Jets and Outflows From Star to Cloud: Observations Confront Theory

In this review we focus on the role jets and outflows play in the star and planet formation process. Our essential question can be posed as follows: are jets/outflows merely an epiphenomenon associated with star formation or do they play an important role in mediating the physics of assembling stars both individually and globally? We address this question by reviewing the current state of observations and their key points of contact with theory. Our review of jet/outflow phenomena is organized into three length-scale domains: Source and Disk Scales ($0.1-10^2$ au) where the connection with protostellar and disk evolution theories is paramount; Envelope Scales ($10^2-10^5$ au) where the chemistry and propagation shed further light on the jet launching process, its variability and its impact on the infalling envelope; Parent Cloud Scales ($10^5-10^6$ au) where global momentum injection into cluster/cloud environments become relevant. Issues of feedback are of particular importance on the smallest scales where planet formation regions in a disk may be impacted by the presence of disk winds, irradiation by jet shocks or shielding by the winds. Feedback on envelope scales may determine the final stellar mass (core-to-star efficiency) and envelope dissipation. Feedback also plays an important role on the larger scales with outflows contributing to turbulent support within clusters including alteration of cluster star formation efficiencies (feedback on larger scales currently appears unlikely). A particularly novel dimension of our review is that we consider results on jet dynamics from the emerging field of High Energy Density Laboratory Astrophysics (HEDLA). HEDLA is now providing direct insights into the 3-D dynamics of fully magnetized, hypersonic, radiative outflows.Comment: Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014), eds. H. Beuther, R. Klessen, C. Dullemond, Th. Hennin

Alternativas de planejamento para a exploração florestal.

No manejo sustentado em florestas tropicais, há necessidade da garantia de um fluxo constante de recursos para a sua viabilidade. No entanto, isso nem sempre é possível, pelo fato de a exploração ser realizada sem planejamento. Este trabalho tem como finalidade apresentar um método que auxilie no planejamento e na distribuição de recursos disponíveis, através da formulação de cenários para otimização do número de equipes para cada atividade da exploração dependente do tempo limite para conclusão dos trabalhos. Com base no tempo que uma equipe leva para executar determinada atividade e no seu sequenciamento, foram utilizadas técnicas da pesquisa operacional, para determinação do caminho crítico da cadeia de exploração de madeira nativa. Esses métodos, ao mesmo tempo em que organizam o sequenciamento das atividades e determinam quais delas devem receber maior atenção no planejamento, otimizam o número de equipes, para que toda a cadeia seja executada dentro de um tempo limite, o que se faz necessário na região, para que o ciclo de corte se limite à época de seca. O método proposto mostra-se como uma alternativa para o planejamento florestal das atividades de baixo impacto ao garantir o número ótimo de equipes e a realização de todo empreendimento no tempo estipulado

La estimulación neonatal por un ambiente nuevo mejora la producción de huevos en gallinas ponedoras

The development of behavioral and endocrine responses to acute stress is greatly influenced by the early postnatal rearing environment. These environmental effects persist throughout life, resulting in stable individual differences in fearfulness. Early stimulation, such as neonatal novelty exposure decreases behavioral reactivity. Previous reports also show that early–life stimulation, such as neonatal exposure to novelty, reduces behavioural reactivity. The aim of this study was to evaluate whether early stimulation increases egg production in adult laying eggs. One–day–old laying hen chicks were exposed to a T–maze (Method A) or a test based on the latency to peck (Method B), and then reared in an industrial poultry farm until adults. A group of non–stimulated hens was used as a control group. Weekly egg production, individual egg weight and weekly feed intake were measured in laying hens under farm conditions for 25 weeks. An increase in egg number was observed in stimulated laying hens by Method A (5.22 ± 0.06, p < 0.01) and by Method B (5.33 ± 0.08, p < 0.001) compared to the controls (4.78 ± 0.24). Likewise, the food conversion index was also greater for stimulated hens by Method A (0.356 ± 0.042; p < 0.05) and Method B (0.363 ± 0.053; p < 0.01), compared to the control group (0.330 ± 0.085). These results indicate that early stimulation could help to improve the adaptation of laying hens in industrial poultry farms. Key words: chick, early stimulation, egg production, laying hen, stress.El desarrollo de las respuestas comportamentales y endocrinas al estrés agudo está fuertemente influenciado por el entorno postnatal temprano. Estos efectos ambientales persisten a lo largo de la vida, generando diferencias individuales estables en la temerosidad. La estimulación temprana, como la exposición a un ambiente nuevo, disminuye la reactividad comportamental. También se demostró en investigaciones previas que una estimulación temprana en la vida, tal como una exposición neonatal al ambiente nuevo, redujo la reactividad comportamental. El objetivo de este estudio fue evaluar si una estimulación temprana aumenta la producción de huevos en gallinas adultas. Pollitos de gallinas ponedoras de un día de edad se expusieron a un laberinto en T (método A) o una prueba basada en la latencia para picotear un objeto (método B), posteriormente se trasladaron a una granja avícola hasta la edad adulta. Se designó a un grupo de gallinas como control, las cuales no se estimularon por ninguno de los métodos anteriormente nombrados. Durante 25 semanas se registró la postura semanal de huevos, el peso individual de los huevos y el consumo de alimento semanal en las gallinas ponedoras criadas bajo condiciones de granja. Se observó un aumento en el número de huevos en las gallinas estimuladas por el método A (5,22 ± 0,06, p < 0,01) y por el método B (5,33 ± 0,08, p < 0,001) comparadas a los controles no estimulados (4,78 ± 0,24). Del mismo modo, el índice de conversión alimenticia también fue mayor para las gallinas estimuladas por el método A (0,356 ± 0,042, p < 0,05) y el método B (0,363 ± 0,053, p < 0,01) respecto al grupo control (0,330 ± 0,085). Estos resultados indican que la estimulación temprana puede ayudar a mejorar la adaptación de gallinas ponedoras a las condiciones de cría intensiva en las granjas avícolas industriales. Palabras clave: pollito, estimulación temprana, producción de huevos, gallinas ponedoras, estrés

HI 2334+26: An Extended HI Cloud near Abell 2634

We report the serendipitous discovery of a large HI cloud with an associated HI mass of $6(\pm1.5)\times 10^9 h^{-2}$ M$_\odot$ and a heliocentric velocity 8800 \kms, located near the periphery of the cluster of galaxies Abell 2634. Its velocity field appears to be very quiescent, as no gradients in the peak velocity are seen over its extent of 143$h^{-1}$ by 103$h^{-1}$ kpc. The distribution of gas is poorly resolved spatially, and it is thus difficult at this time to ascertain the nature of the cloud. At least two relatively small, actively star--forming galaxies appear to be embedded in the HI gas, which may (a) be an extended gaseous envelope surrounding one or both galaxies, (b) have been spread over a large region by a severe episode of tidal disruption or (c) have been affected by the ram pressure resulting from its motion through the intracluster gas of A2634.Comment: 12 pages plus 2 tables (AAS LaTeX macro v3.0), 4 figures not included. To appear in the A

A rotating molecular disk toward IRAS 18162-2048, the exciting source of HH 80-81

We present several molecular line emission arcsec and subarcsec observations obtained with the Submillimeter Array (SMA) in the direction of the massive protostar IRAS 18162-2048, the exciting source of HH 80-81. The data clearly indicates the presence of a compact (radius~425-850 AU) SO2 structure, enveloping the more compact (radius~150 AU) 1.4 millimeter dust emission (reported in a previous paper). The emission spatially coincides with the position of the prominent thermal radio jet which terminates at the HH 80-81 and HH 80N Herbig-Haro objects. Furthermore, the molecular emission is elongated in the direction perpendicular to the axis of the thermal radio jet, suggesting a disk-like structure. We derive a total dynamic mass (disk-like structure and protostar) of 11-15 msun. The SO2 spectral line data also allow us to constrain the structure temperature between 120-160 K and the volume density > 2x10^9 cm-3. We also find that such a rotating flattened system could be unstable due to gravitational disturbances. The data from C17O line emission show a dense core within this star-forming region. Additionally, the H2CO and the SO emissions appear clumpy and trace the disk-like structure, a possible interaction between a molecular core and the outflows, and in part, the cavity walls excavated by the thermal radio jet.Comment: 13 pages,11 figures. Accepted in the AJ, 07-15-201

CARMA Large Area Star Formation Survey: Observational Analysis of Filaments in the Serpens South Molecular Cloud

We present the N2H+(J=1-0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey (CLASSy). The observations cover 250 square arcminutes and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km/s, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N2H+ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N2H+ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.Comment: 12 pages, 4 figures, published in ApJL (July 2014

On the kinematics of massive star forming regions: the case of IRAS 17233-3606

Direct observations of accretion disks around high-mass young stellar objects would help to discriminate between different models of formation of massive stars. However, given the complexity of massive star forming regions, such studies are still limited in number. Additionally, there is still no general consensus on the molecular tracers to be used for such investigations. Because of its close distance and high luminosity, IRAS 17233-3606 is a potential good laboratory to search for traces of rotation in the inner gas around the protostar(s). Therefore, we selected the source for a detailed analysis of its molecular emission at 230 GHz with the SMA. We systematically investigated the velocity fields of transitions in the SMA spectra which are not affected by overlap with other transitions, and searched for coherent velocity gradients to compare them to the distribution of outflows in the region. Beside CO emission we also used high-angular H2 images to trace the outflow motions driven by the IRAS 17233-3606 cluster. We find linear velocity gradients in many transitions of the same molecular species and in several molecules. We report the first detection of HNCO in molecular outflows from massive YSOs. We discuss the CH3CN velocity gradient taking into account various scenarios: rotation, presence of multiple unresolved sources with different velocities, and outflow(s). Although other interpretations cannot be ruled out, we propose that the CH3CN emission might be affected by the outflows of the region. Higher angular observations are needed to discriminate between the different scenarios. The present observations, with the possible association of CH3CN with outflows in a few thousands AU around the YSOs' cluster, (i) question the choice of the tracer to probe rotating structures, and (ii) show the importance of the use of H2 images for detailed studies of kinematics.Comment: accepted for publication in A&