Study of the Helium Enrichment in Globular Clusters

Globular clusters (GCs) are spheroidal concentrations typically containing of the order of 10^5 to 10^6, predominantly old, stars. Historically, they have been considered as the closest counterparts of the idealized concept of "simple stellar populations." However, some recent observations suggest than, at least in some GCs, some stars are present that have been formed with material processed by a previous generation of stars. In this sense, it has also been suggested that such material might be enriched in helium, and that blue horizontal branch stars in some GCs should accordingly be the natural progeny of such helium-enhanced stars. In this contribution we show that, at least in the case of M3 (NGC 5272), the suggested level of helium enrichment is not supported by the available, high-precision observations.Comment: 4 pages, 2 figures. To appear in the proceedings of IAU Symp. 262 (ed. G. Bruzual & S. Charlot

New Galactic multi-mode Cepheids from the ASAS-SN Survey

A systematic search for multi-mode Cepheids using the database of the ASAS-SN survey has led to the detection of thirteen new double-mode and two triple-mode Cepheids in the Galactic disk. These discoveries have increased the number of Galactic disk multi-mode Cepheids by 33%. One of the new triple-mode variables pulsates simultaneously in the fundamental and in the first and the second radial overtone modes and the other in the first three radial overtone modes. Overtone triple-mode Cepheids were identified only in the Galactic bulge and in the Large and Small Magellanic Clouds previously.Comment: Accepted for publication in Acta Astronomica; 10 pages, 2 figures, 3 tables; v2: corrected minor typos and added clarification about the ASAS-SN classification probability parameter

CIDADES MÉDIAS, GLOBALIZAÇÃO E INTERAÇÕES ESPACIAS INTERESCALARES: OS MINIDISTRITOS INDUSTRIAIS, COMERCIAIS E DE SERVIÇOS EM SÃO JOSÉ DO RIO PRETO

As cidades médias brasileiras passam por transformações de suas funções e de seus papéis desempenhados na rede urbana conforme a ampliação das interações espaciais interescalares promovidas, de um lado, pelas estratégias locais/regionais e, por outro, pelo avanço do processo de globalização. Elas são espaços urbanos onde, cada vez mais, os agentes econômicos buscam promover seu capital produtivo e ampliar seus mercados de consumo. Diante disso, nestas cidades, estes agentes, que também podem estar aliados aos de caráter público, atuam para manter a reprodução do capital frente à capacidade de ampliação dos grandes grupos empresariais. Dentre as estratégias articuladas conjuntamente pelos agentes locais, ressaltamos a experiência dos minidistritos industriais, comerciais e de serviços na cidade de São José do Rio Preto/SP, como estratégia de fortalecer e criar outras empresas de capital local/regional, ao mesmo tempo em que se promove a atuação de agentes econômicos das escalas nacional e internacional

A Superwind from Early Post-Red Giant Stars?

We suggest that the gap observed at 20,000 K in the horizontal branches of several Galactic globular clusters is caused by a small amount of extra mass loss which occurs when stars start to "peel off" the red giant branch (RGB), i.e., when their effective temperature starts to increase, even though they may still be on the RGB. We show that the envelope structure of RGB stars which start to peel off is similar to that of late asymptotic giant branch stars known to have a super-wind phase. An analogous super-wind in the RGB peel-off stars could easily lead to the observed gap in the distribution of the hottest HB stars.Comment: 9 pages; Accepted by ApJ Letters; Available also at http://www.astro.puc.cl/~mcatelan

Uncloaking globular clusters in the inner Galaxy

Extensive photometric studies of the globular clusters located towards the center of the Milky Way have been historically neglected. The presence of patchy differential reddening in front of these clusters has proven to be a significant obstacle to their detailed study. We present here a well-defined and reasonably homogeneous photometric database for 25 of the brightest Galactic globular clusters located in the direction of the inner Galaxy. These data were obtained in the B, V, and I bands using the Magellan 6.5m telescope and the Hubble Space Telescope. A new technique is extensively used in this paper to map the differential reddening in the individual cluster fields, and to produce cleaner, dereddened color-magnitude diagrams for all the clusters in the database. Subsequent papers will detail the astrophysical analysis of the cluster populations, and the properties of the obscuring material along the clusters' lines of sight.Comment: Accepted for publication in A

UMA PROPOSTA METODOLÓGICA PARA O ESTUDO DA MOBILIDADE NO ÂMBITO DA GEOGRAFIA URBANA

Beyond the central-peripheral logic that characterized the structuring of the urban center in Brazil, specially from the mid-20th century onwards, other logics are identified that complexifies the structuring of their spaces, marked by the deepening of socio-spatial inequalities. In this context, seeking to understand the passage from the predominantly center-peripheral socio-spatial logic to the fragmented socio-spatial logic, having as an empirical dimension the socio-spatial mobility of people in the cities of Campo Grande and Dourados in Mato Grosso do Sul, we present a methodology using audiovisual resources through an action camera articulated with the tracked routes carried out with people with focus on capturing the movement and its contents in their socio-spatial mobilities. We detail this methodology by presenting the steps, procedures and materials produced. We consider that the results obtained through it are substantially different from those achieved by static procedures, because keep moving with the research subject is essentially different from capturing their movement from remote mechanisms, since the transitory experience of movement in urban space exposed to its multiple spatiotemporally marked events, combined with the activation of human senses, enables a more accurate reading of the countless conditions in which movement occurs.Para além da lógica centro-periférica que caracterizou a estruturação dos centros urbanos no Brasil sobretudo a partir de meados do século XX, identificam-se outras lógicas que complexificam a estruturação dos seus espaços, marcadas pelo aprofundamento das desigualdades socioespaciais. Nesse contexto, buscando compreender a passagem da lógica socioespacial predominantemente centro-periférica para a lógica socioespacial fragmentária, tendo como dimensão empírica a mobilidade socioespacial dos sujeitos nas cidades de Campo Grande e Dourados no Mato Grosso do Sul, apresentamos uma metodologia utilizando recursos audiovisuais por meio de câmera de ação articulado aos percursos acompanhados realizados com os sujeitos com foco na captação do movimento e de seus conteúdos em suas mobilidades socioespaciais. Detalhamos essa metodologia apresentando as etapas, os procedimentos e os materiais produzidos. Consideramos que os resultados obtidos por meio dela são substancialmente diferentes daqueles alcançados por procedimentos estáticos, pois estar em movimento com o sujeito da pesquisa é essencialmente diferente de capturar o seu movimento a partir de mecanismos remotos, visto que a experiência transitória do movimento no espaço urbano exposto aos seus múltiplos eventos marcados espaço-temporalmente, aliada a ativação dos sentidos humanos, possibilita uma leitura mais apurada das inúmeras condições nas quais o movimento ocorre.Mas allá de la lógica centro-periférica que caracterizó la estructuración de los centros urbanos en Brasil, sobre todo a partir de mediados del siglo XX, se identifican otras lógicas que complican la estructuración de sus espacios, marcados por la profundización de las desigualdades socioespaciales. En ese contexto, se busca comprender el paso de la lógica socioespacial predominantemente centro-periférica a la lógica socioespacial fragmentada, teniendo como dimensión empírica la movilidad socioespacial de los sujetos en las ciudades de Campo Grande y Dourados en Mato Grosso del Sur, presentamos una metodología que utiliza recursos audiovisuales a través de una cámara de acción articulada con los recorridos realizados con los sujetos con foco en capturar el movimiento y sus contenidos en sus movilidades socioespaciales. Detallamos esta metodología presentando las etapas, los procedimientos y los materiales producidos. Consideramos que los resultados logrados por esse medio son sustancialmente distintos a los logrados mediante procedimientos estáticos, ya que estar en movimiento con el sujeto de investigación es esencialmente diferente a captar su movimiento desde mecanismos remotos, ya que la experiencia transitoria del movimiento en el espacio urbano expuesto a sus múltiples eventos marcados espacio temporalmente, combinados con la activación de los sentidos humanos, permite una lectura más precisa de las innumerables condiciones en las que se produce el movimiento

Neutrino and axion bounds from the globular cluster M5 (NGC 5904)

The red-giant branch (RGB) in globular clusters is extended to larger brightness if the degenerate helium core loses too much energy in "dark channels." Based on a large set of archival observations, we provide high-precision photometry for the Galactic globular cluster M5 (NGC 5904), allowing for a detailed comparison between the observed tip of the RGB with predictions based on contemporary stellar evolution theory. In particular, we derive 95% confidence limits of $g_{ae}<4.3\times10^{-13}$ on the axion-electron coupling and $\mu_\nu<4.5\times10^{-12}\,\mu_{\rm B}$ (Bohr magneton $\mu_{\rm B}=e/2m_e$) on a neutrino dipole moment, based on a detailed analysis of statistical and systematic uncertainties. The cluster distance is the single largest source of uncertainty and can be improved in the future.Comment: 5 pages, 2 figures, accepted for publication in Physical Review Letter