ORCID Profile
0000-0002-6858-5063
Current Organisation
NASA Jet Propulsion Laboratory
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Publisher: American Astronomical Society
Date: 18-07-2016
Publisher: Emerald
Date: 26-06-2009
DOI: 10.1108/17511340910964135
Abstract: This paper analyzes Chandler's biography of Henry Varnum Poor to assess Chandler's contribution to management history as a biographer. Using Winter's content thematic analysis, measure Poor's motivational needs for achievement, affiliation‐intimacy, and power, as they are depicted by Chandler throughout the stages of Poor's career as a business editor, analyst, and reformer. Our analysis shows that Chandler views Poor's motivation as stable throughout Poor's three professional roles. This paper found that Chandler views Poor as primarily driven by his need for power, followed by a significant need for achievement, and a minor need for affiliation throughout his working life. This research is unique because it provides the first social‐scientific assessment of Chandler's contribution to management history as a biographer.
Publisher: American Astronomical Society
Date: 29-10-2009
Publisher: EDP Sciences
Date: 03-2023
DOI: 10.1051/0004-6361/202245398
Abstract: Context . Low- and intermediate-mass asymptotic giant stars and massive red supergiant stars are important contributors to the chemical enrichment of the Universe. They are among the most efficient dust factories of the Galaxy, harboring chemically rich circumstellar environments. Yet, the processes that lead to dust formation or the large-scale shaping of the mass loss still escape attempts at modeling. Aims . Through the A TOMIUM project, we aim to present a consistent view of a s le of 17 nearby cool evolved stars. Our goals are to unveil the dust-nucleation sites and morphologies of the circumstellar envelope of such stars and to probe ambient environments with various conditions. This will further enhance our understanding of the roles of stellar convection and pulsations, and that of companions in shaping the dusty circumstellar medium. Methods . Here we present and analyze VLT/SPHERE-ZIMPOL polarimetric maps obtained in the visible (645–820 nm) of 14 out of the 17 A TOMIUM sources. They were obtained contemporaneously with the ALMA high spatial resolution data. To help interpret the polarized signal, we produced synthetic maps of light scattering by dust, through 3D radiative transfer simulations with the RADMC3D code. Results . The degree of linear polarization (DoLP) observed by ZIMPOL spreads across several optical filters. We infer that it primarily probes dust located just outside of the point spread function of the central source, and in or near the plane of the sky. The polarized signal is mainly produced by structures with a total optical depth close to unity in the line of sight, and it represents only a fraction of the total circumstellar dust. The maximum DoLP ranges from 0.03–0.38 depending on the source, fractions that can be reproduced by our 3D pilot models for grains composed of olivine, melilite, corundum, enstatite, or forsterite. The spatial structure of the DoLP shows a erse set of shapes, including clumps, arcs, and full envelopes. Only for three sources do we note a correlation between the ALMA CO υ = 0, J = 2−1 and SiO υ = 0, J = 5−4 lines, which trace the gas density, and the DoLP, which traces the dust. Conclusions . The clumpiness of the DoLP and the lack of a consistent correlation between the gas and the dust location show that, in the inner environment, dust formation occurs at very specific sites. This has potential consequences for the derived mass-loss rates and dust-to-gas ratio in the inner region of the circumstellar environment. Except for π 1 Gru and perhaps GY Aql, we do not detect interactions between the circumstellar wind and the hypothesized companions that shape the wind at larger scales. This suggests that the orbits of any other companions are tilted out of the plane of the sky.
Publisher: American Astronomical Society
Date: 27-09-2006
DOI: 10.1086/507329
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-09-2020
Abstract: Stars less than eight times the mass of the Sun end their lives as planetary nebulae, structures of ionized gas thrown off by the star and heated by the exposed stellar core. Planetary nebulae are often bipolar in shape or contain complex morphological features such as rings or spirals. Decin et al. observed the stellar winds of 14 stars during their asymptotic giant branch (AGB) phase of stellar evolution, which immediately precedes the planetary nebula phase. They found morphologies in the AGB winds similar to planetary nebulae and demonstrated that they are produced by the influence of a binary companion on the AGB wind. Science , this issue p. 1497
Publisher: EDP Sciences
Date: 29-04-2014
Publisher: Oxford University Press (OUP)
Date: 10-07-2012
Publisher: American Astronomical Society
Date: 08-04-2010
Publisher: American Astronomical Society
Date: 31-07-2023
Publisher: EDP Sciences
Date: 29-11-2016
Publisher: American Astronomical Society
Date: 10-07-2002
DOI: 10.1086/341969
Publisher: American Astronomical Society
Date: 13-08-2008
Location: United States of America
No related grants have been discovered for Raghvendra Sahai.