Starburst Driven Galactic Superbubbles Radiating to 10 K

Our three-dimensional hydro-dynamical simulations of starbursts examine the formation of superbubbles over a range of driving luminosities and mass loadings that determine superbubble growth and wind velocity. From this we determine the relationship between the velocity of a galactic wind and the power of the starburst. We find a threshold for the formation of a wind, above which the speed of the wind is not affected by grid resolution or the temperature floor of our radiative cooling. We investigate the effect two different temperature floors in our radiative cooling prescription have on wind kinematics and content. We find that cooling to $10$ K instead of to $10^4$ K increases the mass fraction of cold neutral and hot X-ray gas in the galactic wind while halving that in warm H$\alpha$. Our simulations show the mass of cold gas transported into the lower halo does not depend on the starburst strength. Optically bright filaments form at the edge of merging superbubbles, or where a cold dense cloud has been disrupted by the wind. Filaments formed by merging superbubbles will persist and grow to $>400$ pc in length if anchored to a star forming complex. Filaments embedded in the hot galactic wind contain warm and cold gas that moves $300-1200$ km s$^{-1}$ slower than the surrounding wind, with the coldest gas hardly moving with respect to the galaxy. Warm and cold matter in the galactic wind show asymmetric absorption profiles consistent with observations, with a thin tail up to the wind velocity.Comment: 14 pages, 14 figures. Published in Ap

Influence of the active nucleus on the multiphase interstellar medium in NGC 1068

The luminous spiral NGC 1068 has now been imaged from x-ray to radio wavelengths at comparably high resolution (approximately less than 5 in. FWHM). The bolometric luminosity of this well-known Seyfert is shared almost equally between the active nucleus and an extended 'starburst' disk. In an ongoing study, we are investigating the relative importance of the nucleus and the disk in powering the wide range of energetic activity observed throughout the galaxy. Our detailed analysis brings together a wealth of data: ROSAT HRI observations, VLA lambda lambda 6-20 cu cm and OVRO interferometry, lambda lambda 0.4-10.8 micron imaging, and Fabry-Perot spectrophotometry

Tightly Correlated X-ray/Hα\alpha Emitting Filaments in the Superbubble and Large-Scale Superwind of NGC 3079

Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0."8 resolution. This tight match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces. We find that the soft X-ray plasma has thermal and kinetic energies of $2\times10^{56}\sqrt{\eta_x}$ and $5\times10^{54}\sqrt{\eta_X}$ erg respectively, where $\eta_X$ is the filling factor of the X-ray gas and may be small; these are comparable to the energies of the optical line-emitting gas. X-rays are also seen from the base of the radio counterbubble that is obscured optically by the galaxy disk, and from the nucleus (whose spectrum shows the Fe K$\alpha$ line). Hydrodynamical simulations reproduce the obbservations well using large filling factors within both filament systems; assuming otherwise seriously underestimates the mass loss in the superwind. The superbubble is surrounded by a fainter conical halo of X-rays that fill the area delineated by high angle, H$\alpha$-emitting filaments, supporting our previous assertion that these filaments form the contact discontinuity/shock between galaxy gas and shocked wind. About 40\arcsec (3 kpc) above the disk, an X-ray arc may partially close beyond the bubble, but the north-east quadrant remains open, consistent with the superwind having broken out into at least the galaxy halo.Comment: 8 pages, 3 figures, to appear in Sept. 10 Ap

Scaling Relations of Starburst-driven Galactic Winds

Using synthetic absorption lines generated from 3D hydrodynamical simulations, we explore how the velocity of a starburst-driven galactic wind correlates with the star formation rate (SFR) and SFR density. We find strong correlations for neutral and low ionized gas, but no correlation for highly ionized gas. The correlations for neutral and low ionized gas only hold for SFRs below a critical limit set by the mass loading of the starburst, above which point the scaling relations flatten abruptly. Below this point the scaling relations depend on the temperature regime being probed by the absorption line, not on the mass loading. The exact scaling relation depends on whether the maximum or mean velocity of the absorption line is used. We find that the outflow velocity of neutral gas can be up to five times lower than the average velocity of ionized gas, with the velocity difference increasing for higher ionization states. Furthermore, the velocity difference depends on both the SFR and mass loading of the starburst. Thus, absorption lines of neutral or low ionized gas cannot easily be used as a proxy for the outflow velocity of the hot gas

A Side of Mercury Not Seen By Mariner 10

More than 60,000 images of Mercury were taken at ~29 deg elevation during two sunrises, at 820 nm, and through a 1.35 m diameter off-axis aperture on the SOAR telescope. The sharpest resolve 0.2" (140 km) and cover 190-300 deg longitude -- a swath unseen by the Mariner 10 spacecraft -- at complementary phase angles to previous ground-based optical imagery. Our view is comparable to that of the Moon through weak binoculars. Evident are the large crater Mozart shadowed on the terminator, fresh rayed craters, and other albedo features keyed to topography and radar reflectivity, including the putative huge ``Basin S'' on the limb. Classical bright feature Liguria resolves across the northwest boundary of the Caloris basin into a bright splotch centered on a sharp, 20 km diameter radar crater, and is the brightest feature within a prominent darker ``cap'' (Hermean feature Solitudo Phoenicis) that covers the northern hemisphere between longitudes 140-250 deg. The cap may result from space weathering that darkens via a magnetically enhanced flux of the solar wind, or that reddens low latitudes via high solar insolation.Comment: 7 pages, 4 PDF figures, pdfLaTeX, typos corrected, Fig. 2 modified slightly to add crater diameters not given in published versio

Managing Performance in Extension: Redesigning the Performance Evaluation System at Illinois

This article describes the initiative of a large Extension system to improve its performance management system. Information on the utility of the present system was sought from a wide range of stakeholders, and key strengths and weaknesses were identified. The revision focused on updating and simplifying the performance dimensions, creating a single set of requirements for all levels of staff, and moving towards an electronic submission, storage, and retrieval system for evaluative information. The article concludes with implementation and evaluation strategies and lessons learned along the continuous improvement path of performance management at Illinois

La planificación y las realidades de geografía humana en la industria pesquera de Barbados

En la última mitad del siglo, la industria pesquera de Barbados ha evolucionado desde una flota impulsada completamente por la vela hasta una flotilla mixta de navíos tradicionales y modernos. Varios períodos importantes en la forma de adopción de nuevos tipos de navíos de pesca, ocurrieron durante esta evolución, coexistente con la tecnología cambiante, sabores del consumidor, el mercadeo y proceso, y la financiación interior y externa de la flota y sus infraestructuras. Si Barbados es un país de solamente 431 kilómetros cuadrados, uno puede fácilmente llegar a pensar que el plan de desarrollo de la industria pesquera es una cuestión bastante simple. Sin embargo, realidades en la tierra, la percepción y conducta de los diferentes grupos pesqueros, dan indicaciones de lo contrario. Claro está que los planes de desarrollo son redactados y ejecutados todo el tiempo, sobretodo más en los países grandes, sin tomar tanto cuidado a las realidades de la geografía humana. Pero estudios de campo, que buscan una verdad objetiva, sugieren que los planes generales nunca pueden ser completamente abarcados. Aunque tales planes tienen éxito, von los grados y variantes, ellos llevan por su misma naturaleza la desilusión para algunos, creando varias desgracias humanas. Este ensayo es una parte pequeña de un estudio del caso más grande (Cecil, 1999) que ilustra estas realidades. Este trabajo ofrece una mirada breve a la historia del desarrollo de la flotilla de Barbados y un examen de los sitios o lugares de desembarque en la isla que dan énfasis a las características geográficas microscópicas. Hay un fuerte acento en la comprensión de los complejos geográficos de la localidad en pequeña-escala y que son de suma importancia al procedimiento del plan de desarrollo económico. La preocupación subyacente del papel se encuentra en el rol de la geografía regional, en su comprensión y la explicación de su condición humana. Detalles de pequeño-nivel de gran preocupación para los habitantes locales y de mayor importancia para ellos que los modelos macro-nivelados. La geografía regional está sobre todas las personas, y su práctica al nivel local está sobre las actitudes, necesidades, deseos y comportamiento de las personas para quienes supuestamente se han pensado en el planeamiento final. También, está más allá de los límites previstos por los cuales los planificadores no pueden satisfacer las necesidades del individuo y los grupos de interés.Evento también conocido bajo el nombre de "II Jornadas Platenses de Geografía"Facultad de Humanidades y Ciencias de la Educació

Inclined Gas Disks in the Lenticular Seyfert Galaxy NGC 5252

We discuss the morphology and kinematics of the extended gas in the type 2 Seyfert galaxy NGC 5252 based on Hubble Space Telescope (HST) WFPC2 continuum and emission-line images (including a new [O III] λ5007 image) and a ground-based Fabry-Perot (F-P) velocity map of the ionized gas. The fine-scale morphology of the ionized gas in this galaxy's very extended (~40 kpc) ionization bicone consists of a complex network of filamentary strands. The new WFPC2 [O III] image also reveals more detail in the circumnuclear (~3 kpc) gas disk than is seen in the Hα + [N II] image presented previously by Tsvetanov and coworkers. The F-P velocity map shows an obvious antisymmetry of the velocity field of the ionized gas across the nucleus. We conclude that there are three dynamical components to the extended gas in NGC 5252. Two of these components are gas disks aligned with the stellar disk, one rotating with the stars and the other counterrotating. The third component is the circumnuclear gas disk seen in the HST observations and its extension to larger scales; this disk has an inclination of ~40° and a kinematic major axis in P.A. ~ 90°-135°, some 80°-125° from the major axis of the stellar disk. This simple model of two inclined rotating disks, superposed along the line of sight, describes well the seemingly complex kinematics observed in the optical emission lines and the H I 21 cm radio maps. The large misalignment between the second disk and the stellar disk suggests that the gas distribution, and possibly the nuclear activity, in NGC 5252 may have resulted from a galaxy merger event. The absence of significant radial motions, together with the well-defined ionization cones, strongly suggests that the gas is photoionized by a compact nuclear source rather than being ionized in situ by shock waves in a large-scale outflow