From dust to light: a study of star formation in NGC 2264

Tese de doutoramento em Astronomia e Astrofísica, apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008The goal of this dissertation is to characterize the star formation history of the young cluster NGC2264 using the unique observational capabilities of the Spitzer Space Telescope. The motivation to conduct this study stems from the fact that most stars are formed within clusters, so the formation and evolution of the latter will effect the stellar mass distribution in the field. Detailed observational studies of young stellar clusters are therefore crucial to provide necessary constraints for theoretical models of cloud and cluster formation and evolution. This study also addresses the evolution of circumstellar disks in NGC2264; empirical knowledge of protoplanetary disk evolution is required for the understanding of how planetary systems such as our own form. The first result obtained from this study was both completely new and unexpected. A dense region within NGC2264 was found to be teeming with bright 24 µm Class I protostars; these sources are embedded within dense submillimeter cores and are spatially distributed along dense filamentary fingers of gas and dust that radially converge on a B-type binary Class I source. This cluster of protostars was baptized the "Spokes cluster" and its analysis provided further insight into the role of thermal support during core formation, collapse and fragmentation. The nearest neighbor projected separation distribution of these Class I sources shows a characteristic spacing that is similar to the Jeans length for the region, indicating that the dusty filaments may have undergone thermal fragmentation. The submillimeter cores of the Spokes cluster were observed at 230GHz using the SubMillimeter Array (SMA) and the resulting high resolution (1.300) continuum observations revealed a dense grouping of 7 Class 0 sources embedded within a particular core, D-MM1 (2000x2000). The compact sources have masses ranging between 0.4M and 1.2M, and radii of 600AU. The mean separation of the Class 0 sources within D-MM1 is considerably smaller than the characteristic spacing between the Class I sources in the larger Spokes cluster and is consistent with hierarchical thermal fragmentation of the dense molecular gas in this region. The results obtained by the study of the Spokes cluster show that the spatial substructuring of a cluster or subcluster is correlated with age, i.e., groupings of very young protostars have clearly more concentrated and substructured spatial distributions. The Spokes cluster could thus be one of several building blocks of NGC2264, and will likely expand and disperse its members through the surrounding region, adding to the rest of NGC2264's stellar population. To further explore this scenario, I identified Pre-Main Sequence (PMS) diskbearing sources in the whole region of NGC2264, as surveyed by InfraRed Array Camera (IRAC) analyzing both their spatial distributions and ages. Of the 1404 sources detected in all four IRAC bands, 116 sources were found to have anemic IRAC disks and 217 sources were found to have thick IRAC disks; the disk fraction was calculated to be 37.5%+-6.3% and found to be a function of spectral type, increasing for later type sources. I identified 4 candidate sources with transition disks (disks with inner holes), as well as 6 sources with anemic inner disks and thick outer disks that could be the immediate precursors of transition disks. This is a relevant result for it suggests planet formation may be occurring in the inner disk at very early ages. I found that the spatial distribution of the disk-bearing sources was a function of both disk type and amount of reddening. This spatial analysis enabled the identification of three groups of sources, namely, (i) embedded (AV> 3 magnitudes) sources with thick disks, (ii) unembedded sources with thick disks, and (iii) sources with anemic disks. The first group was found to have a median age of 1 Myr and its spatial distribution is highly concentrated and substructured. The second group, (ii), has a median age of 2 Myr and its spatial distribution is less concentrated and substructured than group (i), but more than the group of sources with anemic disks the spatial distribution of this third group (age 2 Myr) is not substructured and is more distributed, showing no particular peak or concentration. The star formation history of NGC2264 appears to be as follows: the northern region appears to have undergone the first epoch or episode of star formation, while the second epoch is currently occurring in the center (Spokes cluster) and south (near Allen's source).O objectivo desta dissertação é o estudo da história da formação estelar do exame estelar jovem NGC2264, bem como a caracterização da população estelar da pré-sequência principal que possui discos circum-estelares. Este trabalho foi realizado usando primariamente dados do telescópio espacial Spitzer, nomeadamente, imagens obtidas com os detectores "InfraRed Array Camera (IRAC)" (filtros centrados em 3.6 µm, 4.5 µm, 5.8 µm, e 8 µm) e "Multiband Imaging Photometer for SIRTF (Spitzer ) (MIPS)" (filtros centrados em 24 µm, 70 µm, e 160 µm). A capacidade observacional do Spitzer é única, sendo o telescópio com a melhor combinação de sensibilidade e resolução espacial actualmente existente que observa na janela espectral definida pelos comprimentos de onda 3.6 µm e 160 µm. A motivação deste estudo resulta do facto de que a maior parte das estrelas nasce em enxames estelares, pelo que a formação e evolução de enxames determina consequentemente a distribuição de masses estelares. Estudos observacionais detalhados de enxames jovens são cruciais para desenvolver modelos teóricos que descrevam a formação e evolução de nuvens moleculares e enxames de uma forma mais realista. O estudo de discos circum-estelares em NGC2264 fornece dados empíricos da evolução de discos proto-planetários que são igualmente necessários para a compreensão de como sistemas planetários, tal como o nosso, formam. O primeiro resultado obtido neste trabalho doutoral, e um dos primeiros da era Spitzer, foi completamento novo e inesperado. Descobrimos numa região da nuvem molecular associada ao exame NGC2264 caracterizada por matéria molecular densa (n _ 104 cm-3), um aglomerado ou sub-enxame rico em proto-estrelas Class I. As proto-estrelas estão embebidas em núcleos ou glóbulos submilimétricos bastante densos (n _ 105 cm-3), e encontram-se distribuídas espacialmente ao longo de dedos filamentares de gás e poeira que convergem numa fonte binária de Class I de tipo espectral B (IRS 2). Este sub-enxame de proto-estrelas Class I foi baptizado de enxame "Spokes", e a sua análise permitiu compreender melhor o papel desempenhado pelo pressão térmica durante a formação, colapso, e fragmentação de filamentos e glóbulos ou núcleos de gás e poeira. A distribuição da distância (projectada) entre as proto-estrelas Class I e as suas vizinhas mais próximas é caracterizada por um espaçamento (2000± 500) que é semelhante ao comprimento de Jeans para a região (2600), indicando que os filamentos de poeira possam ter fragmentado por um processo em que a pressão térmica era dominante (comparada com a pressão da turbulência ou pressão magnética) fragmentação térmica. Os núcleos ou góbulos submilmétricos do enxame Spokes foram observados a uma frequência de 230 GHz usando o radiotelescópio interferométrico "SubMillimeter Array (SMA)"; as resultantes observações no contínuo são de alta resolução (_1.300) e revelaram um denso aglomerado de 7 fontes compactas embebidas num particular núcleo ou glóbulo designado de D-MM1 (_2000×2000, n _ 106 cm-3). As fontes compactas têm massas entre 0.4M_ e 1.2M_, e diâmetros de _1200AU, e o seu estado evolucionário corresponde ao de proto-estrelas Class 0. A distância média (projectada) entre as proto-estrelas Class 0 em D-MM1 (6.900) é consideravelmente menor do que o espaçamento característico entre as protoestrelas Class I do enxame Spokes, mas semelhante ao comprimento de Jeans para D-MM1 (5.900); este resultado é indicativo de que possa ter havido fragmentação térmica hierárquica do gás molecular denso no enxame Spokes. O estudo do enxame Spokes mostra portanto que a sub-estruturação espacial de um exame ou sub-enxame está correlacionado com a idade das suas fontes, i.e., aglomerados de proto estrelas muito jovens têm claramente distribuições espaciais mais concentradas e sub-estruturadas. O enxame Spokes poderá ser desta forma um de vários blocos construtores de NGC2264: irá expandir e dispersar os seus membros pela região circundante, adicionando membros à população estelar já existente. Para poder continuar a explorar este cenário, identifiquei a população de estrelas da pré-sequência principal que têm discos circum-estelares em toda a região de NGC2264 observada pelo IRAC, e analisei a sua estrutura espacial e distribuição de idades. Os discos circum-estelares, ou proto-planetários, foram classificados em dois tipos de acordo com o declive, entre 3.6 µm e 8 µm, da distribuição espectral de energia da respectiva fonte, _IRAC: discos espessos têm -1.8 _ _IRAC 3 magnitudes) e que têm discos espessos, (ii) fontes não embebidas (AV_ 3 magnitudes) e que têm discos espessos, e (iii) fontes com discos anémicos. Encontrou-se que o primeiro grupo tem uma idade mediana de 1 milhão de anos e a sua distribuição espacial é altamente concentrada e sub-estruturada. O segundo grupo, (ii), tem uma idademediana de 2 milhões de anos e a sua distribuição espacial é menos concentrada e apresenta menos sub-estruturação que o grupo (i), mas mais do que o grupo de fontes com discos anémicos a distribuição espacial deste último grupo (idade _ 2 milhões de anos) não apresenta sub-estruturação e é mais dispersa, sem nenhum particular pico ou concentração. A história da formação estelar de NGC2264 aparenta ter ocorrido da seguinte forma: o primeiro episódio ou época de formação estelar deu-se no norte da nuvem molecular associada com NGC2264, enquanto que o segundo episódio ou época de formação estelar esteja a correr no centro (onde se encontra o enxame Spokes) e no sul (perto da fonte Allen) da nuvem

ALMA Fragmented Source Catalogue in Orion (FraSCO) I. Outflow interaction within an embedded cluster in OMC-2/FIR3, FIR4, and FIR5

We present a high angular resolution ($\sim1"$) and wide-field ($2'.9 \times 1'.9$) image of the 1.3-mm continuum, CO($J$ = 2--1) line, and SiO($J$ = 5--4) line emissions toward an embedded protocluster, FIR3, FIR4, and FIR5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array (ALMA). We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and $\mathrm{H_2}$ gas number densities are estimated to be $3.8 \times 10^{-5}$--$1.1 \times 10^{-2} \mathrm{M_{\odot}}$, 290--2000 au, and $6.4 \times 10^{6}$--$3.3 \times 10^{8}\,\mathrm{cm^{-3}}$, respectively. The results of a Jeans analysis show that $\sim80\,\%$ of the protostellar sources and $\sim15\,\%$ of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO($J$ = 2--1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO($J$ = 5--4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between a dust condensation, FIR4, and an energetic outflow driven by HOPS-370 located within FIR3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star-formation scenario in FIR4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the $\mathrm{N_2H^+}$ line.Comment: 45 pages, 24 figures, 2 figure sets, 2 animations, Accepted for publication in Ap

ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow interaction within an embedded cluster in OMC-2/FIR 3, FIR 4, and FIR 5

Funding: This work was supported by NAOJ ALMA Scientific Research grant No. 2022-22B. The present study was supported by JSPS KAKENHI grants (JP17H06360, JP17K05387, JP17KK0096, JP21H00046, JP21K03617: MNM, 20K04034: SI). L.A.Z. acknowledges financial support from CONACyT-280775 and UNAM-PAPIIT IN110618 grants, México. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 851435).We present a high-angular resolution (∼1″) and wide-field ( 2.′9×1.′9 ) image of the 1.3 mm continuum, CO(J = 2–1) and SiO(J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H2 gas number densities are estimated to be 3.8 × 10−5–1.1 × 10−2 M⊙, 290–2000 au, and 6.4 × 106–3.3 × 108 cm−3, respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO(J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO(J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N2H+ line.Publisher PDFPeer reviewe

ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow Interaction within an Embedded Cluster in OMC-2/FIR 3, FIR 4, and FIR 5

We present a high-angular resolution (∼1'') and wide-field () image of the 1.3 mm continuum, CO(J = 2–1) and SiO(J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H2 gas number densities are estimated to be 3.8 × 10−5–1.1 × 10−2 M⊙, 290–2000 au, and 6.4 × 106–3.3 × 108 cm−3, respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO(J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO(J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N2H+ line

Cegueira silenciosa: revisão narrativa e estudo epidemiológico do glaucoma no Brasil entre 2017 e 2022: Silent blindness: narrative review and study epidemiology of glaucoma in Brazil between 2017 and 2022

Considerado um problema de saúde pública por representar importante causa de cegueira irreversível, além de demandar altos gastos ao Sistema Único de Saúde, o glaucoma urge atenção especializada no Brasil. Objetivou-se, primeiramente, alcançar perspectivas específicas no que tange ao glaucoma, abrangendo questões etiológicas, fisiopatológicas, clínico-sintomatológicas, comportamentais, diagnósticas, técnicas terapêuticas, além de levantar dados epidemiológicos acerca da prevalência do glaucoma. As tabulações de dados advindas do DATASUS-TabNet evidenciam as seguintes variáveis atreladas à doença: história familiar positiva, faixa etária acima de 45 anos, acometimento majoritário em indivíduos do sexo masculino, etnia negra, preponderância na região Sudeste do Brasil, escolaridade limitada e recorrência alinhada a fatores de risco comportamentais presentes ao longo da vida. O diagnóstico perfaz a realização de exame oftalmológico atrelado a exames complementares. Em relação ao acompanhamento e ao tratamento, é fundamental uma postura individualizada para o direcionamento de condutas especializadas para cada paciente

Os desfechos da cirurgia de catarata em pacientes com Doença de Alzheimer: uma revisão de literatura

Este artigo buscou demonstrar que a cirurgia para a retirada da catarata em pessoas com o diagnóstico de Alzheimer traz importante melhora na acuidade visual e cognição destes pacientes. A DA é uma condição neurodegenerativa associada ao declínio de funções executivas, cognitivas, de linguagem e memória, que impacta negativamente na qualidade de vida, especialmente por poderem apresentar alterações visuais. A catarata relacionada à idade é uma das principais causas de cegueira reversível cirurgicamente e que acomete a população idosa, de modo que o número de cirurgias aumenta a cada ano e também sua associação com a doença de Alzheimer. A cirurgia de catarata tem pontos positivos, como melhora da acuidade visual, da função cognitiva e maior autonomia. Com base nas literaturas, certificou-se que a cirurgia de catarata em pessoas com Alzheimer contribui para a melhora da acuidade visual do paciente e de suas habilidades cognitivas. Porém, há poucos estudos que relacionam diretamente a catarata e a DA, e ainda faz-se necessário maior investigação sobre os riscos e benefícios da cirurgia de catarata em pacientes com Alzheimer

VISIONS:the VISTA Star Formation Atlas I. Survey overview

VISIONS is an ESO public survey of five nearby (d < 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried out with the Visible and Infrared Survey Telescope for Astronomy (VISTA), using the VISTA Infrared Camera (VIRCAM), and collected data in the near-infrared passbands J (1.25 μm), H (1.65 μm), and KS (2.15 μm). With a total on-sky exposure time of 49.4h VISIONS covers an area of 650 deg2, it is designed to build an infrared legacy archive with a structure and content similar to the Two Micron All Sky Survey (2MASS) for the screened star-forming regions. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations undertaken within the survey are grouped into three different subsurveys. First, the wide subsurvey comprises shallow, large-scale observations and it has revisited the star-forming complexes six times over the course of its execution. Second, the deep subsurvey of dedicated high-sensitivity observations has collected data on areas with the largest amounts of dust extinction. Third, the control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS observation program offers multi-epoch position measurements, with the ability to access deeply embedded objects, and it provides a baseline for statistical comparisons and sample completeness – all at the same time. In particular, VISIONS is designed to measure the proper motions of point sources, with a precision of 1 mas yr−1 or better, when complemented with data from the VISTA Hemisphere Survey (VHS). In this way, VISIONS can provide proper motions of complete ensembles of embedded and low-mass objects, including sources inaccessible to the optical ESA Gaia mission. VISIONS will enable the community to address a variety of research topics from a more informed perspective, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law

VISIONS:the VISTA Star Formation Atlas I. Survey overview

VISIONS is an ESO public survey of five nearby (d < 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried out with the Visible and Infrared Survey Telescope for Astronomy (VISTA), using the VISTA Infrared Camera (VIRCAM), and collected data in the near-infrared passbands J (1.25 μm), H (1.65 μm), and KS (2.15 μm). With a total on-sky exposure time of 49.4h VISIONS covers an area of 650 deg2, it is designed to build an infrared legacy archive with a structure and content similar to the Two Micron All Sky Survey (2MASS) for the screened star-forming regions. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations undertaken within the survey are grouped into three different subsurveys. First, the wide subsurvey comprises shallow, large-scale observations and it has revisited the star-forming complexes six times over the course of its execution. Second, the deep subsurvey of dedicated high-sensitivity observations has collected data on areas with the largest amounts of dust extinction. Third, the control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS observation program offers multi-epoch position measurements, with the ability to access deeply embedded objects, and it provides a baseline for statistical comparisons and sample completeness – all at the same time. In particular, VISIONS is designed to measure the proper motions of point sources, with a precision of 1 mas yr−1 or better, when complemented with data from the VISTA Hemisphere Survey (VHS). In this way, VISIONS can provide proper motions of complete ensembles of embedded and low-mass objects, including sources inaccessible to the optical ESA Gaia mission. VISIONS will enable the community to address a variety of research topics from a more informed perspective, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law

VISIONS: The VISTA Star Formation Atlas -- I. Survey overview

© The Authors 2023. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0).VISIONS is an ESO public survey of five nearby (d < 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried out with VISTA, using VIRCAM, and collected data in the near-infrared passbands J, H, and Ks. With a total on-sky exposure time of 49.4 h VISIONS covers an area of 650 deg$^2$, and it was designed to build an infrared legacy archive similar to that of 2MASS. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations are grouped into three different subsurveys: The wide subsurvey comprises shallow, large-scale observations and has visited the star-forming complexes six times over the course of its execution. The deep subsurvey of dedicated high-sensitivity observations has collected data on the areas with the largest amounts of dust extinction. The control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS survey offers multi-epoch position measurements, is able to access deeply embedded objects, and provides a baseline for statistical comparisons and sample completeness. In particular, VISIONS is designed to measure the proper motions of point sources with a precision of 1 mas/yr or better, when complemented with data from VHS. Hence, VISIONS can provide proper motions for sources inaccessible to Gaia. VISIONS will enable addressing a range of topics, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law.Peer reviewe

The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope. IV. Aperture Masking Interferometry

The James Webb Space Telescope’s Near Infrared Imager and Slitless Spectrograph (JWST-NIRISS) flies a 7-hole non-redundant mask (NRM), the first such interferometer in space, operating at 3-5 μm wavelengths, and a bright limit of ≃4 mag in W2. We describe the NIRISS Aperture Masking Interferometry (AMI) mode to help potential observers understand its underlying principles, present some sample science cases, explain its operational observing strategies, indicate how AMI proposals can be developed with data simulations, and how AMI data can be analyzed. We also present key results from commissioning AMI. Since the allied Kernel Phase Imaging (KPI) technique benefits from AMI operational strategies, we also cover NIRISS KPI methods and analysis techniques, including a new user-friendly KPI pipeline. The NIRISS KPI bright limit is ≃8 W2 (4.6 μm) magnitudes. AMI NRM and KPI achieve an inner working angle of ∼70 mas, which is well inside the ∼400 mas NIRCam inner working angle for its circular occulter coronagraphs at comparable wavelengths