1,721,154 research outputs found
Resolving the Vela C ridge with P-ArTeMiS and Herschel
Get PDFInternational audienceWe present APEX/P-ArTéMiS 450\mu m continuum observations of RCW 36 and the adjacent ridge, a high-mass high-column density filamentary structure at the centre of the Vela C molecular cloud. These observations, at higher resolution than Herschel's SPIRE camera, reveal clear fragmentation of the central star-forming ridge. Combined with PACS far-infrared and SPIRE sub-millimetre observations from the Herschel HOBYS project we build a high resolution column density map of the region mapped with P-ArTéMiS. We extract the radial density profile of the Vela C ridge which with a ~ 0.1pc central width is consistent with that measured for low-mass star-forming filaments in the Herschel Gould Belt survey. Direct comparison with Serpens South, of the Gould Belt Aquila complex, reveals many similarities between the two regions. Despite likely different formation mechanisms and histories, the Vela C ridge and Serpens South filament share common characteristics, including their filament central widths
Sobre el divorcio - Tomás Vela C.
No full textLa tesis que a continuación se comenta fue presentada en 1891 por el estudiante
Tomás Vela C. ante el Consejo de Profesores del Externado. Llama la atención
el tema de su investigación: El divorcio, tema bastante controversial para
la época por cuanto existía una fuerte influencia en contra de la disolución del
vínculo matrimonial por divorcio; así lo establecía la legislación y lo reforzaban
las ideas religiosas de la época
SUBMILLIMETER POLARIZATION SPECTRUM IN THE VELA C MOLECULAR CLOUD
Get PDFPolarization maps of the Vela C molecular cloud were obtained at 250, 350, and 500 μm during the 2012 flight of the balloon-borne telescope BLASTPol. These measurements are used in conjunction with 850 μm data from Planck to study the submillimeter spectrum of the polarization fraction for this cloud. The spectrum is relatively flat and does not exhibit a pronounced minimum at λ ∼ 350 μm as suggested by previous measurements of other molecular clouds. The shape of the spectrum does not depend strongly on the radiative environment of the dust, as quantified by the column density or the dust temperature obtained from Herschel data. The polarization ratios observed in Vela C are consistent with a model of a porous clumpy molecular cloud being uniformly heated by the
interstellar radiation field
Submillimeter Polarization Spectrum in the Vela C Molecular Cloud
Get PDFPolarization maps of the Vela C molecular cloud were obtained at 250, 350, and 500 μm during the 2012 flight of the balloon-borne telescope BLASTPol. These measurements are used in conjunction with 850 μm data from Planck to study the submillimeter spectrum of the polarization fraction for this cloud. The spectrum is relatively flat and does not exhibit a pronounced minimum at λ ~ 350 μm as suggested by previous measurements of other molecular clouds. The shape of the spectrum does not depend strongly on the radiative environment of the dust, as quantified by the column density or the dust temperature obtained from Herschel data. The polarization ratios observed in Vela C are consistent with a model of a porous clumpy molecular cloud being uniformly heated by the interstellar radiation field
Dense cores and star formation in the giant molecular cloud Vela C
No full textContext. The Vela Molecular Ridge is one of the nearest (700 pc) giant molecular cloud (GMC) complexes hosting intermediate-mass (up to early B, late O stars) star formation, and is located in the outer Galaxy, inside the Galactic plane. Vela C is one of the GMCs making up the Vela Molecular Ridge, and exhibits both sub-regions of robust and sub-regions of more quiescent star formation activity, with both low- and intermediate(high)-mass star formation in progress. Aims. We aim to study the individual and global properties of dense dust cores in Vela C, and aim to search for spatial variations in these properties which could be related to different environmental properties and/or evolutionary stages in the various sub-regions of Vela C. Methods. We mapped the submillimetre (345 GHz) emission from vela C with LABOCA (beam size ~19′′2, spatial resolution ~0.07 pc at 700 pc) at the APEX telescope. We used the clump-finding algorithm CuTEx to identify the compact submillimetre sources. We also used SIMBA (250 GHz) observations, and Herschel and WISE ancillary data. The association with WISE red sources allowed the protostellar and starless cores to be separated, whereas the Herschel dataset allowed the dust temperature to be derived for a fraction of cores. The protostellar and starless core mass functions (CMFs) were constructed following two different approaches, achieving a mass completeness limit of 3.7 M. Results. We retrieved 549 submillimetre cores, 316 of which are starless and mostly gravitationally bound (therefore prestellar in nature). Both the protostellar and the starless CMFs are consistent with the shape of a Salpeter initial mass function in the high-mass part of the distribution. Clustering of cores at scales of 1-6 pc is also found, hinting at fractionation of magnetised, turbulent gas
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Pose determination of passively cooperative spacecraft in close proximity using a monocular camera and AruCo markers
No full textMissions requiring autonomous, close-proximity operations of spacecraft, such as On-Orbit Servicing, On-Orbit Assembly and Active Debris Removal, have become a thriving topic in the aerospace research community over the last decades, not only from an economic, operative, and scientific perspective, but also as a mean of ensuring the sustainability of the space environment. These operations involve a variety of technological challenges, most of which are related to the need of autonomous and safe Guidance, Navigation and Control systems. Since the future of these mission scenarios is strictly tied to spacecraft standardisation and modularity, relative navigation employing monocular cameras on servicing platforms to approach targets equipped with artificial markers for pose estimation purposes has drawn great attention. Following this trend, this paper presents an original vision-based pose estimation architecture for relative navigation with respect to passively cooperative targets equipped with ArUco markers. The proposed architecture foresees two operative modes, namely Acquisition and Tracking. The first features ArUco's detection through hue-saturation-value image representation, their identification by reading their built-in code and the computation of the pose without a-priori knowledge. The second, instead, takes advantage of prior pose estimates to speed up the entire processing pipeline. Performance is assessed through an extensive numerical simulation campaign, considering as test scenario the final approach phase of a rendezvous manoeuvre to reach a satellite belonging to a large constellation in Low Earth Orbit, and using the Planet and Asteroid Natural scene Generation Utility tool for realistic synthetic image generation. The dedicated tests on the Acquisition mode show that successful marker detection and pose initialization is achieved from up to 99.76% of the possible relative position and attitude states of the chaser with respect to the target at beginning of the final approach trajectory. As the chaser gets closer to the target, results highlight significant robustness of both operative modes against illumination conditions and uncertainties in the knowledge of camera intrinsic parameters. Overall, the architecture shows pose estimation accuracies up to millimetric and sub-degree levels
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