We present new results of a program aimed at studying the physical
properties, origin and evolution of those phenomena which go under the somewhat
generic definition of "low-ionization, small-scale ...structures in PNe". We have
obtained morphological and kinematical data for 10 PNe, finding low-ionization
structures with very different properties relative to each other, in terms of
expansion velocities, shapes, sizes and locations relatively to the main
nebular components. It is clear that several physical processes have to be
considered in order to account for the formation and evolution of the different
structures observed. We present here some results that are illustrative of our
work - on IC 4593, NGC 3918, K 1-2, Wray 17-1, NGC 6337, He 2-186 and K 4-47 -
and some of the questions that we try to address.
Astrophys.J.Suppl. 127 (2000) 125-140 We present near-IR narrow-band continuum-subtracted images in the H$_2$
$2.122\mu$m, and Br$\gamma$ $2.166\mu$m emission lines for a sample of 15
bipolar ...planetary nebulae. H$_2$ emission was definitely detected for most of
the objects in this sample (13 out of 15). The very high H$_2$ detection rate
supports the idea that bipolar planetary nebulae have important reservoirs of
molecular material and offer suitable physical conditions for the excitation of
H$_2$. The strength of the H$_2$ emission and the H$_2$/Br$\gamma$ flux ratio
are found to correlate with the morphology of the bipolar nebulae observed.
Bipolar PNe with broad and bright rings exhibit stronger H$_2$ emission than
bipolar PNe with narrow twists. High-quality (sub-arcsec) N~{\sc ii} and
H$\alpha$ optical images have been used to compare the distribution of the
ionized and molecular material. The H$_2$ emission lies just outside the
optical N~{\sc ii} emission zone.
In 2016, the Bloomberg Philanthropies Data for Health initiative assisted the Philippine Statistical Authority in implementing Iris, an automated coding software program that enables medical death ...certificates to be coded according to international standards. Iris was implemented to improve the quality, timeliness, and consistency of coded data as part of broader activities to strengthen the country's civil registration and vital statistics system. This study was conducted as part of the routine implementation of Iris to ensure that automatically coded cause of death data was of sufficient quality to be released and disseminated as national mortality statistics. Data from medical death certificates coded with Iris between 2017 and 2019 were analysed and evaluated for apparent errors and inconsistencies, and trends were examined for plausibility. Cause-specific mortality distributions were calculated for each of the 3 years and compared for consistency, and annual numeric and percentage changes were calculated and compared for all age groups. The typology, reasons, and proportions of records that could not be coded (Iris 'rejects') were also studied. Overall, the study found that the Philippine Statistical Authority successfully operates Iris. The cause-specific mortality fractions for the 20 leading causes of death showed reassuring stability after the introduction of Iris, and the type and proportion of rejects were similar to international experience. Broadly, this study demonstrates how an automated coding system can improve the accuracy and timeliness of cause of death data-providing critical country experiences to help build the evidence base on the topic.In 2016, the Bloomberg Philanthropies Data for Health initiative assisted the Philippine Statistical Authority in implementing Iris, an automated coding software program that enables medical death certificates to be coded according to international standards. Iris was implemented to improve the quality, timeliness, and consistency of coded data as part of broader activities to strengthen the country's civil registration and vital statistics system. This study was conducted as part of the routine implementation of Iris to ensure that automatically coded cause of death data was of sufficient quality to be released and disseminated as national mortality statistics. Data from medical death certificates coded with Iris between 2017 and 2019 were analysed and evaluated for apparent errors and inconsistencies, and trends were examined for plausibility. Cause-specific mortality distributions were calculated for each of the 3 years and compared for consistency, and annual numeric and percentage changes were calculated and compared for all age groups. The typology, reasons, and proportions of records that could not be coded (Iris 'rejects') were also studied. Overall, the study found that the Philippine Statistical Authority successfully operates Iris. The cause-specific mortality fractions for the 20 leading causes of death showed reassuring stability after the introduction of Iris, and the type and proportion of rejects were similar to international experience. Broadly, this study demonstrates how an automated coding system can improve the accuracy and timeliness of cause of death data-providing critical country experiences to help build the evidence base on the topic.
We present images and high-resolution spectra of the planetary nebulae IC 2553 and NGC 5882. Spatio-kinematic modeling of the nebulae shows that they are composed of a markedly elongated inner shell, ...and of a less aspherical outer shell expanding at a considerably higher velocity than the inner one. Embedded in the outer shells of both nebulae are found several low-ionization knots. In IC 2553, the knots show a point-symmetric distribution with respect to the central star: one possible explanation for their formation is that they are the survivors of pre-existing point-symmetric condensations in the AGB wind, a fact which would imply a quite peculiar mass-loss geometry from the giant progenitor. In the case of NGC 5882, the lack of symmetry in the distribution of the observed low-ionization structures makes it possible that they are the result of in situ instabilities.
We present new results of a program aimed at studying the physical properties, origin and evolution of those phenomena which go under the somewhat generic definition of "low-ionization, small-scale ...structures in PNe". We have obtained morphological and kinematical data for 10 PNe, finding low-ionization structures with very different properties relative to each other, in terms of expansion velocities, shapes, sizes and locations relatively to the main nebular components. It is clear that several physical processes have to be considered in order to account for the formation and evolution of the different structures observed. We present here some results that are illustrative of our work - on IC 4593, NGC 3918, K 1-2, Wray 17-1, NGC 6337, He 2-186 and K 4-47 - and some of the questions that we try to address.
We present near-IR narrow-band continuum-subtracted images in the H\(_2\) \(2.122\mu\)m, and Br\(\gamma\) \(2.166\mu\)m emission lines for a sample of 15 bipolar planetary nebulae. H\(_2\) emission ...was definitely detected for most of the objects in this sample (13 out of 15). The very high H\(_2\) detection rate supports the idea that bipolar planetary nebulae have important reservoirs of molecular material and offer suitable physical conditions for the excitation of H\(_2\). The strength of the H\(_2\) emission and the H\(_2\)/Br\(\gamma\) flux ratio are found to correlate with the morphology of the bipolar nebulae observed. Bipolar PNe with broad and bright rings exhibit stronger H\(_2\) emission than bipolar PNe with narrow twists. High-quality (sub-arcsec) N~{\sc ii} and H\(\alpha\) optical images have been used to compare the distribution of the ionized and molecular material. The H\(_2\) emission lies just outside the optical N~{\sc ii} emission zone.
Astron.Astrophys.Suppl.Ser.138:455-456,1999 We report on near-infrared and optical observations of the GRB 970616 error
box and of the X-ray sources discovered by ASCA and ROSAT in the region. No
...optical transient was found either within the IPN band or in the X-ray error
boxes, similarly to other bursts, and we suggest that either considerable
intrinsic absorption was present (like GRB 970828) or that the optical
transient displayed a very fast decline (like GRB 980326 and GRB 980519).
We report on near-infrared and optical observations of the GRB 970616 error box and of the X-ray sources discovered by ASCA and ROSAT in the region. No optical transient was found either within the ...IPN band or in the X-ray error boxes, similarly to other bursts, and we suggest that either considerable intrinsic absorption was present (like GRB 970828) or that the optical transient displayed a very fast decline (like GRB 980326 and GRB 980519).
We present the Spitzer/Infrared Spectrograph (IRS) spectra of 157 compact Galactic planetary nebulae (PNe). These young PNe provide insight on the effects of dust in early post-asymptotic giant ...branch evolution, before much of the dust is altered or destroyed by the hardening stellar radiation field. Most of the selected targets have PN-type IRS spectra, while a few turned out to be misclassified stars. We inspected the group properties of the PN spectra and classified them based on the different dust classes (featureless or F, carbon-rich dust or CRD, oxygen-rich dust or ORD, mixed-chemistry dust or MCD) and subclasses. The Galactic PNe that show solid-state features are almost equally divided among the CRD, ORD, and MCD. By comparing the sample of this paper to that of Magellanic Cloud PNe, we find that the latter sample does not include MCD PNe, and the other dust classes are differently populated, with continuity of the fraction of F, CRD, ORD, and MCD populations from high to low metallicity environments.
We present an analysis of elemental abundances of He, N, O, Ne, S, and Ar in Magellanic Cloud planetary nebulae (PNe) and focus initially on 14 PNe in the Small Magellanic Cloud (SMC). We derive the ...abundances from a combination of deep, high-dispersion optical spectra, as well as mid-infrared (IR) spectra from the Spitzer Space Telescope. A detailed comparison with prior SMC PN studies shows that significant variations in relative emission-line flux determinations among the authors, lead to systematic discrepancies in derived elemental abundances between studies that are {approx_gt}0.15 dex, in spite of similar analysis methods. We use ionic abundances derived from IR emission lines, including those from ionization stages not observable in the optical, to examine the accuracy of some commonly used recipes for ionization correction factors (ICFs). These ICFs, which were developed for ions observed in the optical and ultraviolet, relate ionic abundances to total elemental abundances. We find that most of these ICFs work very well even in the limit of substantially sub-solar metallicities, except for PNe with very high ionization. Our abundance analysis shows enhancements of He and N that are predicted from prior dredge-up processes of the progenitors on the asymptotic giant branch (AGB), as well as the well-known correlations among O, Ne, S, and Ar that are little affected by nucleosynthesis in this mass range. We identify MG 8 as an interesting limiting case of a PN central star with a {approx}3.5 M{sub sun} progenitor in which hot-bottom burning did not occur in its prior AGB evolution. We find no evidence for O depletion in the progenitor AGB stars via the O-N cycle, which is consistent with predictions for lower-mass stars. We also find low S/O ratios relative to SMC H II regions, with a deficit comparable to what has been found for Galactic PNe. Finally, the elemental abundances of one object, SMP-SMC 11, are more typical of SMC H II regions, which raises some doubt about its classification as a PN.
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