Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session C5: Planetary Science |
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Chair: Bradley Carroll, Weber State University Room: Green Center 215 |
Friday, October 23, 2009 3:40PM - 3:52PM |
C5.00001: An Investigation of Polar Mesospheric Clouds Using Satellite and Ground-based Measurements Jaimy Tomlinson, Michael Taylor, Matthew Deland, Mark Zalcik Noctilucent clouds (NLCs) occur in the very cold summer mesosphere at high latitudes. They stand out brightly against a dark twilight sky because they are high enough that the sun still illuminates them when it is 5 to 16 degrees below the horizon. These clouds are also known as polar mesospheric clouds (PMCs) when observed from space. Satellite data have shown an increase in brightness and occurrence frequency over the past 30 years, possibly associated with climate change. In this presentation, I will discuss our work in mapping and correlating satellite data from OMI and SBUV orbiting instruments with ground-based Canadian-American and European NLC observing networks, and our efforts to find patterns and trends in the data. I will show animations that demonstrate the evolution of the clouds through the northern hemisphere 2007 and 2008 seasons. We have identified several days during the 2007 and 2008 seasons with OMI detections coinciding in time and space with visual ground-based observations. [Preview Abstract] |
Friday, October 23, 2009 3:52PM - 4:04PM |
C5.00002: ABSTRACT WITHDRAWN |
Friday, October 23, 2009 4:04PM - 4:16PM |
C5.00003: Exoplanet's Atmospheres Characteristics vs. Exoplanet's Orbital Elements Karan Molaverdikhani 400 years after Galileo Galilei was detected Jovian system, we know about 400 exoplanets in other stellar systems. But we identify just about their major properties like some of orbital elements, planet's radii or density. Also, there are many scientists who interested in searching for life or habitability on these planets. They are working in different ways such as planetary formation, planetary orbital stability or immigration, HabStars, composition of atmospheres, most probable zone in sky for exoplanets detection, etc. In this research we distinct and defined some main characteristics of terrestrial planet's atmospheres with surveying on solar system's planets and matching with current theorems on atmosphere formation. On the other hand, we were modeled Mars, Venus, Titan, single Hadley Earth and virtual Venus with different tilt angel (applying Global Circulation Modeling) to finding a critical limit on Polar Vortex formation in our last research. With extension this method on hypothetical terrestrial planets in constraint mass between 0.7 to 2.5 Earth's mass on Green Belt and applying host stars from 0.5 to 1.5 Sun's mass, we found some limitations on planet's atmosphere formation and estimation values of atmosphere's main characteristics. [Preview Abstract] |
Friday, October 23, 2009 4:16PM - 4:28PM |
C5.00004: Methane Imaging Search for Planetary Mass Objects in Rho Ophiuchi Sherene Higley, Karl E. Haisch Jr., Mary Barsony, Chris Tinney T dwarfs are the coolest and least massive compact astrophysical objects that we can directly observe outside our Solar System. They share many properties with the expanding population of known exoplanets (almost all of which are inaccessible to direct observation themselves). An understanding of T dwarf atmospheres, therefore, is critical to our developing understanding of exoplanets. Moreover, T dwarf surveys in young star clusters can provide important answers to questions such as ``Is there a minimum mass for star formation?'' and ``How important is dynamical evolution for cluster mass functions?'' In recent years, methane imaging has emerged as a powerful tool for identifying T dwarf candidates in very young clusters, where T dwarfs are at their brightest and have not yet been subject to possible dynamical ejection from their clusters. We have recently conducted a methane imaging survey of the Rho Ophiuchi cluster for T dwarfs using the IRIS2 near-infrared imaging spectrograph on the Anglo-Australian Telescope. The Rho Ophiuchi cluster is the closest (d $\sim$ 120 parsecs) star-forming region to Earth that has a compact core harboring several hundred young ($\sim$ 1 Myr) stellar objects. In this talk, we present the results of our imaging survey. [Preview Abstract] |
Friday, October 23, 2009 4:28PM - 4:40PM |
C5.00005: Can a Planetary System Survive a Host Star Supernova Explosion? Alexander Panin, Justin Giovannoni The recent search for extrasolar planets has brought a surprising discovery -- almost any star seems to have a planetary system around it. We know that massive stars end their lives in a violent supernova explosion, during which extremely large amount of energy (3x10 46J) is released by the star in a very short time. Can a planetary system survive such a violent event? Can a planet survive? Can planetary biosphere survive? In the current presentation we analyze, based on known physics, the effect of a supernova explosion on a planet orbiting such a star in its habitable zone. Our calculations show that even a small Earth-like planet is not destroyed mechanically nor thermally in such an explosion (and larger planets are even more stable). Nor is a planet kicked out of its orbit due to the momentum of exploding star shell or of due to star's radiation pressure. In some cases even a portion of a planetary biosphere (deep in planet's crust) can survive. However, if a star loses too much mass, a planet would leave. Also, if star's collapse is asymmetric then the star itself can leave the planetary system. The sequence of events during supernova explosion and how they influence such a planet is discussed in the presentation. [Preview Abstract] |
Friday, October 23, 2009 4:40PM - 4:52PM |
C5.00006: The Elasticity of (Fe,Ni) Alloys Owen Boberg, Boris Kiefer The Earth's core is the most remote part of the interior of our planet. Astronomical and cosmochemical evidence suggest that the composition of the core is dominated by an iron-rich (Fe$_{1-x}$,Ni$_{x})$ alloy that likely contains at least one light element. At ambient conditions Fe adopts a bcc structure and undergoes a phase transition to hcp at high pressure (P $>\sim $13 GPa). However, the stable phase in the presence of nickel and/or light element(s) at inner core pressures (P$\sim $3.7 million atmospheres) is much less certain. Using \textit{state-of-the-art} density-functional-theory calculations we determined the effects of Ni concentration on the elasticity and stability of FeNi alloys. We find that hcp derived FeNi alloys are stable at 0K, at least for 3.1 at{\%}, 6.2 at{\%}, and 12.5 at{\%} nickel content, which encompasses the expected nickel content in the Earth's core ($\sim $5-10 at{\%}). Furthermore we find that the bcc structure is least stable. This is in contrast to recent work that finds that bcc derived FeNi is stable. We will discuss possible reasons for this difference and its implications for core chemistry and structure. [Preview Abstract] |
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