137 research outputs found
Report on the ESO Workshop ''Spiral Structure in the Milky Way: Confronting Observations and Theory''
No full textThe main objectives of the workshop were to review current observational evidence for spiral arms in our Galaxy and confront them with models of spiral structure in order to arrive at a consistent picture. Of primary importance was to understand just what additional information is required to resolve outstanding issues related to the spiral structure in the Milky Way, especially as new survey instruments (e.g., ALMA, VISTA and VST) are coming online and major space missions like GAIA will be launched in the near future
Model-independent diagnostics of highly reddened Milky Way star clusters: age calibration
No full textContext: The next generation near- and mid-infrared Galactic surveys will yield a large number of new highly obscured star clusters. Detailed characterization of these new objects with spectroscopy is time-consuming.
Aims: Diagnostic tools that will be able to characterize clusters based only on the available photometry will be needed to study large samples of the newly found objects.
Methods: The brightness difference between the red clump and the main-sequence turn-off point have been used as a model-independent age calibrator for clusters with ages from a few 108 to 1010 yr in the optical. Here we apply for the first time the method in the near-infrared.
Results: We calibrated this difference in K-band, which is likely to be available for obscured clusters, and we apply it to a number of test clusters with photometry comparable to the one that will be yielded by the current or near-future surveys.
Conclusions: The new calibration yields reliable ages over the range of ages for which the red clump is present in clusters. The slope of the relation is smoother than that of the corresponding V-band relation, reducing the uncertainty in the age determinations with respect to the optical ones
Estudio en el infrarrojo cercano de agrupaciones estelares en M 83
No full textNear infrared photometric observations (JHKBr) have been made in the field of the galaxy M 83, reaching a magnitude limit K = 20. The quality of data has allowed the systematic search and identification of large numbers of stellar clusters which are intended to determine their fundamental param- eters, as the number of prospective members, reddening, age and luminosity function
On Our Multi-Wavelength Campaign of the 2011 Outburst of T Pyx
No full textThe well-known recurrent nova T Pyx has brightened by 7 magnitudes, starting on 2011 April 14, its first eruption since 1966. T Pyx is unique amongst recurrent novæ in being surrounded by a nebula formed of material ejected during previous eruptions. The latest eruption therefore offers the rare opportunity to observe a light echo sweeping through the existing shell, and a new one forming. The sudden exposure of the existing shell to high-energy light is expected to result in a change of the dust morphology as well as in the part destruction of molecules. We observe this process in the near- and mid-IR during several epochs using ESO's VLT instruments Sinfoni, Visir and Isaac. Unfortunately, in the data analysed so far we only have a tentative detection in Brα from the shell, so might in the end have to be content with upper limits for the emission from the various molecular bands and ionised lines
The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess
No full textRecent ground-based near-IR (NIR) studies of stellar clusters in nearby galaxies have suggested that young clusters remain embedded for 7-10 Myr in their progenitor molecular cloud, in conflict with optical-based studies which find that clusters are exposed after 1-3 Myr. Here, we investigate the role that spatial resolution plays in this apparent conflict. We use a recent catalogue of young (5000 M⊙) clusters in the nearby spiral galaxy, M83, along with Hubble Space Telescope (HST) imaging in the optical and NIR, and ground-based NIR imaging, to see how the colours (and hence estimated properties such as age and extinction) are affected by the aperture size employed, in order to simulate studies of differing resolution. We find that the NIR is heavily affected by the resolution, and when aperture sizes >40 pc are used, all young/blue clusters move redwards in colour space, which results in their appearance as heavily extincted clusters. However, this is due to contamination from nearby sources and nebular emission, and is not an extinction effect. Optical colours are much less affected by resolution. Due to the larger effect of contamination in the NIR, we find that, in some cases, clusters will appear to show NIR excess when large (>20 pc) apertures are used. Our results explain why few young (<6 Myr), low-extinction ({A_V}< 1 mag) clusters have been found in recent ground-based NIR studies of cluster populations, while many such clusters have been found in higher resolution HST-based studies. Additionally, resolution effects appear to (at least partially) explain the origin of the NIR excess that has been found in a number of extragalactic young massive clusters
A MAD view of Trumpler 14
No full textWe present adaptive optics (AO) near-infrared observations of the core of the Tr 14 cluster in the Carina region obtained with the ESO multi-conjugate AO demonstrator, MAD. Our campaign yields AO-corrected observations with an image quality of about 0.2 '' across the 2' field of view, which is the widest AO mosaic ever obtained. We detected almost 2000 sources spanning a dynamic range of 10 mag. The pre-main sequence (PMS) locus in the colour-magnitude diagram is well reproduced by Palla & Stahler isochrones with an age of 3 to 5 x 10(5) yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n(0) similar to 4.5(+/- 0.5) x 10(4) pc(-3) and estimate the total mass of the cluster to be about similar to 4.3(-1.5)(+3.3) x 10(3) M-circle dot, although contamination of the field of view might have a significant impact on the derived mass. We show that the pairing process is largely dominated by chance alignment so that physical pairs are difficult to disentangle from spurious ones based on our single epoch observation. Yet, we identify 150 likely bound pairs, 30% of these with a separation smaller than 0.5 '' (similar to 1300 AU). We further show that at the 2 sigma level massive stars have more companions than lower-mass stars and that those companions are respectively brighter on average, thus more massive. Finally, we find some hints of mass segregation for stars heavier than about 10 M-circle dot. If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster
Сказка о соционике, или Соционика в лисах
No full textThe fairy tale, in which process of discovery of own socionic type is shown, is presented. The attentive reader can recognise in heroes of a fairy tale — socionic types, and in prominent features of heroes — displays of work of functions in model A and dichotomic criteria. Also in a fairy tale intertype relationships and others socionic rules are reflected. In the end the author conducts socionic analysis of this fairy tale.Повесть-сказка, в которой показан процесс открытия собственного соционического типа. Внимательный читатель распознает в героях сказки соционические типы, а в характерных особенностях героев — проявления и работы функций в модели А и дихотомических признаков. Также в сказке отражены интертипные отношения и другие соционические закономерности. В конце автор проводит соционический анализ сказки
Сказка о соционике, или Соционика в лисах
No full textThe fairy tale, in which process of discovery of own socionic type is shown, is presented. The attentive reader can recognise in heroes of a fairy tale — socionic types, and in prominent features of heroes — displays of work of functions in model A and dichotomic criteria. Also in a fairy tale intertype relationships and others socionic rules are reflected. In the end the author conducts socionic analysis of this fairy tale.Повесть-сказка, в которой показан процесс открытия собственного соционического типа. Внимательный читатель распознает в героях сказки соционические типы, а в характерных особенностях героев — проявления и работы функций в модели А и дихотомических признаков. Также в сказке отражены интертипные отношения и другие соционические закономерности. В конце автор проводит соционический анализ сказки
Сказка о соционике, или Соционика в лисах
No full textThe fairy tale, in which process of discovery of own socionic type is shown, is presented. The attentive reader can recognise in heroes of a fairy tale — socionic types, and in prominent features of heroes — displays of work of functions in model A and dichotomic criteria. Also in a fairy tale intertype relationships and others socionic rules are reflected. In the end the author conducts socionic analysis of this fairy tale.Повесть-сказка, в которой показан процесс открытия собственного соционического типа. Внимательный читатель распознает в героях сказки соционические типы, а в характерных особенностях героев — проявления и работы функций в модели А и дихотомических признаков. Также в сказке отражены интертипные отношения и другие соционические закономерности. В конце автор проводит соционический анализ сказки
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