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Investigating Magmas of Augustine Volcano, Alaska, and their Role in Explosive Eruptive Activities Advisor: Jim Webster Augustine is one of the more than 40 historically active volcanoes of the Aleutian arc that pose a risk to the inhabitants and businesses of southern Alaska. It has undergone 7 violent eruptions in the past 200 years including the early 2006 eruptive event. As part of our ongoing research on explosive volcanic eruptions of Augustine during the past 12,000 years, we are interested in working with a student on methods of determining the abundances of volatile components (e.g., H2O, CO2, S, and Cl) in magmas associated with past eruptions. It is the escape and expansion of the volatile components in magmas that provide the driving force for explosive volcanic eruptive behavior. The student will have the opportunity to gain experience in volcanology, petrography, analytical methods including electron microprobe, laser ICP-MS, infrared spectroscopy, and experimental petrology. |
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An infrared view of the Solar neighborhood: analysis of nearby stars imaged by the NASA Wide-field Infrared Survey Explorer (WISE) Advisor: Sebastien Lepine Now entering its third year of operation, the WISE mission has been collecting images in the mid-infrared for a large fraction of the sky, opening a new window in the electromagnetic spectrum. Thousands of stars in the Solar neighborhood (within 100 light-years of the Sun) have now been imaged at 4.6 microns and 12 microns for the first time. We will be taking a fresh look at those stars in light of these new data, comparing the infrared brightness of the stars to their recorded flux in the near-infrared, optical, and ultra-violet. We will search for brown dwarf companions and dust debris disks possibly orbiting some of the stars, and which would have been hiding from view until now. |
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Thermal Metamorphism of the Howardites and the Surface of Vesta Advisor: Joe Boesenberg The howardite meteorites are impact breccias containing clasts of two other differentiated (melted) meteorite groups: the eucrites (fine-grained basalts) and the diogenites (coarse grained pyroxenites). All three of these meteorite types likely derived from the surface of the second largest asteroid, Vesta, which is presently being mapped and observed by the DAWN spacecraft. There are a variety of models that have been suggested to explain the formation of the eucrites and diogenites. Some models form them independently, while others form them together during either melting or crystallization processes. The advisor of this project has found some interesting mineral data in several howardites that suggests that the eucrites and diogenites form unbroken crystallization sequences. That is, in any howardite meteorite, the eucrite and diogenite clasts are related by derivation from a single common body of magma. One of the potential complications in this interpretation, however, is that the howardites have been metamorphosed (thermally altered) to varying degrees, which can obscure or alter the original chemical trends within the minerals. Therefore, the student will use the electron microprobe, optical microscopy and algebra to analyze and investigate the howardite samples. They will apply different types of mineral-mineral thermometry calculations on a variety of clasts in individual howardites to determine 1) the range of thermal alteration (peak closure temperatures) experienced by the clasts in individual howardites; 2) whether the different techniques correlate to one another; 3) whether the diogenitic and eucritic clasts experienced the same level of thermal alteration within each howardite; and 4) whether the individual howardites are reliably recording their original igneous signatures or have been substantially reset by the metamorphism. |
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Connections Between Brown Dwarfs, Very Low-Mass Stars And Exoplanets Advisor: Kelle Cruz Brown dwarfs and very low-mass stars share may physical properties with massive extrasolar planets. However, we can study brown dwarfs and very low-mass stars in much greater detail than is currently possible for most planets. Professor Cruz has several projects focused on using brown dwarf spectra to determine the underlying physical properties, such as mass and age, of these complex objects. The results of these endeavors are critical to testing and challenging out current understanding of the nature of extrasolar planets. |
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Tracking the Evolution of Topaz Rhyolites with Melt Inclusions and Fe-Ti oxide Thermometry Advisor: Aaron S. Bell Topaz rhyolites are a relatively uncommon and unique class of volcanic rocks in the western United States. These magmas have unusually elevated concentrations of fluorine and lithophile elements (Be, Li, U, Th, Sn). This project aims to track the pre-eruptive temperature and volatile content of the Keg Mountain topaz rhyolite (west-central Utah) in order to constrain the conditions under which the magma was generated. A student who works with me will have the opportunity to analyze the major element and volatile content of melt inclusions (tiny aliquots of silicate melt trapped and preserved within growing crystals) with the electron microprobe and infrared spectroscopy. My students will also get hands on experience analyzing the compositions Fe-Ti oxide crystals with the electron microprobe. The measured composition of these oxides will be used to calculate the temperature and oxidation state of the magma from which they grew. |
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Analyzing Model Spectra of Cool Atmospheres for Low Mass Stars, Brown Dwarfs, and Exoplanets Advisor: Emily Rice The PHOENIX atmosphere model (http://www.hs.uni-hamburg.de/EN/For/ThA/phoenix/index.html) is a state-of-the-art radiative transfer code for modeling stellar atmospheres and related phenomena. The code can be used to create synthetic spectra at any wavelength regime and with any spectral resolution for comparison to observed data. Analysis of the synthetic spectra will contribute to studies of very low mass stars, young stars, metal-poor stars, brown dwarfs, and exoplanets that are ongoing at AMNH. The analysis can include measuring line strengths, spectral indeces and slopes, and identifying trends with physical parameters (e.g. temperature, surface gravity, or metallicity). This research project can be adapted to match the successful applicant's prior experience and research interests. |
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Investigating the massive stellar content of NGC 6744. Advisors: Joanne Bibby & Dave Zurek NGC 6744 is a nearby spiral galaxy, which we have observed at several different wavelengths using the Very Large Telescope in Chile. Using photometric techniques, you will analyze each set of observations to determine the massive stellar population of the galaxy, identifying massive O stars, Red Supergiants, and evolved O stars called Wolf-Rayet stars. These results are critical to test the predictions of stellar evolutionary theory and could also help identify progenitors of future supernova explosions. |
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Martian Magmas: calculating theirs compositions from melt inclusions in martian meteorites. Advisor: Julianne Gross Martian meteorites are basaltic igneous rocks that provide a window into the interior of Mars. They are products of magmas generated by melting at various depths in the planet, and can provide critical information about the chemistry, structure and history of their source regions. Most Martian meteorites are not pure magma compositions because they contain accumulated (added) crystals (olivine and/or pyroxene). Therefore, one of the major goals in studying them is to determine the compositions of their so-called parent magmas - the magmas where they originated from. A student who works with me will analyze melt inclusion in olivine in the Martian meteorite NWA 5789. In principle, melt inclusions represent the liquids with which their hosts (in this case olivine) were in equilibrium and can provide information about the major, minor and volatile element composition of those liquids, as well as conditions of T, P and fO2 during early magmatic evolution. The student will learn use the electron microprobe to analyze the major and minor elements in those inclusions as well as the volatile (Cl, F, P, H2O) content. My student will also gain experience in mapping trace elements (particularly P) to reveal growth regimes in host olivines to identify the earliest generation of melt inclusions. By the end of the project we will then use the calculated parent magma compositions to address the specific petrogenetic problems of this meteorite. |
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Hunting for Erupting Novae around Messier 81 Advisors: Michael Shara and Dave Zurek Astronomers have long believed that most of the stars in the Universe live in galaxies, and that 99.9% of the volume of the Universe - outside of galaxies - is nearly devoid of stars. During the past decade we've learned that up to 1/3 of all stars in rich clusters of galaxies live between the galaxies. These "intergalactic tramp" stars have been stripped out of their host galaxies by tides raised during near-collisions of galaxies. We'll be checking, for the first time, if the same process operates in a nearby, sparse cluster of galaxies: the Messier 81 group. Using hundreds of images of M81 taken over several years we will be measuring the rate at which novae are erupting inside Messier 81, and compare that to the nova rate around M81. We will thus determine if intergalactic tramps live everywhere, or only inside rich galaxy clusters. |
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Studying Galaxies with COSMOS Advisor: Charles Liu COSMOS is a major Hubble Space Telescope survey with a massive international multiwavelength followup effort that is being applied to answer a wide variety of astronomical questions. One preliminary study to be conducted, using portions of the COSMOS data, will be to identify subsets of strongly star-forming galaxies in the survey and measure their luminosities, positions, and spatial distributions. The eventual goal of such a study would be to measure and understand the changes that have occurred in the field galaxy population as a function of cosmic time. |
Division of Physical Sciences
Hayden Planetarium