Starburst in the ultraluminous galaxy Arp 220: Constraints from observations of radio recombination lines and continuum

We present observations of radio recombination lines (RRL) from the starburst galaxy Arp 220 at 8.1 GHz (H92 alpha) and 1.4 GHz (H167 alpha and H165 alpha) and at 84 GHz (H42 alpha), 96 GHz (H40 alpha) and 207 GHz (H31 alpha) using the Very Large Array and the IRAM 30 m telescope, respectively. RRLs were detected at all the frequencies except 1.4 GHz, where a sensitive upper limit was obtained. We also present continuum flux measurements at these frequencies as well as at 327 MHz made with the VLA. The continuum spectrum, which has a spectral index alpha similar to -0.6 (S-nu proportional to nu(alpha)) between 5 and 10 GHz, shows a break near 1.5 GHz, a prominent turnover below 500 MHz, and a flatter spectral index above 50 GHz. We show that a model with three components of ionized gas with different densities and area covering factors can consistently explain both RRL and continuum data. The total mass of ionized gas in the three components is 3.2 x 10(7) M., requiring 3 x 10(5) O5 stars with a total Lyman continuum production rate N-Lyc similar to 1.3 x 10(55) photons s(-1). The ratio of the expected to observed Br alpha and Br gamma fluxes implies a dust extinction A(V) similar to 45 mag. The derived Lyman continuum photon production rate implies a continuous star formation rate (SFR) averaged over the lifetime of OB stars of similar to 240 M yr(-1). The Lyman continuum photon Production rate of similar to 3% associated with the high-density H II regions implies a similar SFR at recent epochs (t < 10(5) yr). An alternative model of high-density gas, which cannot be excluded on the basis of the available data, predicts 10 times higher SFR at recent epochs. If confirmed, this model implies that star formation in Arp 220 consists of multiple starbursts of very high SFR (few times 10(3) M. yr(-1)) and short duration (similar to 10(5) yr). The similarity of IR excess, L-IR/L-Ly alpha similar to 24, in Arp 220 to values observed in starburst galaxies shows that most of the high luminosity of Arp 220 is due to the ongoing starburst rather than to a hidden active galactic nucleus (AGN). A comparison of the IR excesses in Arp 220, the Galaxy, and M33 indicates that the starburst in Arp 220 has an initial mass function that is similar to that in normal galaxies and has a duration longer than 107 yr. If there was no infall of gas during this period, then the star formation efficiency (SFE) in Arp 220 is similar to 50%. The high SFR and SFE in Arp 220 is consistent with their known dependences on mass and density of gas in star-forming regions of normal galaxies.

Sapientia, 2006, Vol. LXI, nº 219-220 (número completo)

Contenido: Editorial – Sesenta años después / Mario Enrique Sacchi – Homenaje a Cornelio Fabro : La importancia del padre Fabro en la búsqueda de un tomismo esencial / Mons. Héctor Aguer – Le premesse filosofiche dell’antitotalitarismo e dell’antinihilismo político di Cornelio Fabro / Danilo Castellano – La noción de libertad en el tomismo esencial de Cornelio Fabro / Christian Ferraro, Ive – De la libertad al ser en Cornelio Fabro / Marcelo Sánchez Sorondo -- Artículos : Aristóteles, fuente principal del De principiis naturae / Thomas Rego – La gracia de la medida: Afrodita, salvadora del placer / Beatriz Bossi López – La disolución de las identidades en la cultura contemporánea / Marisa Mosto – Consecuencias normativas de la naturaleza / José Tomás Alvarado Marambio – Acción y sentido en John Dewey / Juan Carlos Pablo Ballesteros – El problema del innatismo en Antonio Rosmini (parte I) / Juan Francisco Franck – Jacques Maritain y la polémica sobre la Teoría de la Relatividad / Oscar H. Beltrán – La cuestión filosófica de la expansión del universo / Mario Enrique Sacchi – Notas y reseñas – Bibliografía -- Resúmenes de los artículos

Diário da Constituinte [gravação de vídeo] : [programa n. 220]

O Relator Bernardo Cabral decidiu dar tratamento privilegiado na distribuição de recursos públicos para as regiões Norte, Nordeste e Centro-Oeste. O Deputado Joaci Góes (PMDB-BA) opina que a mais importante das propostas acolhidas é a da regionalização dos orçamentos. A Deputada Sandra Cavalcanti (PFL-RJ) esclarece que os principais avanços foram a permanência da Zona Franca de Manaus e a mudança na maneira de fazer os repasses dos recursos da União, que servirão para o fomento do desenvolvimento das regiões. O Senador Fernando Henrique Cardoso (PMDB-SP) propõe ao Relator da Assembleia Nacional Constituinte (ANC) a divisão da votação em duas partes. O Senador Virgílio Távora (PDS-CE) avalia que não há previsão para o encerramento dos trabalhos. A Bancada Feminina luta não apenas pelo direitos das mulheres, mas também por avanços em outras áreas, como a Reforma Agrária. A Deputada Wilma Maia (PDS-CE) pede título de propriedade da terra para homens ou mulheres, esposas ou companheiras. A Deputada Anna Maria Rattes (PFL-RJ) afirma o engajamento da bancada feminina em todos os pontos polêmicos da Assembleia Nacional Constituinte (ANC). A Deputada Moema São Thiago (PDT-CE) informa que a mulher pode esperar reconhecimento da igualdade entre homens e mulheres. Velado o corpo de Marcos Freire, no Salão Negro do Congresso Nacional , com missa de corpo presente.

Assessment of the structural properties of GaAs/Si epilayers using X-ray (004) and (220) reflections

We improved the method previously used to determine the lattice constants and misorientation of GaAs/Si by recording the patterns of X-ray (004) and (220) reflections. The (220) reflection was measured from the (110) cross section of a GaAs/Si epilayer. The structural properties of the GaAs/Si epilayers grown by metal-organic chemical-vapor deposition (MOCVD) using an ultrathin a-Si buffer layer were investigated. The rotation angle of GaAs/Si epilayers grown by MOCVD using an a-Si buffer layer is very small and the lattice constants of these GaAs/Si epilayers agree quite well with elastic theory.

Características e desempenho agronômico da cultivar de trigo BRS 220 no estado de Santa Catarina.

2005

Process simulation of co-firing torrefied biomass in a 220 MWe coal-fired power plant

Torrefaction based co-firing in a pulverized coal boiler has been proposed for large percentage of biomass co-firing. A 220 MWe pulverized coal-power plant is simulated using Aspen Plus for full understanding the impacts of an additional torrefaction unit on the efficiency of the whole power plant, the studied process includes biomass drying, biomass torrefaction, mill systems, biomass/coal devolatilization and combustion, heat exchanges and power generation. Palm kernel shells (PKS) were torrefied at same residence time but 4 different temperatures, to prepare 4 torrefied biomasses with different degrees of torrefaction. During biomass torrefaction processes, the mass loss properties and released gaseous components have been studied. In addition, process simulations at varying torrefaction degrees and biomass co-firing ratios have been carried out to understand the properties of CO₂ emission and electricity efficiency in the studied torrefaction based co-firing power plant. According to the experimental results, the mole fractions of CO ₂ and CO account for 69-91% and 4-27% in torrefied gases. The predicted results also showed that the electrical efficiency reduced when increasing either torrefaction temperature or substitution ratio of biomass. A deep torrefaction may not be recommended, because the power saved from biomass grinding is less than the heat consumed by the extra torrefaction process, depending on the heat sources. 

Resolución N° 220 ¿Cuáles son los presupuestos necesarios para la inscripción de modificación de situaciones de control? Puede la Cámara de Comercio abstenerse de registrar un acto de modificación de tal situación cuando quien alega dicha modificación es una ESAL afirmando que solo procede tal registro cuando se trate sociedades comerciales?

Servicios registrales

Resolución N° 220 ¿Cuáles son los criterios legales en los que se fundamenta la Cámara de comercio para evaluar la legalidad de un nombramiento? ¿Tiene la Cámara de comercio competencia para pronunciarse sobre la falsedad del documento presentado para registro?

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915 220 827 : el teléfono que defiende al profesor.

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