Context. The Galactic H ii region NGC 2579 has stayed undeservedly unexplored due to identification problems which persisted until recently. Both NGC 2579 and its companion ESO 370-9 have been misclassified as planetary or reflection nebula, confused with each other and with other objects. Due to its high surface brightness, high excitation, angular size of few arcminutes and relatively low interstellar extinction, NGC 2579 is an ideal object for investigations in the optical range. Located in the outer Galaxy, NGC 2579 is an excellent object for studying the Galactic chemical abundance gradients. Aims. To present the first comprehensive observational study on the nebular and stellar properties of NGC 2579 and ESO 370-9, including the determination of electron temperature, density structure, chemical composition, kinematics, distance, and the identification and spectral classification of the ionizing stars, and to discuss the nature of ESO 370-9. Methods. Long slit spectrophotometric data in the optical range were used to derive the nebular electron temperature, density and chemical abundances and for the spectral classification of the ionizing star candidates. Hα and UBV CCD photometry was carried out to derive stellar distances from spectroscopic parallax and to measure the ionizing photon flux. Results. The chemical abundances of He, N, O, Ne, S, Cl, and Ar were obtained. Maps of electron density and radial velocity with a spatial resolution of 5 × 5 were composed from long slit spectra taken at different declinations. Three O stars classified as O5 V, O6.5 V, and O8 V were found responsible for the ionization of NGC 2579, while ESO 370-9 is ionized by a single O8.5 V star. The estimated mass of ionized gas of ≈25 M indicates that ESO 370-9 is not a planetary nebula, but a small H ii region. A photometric distance of 7.6 ± 0.9 kpc and a kinematic distance of 7.4 ± 1.4 kpc were obtained for both objects. At the galactocentric distance of 12.8 ± 0.7 kpc, NGC 2579 is one of the most distant Galactic H ii regions for which direct abundance determinations have been accomplished. Key words. ISM: H ii regions -ISM: planetary nebulae: general IntroductionDue to observational difficulties, the knowledge acquisition in many research areas of astrophysics has still relied largely on data obtained from a small group of characteristic objects. This is certainly the case of the optical studies of Galactic H ii regions. In this field, the Orion Nebula is by far the most studied object. In fact, the number of papers on this object is comparable to the total number of optical studies of all other Galactic H ii regions. Even the standard procedure of measuring the electron temperature in Galactic H ii regions from optical emission line ratios, such as [O iii] (λ4959 + λ5007)/λ4363 and [N ii] (λ6548 + λ6584)/λ5755, until now could only be accomplished in a small sample of a dozen or so objects. So, the addition of new members to the selected list of well studied (or easy to observe) objects is welcome, especially becaus...

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Aims. We attempt to identify the ionising stars and to determine the photometric distances of nine southern Galactic H ii regions.Methods. We carried out optical spectroscopy and UBV photometry of the stellar content of these objects. The distance of individual stars were obtained by spectroscopic parallax. To avoid using a fixed value for the total-to-selective extinction ratio R V , the reddening A V was determined directly by the colour-difference approach by comparing our V apparent magnitudes and the JHK magnitudes from the 2MASS survey with the intrinsic colour indices. Results. As types O or B, we classified 24 of the 31 stars for which optical spectra were obtained. In particular, we identified two new O stars, one in RCW 98 and the other in RCW 99. The values of reddening obtained correspond to a mean R V = 3.44, which is about 10% higher than the value found for field stars. For three of the H ii regions studied (Bran 186, NGC 2626, and RCW 32), the distance estimates (with errors from 25% to 50%) were based on the data obtained for only one star. For the other six objects (NGC 3503, NGC 6334, RCW 55, RCW 87, RCW 98, and RCW 99), we obtained more precise photometric distances (with a mean error of ≈18%) calculated to be the median of the parallax distances obtained for two to six different stars in each nebulae. The parallax distances of individual stars belonging to a given nebula were similar to each other, with internal errors smaller than 5%, as a consequence of the method used to derive the reddening correction A V . The distance of 1.23 ± 0.30 kpc obtained for RCW 87 disagrees with the value of 7.6 kpc previously found. Conclusions. The dispersion in individual distance estimates for stars in a given nebula can be significantly reduced by calculating the reddening A V from a comparison between the V and the 2MASS JHK magnitudes instead of using A V = R V E(B − V) with a fixed value for R V . Therefore, more precise distances can be calculated with our proposed method.

The aim of the present study was to evaluate the possible effects of zinc chloride against the gastrointestinal lesions caused by oral administration of ethanol in rats. Rats were divided into five groups, namely, saline, ethanol, zn, zn+ethanol and ethanol+zn. Ethanol 70% (2 mL/kg) was administered by gavage in 36 h fasted rats. Zinc chloride (27 mg/kg, ~13 mg/kg of zinc) was given by gavage 1h before or 1h after the administration of ethanol. Oral administration of ethanol consistently induced damage in the rat glandular stomach and intestine. Zinc did not demonstrate effect per se and significantly reduced gastrointestinal lesions when administered either before or after lesion induction. Ethanol induced enhancement of thiobarbituric acid reactive substance and reactive species levels, diminished the ascorbic acid and total protein SH content as well as superoxide dismutase and catalase activity in stomach and intestine of rats. Zinc treatment prevented and reversed these alterations induced by ethanol. Stomach and intestine of rats treated with zinc presented higher zinc content than the tissues of rats treated only with ethanol. Non-protein SH content was not altered by any treatment. Results suggested that the gastrointestinal protective effect of zinc in this experimental model could be due to its antioxidant effect.