| 1. |
- Ueta, T., et al.
(författare)
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Herschel Planetary Nebula Survey (HerPlaNS)
- 2014
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Ingår i: Asymmetrical Planetary Nebulae VI conference, Proceedings of the conference held 4-8 November, 2013. ; , s. 106-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Herschel Planetary Nebula Survey (HerPlaNS) is one of the largest Open Time programs carried out by the Herschel Space Observatory, by which we simultaneously probe the dust and gas components of the circumstellar environments of evolved stars. HerPlaNS is part of a community-wide panchromatic (from X-ray to Radio) observational initiative to furnish substantial PN data resources that would allow us - PN astronomers - to tackle a multitude of issues in PN physics. In this contribution we will give a general overview of the survey and a glimpse of what the data can tell us using NGC 6781 as an example.
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| 2. |
- Ueta, T., et al.
(författare)
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The Herschel Planetary Nebula Survey (HerPlaNS) I. Data overview and analysis demonstration with NGC 6781
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 565, s. A36-
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Tidskriftsartikel (refereegranskat)abstract
- Context. This is the first of a series of investigations into far-IR characteristics of 11 planetary nebulae (PNe) under the Herschel Space Observatory open time 1 program, Herschel Planetary Nebula Survey (HerPlaNS). Aims. Using the HerPlaNS data set, we look into the PN energetics and variations of the physical conditions within the target nebulae. In the present work, we provide an overview of the survey, data acquisition and processing, and resulting data products. Methods. We performed (1) PACS/SPIRE broadband imaging to determine the spatial distribution of the cold dust component in the target PNe and (2) PACS/SPIRE spectral-energy-distribution and line spectroscopy to determine the spatial distribution of the gas component in the target PNe. Results. For the case of NGC 6781, the broadband maps confirm the nearly pole-on barrel structure of the amorphous carbon-rich dust shell and the surrounding halo having temperatures of 26-40 K. The PACS/SPIRE multiposition spectra show spatial variations of far-.IR lines that reflect the physical stratification of the nebula. We demonstrate that spatially resolved far-IR line diagnostics yield the (T-e, n(e)) profiles, from which distributions of ionized, atomic, and molecular gases can be determined. Direct comparison of the dust and gas column mass maps constrained by the HerPlaNS data allows to construct an empirical gas-to-dust mass ratio map, which shows a range of ratios with the median of 195 +/- 110. The present analysis yields estimates of the total mass of the shell to be 0.86 M-circle dot, consisting of 0.54 M-circle dot of ionized gas, 0.12 M-circle dot of atomic gas, 0.2 M-circle dot of molecular gas, and 4 x 10(-3) M-circle dot of dust grains. These estimates' also suggest that the central star of about 1.5 M-circle dot initial mass is terminating its PN evolution onto the white dwarf cooling track. Conclusions. The HerPlaNS data provide various diagnostics for both the dust and gas components in a spatially resolved manner. In the forthcoming papers of the HerPlaNS series we will explore the HerPlaNS data set fully for the entire sample of 11 PNe.
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| 3. |
- Ueta, T., et al.
(författare)
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Planetary Nebula dust haloes revealed by Herschel
- 2013
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Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039.
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Konferensbidrag (refereegranskat)abstract
- Herschel Planetary Nebula Survey (HerPlaNS) is a far-IR imaging and spectroscopic survey of planetary nebulae, performedwith the Herschel Space Observatory, aiming at (1) establishing the spatially-resolved far-IR characteristics of the target nebulae and (2) understanding the energetics and shaping history of the circumstellar nebulae. Below we briefly demonstrate the breadth and depth of the HerPlaNS data set using one of the targets, NGC6781, as an example, and explore expectations in the era of SPICA, the next-generation far-IR mission.
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| 4. |
- Malkawi, A. H., et al.
(författare)
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Sizing Fenestrated Aortic Stent-grafts
- 2011
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1532-2165 .- 1078-5884. ; 41:3, s. 311-316
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Fenestrated aortic stent-grafts are increasingly being used to treat patients with juxtarenal abdominal aortic aneurysms (AM). Sizing of these stent-grafts is critical to ensure success and requires detailed expert assessment of aortic morphology. At present little is known about how sizing of these stent-grafts varies between observers and the necessary tolerances involved to ensure a successful procedure. Methods: CT scans of 19 consecutive patients with juxtarenal aortic aneurysms that underwent successful endovascular repair with fenestrated stent-grafts were selected. Sizing of fenestrated aortic stent-grafts was performed independently by four experienced endovascular surgeons and results were compared. Data from the stent-graft manufacturer was available for comparison in 12 cases. Results: All observers agreed on the number of fenestrations; 16 devices had 3 fenestrations and 3 had 4. The overall inter-observer measurement error for all target vessel orientation was +/- 12.6 degrees (10.8-14.4 95% CI), and for distance between target vessels +/- 5.3 mm (4.4-6.2 95% CI). The median difference in internal stent-graft diameter was 1 stent size. Agreement on fenestration type ranged from (84-95%). Comparison was performed with the manufactured stent-graft in 12 cases. The overall mean difference of target vessel orientation between the manufactured devices and the four observers was -1.3 degrees (SD +/- 6.9, -3.8-1.2 95% CI). There was less agreement between observers and device manufacturers on body and limb lengths and distal limb diameters. Conclusions: There was generally a high level of agreement between experienced endovascular surgeons in sizing the fenestrated stent component. There were differences in component lengths but these could have been accommodated by varying the degree of overlap between components. (C) 2010 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
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