相关论文: Confidence levels of evolutionary synthesis models
Most structural and evolutionary properties of galaxies strongly rely on the stellar initial mass function (IMF), namely the distribution of the stellar mass formed in each episode of star formation. As the IMF shapes the stellar population…
New estimates of globular cluster distances, combined with revised ranges for input parameters in stellar evolution codes and recent estimates of the earliest redshift of cluster formation allow us to derive a new 95% confidence level lower…
We compute population synthesis models for the variation of H-alpha absorption indices (HaA and HaF), as a function of age and metallicity in old stellar systems. The models are based on the STELIB spectral library, and defined at…
The H alpha equivalent width (EW) is the ratio of the H alpha flux to the continuum at 6565{\AA}. In normal star forming galaxies the H alpha flux is dominated by reprocessed photons from stars with masses greater than 10 M_o and the…
We present homogeneous age determinations for a large sample of 55 Galactic globular clusters, which constitute about 30% of the total Galactic population. A study of their age distribution reveals that all clusters from the most metal poor…
Observations have not yielded convincing results concerning the form of the stellar initial mass function (IMF) or its variations in space and time, so it is proposed that theoretical models may provide useful guidance. Several classes of…
Determining the properties of old stellar populations (those with age >1 Gyr) has long involved the comparison of their integrated light, either in the form of photometry or spectroscopic indexes, with empirical or synthetic templates. Here…
We investigate the dynamical evolution of star clusters during their formation, assuming that they are born from a turbulent starless clump of a given mass that is embedded within a parent self-gravitating molecular cloud characterized by a…
Star clusters are born in a highly compact configuration, typically with radii of less than about 1 pc roughly independently of mass. Since the star-formation efficiency is less than 50 per cent by observation and because the residual gas…
The initial mass function (IMF) succinctly characterizes a stellar population, provides a statistical measure of the end result of the star-formation process, and informs our under- standing of the structure and dynamical evolution of…
In this contribution we investigate how to describe the results and usage of evolutionary synthesis models. In particular, we look for an explicit and quantitative description of the parameter space of synthesis models and the evaluation of…
Recent observations have revealed a variety of young star clusters, including embedded systems, young massive clusters, and associations. We study the formation and dynamical evolution of these clusters using a combination of simulations…
We present a novel and easy-to-use method for calibrating error-rate based confidence intervals to evidence-based support intervals. Support intervals are obtained from inverting Bayes factors based on a parameter estimate and its standard…
We analyse multi-wavelength observations of 32 young star clusters and associations in M33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7), using ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (HI)…
The uncertainties in the modelling of some important inputs of stellar evolution must be taken into account for a correct interpretation, both of the HR diagrams of individual stars, and of the integrated colors, of stellar clusters. After…
Emission-line stars in young open clusters are identified to study their properties, as a function of age, spectral type and their evolutionary state. 207 open star clusters were observed using slitless spectroscopy method and 157 emission…
Some of the youngest stars (age $\lesssim 10$ Myr) are clustered, while many others are observed scattered throughout star forming regions or in complete isolation. It has been intensively debated whether the scattered or isolated stars…
Molecular clouds at very high latitudes ($b > 60^o$) away from the Galactic plane are considered rare and not conventional sites of star formation. Contrary to this, the recent discovery of high latitude embedded Clusters can possibly…
We summarize the principles and fundamental ingredients of evolutionary synthesis models, which are stellar evolution, stellar atmospheres, the IMF, star-formation histories, nebular emission, and also attenuation from the ISM and IGM. The…
The study of young stellar populations has revealed that most stars are in binary or higher order multiple systems. In this study the influence on the stellar initial mass function (IMF) of large quantities of unresolved multiple massive…