English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Aims. We study how IMF sampling affects the ionizing flux and emission linespectra of low mass stellar clusters. Methods. We performed 2 x 10^6 MonteCarlo simulations of zero-age solar-metallicity stellar clusters covering the20 - 10^6 Mo mass range. We study the distribution of cluster stellar masses,Mclus, ionizing fluxes, Q(H0), and effective temperatures, Tclus. We computephotoionization models that broadly describe the results of the simulations andcompare them with photoionization grids. Results. Our main results are: (a) Alarge number of low mass clusters (80% for Mclus = 100 Mo) are unable to forman H ii region. (b) There are a few overluminous stellar clusters that form Hii regions. These overluminous clusters preserve statistically the mean valueof <Q(H0)> obtained by synthesis models, but the mean value cannot be used as adescription of particular clusters. (c) The ionizing continuum of clusters withMclus < 10^4 Mo is more accurately described by an individual star withself-consistent effective temperature(T*) and Q(H0) than by the ensemble ofstars (or a cluster Tclus) produced by synthesis models. (d)Photoionizationgrids of stellar clusters can not be used to derive the global properties oflow mass clusters. Conclusions. Although variations in the upper mass limit,mup, of the IMF would reproduce the effects of IMF sampling, we find that an adhoc law that relates mup to Mclus in the modelling of stellar clusters isuseless, since: (a) it does not cover the whole range of possible cases, and(b) the modelling of stellar clusters with an IMF is motivated by the need toderive the global properties of the cluster: however, in clusters affected bysampling effects we have no access to global information of the cluster butonly particular information about a few individual stars.

Modeling the ionizing spectra of H ii regions: individual stars versus stellar ensembles