Processing and Transmission of Information

Contains report on one research project.National Aeronautics and Space Administration (Grant NsG-334)Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

Swift/UVOT Photometry of the Planetary Nebula WeBo 1: Unmasking A Faint Hot Companion Star

We present an analysis of over 150 ks of data on the planetary nebula WeBo 1 (PN G135.6+01.0) obtained with the Swift Ultraviolet Optical Telescope (UVOT). The central object of this nebula has previously been described as a late-type K giant barium star with a possible hot companion, most likely a young pre-white dwarf. UVOT photometry shows that while the optical photometry is consistent with a large cool object, the near-ultraviolet (UV) photometry shows far more UV flux than could be produced by any late-type object. Using model stellar atmospheres and a comparison to UVOT photometry for the pre-white dwarf PG 1159-035, we find that the companion has a temperature of at least 40,000 K and a radius of, at most, 0.056 R_sun. While the temperature and radius are consistent with a hot compact stellar remnant, they are lower and larger, respectively, than expected for a typical young pre-white dwarf. This likely indicates a deficiency in the assumed UV extinction curve. We find that higher temperatures more consistent with expectations for a pre-white dwarf can be derived if the foreground dust has a strong "blue bump" at 2175 AA and a lower R_V. Our results demonstrate the ability of Swift to both uncover and characterize hot hidden companion stars and to constrain the UV extinction properties of foreground dust based solely on UVOT photometry.Comment: 26 pages, 9 figure, accepted to Astronomical Journa

Modeling the resolution of inexpensive, novel non-seismic geophysical monitoring tools to monitor CO2 injection into coal beds

A sensitivity study of gravity and electromagnetic (EM) techniques, and amplitude vs. angle (AVA) analysis for CO{sub 2} movement in coal beds was based on the SECARB pilot test planned in the Black Warrior basin in Alabama. In the area of interest, coalbed methane is produced mainly from the Black Creek, Mary Lee, and Pratt coal zones at depths between 400 and 700 m and approximately 3 m thick on average. The permeability of coal in the Black Warrior basin decreases exponentially with depth as overburden stress increases. The permeability of the top layer is 100 mD, while the permeability of the deepest layer is around 1 mD. The pilot field test will include injecting a total of 1000 tons of CO{sub 2} into these three coal zones ({approx}300 tons to each zone). The density, sonic and resistivity well-logs from a deep disposal well a couple of miles from the pilot test site were used to create background (pre-injection) models. Our laboratory measurements of seismic velocity and electrical resistivity as a function of CO{sub 2} saturation on coal core samples were used to provide a link between the coalbed CO{sub 2} flow simulation models and the geophysical models. The sensitivity studies showed that while the response to the 300 tons of CO{sub 2} injected into a single layer wouldn't produce measurable surface response for either gravity or EM, the response due to an industrial-size injection would produce measurable surface signal for both techniques. Gravity inversion results illustrated that, provided we can collect high-quality gravity data in the field and we have some a priori information about the depth of the reservoir, we can recover the spatial location of CO{sub 2} plume correctly, although with the smoothing constraint of the inversion, the area was slightly overestimated, resulting in an underestimated value of density change. AVA analysis showed that by inverting seismic and EM data jointly, much better estimates of CO{sub 2} saturation can be obtained, especially in the third injection zone, where seismic AVA data fail to detect the high CO{sub 2} saturation. Analysis of spatial resolution and detectability limits show that gravity and EM measurements could, under certain circumstances, be used as a lower-cost alternative to seismic measurements

Detection and Estimation Theory

Contains reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U.S. Air Force)under Contract DA 28-043-AMC-02536(E

Processing and Transmission of Information

Contains research objectives, summary of research and reports on two research projects.National Aeronautics and Space Administration (Grant NGL 22-009-013)National Aeronautics and Space Administration (Contract NAS8-27733)U. S. Army Research Office - Durham (Contract DAHC04-69-C-0042)U. S. Army Research Office - Durham (Contract DAHC04-71-C-0039)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-030

Processing and Transmission of Information

Contains reports on four research projects.National Aeronautics and Space Administration (Grant NGL 22-009-013

Processing and Transmission of Information

Contains research objectives, summary of research and reports on one research project.Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)National Aeronautics and Space Administration (Grant NGL-22-009-013

Processing and Transmission of Information

Contains research objectives and reports on three research projects.National Aeronautics and Space Administration (Grant NsG-334)Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E

Processing and Transmission of Information

Contains research objectives and reports on two research projects.National Aeronautics and Space Administration (Grant NsG-334)National Aeronautics and Space Administration (Grant NsG-496)Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GP-835)Sloan Fund for Basic Research (M.I.T. Grant