Surface magnetic fields on two accreting T Tauri stars: CV Cha and CR Cha

We have produced brightness and magnetic field maps of the surfaces of CV Cha and CR Cha: two actively accreting G and K-type T Tauri stars in the Chamaeleon I star-forming cloud with ages of 3-5 Myr. Our magnetic field maps show evidence for strong, complex multi-polar fields similar to those obtained for young rapidly rotating main sequence stars. Brightness maps indicate the presence of dark polar caps and low latitude spots -- these brightness maps are very similar to those obtained for other pre-main sequence and rapidly rotating main sequence stars. Only two other classical T Tauri stars have been studied using similar techniques so far: V2129 Oph and BP Tau. CV Cha and CR Cha show magnetic field patterns that are significantly more complex than those recovered for BP Tau, a fully convective T Tauri star. We discuss possible reasons for this difference and suggest that the complexity of the stellar magnetic field is related to the convection zone; with more complex fields being found in T Tauri stars with radiative cores (V2129 Oph, CV Cha and CR Cha). However, it is clearly necessary to conduct magnetic field studies of T Tauri star systems, exploring a wide range of stellar parameters in order to establish how they affect magnetic field generation, and thus how these magnetic fields are likely to affect the evolution of T Tauri star systems as they approach the main sequence.Comment: Accepted for publication by MNRAS: 15 pages, 11 figure

Exploring the magnetic topologies of cool stars

Magnetic fields of cool stars can be directly investigated through the study of the Zeeman effect on photospheric spectral lines using several approaches. With spectroscopic measurement in unpolarised light, the total magnetic flux averaged over the stellar disc can be derived but very little information on the field geometry is available. Spectropolarimetry provides a complementary information on the large-scale magnetic topology. With Zeeman-Doppler Imaging (ZDI), this information can be retrieved to produce a map of the vector magnetic field at the surface of the star, and in particular to assess the relative importance of the poloidal and toroidal components as well as the degree of axisymmetry of the field distribution. The development of high-performance spectropolarimeters associated with multi-lines techniques and ZDI allows us to explore magnetic topologies throughout the Hertzsprung-Russel diagram, on stars spanning a wide range of mass, age and rotation period. These observations bring novel constraints on magnetic field generation by dynamo effect in cool stars. In particular, the study of solar twins brings new insight on the impact of rotation on the solar dynamo, whereas the detection of strong and stable dipolar magnetic fields on fully convective stars questions the precise role of the tachocline in this process.Postprin

Abdominal Obesity Associated To Medical-Related Absenteeism At A Company Of Metal-Mechanical Industry In Cali, Colombia

Con el objetivo de examinar la frecuencia de obesidad abdominal y el ausentismo laboral por causa médica, se realizó un estudio transversal en 185 varones pertenecientes a una industria metalmecánica. En ellos, además de datos sociodemográficos, se recogió datos antropométricos y se midió la circunferencia de cintura (CC) en centímetros como indicador de obesidad abdominal. Se encontró, además de una alta frecuencia de obesidad abdominal (28,7%), que los trabajadores con obesidad abdominal presentaron mayor frecuencia, mayor tiempo y mayores costos por las incapacidades médicas. Se concluye que la obesidad abdominal en esta muestra fue altamente frecuente; no obstante, al tratarse de un riesgo reversible, las empresas podrían beneficiarse, en términos de ausentismo laboral, de programas preventivo promocionales destinados a controlar este problemaThe aim of this study was examined the abdominal obesity prevalence and association with medical-related absenteeism. A cross-sectional study in 185 men from the metal-mechanical industry was conducted. Sociodemografic and antropometrics data of was gathered, waist circumference was measured as an indicator of abdominal obesity. The prevalence of central obesity was 28.7 %. Subjects with higher values of central obesity showed higher frequency, higher duration and higher costs of medical-related absenteeism, however, this relationship was not significant. We conclude that abdominal obesity is highly frequent in this sample; however, since it’s a reversible risk, enterprises could get benefits from preventive and promotional programs destiny to control this problem