46 research outputs found

    A Search for Hydrodynamical Interaction Between the ISM and Radio Jets in IC4296

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    The ROSAT HRI Data set on IC 4296 has been reduced and analysed. A draft paper on the small-scale structure of x-ray emission and its relation to the radio emission has been written. Mackie left the Smithsonian Astrophysical Observatory in September 1997 and in January 1998 he joined the staff at Carter Observatory, New Zealand. Mackie is currently (May 1998) upgrading computer software at Carter to run IRAF-PROS and XSPEC x-ray software packages in order to reduce and analyze archival ROSAT PSPC data on IC 4296. The PSPC results are needed to investigate the hot gas temperature and abundance properties that will be used in conjunction with the radio jet properties to determine the hydrodynamical interaction status of IC 4296, and finalize the results of a research paper

    A 2dF spectroscopic study of globular clusters in NGC 5128: Probing the formation history of the nearest giant Elliptical

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    We have performed a spectroscopic study of globular clusters (GCs) in the giant elliptical NGC 5128 using the 2dF facility at the Anglo-Australian telescope. We obtained integrated optical spectra for a total of 254 GCs, 79 of which are newly confirmed on the basis of their radial velocities and spectra. In addition, we obtained an integrated spectrum of the galaxy starlight along the southern major axis. We derive an empirical metallicity distribution function (MDF) for 207 GCs (~14 of the estimated total GC system) based upon Milky Way GCs. This MDF is multimodal at high statistical significance with peaks at [Z/H]~-1.3 and -0.5. A comparison between the GC MDF and that of the stellar halo at 20 kpc (~4 Reff) reveals close coincidence at the metal-rich ends of the distributions. However, an inner 8 kpc stellar MDF shows a clear excess of metal-rich stars when compared to the GCs. We compare a higher S/N subsample (147 GCs) with two stellar population models which include non-solar abundance ratio corrections. The vast majority of our sample (~90%) appears old, with ages similar to the Milky Way GC system. There is evidence for a population of intermediate-age (~4-8 Gy) GCs (<15% of the sample) which are on average more metal-rich than the old GCs. We also identify at least one younger cluster (~1-2 Gy) in the central regions of the galaxy. Our observations are consistent with a picture where NGC 5128 has undergone at least two mergers and/or interactions involving star formation and limited GC formation since z=1, however the effect of non-canonical hot stellar populations on the integrated spectra of GCs remains an outstanding uncertainty in our GC age estimates.Comment: 17 figures, some long table

    Reduction of PG:1115+080 Images

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    The data are three exposures in PC6 through F785LP obtained on March 3, 1991. The exposure times are 120, 400, and 400 seconds. The data are reduced with the "standard" WFPC reduction scheme: A-to-D correction, DC bias subtraction, AC bias subtraction, dark current subtraction, preflash subtraction, and flat field normalization, using the best available calibration data. The exposures are combined into a weighted average normalized to 400 seconds exposure time, so one DN (data number) is about 17.25 electrons. At this step, cosmic rays are removed by intercomparison of the three images

    Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

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    BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

    The stellar content of central dominant galaxies II: colors of cD envelopes

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    The study presents deep g- and r-band CCD imaging of three rich clusters, A2589, A2634, and A407, containing cD galaxies or structures possibly relating to cD envelopes. Scattered light r exp -2 halos were modeled and subtracted from the images. The (g-r) color profiles of the cDs NGC 7647 (A2589) and NGC 7720 (A2634) down to the start of the envelopes are found to be quite flat. There is no evidence of a change in color at the surface brightness break that signifies the start of the cD envelope, nor are the colors of the envelope dramatically blue. The color profile of the D galaxy NGC 7728 also in A2634 displays a steeper blueward color gradient than NGC 7720. A407, which has nine nuclei in a common envelope, may also possess a red envelope in comparison to its higher surface brightness region, and thus may evolve into a cD similar to NGC 7647. The implications for cD envelope formation and evolution are discussed

    Swinburne Astronomy Online Graduations, October 2010

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    Swinburne Astronomy Online graduates, October 2010. Back row: Chris Fluke and Glen Mackie (back row). Front row: Fernando Lopez Blanco, Sarah Maddison, Lee Spitler

    STaRS: space science teaching and resource site

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    A World Wide Web site has been developed by astronomers and educators at Carter Observatory. STaRS is the Space science Teaching and Resource Site (www.vuw.ac.nz/similar to mackie/STaRS.html) and its objectives are to (1) present astronomy investigations for 8 to 12 year olds and (2) promote topical astronomy and space science studies for a general audience. The educational investigations drawn from local and international sources and the resources provided to teachers are described. The structure and content of the general audience pages are summarised. Details of site promotion and usage and critical comment from users and educators are given

    The multiwavelength atlas of galaxies

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    Valuable reference resource for students and researchers containing over 250 full-color images of some of the best-observed galaxies

    The Multiwavelength Atlas of Galaxies - dealings with publishers, editors, typesetters and creating an academic textbook (Free Astronomy Public Lectures)

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    Galaxies have been observed from ultra high energy gamma rays to long wavelength radio waves, providing fundamental insights into their formation and evolution. Until now, astronomy atlases preferentially showed (only) optical images of galaxies. Unveiling the secrets of some of the best observed galaxies, the published MAG contains over 250 full colour images of 35 galaxies spanning the whole electromagnetic spectrum. MAG explains why we see the component stars, gas and dust via different radiation processes, and describes the telescopes and instruments used. The lecture will discuss the metamorphosis from a personal web site to an academic textbook, the author - publisher (Cambridge University Press) relationship, and highlights from the textbook

    Kinematics of brightest cluster galaxies in the 2DFGRS

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    We have initiated a study of BCG peculiar velocities using the targeted study of catalogued clusters in the 2dFGRS by de Propris et al (2002). Our total sample includes 60 rich clusters (with cz &lt; 33,000 km/s) with an average 70 member redshifts per cluster. Approximately 1 out of 3 clusters have BCG V_peculiar &gt; 300 km/s. This result may suggest a substantial fraction of clusters are undergoing recent or ongoing cluster evolution (i.e. sub-cluster merging) at the sampled epoch, and has implications for the formation and evolution of BCGs. We shall discuss our result in relation to cluster properties (velocity dispersion, BM type, number of cluster member redshifts and presence of sub-structure). Reference: de Propris, R. et al. 2002, M.N.R.A.S., v.329, 87
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