Papers by Denilso Camargo
Astronomy & astrophysics, Jul 2, 2024
VizieR Online Data Catalog (other), Jun 1, 2015
Monthly Notices of the Royal Astronomical Society, May 2, 2012
We investigate the nature of 48 low-level stellar overdensities (from Froebrich, Scholz and Rafte... more We investigate the nature of 48 low-level stellar overdensities (from Froebrich, Scholz and Raftery catalogue-FSR07) projected towards the Galactic anticentre and derive fundamental parameters for the confirmed clusters, thus improving the open cluster (OC) census in that direction. Parameters are derived with field-star decontaminated photometry, colour-magnitude filters and stellar radial density profiles. Among the 48 targets, we identified 18 star clusters, six previously studied OCs and seven probable clusters that require deeper photometry to establish the nature. We discovered seven new clusters, six of them forming an association of clusters with BPI 14, FSR 777, Kronberger 1 and Stock 8 in the region of the nebula IC 417 and related to the Aur OB2 association, and one embedded in the nebula Sh2-229. We also derive parameters for these three non-FSR07 clusters, because they are important in determining the structure of the Galactic anticentre. Thus, 58 objects are analysed in this work and we could derive fundamental parameters for 28 of them. The scenario in the IC 417 star-forming region is consistent with a sequential event. FSR 888 and FSR 890 are embedded in Sh2-249 within the Gem OB1 association. According to the distance derived for these clusters and those in the association of clusters, both Aur OB2 and Gem OB1 are located in the Perseus arm.
Monthly Notices of the Royal Astronomical Society, May 1, 2013
In this paper, we investigate the nature of 27 star cluster candidates, most of them projected to... more In this paper, we investigate the nature of 27 star cluster candidates, most of them projected towards the Galactic anticentre. We derive fundamental parameters for 20 confirmed clusters, among these 7 are new identifications. Four of the remaining are uncertain cases that require deeper photometry to establish their nature, and four are probably field fluctuations. In addition, we provide a partial census of the open clusters towards the Galactic anticentre. We also include in this study some interesting objects outside the anticentre region, in the second and third Galactic quadrants, mainly in the Perseus and outer arms. These clusters confirm the extension of the outer arm along the third quadrant. We also point out that the embedded cluster FSR 486, at a distance of 7.2 ± 1.3 kpc from the Sun, is projected on the line of sight of the Local Group irregular dwarf galaxy IC 10. Thus, part of the unusual properties of IC 10 may be explained by a Galactic contamination. We point out the importance of embedded clusters in tracing the spiral structure.
VizieR Online Data Catalog, May 1, 2017
Astronomy & Astrophysics, 2021
Context. Globular clusters (GCs) are the oldest objects known in the Milky Way, so each discovery... more Context. Globular clusters (GCs) are the oldest objects known in the Milky Way, so each discovery of a new GC is astrophysically important. In the inner Galactic bulge regions these objects are difficult to find due to extreme crowding and extinction. However, recent near-IR surveys have discovered a number of new bulge GC candidates that need to be further investigated. Aims. Our main objective is to use public data from the Gaia mission, the VISTA Variables in the Via Lactea (VVV) survey, the Two Micron All Sky Survey, and the Wide-field Infrared Survey Explorer to measure the physical parameters of Minni 48, a new candidate globular star cluster located in the inner bulge of the Milky Way at l = 359.35 deg, b = 2.79 deg. The specific goals are to measure its main astrophysical parameters, such as size, proper motions, metallicity, reddening and extinction, distance, total luminosity, and age. Methods. Even though there is a bright foreground star contaminating the field, this clu...
Monthly Notices of the Royal Astronomical Society: Letters, 2019
This work reports the discovery of three new globular clusters (GCs) towards the Galactic bulge-C... more This work reports the discovery of three new globular clusters (GCs) towards the Galactic bulge-Camargo 1107, 1108, and 1109. The discovery was made using the WISE, 2MASS, VVV, and Gaia-DR2 photometry. The new findings are old (12.0−13.5 Gyr) and metal-poor GCs ([Fe/H] < −1.5 dex) located in the bulge area close to the Milky Way (MW) mid-plane. Although the old ages and low metallicities suggest that the newly discovered GCs are likely associated with the inner halo, the possibility of these clusters being part of a primordial bulge GC subpopulation cannot be ruled out. Camargo 1107, for instance, presents a metallicity of [Fe/H] = −2.2 ± 0.4 dex and an age of 13.5 ± 2 Gyr, which may suggest that this cluster formed just after the big bang in the very early Universe. The discovery of GCs such as the new findings is crucial to built a coherent picture of the inner Galaxy. It is likely that at least a few more dozens of GCs are still to be discovered in the bulge.
The Astrophysical Journal, Dec 1, 2021
This work communicates the discovery of a binary open cluster within the Galaxy. NGC 1605 present... more This work communicates the discovery of a binary open cluster within the Galaxy. NGC 1605 presents an unusual morphology with a sparse stellar distribution and a double core in close angular proximity. The 2MASS and Gaia-EDR3 field-star decontaminated colour-magnitude diagrams (CMDs) show two distinct stellar populations located at the same heliocentric distance of ∼ 2.6 kpc suggesting that there are two clusters in the region, NGC 1605a and NGC 1605b, with ages of 2 Gyr and 600 Myr, respectively. Both Gaia parallax and PM distributions are compact and very similar indicating that they are open clusters (OCs) and share the same kinematics. The large age difference, 1.4 Gyr, points to a formation by tidal capture during a close encounter and the close spatial proximity and similar kinematics suggest an ongoing merger event. There are some prominent tidal debris that appear to trace the clusters' orbits during the close encounter and, unexpectedly, some of them appear to be bound structures, which may suggest that additionaly to the evaporation the merging clusters are being broken apart into smaller structures by the combination of Galactic disk, Perseus arm, and mutual tidal interactions. In this sense, the newly found binary cluster may be a key object on the observational validation of theoretical studies on binary cluster pairs formation by tidal capture as well as in the formation of massive clusters by merging, and tidal disruption of stellar systems.
This work communicates the discovery of a binary open cluster within the Galaxy. NGC 1605 present... more This work communicates the discovery of a binary open cluster within the Galaxy. NGC 1605 presents an unusual morphology with a sparse stellar distribution and a double core in close angular proximity. The 2MASS and Gaia-EDR3 field-star decontaminated colour-magnitude diagrams (CMDs) show two distinct stellar populations located at the same heliocentric distance of ∼2.6 kpc suggesting that there are two clusters in the region, NGC 1605a and NGC 1605b, with ages of 2 Gyr and 600 Myr, respectively. Both Gaia parallax and PM distributions are compact and very similar indicating that they are open clusters (OCs) and share the same kinematics. The large age difference, 1.4 Gyr, points to a formation by tidal capture during a close encounter and the close spatial proximity and similar kinematics suggest an ongoing merger event. There are some prominent tidal debris that appear to trace the clusters' orbits during the close encounter and, unexpectedly, some of them appear to be bound s...
Astronomy and Astrophysics, 2010
Aims. In this work we investigate the nature of 50 overdensities from the catalogue of Froebrich,... more Aims. In this work we investigate the nature of 50 overdensities from the catalogue of Froebrich, Scholz, and Raftery (FSR) projected towards the Galactic anticentre, in the sector 160 • ≤ ≤ 200 •. The sample contains candidates with |b| ≤ 20 • classified by FSR as probable open cluster (OC) and labelled with quality flags 2 and 3. Our main purpose is to determine the nature of these OC candidates and the fraction of these objects that are unknown OCs, as well as to derive astrophysical parameters (age, reddening, distance, core and cluster radii) for the clusters and to investigate the relationship among parameters. Methods. The analysis is based on 2MASS J, (J − H), and (J − K s) colour-magnitude diagrams (CMDs), and stellar radial density profiles (RDPs) built with decontamination tools. The tools are a field star decontamination algorithm, used to uncover the cluster's intrinsic CMD morphology, and colour-magnitude filters to isolate stars with a high probability of being cluster members.
Astronomy & Astrophysics, 2016
Context. Until recently it was thought that high Galactic latitude clouds were a non-star-forming... more Context. Until recently it was thought that high Galactic latitude clouds were a non-star-forming ensemble. However, in a previous study we reported the discovery of two embedded clusters (ECs) far away from the Galactic plane (∼5 kpc). In our recent star cluster catalogue we provided additional high and intermediate latitude cluster candidates. Aims. This work aims to clarify whether our previous detection of star clusters far away from the disc represents just an episodic event or whether star cluster formation is currently a systematic phenomenon in the Galactic halo. We analyse the nature of four clusters found in our recent catalogue and report the discovery of three new ECs each with an unusually high latitude and distance from the Galactic disc midplane. Methods. The analysis is based on 2MASS and WISE colour-magnitude diagrams (CMDs), and stellar radial density profiles (RDPs). The CMDs are built by applying a field-star decontamination procedure, which uncovers the cluster's intrinsic CMD morphology. Results. All of these clusters are younger than 5 Myr. The high-latitude ECs C 932, C 934, and C 939 appear to be related to a cloud complex about 5 kpc below the Galactic disc, under the Local arm. The other clusters are above the disc, C 1074 and C 1100 with a vertical distance of ∼3 kpc, C 1099 with ∼2 kpc, and C 1101 with ∼1.8 kpc. Conclusions. According to the derived parameters ECs located below and above the disc occur, which gives evidence of widespread star cluster formation throughout the Galactic halo. This study therefore represents a paradigm shift, by demonstrating that a sterile halo must now be understood as a host for ongoing star formation. The origin and fate of these ECs remain open. There are two possibilities for their origin, Galactic fountains or infall. The discovery of ECs far from the disc suggests that the Galactic halo is more actively forming stars than previously thought. Furthermore, since most ECs do not survive the infant mortality, stars may be raining from the halo into the disc, and/or the halo may be harbouring generations of stars formed in clusters like those detected in our survey.
RENOTE
Este trabalho proporciona aos alunos, a oportunidade de desenvolver a capacidade de estabelecer r... more Este trabalho proporciona aos alunos, a oportunidade de desenvolver a capacidade de estabelecer relações, entre diferentes campos do conhecimento, através de atividades que envolvem Matemática e Física. Envolvemos os alunos em uma série de atividades, que os levou a entender o conceito de função, particularmente a função de primeiro grau e suas aplicações. Iniciamos o estudo das funções com uma abordagem experimental que relaciona o estudo do movimento uniforme na Física com o estudo da função de primeiro grau na Matemática. O software Winplot foi posteriormente utilizado para consolidar o conceito de função, bem como analisar o efeito no gráfico da variação dos parâmetros na equação que o descreve. Finalmente, os alunos foram convidados a selecionar e analisar gráficos de fontes publicadas (por exemplo, jornais e revistas) aplicando as habilidades desenvolvidas.
The Astrophysical Journal
Monthly Notices of the Royal Astronomical Society, 2015
We report the discovery of 652 star clusters, stellar groups and candidates in the Milky Way with... more We report the discovery of 652 star clusters, stellar groups and candidates in the Milky Way with WISE. Most of the objects are projected close to Galactic Plane and are embedded clusters. The present sample complements a similar study (Paper I) which provided 437 star clusters and alike. We find evidence that star formation processes span a wide range of sizes, from populous dense clusters to small compact embedded ones, sparse stellar groups or in relative isolation. The present list indicates multiple stellar generations during the embedded phase, with giant molecular clouds collapsing into several clumps composing an embedded cluster aggregate. We investigate the field star decontaminated Colour Magnitude Diagrams and Radial Density Profiles of 9 cluster candidates in the list, and derive their parameters, confirming them as embedded clusters.
We analyse 20 star cluster candidates projected mostly in the bulge direction (|ℓ| < 60 •). The s... more We analyse 20 star cluster candidates projected mostly in the bulge direction (|ℓ| < 60 •). The sample contains all candidates in that sector classified by Froebrich, Scholz & Raftery (2007) with quality flags denoting high probability of being star clusters. Bulge contamination in the colour-magnitude diagrams (CMDs) is in general important, while at lower Galactic latitudes disk stars contribute as well. Properties of the candidates are investigated with 2MASS CMDs and stellar radial density profiles (RDPs) built with field star decontaminated photometry. To uncover the nature of the structures we decontaminate the CMDs from field stars using tools that we previously developed to deal with objects in dense fields. We confirm in all cases excesses in the RDPs with respect to the background level, as expected from the method the candidates were originally selected. CMDs and RDPs taken together revealed 6 open clusters, 5 uncertain cases that require deeper observations, while 9 objects are possibly field density fluctuations.
Agradeço aos meus pais que tornaram os meus sonhos possíveis. Especialmente ao meu pai por me per... more Agradeço aos meus pais que tornaram os meus sonhos possíveis. Especialmente ao meu pai por me permitir optar por estudar e por sempre deixar claro quais eram os nossos papéis. Aos meus irmãos e demais familiares pela parceria tanto nos bons quanto nos maus momentos. Agradeçoà minha esposa Josy pelo carinho, dedicação, incentivo e principalmente paciência ao longo dos anos de mestrado e doutorado. Agradeço também aos pais da Josy (José e Lecy) por entenderem a sua ausência nosúltimos anos. Aos meus orientadores Drs. Charles Bonatto e Eduardo Bica pelo suporte, aprendizado e excelente orientação. Agradeço a todos que de alguma forma contribuiram para a minha formação, principalmente os professores. Em especial ao professor Dr. Basílio X. Santiago com quem cursei a maioria das disciplinas de Astronomia. Aos colegas da sala M207 pela convivência e troca de ideias. Aos colegas da Astronomia que de alguma forma participaram deste trabalho-destaco Sandro Javiel e Rogemar Riffel e espero que os demais se sintam representados. Aos amigos dos churrascos com cervejas (ou o contrário) dos finais de semana. Por fim, agradeço ao S.C. Internacional pelas tantas alegrias dosúltimos anos. E bom ser colorado! Denilso da S. Camargo Universidade Federal do Rio Grande do Sul Abril 2012 Construímos diagramas que relacionam cores, magnitudes e idades para diferentes metalicidades e analisamos os efeitos da metalicidade na evolução dos aglomerados. Aparentemente, os aglomerados de maior metalicidade evoluem mais rapidamente do que os de menor metalicidade. Usando os diagramas construídos derivamos idades de OCs da Galáxia. Para finalizar, analisamos a distribuição de idades dos aglomerados do anticentro Galáctico. Baseando-se nessa distribuição deduzimos que ∼ 80% dos aglomerados dessa região são dissolvidos em menos de 1 Gyr, e estimamos uma idade média de ∼ 570 Myr para esses objetos. Além disso, estimamos uma escala de tempo entre 2 e 5 Myr para a fase de ECs dos aglomerados na direção do anti-centro.
Monthly Notices of the Royal Astronomical Society, 2015
In the present work we investigate the properties of 18 embedded clusters (ECs). The sample inclu... more In the present work we investigate the properties of 18 embedded clusters (ECs). The sample includes 11 previously known clusters and we report the discovery of 7 ECs on WISE images, thus complementing our recent list of 437 new clusters. The main goal is to use such clusters to shed new light on the Galactic structure by tracing the spiral arms with cluster distances. Our results favour a four-armed spiral pattern tracing three arms, Sagitarius-Carina, Perseus, and the Outer arm. The Sagitarius-Carina spiral arm is probed in the borderline of the third and fourth quadrants at a distance from the Galactic centre of d 1 ∼ 6.4 kpc adopting R ⊙ = 7.2 kpc, or d 2 ∼ 7.2 kpc for R ⊙ = 8.0 kpc. Most ECs in our sample are located in the Perseus arm that is traced in the second and third quadrants and appear to be at Galactocentric distances in the range d 1 = 9 − 10.5 kpc or d 2 = 9.8 − 11.3 kpc. Dolidze 25, Bochum 2, and Camargo 445 are located in the Outer arm that extends along the second and third Galactic quadrants with a distance from the Galactic centre in the range of d 1 = 12.5 − 14.5 kpc or d 2 = 13.5 − 15.5 kpc. We find further evidence that in the Galaxy ECs are predominantly located within the thin disc and along spiral arms. They are excellent tools for tracing these Galactic features and therefore new searches for ECs can contribute to a better understanding of the Galactic structure. We also report an EC aggregate located in the Perseus arm.
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Papers by Denilso Camargo