1,721,290 research outputs found
GLIMPSE Extended Green Objects and the Early Stages of Massive Star Formation
No full textLarge-scale Spitzer surveys of the Galactic plane have yielded a new tracer of massive young stellar objects (MYSOs) that are actively accreting and driving outflows: extended emission in the IRAC 4.5 μmband, believed to arise from shocked molecular gas. The GLIMPSE catalog of extended 4.5 μm sources (called EGOs, Extended Green Objects, forthe common coding of 3-color IRAC images) is a unique sample,well-suited for studying the initial stages of massive star formation and establishing an observation-based MYSO evolutionary sequence. In this proceeding, we present results from extensive recent high-resolution Submillimeter Array (SMA) and Very Large Array (VLA)observations of EGOs at cm-mm wavelengths, including maser, molecular line, and continuum studies. These observations often reveal (proto)clusters that exhibit chemical and evolutionary diversity
Social networking: an astronomer's field guide
No full textWe present a brief introduction to the phenomenon of "social networking" and its potentially powerful use as an astronomy outreach and educational tool. We briefly discuss the development of applications for websites and facebook and the use of web trackers e.g. Google Analytics to analyze your audience. Finally we discuss how social bookmarking can be used to promote your work to unexpected audiences
Modelling star formation in Ophiuchus
No full textWe perform simulations of prestellar core collapse with initial conditions inferred from observations of Ophiuchus. The cores in Ophiuchus are mostly isolated, hence we run multiple simulations of individual cores. We statistically model the intrinsic shapes of cores as a population of triaxial ellipsoids with a single free parameter which is fitted to aspect ratio data. We assume a turbulent velocity field with modifications which add ordered radial and rotational motion. Mass, size and non-thermal velocity dispersion are drawn randomly from observational data. Preliminary results show a largely realistic IMF. Future work will explore solenoidal to compressive velocity mode ratios and the effects of accretion luminosity. Results will lead to inferences on quantities such as star formation efficiency in the region
Estimating the Galactic Coronal Density via Ram-Pressure Stripping from Dwarf Satellites
No full textCosmological simulations and theories of galaxy formation predict that the Milky Way should be embedded in an extended hot gaseous halo or corona. To date, a definitive detection of such a corona in the Milky Way remains elusive. We have attempted to estimate the density of the Milky Way's cosmological corona using the effect that it has on the surrounding population of dwarf galaxies. We have considered two dSphs close to the Galaxy: Sextans and Carina. Assuming that they have lost all their gas during the last pericentric passage via ram-pressure stripping, we were able to estimate the average density (n ˜ 2 ṡ 10-4 cm-3) of the corona at a distance of ˜ 70 kpc from the Milky Way. If we consider an isothermal profile and extrapolate it at large radii, the corona could contain a significant fraction of the missing baryons associated to the Milky Way
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
The Role of Magnetic Fields in the Formation of Stars
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
The Role of Magnetic Fields in the Formation of Stars
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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