81. Neutron capture cross section of unstable 63-Ni: implications for stellar nucleosynthesis - Lederer, C.; Massimi, C.; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Gómez Hornillos, María Belén
The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from   kT=5–100  keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

82. Neutron capture cross section of unstable 63-Ni: implications for stellar nucleosynthesis - Lederer, C.; Massimi, C.; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Gómez Hornillos, María Belén
The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from   kT=5–100  keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

83. the Local Group - Università Degli Studi Di Trieste; Settore Fis; Astronomia E Astrofisica; Coordinatore Del; Collegio Dei Docenti; Gabriele Cescutti; Prof Francesca Matteucci
Chemical evolution of neutron capture elements in our Galaxy and in the dwarf spheroidal galaxies of

84. Production of short-lived radioactive nuclei in super asymptotic giant branch star - Doherty, Carolyn L.; Lugaro, M.; Lau, H.; Siess, Lionel; Lattanzio, John; Gil Pons, Pilar

85. Production of short-lived radioactive nuclei in super asymptotic giant branch star - Doherty, Carolyn L.; Lugaro, M.; Lau, H.; Siess, Lionel; Lattanzio, John; Gil Pons, Pilar

86. The upper-mass limit for the formation of super-agb stars and the dredge-out phenomenon - Gil Pons, Pilar; Doherty, Carolyn L.
We have computed the evolution of Super-AGB stars from the main sequenceand up to a few hundred thermal pulses, with special attention to the low metallicity cases(Z = 10 10; 10 5; 10 4 and 10 3). Our computations have been performed using time–dependent mixing and new opacity tables that admit variations in the abundances of carbonand oxygen. By following the evolution along the main central burning stages and theearly TP-SAGB, we resolve the upper mass limits for the formation of TP-SAGB stars anddetermine the mass range at which the dredge-out phenomenon occurs. This phenomenoninvolves the merger of a convective...

87. On the fate of extremely low metallicity stars - Gil Pons, Pilar; Gutierrez Cabello, Jorge Luis; García-Berro Montilla, Enrique; Althaus, Leandro G.
We have computed and analyzed the evolution of intermediate-mass stars of metallicityZ = 10−5 from the main sequence until the early stages of the TP-(S)AGB phase. In order to checkthe influence of mixing we have performed our calculations using two different evolutionary codes,EVOLVE — which does not include diffusion but allows for overshooting— and LPCODE, whichincludes diffusion and overshooting “à-la-Herwig”. Important differences appear during the TP–AGB phase, as the calculations done with EVOLVE lead to an almost negligible third dredge-up,whereas the sequences computed with LPCODE show important third dredge-up and, therefore,significant enrichment in metals of the envelope. This fact has...

88. The upper-mass limit for the formation of super-agb stars and the dredge-out phenomenon - Gil Pons, Pilar; Doherty, Carolyn L.
We have computed the evolution of Super-AGB stars from the main sequence and up to a few hundred thermal pulses, with special attention to the low metallicity cases (Z = 10 10; 10 5; 10 4 and 10 3). Our computations have been performed using time– dependent mixing and new opacity tables that admit variations in the abundances of carbon and oxygen. By following the evolution along the main central burning stages and the early TP-SAGB, we resolve the upper mass limits for the formation of TP-SAGB stars and determine the mass range at which the dredge-out phenomenon occurs. This phenomenon involves the merger of a convective...

89. On the fate of extremely low metallicity stars - Gil Pons, Pilar; Gutierrez Cabello, Jorge Luis; García-Berro Montilla, Enrique; Althaus, Leandro Gabriel
We have computed and analyzed the evolution of intermediate-mass stars of metallicity Z = 10−5 from the main sequence until the early stages of the TP-(S)AGB phase. In order to check the influence of mixing we have performed our calculations using two different evolutionary codes, EVOLVE — which does not include diffusion but allows for overshooting— and LPCODE, which includes diffusion and overshooting “à-la-Herwig”. Important differences appear during the TP– AGB phase, as the calculations done with EVOLVE lead to an almost negligible third dredge-up, whereas the sequences computed with LPCODE show important third dredge-up and, therefore, significant enrichment in metals of the envelope. This fact has...

90. Estudio de las constelaciones del hemiferio norte en comapración con las del hemisferio sur y su utilización en navegación - Gironès Ruiz, Jessica
El Proyecto de Final de Carrera titulado “Estudio de las constelaciones del hemisferio norte en comparación con las del hemisferio sur y su utilización en la navegación” está dividido en varias partes diferenciadas. La primera parte es la historia, desde los más antiguos descubridores de las constelaciones hasta hoy en día. La segunda parte son definiciones sobre las estrellas, magnitudes, constelaciones, los movimientos de la tierra y las coordenadas celestes.La tercera parte y más extensa, son las 88 constelaciones reconocidas actualmente por laUnión Astronómica Internacional (UAI) quien a partir de 1928 decidió reagrupar oficialmente la esfera celeste en estas constelaciones...

91. Testing the concept of integral approach to derivatives within the smoothed particle hydrodynamics technique in astrophysical scenarios - Cabezón Gómez, Rubén Martín; García Senz, Domingo; Escartín Vigo, José Antonio
Context. The smoothed particle hydrodynamics (SPH) technique is a well-known numerical method that has been applied to simulating the evolution of a wide variety of systems. Modern astrophysical applications of the method rely on the Lagrangian formulation of fluid Euler equations, which is fully conservative. A different scheme, based on a matrix approach to the SPH equations is currently being used in computational fluid dynamics. An original matrix formulation of SPH based on an integral approach to the derivatives, called IAD0, has been recently proposed and is fully conservative and well-suited to simulating astrophysical processes.Aims. The behavior of the IAD0...

92. Reaction rates for the s-process neutron source Ne-22+alpha - Longland, Richard Leigh; Iliadis, Christian; Karakas, A.I.
The 22Ne(α, n)25Mg reaction is an important source of neutrons for the s-process. In massive stars responsible for the weak component of the s-process, 22Ne(α, n)25Mg is the dominant source of neutrons, both during core helium burning and in carbon-shell burning. For the main s-process component produced in asymptotic giant branch (AGB) stars, the 13C(α, n)16O reaction is the dominant source of neutrons operating during the interpulse period, with the 22Ne + α source affecting mainly the s-process branchings during a thermal pulse. Rate uncertainties in the competing 22Ne(α, n)25Mg and 22Ne(α, γ)26Mg reactions result in large variations of s-process...

93. Recent advances in the modelling of classical novae and type I X-ray bursts - José Pont, Jordi; Casanova Bustamante, Jordi; Parikh, Anuj Ramesh; García-Berro Montilla, Enrique
Classical nova outbursts and type I X-ray bursts are thermonuclear stellar explosions driven by charged-particle reactions. Extensive numerical simulations of nova explosions have shown that the accreted envelopes attain peak temperatures between 0.1 and 0.4 GK, for about several hundred seconds, and therefore, their ejecta is expected to show signatures of significant nuclear activity. Indeed, it has been claimed that novae play some role in the enrichment of the interstellar medium through a number of intermediate-mass elements. This includes 17O, 15N, and 13C, systematically overproduced in huge amounts with respect to solar abundances, with a lower contribution to a number...

94. Optimal low-thrust transfers between libration point orbits - Ren, Yuan; Pergola, Pierpaolo; Fantino, Elena; Thiere, B.
Over the past three decades, ballistic and impulsive trajectories between librationpoint orbits (LPOs) in the Sun–Earth–Moon system have been investigated to a large extent.It is known that coupling invariant manifolds of LPOs of two different circular restrictedthree-body problems (i.e., the Sun–Earth and the Earth–Moon systems) can lead to significantmass savings in specific transfers, such as from a low Earth orbit to the Moon’s vicinity.Previous investigations on this issuemainly considered the use of impulsive maneuvers alongthe trajectory. Here we investigate the dynamical effects of replacing impulsive V’s withlow-thrust trajectory arcs to connect LPOs using invariant manifold dynamics. Our investigationshows that the...

95. Revista Mexicana de Astronomía y Astrofísica, 00, 1–17 (2001) A LOSSY METHOD FOR COMPRESSING RAW CCD IMAGES - Alan M. Watson
Se presenta un método para comprimir las imágenes crudas de dispositivos como los CCD. El método es muy sencillo: cuantización con pérdida y luego compresión sin pérdida con herramientas de uso general como gzip o bzip2. Se converten los archivos comprimidos a archivos de FITS descomprimiéndolos con gunzip o bunzip2, lo cual es una ventaja importante en distribuir datos comprimidos. El grado de cuantización se elige para eliminar los bits de bajo orden los cuales sobre muestrean el ruido, no proporcionan información, y son difíciles o imposibles comprimir. El método es con pérdida, pero proporciona ciertas garantías sobre la diferencia...

96. To appear in Revista Mexicana de Astronomía y Astrofísica QUANTITATIVE STELLAR SPECTRAL CLASSIFICATION. III. SPECTRAL RESOLUTION - J. García; J. Stock; M. J. Stock; N. Sánchez
absolutas y colores intrínsecos se aplica a espectros simulados de baja resolución. La simulación se realiza convolusionando espectros verdaderos con una función Gaussiana, donde σ (el ancho a la altura media) está relacionado con la resolución final del espectro. La precisión con la cual se determinan los parámetros estelares indica que este método puede ser aplicado a espectros típicos de prisma objetivo. Sin embargo, los resultados muestran que las variaciones en la resolución espectral no afectan los parámetros derivados sólo para las estrellas más tempranas, mientras que para las estrellas de tipo más tardías se hace necesario mejorar el método...

97. To appear in “Revista Mexicana de Astronomía y Astrofísica (2003)” RevMexAA(SC) THE PRIMORDIAL BINARY POPULATION IN OB ASSOCIATIONS - M. B. N. Kouwenhoven; A. G. A. Brown; A. Gual; L. Kaper; S. F. Portegies Zwart; H. Zinnecker
We present the first results of our adaptive optics survey of 200 (mainly) A-type stars in the nearby OB association Sco OB2, which we will use, together with literature data and detailed simulations of young star clusters, to determine the primordial binary population.

98. Revista Mexicana de Astronomia y Astrofisica - Héctor Aceves; Héctor Velázquez; Unam Ensenada
Se presenta una serie de simulaciones de N-cuerpos destinadas a estudiar la dinámica de grupos pequeños de galaxias. En particular, se comparan los resultados obtenidos con las propiedades dinámicas de los grupos de Hickson. Se consideran condiciones iniciales partiendo de una ‘expansión máxima ’ y de equilibrio virial, y no se considera un halo oscuro común primigenio. Se encuentra muy buena concordancia con las propiedades de grupos pequeños de galaxias, y las propiedades de los grupos compactos de Hickson son reproducidas adecuadamente por aquellos sistemas que se encuentran en un estado avanzado de un colapso gravitacional. No se encuentra un...

99. To appear in Revista Mexicana de Astronomía y Astrofísica OPTICAL PHOTOMETRIC AND SPECTROSCOPIC STUDY OF THE SEYFERT GALAXY SBS 0748+499 - J. Torrealba; E. Benítez; A. Franco-balderas; V. H. Chavushyan
El resumen será traducido al español por los editores. We present the first optical photometric study of the active galaxy SBS 0748+499. First, we present B, V, R and I photometric data: total magnitudes and B −V, B −R, B −I colors; surface brightness, color and geometric profiles, with emphasis on the morphology and its relation to the global photometric properties of this galaxy. Then, from our surface photometry study we derive the bulge–to–disk luminosity ratio B/D in the four bands. We find that the host galaxy shows a bar (a ∼ 8 kpc) and a low– brightness spiral structure....

100. To appear in Revista Mexicana de Astronomía y Astrofísica MORPHO-KINEMATIC MODELING OF GASEOUS NEBULAE WITH SHAPE - Wolfgang Steffen; José Alberto López
Presentamos una nueva herramienta poderosa para analizar y desenredar la geometría 3-D y la estructura cinemática de nebulosas gaseosas. El método consiste en combinar software comercial para animación digital para simular la estructura 3-D y el modo de expansión de la nebulosa junto con un software de representación gráfica de imagenes y perfiles de línea diseñado especialmente para este propósito. Las imágenes resultantes se comparan directamente con datos reales. Presentamos resultados para las complejas nebulosas planetarias NGC 6369 y Abell 30 basados en espectros de rendija larga obtenidos en el observatorio de San Pedro Mártir. We present a powerful new...

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