Context. Our understanding of stellar systems depends on the adopted interpretation of the initial mass function, IMF φ(m). Unfortunately, there is not a common interpretation of the IMF, which leads to different methodologies and diverging analysis of observational data. Aims: We study the correlation between the most massive star that a cluster

Context. In a probabilistic framework of the interpretation of the initial mass function (IMF), the IMF cannot be arbitrarily normalized to the total mass, ℳ, or number of stars, N, of the system. Hence, the inference of ℳ and N when partial information about the studied system is available must be revised (i.e., the contribution to the total

We present a study of the host bulge properties and their relations with the black hole mass for a sample of 10 intermediate-type active galactic nuclei (AGNs). Our sample consists mainly of early-type spirals, four of them hosting a bar. For 70+10 –17% of the galaxies, we have been able to determine the type of the bulge, and find that these

A sample of 10 nearby intermediate-type active galactic nuclei (AGNs) drawn from the Sloan Digital Sky Survey is presented. The aim of this work is to provide estimations of the black hole (BH) mass for the sample galaxies from the dynamics of the broad-line region. For this purpose, a detailed spectroscopic analysis of the objects was done. Using

We compare calculated intensities of lines of C II, N I, N II, O I and O II with a published deep spectroscopic survey of IC 418. Our calculations use a self-consistent nebular model and a synthetic spectrum of the central star atmosphere to take into account line excitation by continuum fluorescence and electron recombination. We found that the N

Aims: IRAS 19410+2336 is a young massive star forming region with an intense outflow activity. Outflows are frequently studied in the near-infrared (NIR) since the H2 emission in this wavelength range often traces the shocked molecular gas. However, the mechanisms behind the H2 emission detected in IRAS 19410+2336 have not been clarified yet. We

Aims: To show the importance of high-spatial resolution observations of H II regions when compared with observations obtained with larger apertures such as ISO, we present mid-infrared spectra of two Magellanic Cloud H II regions, N88 A and N160 A. Methods: We obtained mid-infrared (8-13 μm), long-slit spectra with TIMMI2 on the ESO 3.6 m telescope

Context: Infrared (IR) spectroscopy and imaging provide a prime tool to study the characteristics of polycyclic aromatic hydrocarbon (PAH) molecules and the mineralogy in regions of star formation. Herbig Ae/Be stars are known to have varying amounts of natal cloud material present in their vicinity. Aims: Our aim is to study the characteristics of

Aims: We study the ionized gas emission from the large scale shock region of Stephan's Quintet (SQ). Methods: We carried out integral field unit (IFU) optical spectroscopy on three pointings in and near the SQ shock. We used Potsdam MultiAperture Spectrometer (PMAS) on the 3.5 m Calar Alto telescope to obtain measures of emission lines that provide

Aims: We analyzed the resolved stellar population of the C component of the extremely metal-poor dwarf galaxy I Zw18 in order to evaluate its distance and star formation history as accurately as possible. In particular, we aimed at answering the question of whether this stellar population is young. Methods: We developed a probabilistic approach to

Aims: In this paper we study the influence of the ionizing cluster mass on the emission line spectrum of H ii regions in order to determine the influence of low mass clusters on the integrated emission line spectra of galaxies. Methods: For this purpose, we present a grid of photoionization models that covers metallicities from Z = 0.001 to Z = 0

Aims: We study how IMF sampling affects the ionizing flux and emission line spectra of low mass stellar clusters. Methods: We performed 2 × 106 Monte Carlo simulations of zero-age solar-metallicity stellar clusters covering the 20-106 M&sun; mass range. We study the distribution of cluster stellar masses, Mclus, ionizing fluxes, Q(H0), and

Nonionizing stellar continua are a potential source of photons for continuum pumping in the hydrogen Lyman transitions. In the environments where these transitions are optically thick, de-excitation occurs through higher series lines. As a result, the emitted flux in the affected lines has a fluorescent contribution in addition to the usual

The metallicities implied by collisionally excited lines (CELs) of heavy elements in H II regions are systematically lower than those implied by recombination lines (RLs) by factors of ~2, introducing uncertainties of the same order in the metallicities inferred for the interstellar medium of any star-forming galaxy. Most explanations of this

Context. Planetary nebulae (PNe) around Wolf-Rayet [WR] central stars ([WR]PNe) constitute a particular photoionized nebula class that represents about 10% of the PNe with classified central stars. Aims: We analyse deep high-resolution spectrophotometric data of 12 [WR] PNe. This sample of [WR]PNe represents the most extensive analysed so far, at

We present results from integral field spectroscopy with the Potsdam Multi-Aperture Spectrograph at the 3.5-m telescope at Calar Alto Observatory of the intense star-forming region [HL90] 111 at the centre of the starburst galaxy IC 10. We have obtained maps with a spatial sampling of 1 × 1 arcsec2= 3.9× 3.9 pc2 of different emission lines and

We present new, deep H I line and 20-cm radio-continuum data of the very puzzling blue compact dwarf galaxy NGC 5253, obtained with the Australia Telescope Compact Array as part of the 'Local Volume H I Survey' (LVHIS). Our low-resolution H I maps show, for the first time, the disturbed H I morphology that NGC 5253 possesses, including tails

We present the results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic HII regions: M8, M17 and NGC 7635. We study the spatial distributions of a large number of nebular parameters, such as the extinction coefficient, line fluxes, physical conditions and

We present the results of long-slit spectroscopy, in several positions, of the Orion Nebula. Our goal is to study the spatial distributions of a large number of nebular quantities, including line fluxes, physical conditions, and ionic abundances, at a spatial resolution of about 1". In particular, we have compared the O++ abundance determined from

We present results from integral field spectroscopy with the Potsdam Multi-Aperture Spectrograph of the head of the Herbig-Haro (HH) object HH202 with a spatial sampling of 1 × 1arcsec2. We have obtained maps of different emission lines, physical conditions - such as electron temperature and density - and ionic abundances from recombination and