Recent Talks
List of all the talks in the archive, sorted by date.
Tuesday March 24, 2009
Dr. Lia Athanassoula
Laboratoire d'Astrophysique de Marseille, France
Abstract
I will propose a new theory to explain the formation and properties of rings and spirals in barred galaxies, focusing on a comparison of theoretical results to observations and giving some predictions for further comparisons. This theory can account for both spirals and rings, the latter both inner and outer. The model outer rings have the observed R1, R_1', R_2, R_2' and R_1R_2 morphologies, including the dimples near the direction of the bar major axis. It explains why the vast majority of spirals in barred galaxies are two armed and trailing and I will discuss what it takes for higher multiplicity arms to form. The shapes of observed and theoretical spirals agree and the theory predicts that stronger non-axisymmetric forcings at and somewhat beyond corotation will drive more open spirals. I will compare the ratio of ring diameters in theory and in observations and predict that more elliptical rings will correspond to stronger forcings. This theory also provides the right building blocks for the rectangular-like bar outline and for ansae.
Friday March 20, 2009
Mr. Jorge Pérez Prieto
Instituto de Astrofísica de Canarias, Spain
Abstract
Thursday March 19, 2009
Mr. Ruymán Azzollini
Instituto de Astrofísica de Canarias, Spain; Instituto de Estructura de la Materia, CSIC, Spain
Abstract
Thursday March 19, 2009
Dr. Fernando Comerón
European Southern Observatory, Garching, Germany
Abstract
Most studies of the stellar and substellar populations of star forming regions rely on the identification of the signatures of accretion, outflows, circumstellar dust, or activity characteristic of the early stages of stellar evolution. However, the decay of these observational signatures with time limits our ability to understand the complete star forming history of young aggregates, and to obtain unbiased samples of young stellar objects at different stages of disk evolution. I will present the results of a wide-area study of the stellar population of selected clouds in the nearby Lupus star forming region, initially defined to complement the data obtained by the Spitzer Space Observatory Legacy Program “From molecular cores to planet-forming disks”. When combined with 2MASS photometry, our data allow us to fit the spectral energy distributions of well over 150,000 sources seen in that direction, and to identify possible new members based on their photospheric fluxes alone, with independence of the display of signposts of youth. In this way we identify a very clear signature of the existence of a surprisingly numerous and thus far unrecognized population of cool members of Lupus 1 and 3, which is absent from Lupus 4.The approximately 130 new members that we identify show that Lupus 1 and 3 have been forming low mass stars in numbers comparable to, or even exceeding in Lupus 1, those revealed by recent sensitive surveys based on the signposts of youth. We hypothesize on several possibilities for the origin of this population that may account for its puzzling properties of general lack of disks, coevality with the disk-bearing population, and preferential off-cloud location, which hint at a picture more complex and interesting than the quiescent formation inside dense molecular clouds.
Thursday March 19, 2009
Mr. Ruymán Azzollini
Instituto de Astrofísica de Canarias, Spain; Instituto de Estructura de la Materia, CSIC, Spain
Abstract
Wednesday March 18, 2009
Mr. Ruymán Azzollini.
Instituto de Astrofísica de Canarias, Spain; Instituto de Estructura de la Materia, CSIC, Spain
Abstract
Wednesday March 18, 2009
Dr. Ana Chies Santos
Astronomical Institute Utrecht, the Netherlands
Abstract
The colour distribution of globular cluster (GC) systems in the majority of galaxies is bi/multimodal in optical colours. It is widely accepted that multiple populations differing in metallicity exist implying different mechanisms/epochs of star formation, with small age differences still being allowed due to the large current uncertainties. Recently Yoon, Yi and Lee (2006) challenged this interpretation stating that the metallicity bimodality is an artifact of the horizontal branch (HB) morphologies that can transform a unimodal metallicity distribution in a bimodal (optical) colour distribution. The combination of optical and near-infrared (NIR) colours can in principal break the age/metallicity degeneracy inherent in optical colours alone, allowing age estimates for a large sample of GCs possible at the same time. It has been shown that the colours that best represent the true metallicity distributions are the combination of optical and NIR (eg. Puzia et al. 2002, Cantiello & Blakeslee 2007). Therefore studying GCs in the NIR is crucial to reveal their true metallicity distributions. We are currently building a homogeneous optical/NIR data set of GC systems in a large sample of elliptical and lenticular galaxies. I will present the sample, an attempt to estimate overall ages and metallicities for the GC systems and the optical/NIR colour distributions.
Wednesday March 18, 2009
Mr. Ruymán Azzollini
Instituto de Astrofísica de Canarias, Spain; Instituto de Estructura de la Materia, CSIC, Spain
Abstract
Tuesday March 17, 2009
Mr. Jorge Pérez Prieto
Instituto de Astrofísica de Canarias, Spain
Abstract
Tuesday March 17, 2009
Mr. Jorge Pérez Prieto
Instituto de Astrofísica de Canarias, Spain
Abstract
Upcoming talks
- UNDARK kick offThursday October 10, 2024 - 9:15 GMT+1 (Aula)
- TBDDr. Nikki ArendseThursday October 17, 2024 - 10:30 GMT+1 (Aula)
Recent Colloquia
Recent Talks
