Un sondeo espectroscópico de estrellas o galácticas

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura. 03-12-2018Los catálogos de clasificaciones espectrales de estrellas masivas que recopilan sus datos de diferentes fuentes, muestran una gran disparidad en las clasificaciones que contienen. Algunas de las discrepancias se deben a las diferentes resoluciones espectrales o relaciones señal-ruido (S/N), otras a la variabilidad en las estrellas (siendo las binarias espectroscópicas las principales culpables), y otros a errores o diferencias entre los clasificadores. Para corregir esta situación, nació en 2007 la idea del sondeo espectroscópico de estrellas O Galácticas (GOSSS). GOSSS es un sondeo en el que se pretenden observar todas las estrellas O galácticas conocidas para crear la mayor base de datos espectroscópica en el azul-violeta (3900-5100 Å) de este tipo de estrellas observables visualmente ( B < 14) utilizando una resolución espectral intermedia (R ~ 2500), una alta S/N (≥ 300), y obteniendo datos de una calidad uniforme. El sondeo empezó sus observaciones partiendo inicialmente de las estrellas contenidas en la segunda versión del catálogo de estrellas O Galácticas (GOSC) y desde el comienzo del proyecto hasta la presentación de esta tesis, se han observado más de 400 noches en 4 observatorios diferentes. Como parte de esta tesis se han observado 449 estrellas dentro del programa GOSSS cuyas clasificaciones han sido incorporadas a la versión 3 de GOSC. A su vez, se ha creado un atlas de estrellas O Galácticas que ha supuesto un gran avance con respecto a los existentes debido a la calidad y uniformidad de los espectros, así como de su completitud. Algunos de los resultados notables relacionados con GOSSS son los siguientes: Se revisan los criterios de clasificación para los tipos entre O8 y B0 con indicadores más precisos que los usados en trabajos anteriores y se amplía a todas las clases de luminosidad el tipo O9.7 (anteriormente solo se clasificaban las clases mayores de III). Se introduce la nueva categoría espectral Ofc y el tipo espectral O9.2. Se introducen criterios uniformes para la definición de los fenómenos f y z. Se descubren dos nuevos miembros de la categoria Of?p y bastantes binarias espectroscópicas no detectadas hasta ahora. Todos estos elementos también han servido para afrontar estudios tan diversos como las leyes de extinción en el óptico e infrarrojo y la multiplicidad de estrellas masivas y servirán para afrontar otros como la distribución espacial de las estrellas masivas o el límite de la IMF (función de masas iniciales) en la vecindad solar. Los resultados mencionados se han publicado en los dos artículos principales que componen la base de esta tesis, que en conjunto acumulan más de 200 citas en ADS (Astrophysics Data System

YETI observations of the young transiting planet candidate CVSO 30 b

Raetz, St. et. al.CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The inner companion, CVSO 30 b, is the first possible young transiting planet orbiting a previously known weak-lined T Tauri star. With five telescopes of the 'Young Exoplanet Transit Initiative' located in Asia, Europe and South America, we monitored CVSO 30 over three years in a total of 144 nights and detected 33 fading events. In two more seasons we carried out follow-up observations with three telescopes. We can confirm that there is a change in the shape of the fading event between different observations and that the fading event even disappears and reappears. A total of 38 fading event light curves were simultaneously modelled. We derived the planetary, stellar and geometrical properties of the system and found them slightly smaller but in agreement with the values from the discovery paper. The period of the fading event was found to be 1.36 s shorter and 100 times more precise than the previous published value. If CVSO 30 b would be a giant planet on a precessing orbit, which we cannot confirm, yet, the precession period may be shorter than previously thought. But if confirmed as a planet it would be the youngest transiting planet ever detected and will provide important constraints on planet formation and migration time-scales.SR is currently a Research Fellow at ESA/ESTEC. SR, CA, RE, MK and RN would like to thank DFG for support in the Priority Programme SPP 1385 on the 'First Ten Million Years of the Solar system' in projects NE 515/34-1 and -2, NE 515/33-1 and -2, and NE 515/35-1 and -2. TK acknowledges support by the DFG program CZ 222/1-1 and RTG 1351 (extrasolar planets and their host stars). MK would like to thank Ronald Redmer and DFG in project RE 882/12-2 for financial support. MF acknowledges financial support from grants AYA2014-54348-C3-1-R and AYA2011-30147-C03-01 of the Spanish Ministry of Economy and Competivity (MINECO), co-funded with EU FEDER funds. DK and VR acknowledge support by project RD 08-81 of Shumen University. Z-YW was supported by the Chinese National Natural Science Foundation grant no. 11373033. This work was also supported by the joint fund of Astronomy of the National Nature Science Foundation of China and the Chinese Academy of Science, under Grant U1231113. XZ was supported by the Chinese National Natural Science Foundation grands no. 11073032, and by the National Basic Research Program of China (973 Program), No. 2014CB845704 and 2013CB834902. MM and CG acknowledge DFG for support in program MU2695/13-1. JS, RN and MMH would like to thank the DFG for support from the SFB-TR 7. CG, and TOBS would like to thank DFG for support in project NE 515/30-1. CM acknowledges support from the DFG through grant SCHR665/7-1. RN would like to thank the German National Science Foundation (Deutsche Forschungsgemeinschaft, DFG) for general support in various projects. We would like to acknowledge financial support from the Thuringian government (B 515-07010) for the STK CCD camera used in this project. This work has been supported by a VEGA Grant 2/0143/13 of the Slovak Academy of Sciences. The observations obtained with the MPG 2.2 m telescope were supported by the Ministry of Education, Youth and Sports project - LG14013 (Tycho Brahe: Supporting Ground-based Astronomical Observations). We would like to thank the observers S. Ehlerova and A. Kawka for obtaining the data.Peer reviewe

Evaluación de sistemas de refrigeración para sistemas comerciales centralizados

Treball Final de Màster Universitari en Enginyeria Industrial. Codi: SJA020. Curs acadèmic: 2015-2016Los sistemas actuales de refrigeración comercial en Europa, especialmente en supermercados, se basan en sistemas de simple o doble etapa de expansión directa, donde destacan como fluidos de trabajo el R134a para el nivel de media temperatura (0–3ºC) y el R404A o R507A para el nivel de baja temperatura (-20ºC). La Unión Europea aprobó en 2014 el nuevo Reglamento F-Gas, que entro en vigor el 1 de enero del 2015 (Reglamento UE 517/2014) que establece la prohibición de fluidos refrigerantes con GWP>150 en sistemas de expansión directa para sistemas multicompresor de más de 40kW a partir del 1/1/2022, con la excepción de los fluidos primarios de las cascadas, donde el límite se establece en 1500. Además, ha establecido también límites en la recarga de equipos existentes con cargas de refrigerante con GWP>2500 que excedan de las 40 toneladas de CO2 equivalente a partir del 1/1/2022. Las implicaciones de esta nueva normativa en el campo de la refrigeración comercial serán la eliminación total del R134a y R404A en los sistemas actualmente empleados. Actualmente se están construyendo plantas piloto a lo largo de toda Europa que trabajan con fluidos adaptados o semiadaptados a la nueva normativa, no obstante, no está clara por ahora cuál es la mejor alternativa para cada zona climática del continente. Por ello, en el presente TFM se pretenden evaluar desde un punto de vista semi-teórico diferentes sistemas de refrigeración adaptados a dicha normativa, empleando básicamente fluidos de bajo GWP y que por tanto estarán adaptados a la nueva normativa. En concreto se considerarán las cascadas con CO2 como fluido de baja temperatura, los sistemas booster con CO2 transcrítico y las cascadas indirectas con fluido secundario a media temperatura. Se diseñarán las centrales frigoríficas (selección de los componentes principales) para un supermercado tipo en Europa (1500m2) y se evaluarán con el software ‘Pack Calculation Pro’ utilizando compresores y estrategias de regulación reales. Con los datos obtenidos de la simulación en diferentes localizaciones climáticas se obtendrán conclusiones comparativas desde un punto energético, ambiental y económico

Diseño, construcción y puesta a punto de un sistema para la medida de la densidad de almacenamiento térmico de sales inorgánicas

Treball Final de Grau en Enginyeria Mecànica. Codi EM1047. Curs acadèmic 2013/201

Efficacy Of Different Protocols Of Ovulation Synchronization And Resynchronization In Argentinian Buffalo Herds

During the last years bufalo reproductive researchers have been tried to develop and apply fxed timed artifcial insemination protocols to increase pregnancy rates to maximize improvement. The objective of this paper is to evaluate the pregnancy rates of diferent protocols of synchronization (Ovsynch and progesterone implants) and resynchronization of ovulation in a meat water bufalo herd during reproductive season of 2016. 194 mature Mediterranean females, were randomly assigned to four diferent protocols, ultrasound evaluation were used to determine cyclicity (presence of corpus luteum or follicles ≥7 mm de diameter). 18 days after insemination all females were resynchronized and at day 25 ultrasound were performed, those nonpregnant females were inseminated 28 days after frst insemination. All inseminations were performed by the same technician and only one bull was used. InfoStat software was used, statistical signifcance was considered when p value was lower than α of the 5%. No statistical signifcance were found within the protocols. Early embryonic dead 50 days after IA was 3.4%. Pregnancy rate was 47.9% and 53.5% for insemination and reinsemination respectively and the fnal pregnancy rate after the adjust for early pregnancy loss 73.2%, during the 28 days of the breeding period. The results obtained allow breeders to choose the best pharmacological option to use FTAI in their herds based on their own needs to improve production without afecting pregnancy rates.Fil: Crudeli, Gustavo Angel. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; ArgentinaFil: Konrad, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: de la Sota, Rodolfo Luzbel. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Yuponi, Roberto Gregorio. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; ArgentinaFil: Vallejos, Natalia. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; ArgentinaFil: Cardona Maya, Walter Darío. Universidad Nacional de Colombia; ColombiaFil: Berdugo, Jesus Alfredo. Universidad de Antioquia; Colombi

On the multiplicity of the zero-age main-sequence O star Herschel 36

We present the analysis of high-resolution optical spectroscopic observations of the zero-age main-sequence O star Herschel 36 spanning six years. This star is definitely a multiple system, with at least three components detected in its spectrum. Based on our radial-velocity (RV) study, we propose a picture of a close massive binary and a more distant companion, most probably in wide orbit about each other. The orbital solution for the binary, whose components we identify as O9 V and B0.5 V, is characterized by a period of 1.5415 +/- 0.0006 days. With a spectral type O7.5 V, the third body is the most luminous component of the system and also presents RV variations with a period close to 498 days. Some possible hypotheses to explain the variability are briefly addressed and further observations are suggested.Comment: 6 pages, 2 figure

Comet 22P/Kopff: Dust environment and grain ejection anisotropy from visible and infrared observations

We present optical observations and Monte Carlo models of the dust coma, tail, and trail structures of comet 22P/Kopff during the 2002 and 2009 apparitions. Dust loss rates, ejection velocities, and power-law size distribution functions are derived as functions of the heliocentric distance using pre- and post-perihelion imaging observations during both apparitions. The 2009 post-perihelion images can be accurately fitted by an isotropic ejection model. On the other hand, strong dust ejection anisotropies are required to fit the near-coma regions at large heliocentric distances (both inbound at $r_h$=2.5 AU and outbound at $r_h$=2.6 AU) for the 2002 apparition. These asymmetries are compatible with a scenario where dust ejection is mostly seasonally-driven, coming mainly from regions near subsolar latitudes at far heliocentric distances inbound and outbound. At intermediate to near-perihelion heliocentric distances, the outgassing would affect much more extended latitude regions, the emission becoming almost isotropic near perihelion. We derived a maximum dust production rate of 260 kg s$^{-1}$ at perihelion, and an averaged production rate over one orbit of 40 kg s$^{-1}$. An enhanced emission rate, accompanied also by a large ejection velocity, is predicted at $r_h>$2.5 pre-perihelion. The model has also been extended to the thermal infrared in order to be applied to available trail observations with IRAS and ISO spacecrafts of this comet. The modeled trail intensities are in good agreement with those observations, which is remarkable taking into account that those data are sensitive to dust ejection patterns corresponding to several orbits before the 2002 and 2009 apparitions.Comment: Accepted by The Astrophysical Journa