60 research outputs found

    The Cool ISM in Elliptical Galaxies. II. Gas Content in the Volume - Limited Sample and Results from the Combined Elliptical and Lenticular Surveys

    Full text link
    We report new observations of atomic and molecular gas in a volume limited sample of elliptical galaxies. Combining the elliptical sample with an earlier and similar lenticular one, we show that cool gas detection rates are very similar among low luminosity E and SO galaxies but are much higher among luminous S0s. Using the combined sample we revisit the correlation between cool gas mass and blue luminosity which emerged from our lenticular survey, finding strong support for previous claims that the molecular gas in ellipticals and lenticulars has different origins. Unexpectedly, however, and contrary to earlier claims, the same is not true for atomic gas. We speculate that both the AGN feedback and merger paradigms might offer explanations for differences in detection rates, and might also point towards an understanding of why the two gas phases could follow different evolutionary paths in Es and S0s. Finally we present a new and puzzling discovery concerning the global mix of atomic and molecular gas in early type galaxies. Atomic gas comprises a greater fraction of the cool ISM in more gas rich galaxies, a trend which can be plausibly explained. The puzzle is that galaxies tend to cluster around molecular-to-atomic gas mass ratios near either 0.05 or 0.5.Comment: 37 pages, including 4 tables and 12 figures. Accepted for publication in the Astrophysical Journa

    The Cool ISM in S0 Galaxies. I. A Survey of Molecular Gas

    Full text link
    Lenticular galaxies remain remarkably mysterious as a class. Observations to date have not led to any broad consensus about their origins, properties and evolution, though they are often thought to have formed in one big burst of star formation early in the history of the Universe, and to have evolved relatively passively since then. In that picture, current theory predicts that stellar evolution returns substantial quantities of gas to the interstellar medium; most is ejected from the galaxy, but significant amounts of cool gas might be retained. Past searches for that material, though, have provided unclear results. We present results from a survey of molecular gas in a volume-limited sample of field S0 galaxies, selected from the Nearby Galaxies Catalog. CO emission is detected from 78 percent of the sample galaxies. We find that the molecular gas is almost always located inside the central few kiloparses of a lenticular galaxy, meaning that in general it is more centrally concentrated than in spirals. We combine our data with HI observations from the literature to determine the total masses of cool and cold gas. Curiously, we find that, across a wide range of luminosity, the most gas rich galaxies have about 10 percent of the total amount of gas ever returned by their stars. That result is difficult to understand within the context of either monolithic or hierarchical models of evolution of the interstellar medium.Comment: 26 pages of text, 15 pages of tables, 10 figures. Accepted for publication in the Astrophysical Journa

    The Cool ISM in Elliptical Galaxies. I. A Survey of Molecular Gas

    Get PDF
    We present preliminary results from a survey of CO emission from members of a volume-limited sample of non-cluster elliptical galaxies. Our intent is to compare the gas properties of these ellipticals to a sample of lenticulars selected using similar criteria. The data, although still sparse, suggest that the cool gas in ellipticals shows the same puzzling upper mass cutoff found in the lenticular galaxies. We find, however, significantly lower detection rates and possibly much lower H2/HI mass ratios in the ellipticals. The detection rate is higher among the lower-mass galaxies, as has been found previously. This seems puzzling given that the deeper potential wells of the larger galaxies ought to make gas retention easier, but perhaps that effect is overwhelmed by feedback from the central suppermassive black hole. As we have observed ~40 percent of our sample, the conclusions are necessarily tentative at this time.Comment: Accepted for publication in the Astrophysical Journa

    Outer space technopolitics and postcolonial modernity in Kazakhstan

    Get PDF
    This is the final version. Available on open access from Routledge via the DOI in this recordThis article examines the role of outer space technopolitics in post-Soviet Kazakhstan. It explores how outer space, the technological artefact of global relevance, works as a postcolonial fetish of modernity that is called upon to produce what it represents, i.e. the reality of a technologically advanced Kazakh nation. The article shows that in its project of becoming a spacefaring nation the country reiterates major incentives that have motivated nuclear and space programme development in the postcolonial context of the Global South. The article explores how collaboration with Russia allows Kazakhstan to claim its share in the Soviet space legacy rather than to distance itself from it. It then traces the rise of a new internationalism in the Kazakhstani space programme outside the post-Soviet context. The article contributes to the debate on postcolonial techonopolitics and shows how outer space has been used to enhance the conventional domain of postcolonial national ideologies – nativism and tradition – with technology and science. Finally, the article depicts how the growing resistance to the space programme among Kazakh civil society groups reveals a close association of the environmental agenda with an “eco-nationalism” permeated by a profoundly anti-imperial and, ultimately, antiauthoritarian political discourse

    Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

    Get PDF
    Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

    Using Authentic Data from NSF’s Ocean Observatories Initiative in Undergraduate Teaching: An Invitation

    No full text
    There are many benefits to using real data in undergraduate science education, including building analytical and problem-solving skills and visualizing concepts through real-world examples. The Ocean Observatories Initiative (OOI) provides a unique source of continuous, long-term oceanographic data from multiple locations in the world ocean. Each of these arrays hosts a suite of co-located instruments that measure physical, chemical, geological, and biological properties. Existing educational resources derived from OOI data can be leveraged for undergraduate teaching activities in and beyond the classroom. We provide example applications of the use of OOI resources in lesson plans and in research experiences for undergraduates. There are also abundant opportunities for new resources to be developed by the community. Our goal is to guide educators in determining appropriate OOI data sets and applications for their own needs
    corecore