Mass-luminosity distribution and physical conditions of ionized gas in NGC 4575

Photographic photometry and spectroscopic observations of NGC 4575 suggest it to be a galaxy of reduced dimensionsD×d=14.4×13.5 kpc and of high luminosityM=–20.7. The rotation curve was also determined. Assuming a model of three homogeneous similar spheroids, we derived the density and mass distribution, and their total mass was found to be _T =2.33 × 10¹⁰.The mass luminosity ratio does not vary withinr=24, indicating that the stellar composition is similar within it, and the ratio _T / _T 1 suggests that this object contains a high proportion of young stars. From the emission lines it is found that the electronic density Ne100 cm^–3 is relatively low in the HII regions. The abundance ratiosN(N)/N(S) andN(N)/N(H) for the nucleus and two emission regions were also derived.     

A comparative study of the stellar content in normal and active nuclei of spiral galaxies

We present spectrophotometry andUBV photometry of the central region of spiral galaxies. The sample consists of the Seyfert galaxies NGC 1566, 3783 and IC 4329A; NGC 1097, 2997, and 5236 containing peculiar nucleus and NGC 5530, 5643, and 6699 with normal nucleus.The stellar composition of the nuclei was derived by treating the equivalent widths of a sample of absorption lines with the method of constrained nonlinear optimization. The observed continua and theUBV colours were compared with the theoretical results in order to obtain the internal reddening and the contribution of the hot gas or non-thermal radiation. The age of the last cycle of star formation, the internal absorption and the theoretical relations M/L and H/K Caii present differences among the three types of nuclei.     

The stellar populations of starburst galaxies through near-infrared spectroscopy

We study the central (inner few hundred parsecs) stellar populations of four starburst galaxies (NGC 34, 1614, 3310 and 7714) in the near-infrared (NIR), from 0.8 to 2.4 μm, by fitting combinations of stellar population models of various ages and metallicities. The NIR spectra of these galaxies feature many absorption lines. For the first time, we fit simultaneously as much as 15 absorption features in the NIR. The observed spectra are best explained by stellar populations containing a sizable amount (20–56 per cent by mass) of ∼1-Gyr-old stellar population with thermally pulsing asymptotic giant branch stars. We found that the metallicity of the stars which dominates the light is solar. Metallicities substantially different from solar give a worse fit. Though the ages and metallicities we estimate using the NIR spectroscopy are in agreement with values from the literature based on the ultraviolet/optical, we find older ages and a larger age spread. This may be due to the fact that the optical is mostly sensitive to the last episode of star formation, while the NIR better maintains the record of previous stellar generations. Another interesting result is that the reddening estimated from the whole NIR spectrum is considerably lower than that based on emission lines. Finally, we find a good agreement of the free emission-line spectrum with photoionization models, using as input spectral energy distribution the synthetic composite template we derived as best fit.     

DDO photometry and metallic abundances of E and SO galaxies and globular clusters of the LMC and SMC

Metallicity of 8 E and SO galaxies as well as that of red globulars of the LMC and SMC were obtained by means of DDO integrated photometry calibrated with galactic globular clusters (Bica and Pastoriza, 1983; hereafter referred to as Paper I). A correction was obtained in order to reduce the colors of the galaxies to zero redshift. The relation metallicity vsM _V for the galaxies is analyzed (adding to our sample the observations of McClure and Van den Bergh, 1968; and Faber, 1973a). For the Magellanic Clouds we found metallicity ranging from intermediate to poor.     

Artisanal fishing in Andalusia (and III): “The Day After…”

During the past 5 years researchers from the University of Cádiz have carried out several studies on artisanal fishing in Andalusia, with the object of determining the state of the fleet and safety on board vessels. These studies have been financed largely with help from the European Union. In this third approach to the topic, the census of the fleet is updated and the changes that have taken place are considered from two perspectives: the influence of the policies implemented by the various governmental authorities, and the dynamic of the new commercial scenarios. For this study special emphasis is given to those communities in the SW of the province of Cádiz where the policies associated with the Treaties with the Kingdom of Morocco have had a decisive impact.     

CCD photometry of seyfert galaxies

Morphology and elliptically averaged luminosity profiles have been derived from CCD surface photometry of thirteen seyfert galaxies. ApparentV andI magnitudes,V-I colour index, as well as absolute Mv and MI magnitudes have been calculatedV andI luminosity profiles of Mk 10, Mk 79, Mk 358, Mk 618, Mk 352, and Mk 110, are adjusted by the usual model bulge plus disk with structural parameters comparable to those observed in normal spirals. The averaged luminosity profiles of Mk 50, Mk 124, Mk 348, and 3C227 are fitted byr ^–1/4 law with structural parameters similar to those observed in ellipticals and red compact galaxies. Mk 42 and NGC 985 show disturbed luminosity profiles.     

On the nature of NGC 5253

It is proposed that NGC 5253 has been the place of a violent event like M82. The presence of a long jet and the characteristics of its nuclear complex points to this interpretation.