News

This section includes scientific and technological news from the IAC and its Observatories, as well as press releases on scientific and technological results, astronomical events, educational projects, outreach activities and institutional events.

  • Figure 1 of the article by C. Galart, M: Zoccali y A. Aparicio

    Work by C. Gallart, M. Zoccali y A. Aparicio has been published in the Annual Review of Astronomy and Astrophysics. The article reviews current knowledge about star populations in nearby galaxies, which allow us to study the galaxies' history and evolution (Gallart, Zoccali and Aparicio, 2005, ARAA 43, 387). ARAA volumes are published yearly, by invitation, and have a wide circulation within the astronomy community.

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  • The emission spectrum observed

    An anomalous emission has been detected in the microwave region of the Perseus Molecular Cloud. This work extends the frequency range of the studies being carried out by the WMAP satellite and finds between 11 and 17 Ghz per emission, 10 times greater than can be explained by normal emission processes in the Milky Way. One possible and attractive explanation is the presence of fullerenes, the bipolar electric emission of which is compatible with the observations (Watson, Rebolo et al., 2005, ApJ 624, L28).

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  • The (O/H), (C/H) and (C/O) gradient in the Milky Way between 6 and 11 Kpc from its centre.

    The galactic gradient of C has been determined for the first time using recombination lines in HII regions. Results from these lines are more reliable than those derived from the traditional collisional excitation lines, which are stronger but subject to variations of temperature in nebulae (Esteban et al., 2005, ApJ 618, 195). These results have made it possible to greatly limit the number of possible models for chemical evolution in the Milky Way.

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  • Intensity profiles of an iron line calculated in a 3D hydrodynamical model of the atmosphere of a metal-poor star, assuming LTE (right panel) and without assuming LTE (left panel). The resulting average profile in each case is that given by thickest line.

    The abundances of oxygen and iron in metal-poor stars have been determined through non-LTE radiative transfer simulations in three-dimensional (3D) hydrodynamical models of their atmospheres. The performing of this type of calculations required to develop first very efficient numerical methods and computer programs. Taking into account that the atmospheres of the stars are 3D systems and the impact of non-LTE effects leads to very significant changes in the derived chemical abundances. It has been concluded that the metalicity of some metal-poor stars could be significantly larger than

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  • The extinction curve observed, compared with that of the LMC (solid line) and the Milky Way (dotted line).

    Using a gravitational lens, the first precise determination of the extinction curve from the optical to the far UV has been carried out in a galaxy outside the Local Group (a z=0,83). It has turned out to be approximately the same as that observed at the LMC and different from that of our galaxy. These studies reveal the properties of interstellar dust in distant galaxies (Mediavilla et al., 2005, ApJ 619, 749).

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  • Spectrum of the planetary nebula in the Sextans A galaxy obtained by the Very Large Telescope (VLT).

    Chemical abundances have been measured of PNe and HII regions in Sex A and Sex B, two galaxies located on the outskirts of the Local Group. These PNe are the farthest ones where such a direct abundance measurement has been obtained. PNe and HII regions in Sex B show unexpectedly similar abundances, suggesting a very low chemical enrichment. In Sex A there is only one PN known, and its anomalous chemistry is helping us to develop new models of stellar evolution in very low metallicity environments. Furthermore, new candidate PNe in NGC 6822 have been discovered, increasing the number of

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