XIII Annual Meeting of the Chilean Astronomical Society Book of abstracts - Talks Antofagasta, March 1-4, 2016 1 Claudia Agliozzo Universidad Nacional Andrés Bello A tale of the mass-loss of the magellanic LBV R127 During their lifetime, Luminous Blue Variable stars (LBVs) must rapidlyexpel their H envelope, with the highest mass-loss rates (> 10^(-5) M_sun/yr), in order to evolve into Wolf-Rayet stars.However, the physical mechanism underlying the mass-loss is not yet understood.I present our extraordinary multi- wavelength dataset of R127, a famousLBV in the Large Magellanic Cloud, widely observed in the past at visiblewavelengths. Our dataset comprises high-resolution centimetre ATCA and submillimetre ALMA data, in addition to new high-spectral resolution optical data acquired with the instrument MIKE at Magellan II telescope.As shown by the different spectral features detected, the mass-loss ishighly complex, with signatures of different episodes, such as have beenseen in previous spectroscopic observations and in the galactic prototypeLBV AG Carinae. We newly discover that from theinner to the outer regions, the stellar wind changes geometry.With all our data together, the picture seems much clearer: theasymmetric morphology of the wind and of the circumstellar nebula aremore likely due to external factors than intrinsic asymmetriesof the mass-loss. I will discuss different scenarios.We don't know yet how common this behaviour is in galactic and magellanic LBVs. However, noticeably, the geometry of the nebula resembles that of Eta Carinae and of the blue-supergiant progenitor of Supernova 1987A. 2 Gustavo Aguayo Universidad de Concepción Optical study of the Be star Mu Centauri We present an optical study of the Be star Mu Centauri, this study was developed using spectroscopic data taken with CHIRON and CORALIE spectrograph, there were measured important parameters of some lines located at the optical range as equivalent width and peak separation, also correlations between equivalent widths of some lines were found and are presented here. The peak separation was used to constrain the extension of the line forming regions and this work is also presented in this poster. Also we present in this poster visual photometry of this star covering the same lapse that the spectra, the result of the correlation between equivalent width of H alpha and magnitude is shown below. 3 Claudia Aguilera Pontificia Universidad Católica Lithium enrichment in red giant branch stars Lithium (Li) is easily destroyed inside low mass. During the red giant branch phase the surface Li abundance decreases even further by dilution, but a small number of giants is known to be Li-rich. This is unexpected and it cannot be accounted for by canonical stellar evolution. One of the possible explanations for these atypical giants is the engulfment of a planet or brown dwarf by the star. In this work, we model the evolution of lithium abundance post first dredge up including the accretion of a sub-stellar mass companion. We consider a wide range of stellar and companion masses and initial lithium abundances, stellar metallicities and time of engulfment, including the most optimistic choices that would produce the highest superficial Li abundances. We find that even with the best possible conditions, i.e., a companion with supermeteoritic Li abundance that produces a maximum signature of A(Li) ∼ 2.7, the accretion of a sub-stellar mass companion alone cannot explain all the observed lithium rich giants andthus it seems necessary to include internal production of the light element plus additional non-canonical physics, such as an extra-mixing process. 4 Alba Aller Universidad de Valparaiso Search for binary central stars of planetary nebulae: exploding archival data With the new binary central stars (CSs) identified in the last years, binary interactions have become the main proposed mechanism to explain the complex morphologies seen in planetary nebulae (PNe). There are around 50 binary CSs detected so far. However, this number remains very small as compared to the more than 3000 known PNe in the Milky Way. In this context, we are involved in a project to study how binary interaction processes influence the shape of PNe. Archival data offer a great opportunity to search for new candidates of binary CSs since surveys like, e.g., Catalina, ASAS and OMC provide light curves of a large number of objects in a long timespan. We are exploding these surveys to search for new candidates that will be subsequently followed-up by means of multi-epoch photometric and spectroscopic observations. In this talk, we will summarize the goals of this project and show the first results. 5 Simón Ángel Pontificia Universidad Católica Characterisation of stellar populations in the CFHTLS Deep fields Combining the information of the CFHTLS (Gwyn 2011) and WIRDS (Bielby et al. 2012) surveys, I constructed multiwavelength catalogues for the four Deep CFHTLS fields. Using the selection tool presented in Muñoz et al. (2014), I produced a clean and deep (limiting magnitude in r ~ 26) subset of stars. Colour, magnitude, metallicity, and distance distributions have been studied, using for the latter, the methods presented in the Milky Way Tomography series of papers (Jurić et al. 2008, Ivezić et al. 2008, Bond et al. 2010) and in Sesar et al. (2011). In this talk, I will present the dataset and the distributions aforementioned, along with comparisons with the Besançon model of stellar population synthesis of the Galaxy (Robin et al. 2003). 6 Rodolfo Angeloni Gemini Observatory The Sanduleak's star in the Large Magellanic Cloud Sanduleak's star is a variable emission-line object in the Large Magellanic Cloud. It was discovered in 1977 and, already in the early 80's, a similarity with eta Carinae and SN 1987A was proposed on the basis on IUE observations which indicated episodic mass outflow, extreme departures from normal cosmic values of nitrogen relative to carbon and oxygen, and an electron temperature which is hard to reconcile with pure photo-ionization models. Sanduleak's star came abruptly back on stage in 2011, when we discovered that it powers a giant, highly-collimated bipolar jet extending over almost 15 pc: to our knowledge, it is the largest stellar jet discovered so far, and the first one clearly resolved beyond the Milky Way. In this contribution we present our follow-up observations of Sanduleak's star obtained over the last few years. In particular: HST-WFC3 narrow-band images, that allow us to resolve the spectacular inner nebula; Magellan-FIRE and MMIRS near-infrared spectra, which give insight on the symbiotic character of the central binary; Magellan-MIKE high-resolution optical spectra, that further constraint the kinematics, chemistry and energetics of the overall system. We thus discuss the nature of Sanduleak's star and place it in the general context of the late stages of stellar evolution, by also highlighting some tentative links with the Intermediate-Luminosity Optical Transients. 7 Javier Arenas Pontificia Universidad Católica de Valparaiso Can pulsar glitches be explained by "starquakes"? Pulsars are the best clocks known in universe, with very precisely periodic pulses due to the rotation of a neutron star with a strong dipolar magnetic field. The pulses slow down progressively, due to the release of rotational energy. In addition, there are timing irregularities, the most prominent of which are "glitches", sudden spin-up events, in which about 1 % of the spin-down is "recovered".There are two main mechanisms discussed in the scientific literature to explain this kind of events. The first is the sudden transfer of angular momentum from the superfluid (or part of it) to the solid crust of the star. The second is a "starquake", a sudden breaking of the solid crust due to stress accumulated by the spin-down of the star. Our object of study is the second of these mechanisms, which was previously studied by Baym & Pines (1969). They showed that, for known values of Crab pulsar, starquakes due to spin down cannot explain the relatively short recurrence times (of few years), instead requiring hundreds of years between glitches. For Vela the scenario was much worse, exceeding thousands (even millions) of years the time between glitches. However, the size distribution of glitches is bimodal, so one might still try to explain the smaller glitches through this mechanism. In this investigation, using theory of elasticity to demonstrate how the star is deformed by rotation, we study the plausibility of the model in two scenarios. First in a completely solid star, which could store the maximum stress and the second is a more realistic star with fluid core and solid crust. We use observations of pulsars with only small glitches, as the Crab pulsar, and pulsars with bimodal distribution, as the Vela, to test the models. 8 Maria Argudo-Fernandez Universidad de Antofagasta Evolution of Spiral Isolated Galaxies with MaNGA From models, it is predicted that disks grow from inner to outer parts of galaxies, the so–called inside– out model of galaxy formation. As a consequence, we expect to observe gradients in stellar age and metallicity as a function of galactic radius. Thankfully, new integral field spectroscopy of nearby galaxies now provide us with data at sufficient resolution to study the star formation history (SFH) over the disk of a galaxy. But separating the effect secular evolution on the physical properties of galaxies from that of the environment (nature versus nurture) is also a necessary and challenging question to address. Here we report our efforts to constraint the SFH of isolated galaxies that have been already observed by MaNGA. Our preliminary results are in favour of the scenario where spiral disks grow inside-out. 9 Francisco Aros Pontificia Universidad Católica Axisymmetric dynamical models of dwarf spheroidal galaxies The dynamical analysis of dark matter dominated galaxies is expected to contribute significantly in the understanding of the nature of dark matter.