (IMBH) was recently reported to reside in the centre of the Galactic globular cluster (GC) NGC 6624, based on timing observations of a millisecond pulsar (MSP) located near the cluster centre in projection. We present dynamical models with multiple mass components of NGC 6624 - without an IMBH - which successfully describe the surface brightness profile and proper motion kinematics from the Hubble Space Telescope (HST) and the stellar mass function at different distances from the cluster centre. The maximum line-of-sight acceleration at the position of the MSP accommodates the inferred acceleration of the MSP, as derived from its first period derivative. With discrete realizations of the models we show that the higher-order period derivatives - which were previously used to derive the IMBH mass - are due to passing stars and stellar remnants, as previously shown analytically in literature. We conclude that there is no need for an IMBH to explain the timing observations of this MSP.Comment: 8 pages, 7 figures, MNRAS. Updated to match final journal styl

Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5

Using the example of the tidal stream of the Milky Way globular cluster Palomar 5 (Pal 5), we demonstrate how observational data on streams can be efficiently reduced in dimensionality and modeled in a Bayesian framework. Our approach combines detection of stream overdensities by a Difference-of-Gaussians process with fast streakline models, a continuous likelihood function built from these models, and inference with MCMC. By generating $\approx10^7$ model streams, we show that the geometry of the Pal 5 debris yields powerful constraints on the solar position and motion, the Milky Way and Pal 5 itself. All 10 model parameters were allowed to vary over large ranges without additional prior information. Using only SDSS data and a few radial velocities from the literature, we find that the distance of the Sun from the Galactic Center is $8.30\pm0.25$ kpc, and the transverse velocity is $253\pm16$ km/s. Both estimates are in excellent agreement with independent measurements of these quantities. Assuming a standard disk and bulge model, we determine the Galactic mass within Pal 5's apogalactic radius of 19 kpc to be $(2.1\pm0.4)\times10^{11}$ M$_\odot$. Moreover, we find the potential of the dark halo with a flattening of $q_z = 0.95^{+0.16}_{-0.12}$ to be essentially spherical within the radial range that is effectively probed by Pal 5. We also determine Pal 5's mass, distance and proper motion independently from other methods, which enables us to perform vital cross-checks. We conclude that with more observational data and by using additional prior information, the precision of this method can be significantly increased.Comment: 28 pages, 14 figures, submitted to ApJ (revised version), comments welcom

The tidal tails of NGC 2298

We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leading and trailing tail. We also find that NGC 2298 has extra-tidal structures stretching towards and against the Galactic disk, suggesting strong tidal interaction. Finally, we assess how the matched-filter performs when applied to a globular cluster with and without mass segregation taken into account. We find that disregarding the effects of mass segregation may significantly reduce the detection limit of the matched-filter.Comment: 11 pages, 9 figures, 1 table. Accepted for publication on MNRAS main journa

ED-2: A cold but not so narrow stellar stream crossing the solar neighbourhood

Context. ED-2 is a stellar stream identified as a compact group in integrals-of-motion space in a local sample of halo stars from the third Gaia data release. Aims. We investigate its nature and possible association with known halo substructures. Methods. We explored the current properties of ED-2 members in phase-space and also analysed the expected distribution via orbit integration. In addition, we studied the metallicity of ED-2 using APOGEE DR17 and LAMOST DR8 (and re-calibrated DR3). Results. ED-2 forms a compact group in the x − z (or R − z) plane, showing a pancake-like structure as it crosses the solar neighbourhood. Dynamically, it is most similar to the globular clusters NGC 3201 and NGC 6101 and to the stellar streams Ylgr and Phlegethon. However, its orbit is sufficiently different for none of these objects to likely be the ED-2 progenitor. We also find ED-2 to be quite metal poor: all of its stars have [Fe/H]≤ − 2.42, with a median [Fe/H] = −2.60−0.21+0.20. At this low metallicity, it is unlikely that ED-2 stems from any known globular cluster. Instead, ED-2 seems to be in a similar category as the recently discovered Phoenix and C-19 stellar streams. We find that ED-2 members are scattered across the whole sky, which is due to its current orbital phase. We predict that as this object moves to its next apocentre, it will acquire an on-sky morphology that is similar to that of cold stellar streams. Finally, because ED-2 is nearing pericentre, we predict that additional members found below the plane will have high radial velocities of close to ∼500 km s−1 in the present-day direction of the globular cluster NGC 6101.Juan de la Cierva fellowship (IJC2020-043742-I),MCIN/AEI/10.13039/501100011033European Space Agency (ESA

Workflow científico de anotação genômica funcional e curadoria manual de genomas

Com o advento das tecnologias de sequenciamento de nova geração, o sequenciamento de genomas não se apresentou mais como uma barreira tecnológica. Analisar a estrutura e atribuir um significado biológico para sequências genômicas e proteômicas in silico (anotação genômica), no entanto, se tornou a nova tarefa desafiadora. A anotação funcional é uma etapa crucial neste processo e tem por intuito compreender os processos biológicos dos organismos e guiar novas pesquisas. Entretanto, trata-se de uma tarefa complexa, já que envolve a utilização de um grande número de bancos de dados, web servers e ferramentas para realizar comparações das sequências de interesse com outras sequências disponíveis em repositórios de domínios de proteínas. Cada ferramenta possui arquivos de saída independentes e em formatos específicos, dificultando a organização dos resultados de anotação em um único contexto e o trabalho colaborativo de múltiplos pesquisadores em um mesmo projeto. O objetivo desta pesquisa compreendeu o desenvolvimento de um workflow científico de anotação genômica funcional e curadoria manual de genomas, através da implementação de uma ferramenta web colaborativa que permite a execução automática de ferramentas de anotação funcional e integração dos resultados em uma plataforma unificada. A solução ainda permite a realização de curadoria manual de informações estruturais e funcionais para cada gene, além de suportar a exportação dos dados de anotação para os formatos exigidos no processo de submissão do banco de dados GenBank. O worflow foi testado e validado no processo de anotação genômica das linhagens selvagem (2HH) e mutante (S1M29) do fungo Penicillium echinulatum, conduzido pelo Laboratório de Bioinformática e Biologia Computacional da Universidade de Caxias do Sul e submetido ao GenBank através dos BioProjects PRJNA520890 e PRJNA521489, respectivamente. Além disso, uma versão experimental da ferramenta foi disponibilizada gratuitamente através do endereço https://seq2annot.org. A solução mostrou-se eficiente em função de abstrair a complexidade de execução de ferramentas externas e integrar os resultados de anotação em um ambiente colaborativo unificado. O mecanismo central de tarefas assíncronas permitiu a possibilidade de escalar horizontalmente os recursos de servidor à medida que ocorrer o aumento da demanda de trabalho. A decisão arquitetural de dividir trabalhos em pequenas unidades de trabalho independentes também garantiu que novas ferramentas de anotação funcional possam ser facilmente desenvolvidas e acopladas à aplicação, tornando-a uma solução promissora para ser constantemente aprimorada e utilizada em projetos de anotação genômica em larga escala no futuro. [resumo fornecido pelo autor]With the advent of new generation sequencing technologies, genome sequencing was no longer a scientific barrier. Analysing the structure and giving biological meaning to genomic and proteomic sequences in silico(genome annotation) became, nevertheless, the new challenging task. Functional annotation is a crucial step in this process and aims to understand organisms? biological processes and guide new research. However, it is a complex task, as it involves usinga large set of databases, web servers, and tools to compare all the sequences of interest with other sequences available in protein domain repositories. Each of these tools has independentand format-specific output files, making it difficult to keep annotation data organized in a single-context environment and preventing researchers from working collaboratively within a project. This research aimed to develop a scientific workflow for functional annotation and manual curation of genomes by implementing a collaborative web application that supports the automatic execution of functional annotation tools and integrates results into a single-context platform. The solution also supports manual curation of structural and functional data for each gene and allows users to export annotation results to file formats required by GenBank database?s submission process. The workflow was tested and validated in the annotation process of wild-type (2HH) and mutant (S1M29) strains of Penicillium echinulatum, conducted by Computational Biology and Bioinformatics Laboratory at University of Caxias do Sul and submitted to GenBank under BioProjects PRJNA520890 and PRJNA521489, respectively. Besides, an experimental version of the tool was made freely available at https://seq2annot.org. The solution has proven effective as it abstracts the complexity of the external tools? execution and integrates annotation results in a unified collaborative environment. The core mechanism of asynchronous task execution provided the ability to horizontally scale server resources as demand grows over time. The architectural decision of splitting jobs into single independent tasks also ensured that new functional annotation tools can be easily developed and plugged into the application, making it a promising tool to be continuously improved and used in large-scale genome annotation projects in the future. [resumo fornecido pelo autor]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPE

Evidence for C and Mg variations in the GD-1 stellar stream

Dynamically cold stellar streams are the relics left over from globular cluster dissolution. These relics offer a unique insight into a now fully disrupted population of ancient clusters in our Galaxy. Using a combination of Gaia eDR3 proper motions, optical and near-UV colours we select a sample of likely Red Giant Branch stars from the GD-1 stream for medium-low resolution spectroscopic follow-up. Based on radial velocity and metallicity, we are able to find 14 new members of GD-1, 5 of which are associated with the \emph{spur} and \emph{blob/cocoon} off-stream features. We measured C-abundances to probe for abundance variations known to exist in globular clusters. These variations are expected to manifest in a subtle way in globular clusters with such low masses ($\sim10^4 {\rm ~M_{\odot}}$) and metallicities (${\rm[Fe/H]}\sim-2.1 {\rm ~dex}$). We find that the C-abundances of the stars in our sample display a small but significant ($3\sigma$ level) spread. Furthermore, we find $\sim 3\sigma$ variation in Mg-abundances among the stars in our sample that have been observed by APOGEE. These abundance patterns match the ones found in Galactic globular clusters of similar metallicity. Our results suggest that GD-1 represents another fully disrupted low mass globular cluster where light-element abundance spreads have been found.Comment: 12 pages, 7 figures. Accepted to MNRA

Avaliação de propriedades mecânicas de resinas compostas nanoparticuladas

Este estudo teve como objetivo avaliar as propriedades mecânicas selecionadas (resistência à compressão, resistência à tração diametral, resistência flexural de trêspontos e módulo flexural) de quatro marcas diferentes de resina composta nanoparticuladas e uma resina composta microhíbrida, nas cores A2 esmalte e dentina. Foram confeccionadas dez amostras para cada grupo de cada teste. O módulo flexural foi calculado a partir dos resultados do teste de resistência flexural. Os resultados obtidos nos ensaios foram comparados estatisticamente com análise de variância e teste de Tukey (p < 0,01). Não houve diferença estatisticamente significante para os grupos testados no teste de resistência à compressão, sendo que as médias variaram entre 141,04 MPa para a resina 4 Seasons A2E e 206,08 MPa para a resina Grandio A2O. No teste de resistência flexural, houve diferença estatisticamente significativa entre os grupos, onde as medias variaram entre 59,16 MPa para a resina 4 Seasons A2E e 122 MPa para a resina Supreme XT A2E. Houve diferença estatisticamente significante para módulo flexural e neste teste as médias variaram entre 3,4 GPa para a resina 4 Seasons A2E e 13,30 GPa para a resina Grandio A2O. No teste de resistência à tração diametral, a resina Esthet-X A2O apresentou média (34,87 MPa) estatisticamente menor que os demais grupos, e a resina Supreme XT A2E (50,26 MPa), estatisticamente maior que os demais grupos testados; entre os demais grupos não houve diferença estatisticamente significante. Apesar de diferenças nos valores entre os grupos testados nos testes de resistência flexural, módulo flexural e resistência à tração diametral, as resinas nanoparticuladas, baseados nos resultados obtidos neste estudo, apresentam propriedades mecânicas semelhantes da resina microhíbrida.The purpose of this study was evaluate selected mechanical properties (compressive strength, diametral tensile strength, flexural strength e flexural moduli) of four differents nanofilled composite and a microhybrid composite, in dentin e enamel A2 shades. Were maded ten samples for each group of each test. The flexural moduli was calculated by the results of the flexural strength`s test. The results were compared statistically with ANOVA e Tukey (p<0,01). There was no statistical difference for compressive strength, with values that range into 141. 04 MPa for 4 Seasons A2E and 206. 08 MPa Grandio A2O. For flexural strength, there was statistical difference for the tested groups, and the values range into 59. 16 MPa for 4 Seasons A2E and 122 MPa for Supreme XT A2E. There was statistical difference for flexural moduli and in this test the values range between 3. 4 GPa for 4 Seasons A2E and 13. 30 GPa for Grandio A2O. For diametral tensile strength, Esthet-X A2O showed value (34. 87 MPa) statiscally lower than the others groups, and Supreme XT A2E (50. 26 MPa), statiscally higher than the others tested groups; between the others groups there was no statistical difference. Even with differences for the values between the tested groups for flexural strength, flexural moduli and diametral tensile strength, the nanofiller composites, based in the results of this study, present mechanical properties similar from microhibrid resin

Avaliação da influência da associação de diferentes métodos de envelhecimento na resistência de união de reparos em resina composta

The aim of the study was to evaluate the association of different aging methods on bond strength values of composite repair, through the use of shear test. 96 samples of rectangular section were made with the microhybrid composite Point 4 (Kerr) and were divided into 8 groups (n = 12) as follows: (1) immersion in distilled water for 7 days; (2) immersion in distilled water for 30 days; (3) immersion in citric acid for 7 days; (4) immersion in boiling water for 8 hours; (5) immersion in distilled water for 30 days plus immersion in citric acid for 7 days; (6) immersion in distilled water for 30 days plus immersion in boiling water for 8 hours; (7) immersion in citric acid for 7 days plus immersion in boiling water for 8 hours and (8) immersion in distilled water for 30 days plus immersion in citric acid for 7 days plus immersion in boiling water for 8 hours. After going through the designated method of aging the treatment of prerepair was conducted with roughening the surface with sandpaper grain silicon carbide 120 and application of the adhesive system Single Bond 2 (3MESPE) and then made a repair with the same composite resin. The samples were tested in a universal testing machine (EMIC) for the shear bond strength test at a loading speed of 1mm / min. After the failure all samples were evaluated in an increase of 35x stereomicroscope and two samples from each group were evaluated in the SEM as surface after aging and after roughening with sandpaper silicon carbide. The results for evaluation of values in the bond strength test were subjected to statistical test analysis of variance (ANOVA) followed by Tukey test (p <0. 05) and no significant differences between the groups tested were found. The evaluation of failure occurred in stereomicroscope were made in a descriptive way, with all samples of all groups presented cohesive failures in the aged resin. Conclusion: The association of different aging methods does not influence the bond strength values of resin repairs made when the roughening method simulating diamond burs coarse-grained is used pre-repair.O objetivo do estudo foi avaliar a influência da associação de diferentes métodos de envelhecimento nos valores de resistência de união de reparos de resina composta, através da utilização de teste de cisalhamento. Foram confeccionadas 96 amostras com a resina composta microhíbrida Point 4 (Kerr) de secção retangular que foram divididas em 8 grupos (n=12) sendo: (1) imersão em água destilada por 7 dias; (2) imersão em água destilada por 30 dias; (3) imersão em ácido cítrico por 7 dias; (4) imersão em água em ebulição por 8 horas; (5) imersão em água destilada por 30 dias mais imersão em ácido cítrico por 7 dias; (6) imersão em água destilada por 30 dias mais imersão em água em ebulição por 8 horas; (7) imersão em ácido cítrico por 7 dias mais imersão em água em ebulição por 8 horas e (8) imersão em água destilada por 30 dias mais imersão em ácido cítrico por 7 dias mais imersão em água em ebulição por 8 horas. Após passarem pelo método de envelhecimento designado, foi realizado o tratamento de superfície pré-reparo com asperização com lixa de carbeto de silício de granulação 120 e aplicação do sistema adesivo Single Bond 2 (3MESPE) e então, confeccionado um reparo com a mesma resina composta. As amostras foram testadas em uma máquina de ensaio universal (EMIC) para o teste de cisalhamento a uma velocidade de carregamento de 1mm/min. Após a falha todas as amostras foram avaliadas no estereomicroscópio com aumento de 35x e duas amostras de cada grupo foram avaliadas em MEV quanto à superfície após o envelhecimento e após a asperização com lixas de carbeto de silício. Os resultados para avaliação dos valores no teste de resistência de união foram submetidos ao teste estatístico de análise de variância (ANOVA) seguido do teste de Tukey (p<0,05) e não foram encontradas diferenças significativas entre os grupos testados. A avaliação no estereomicroscópio das falhas ocorridas foram feitas de forma descritiva, sendo que todas as amostras de todos os grupos apresentaram falhas coesivas na resina envelhecida. Conclusão: a associação de diferentes métodos de envelhecimento não influencia nos valores de resistência de união em reparos de resina composta, quando o método de asperização simulando pontas diamantadas de granulação grossa é utilizado pré-reparo