SPECTROSCOPY ASTROPHYSICS

Author: NAVARRO JIMENEZ SILVANA GUADALUPE.
Year: 2004.
University: LA LAGUNA [www.ull.es].
Place of defense: FACULTAD DE FISICA Y MATEMATICAS.
Place of preparation: INSTITUTO DE ASTROFISICA DE CANARIAS.

Summary: This paper makes the implementation of the method of extinción- distance to determine distances to planetary nebulae using the spectral classification that performs an artificial neural network system. The application of the above method requires the spectral classification of a large group of stars field near the line of vision of each planet. The large number of spectra to classify led to the process of automatically using artificial neural networks. This allows us to make this classification accuracies with nearly two subtypes spectral and with it determine distances with uncertainties of between 20 and 30%. This represents a major breakthrough if one takes into account that different determinations of distance, currently in the literature for the same purpose, can vary by factors of 3 or more.

Author: GARCIA HERNANDEZ DOMINGO ANIBAL.
Year: 2004.
University: LA LAGUNA [www.ull.es].
Place of defense: FACULTAD DE FISICA.
Place of preparation: INSTITUTO DE ASTROFISICA DE CANARIAS.

Summary: This thesis is concerned with many aspects related to the study of the still little known phase transition between the Branch Asintótica of Giants and the state of Planetary Nebula. We have analyzed several types of objects in this short evolutionary phase, including AGB stars / post-AGB and proto-nebulosas planets, using a variety of observational data. First, we analyzed for the first time, spectroscopic data in the near-infrared of a representative sample of objects transition completely covering developments post-AGB. Then, the distribution of dust around the proto-nebulosa planetary multipolar IRAS 16594-4656 and the young planetary nebula elliptical IRAS 07027-7934 has been studied for the first time the level of sub-segundo arc with the help of limited by diffraction images in the middle infrared. To conclude this work has been carried out the first study to date of the abundances of Lithium and elementos-s in AGB stars massive and rich in oxygen of our Galaxy.

Author: SIMON DIAZ SERGIO.
Year: 2005.
University: LA LAGUNA [www.ull.es].
Place of defense: FACULTAD DE FÍSICA.
Place of preparation: INSTITUTO DE ASTROFISICA DE CANARIAS.

Summary: This thesis is focused on the study of the interaction of massive stars with the ionized interstellar medium in two galactic HII regions. We present two distinct studies. The first deals with the comparison of chemical abundances in the region of stellar formation associated with the Orion Nebula (M42), obtained from stellar and nebular methods. The second is directed toward the construction of a model fotoinización details of the nebula of Marian (M43) by comparing the predictions of the models with a large number of different types of observable. For the purposes of this thesis has obtained a set of observational data of various types. These data include spectroscopy rendija long in the optical range of massive stars in the nebulae M42 and M43, and image filters close of the nebula M43. In addition they have recovered data spectroscopic M43 used by M. Rodriguez in a prior study of this nebula. It has made use of the model stellar atmosphere last generation FASTWIND to establish the parameters and stellar abundances of oxygen and silicon of the stars of Orion. The reliability of the abundances obtained is based on a detailed analysis is performed prior to the star Tau Sco, a star B0.2V with narrow lines (due to its low vsini). We have found good agreement between the abundance of stellar oxygen obtained for the stars of Orion and that previously estimated by Stephen et al. (2004) for content nebular gas phase. This result suggests a factor of powder deposition for the nebular oxygen in M42 smaller than had been considered so far. The stellar silicon abundances are greater than those obtained from the study of the spectrum FUV of M42. This result confirms the deposit allows a certain amount of silicon in nebular dust grains. The nebula M43 is an HII region apparently spherical ionized by a single star (HD37061, B1V). The parameters of the star stellar ionizing obtained by analyzing its spectrum with optical FASTWIND have been used as input model atmosphere stellar WM-basic to model distribution of ionizing flux. This spectral distribution of energy, along with the nebular abundances obtained from the optical spectrum analysis of M43, and the morphological and photometric inferred from the images of the nebula filters in narrow, have been used as input code photo-ionization CLOUDY for building models to measure the nebula. They are considering two types of spherical models: with constant density and density of a law derived from the adjustment of the surface brightness profile in H alpha. Finally, we have taken the first steps in shaping the nebulos through code CLOUDY-3D, a code pseudo-3D allowing construct models with geometric rate ampoule.

Author: GONZALEZ HERNANDEZ JONAY ISAI.
Year: 2006.
University: LA LAGUNA [www.ull.es].
Place of defense: FACULTAD DE FISICAS.
Place of preparation: INSTITUTO DE ASTROFISICA DE CANARIAS.

Summary: This thesis has been carried out the study of chemical abundances of the secondary star in X-ray binary systems of small mass in order to extract information on nucleosynthesis in massive stars and the formation processes of compact objects, both black holes like neutron stars. The stars secondary could have captured some of the material eyectado in supernova explosions that probably resulted in the formation of compact objects. To carry out this project were performed spectroscopic observations in class 8-10 meter telescopes, the VLT and Keck, espectrógrafos resolution intermedia-alta. The findings establish restrictions on the parameters involved in the explosions of supernova and definition of a preliminary ratio of the mass of compact objects and their parents.