Search Publications
Atmospheric composition, chemistry, and clouds
Esposito, Larry W.; Yung, Yuk L.; Mills, Franklin P.
Venus' atmosphere has a rich chemistry involving interactions among sulfur, chlorine, nitrogen, hydrogen, and oxygen radicals. The chemical regimes in the atmosphere range from ion-neutral reactions in the ionosphere to photochemistry in the middle atmosphere to thermal equilibrium chemistry and surface-atmosphere reactions in the lower atmosphere…
Ptolemy an Instrument to Measure Stable Isotopic Ratios of Key Volatiles on a Cometary Nucleus
Andrews, D. J.; Leese, M. R.; Zarnecki, J. C. +17 more
A fundamental goal of cometary studies is to determine the exact relationship between these bodies and the Solar System - the question(s) can be summarised as follows: did comets originate during the same events that spawned the Sun and planets, are they more primitive bodies that record a pre-solar history, or are they interstellar materials coll…
Feedback in the Antennae Galaxies (NGC 4038/9). I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters
Graham, James R.; Gilbert, Andrea M.
We present high-resolution (R~24,600) near-IR spectroscopy of the youngest super star clusters (SSCs) in the prototypical starburst merger, the Antennae galaxies. These SSCs are young (3-7 Myr old) and massive (105-107 Msolar for a Kroupa initial mass function), and their spectra are characterized by broad, extende…
Role of photoionization in the formation of complex organic molecules in Titan's upper atmosphere
Imanaka, Hiroshi; Smith, Mark A.
Recent observations by the Cassini Orbiter suggest that complex organic chemistry occurs in the upper atmosphere of Titan. To understand the role of EUV-VUV light in the complex organic chemistry of Titan's upper atmosphere, we investigate the formation of gaseous species from a N2/CH4 gas mixture as a function of irradiation…
Measuring PAH Emission in Ultradeep Spitzer IRS Spectroscopy of High-Redshift IR-Luminous Galaxies
Frayer, D. T.; Scott, D.; Chary, R. +9 more
The study of the dominant population of high-redshift IR-luminous galaxies (1011-1012 Lsolar at 1<z<3), requires observation of sources at the ~0.1 mJy level in the mid-IR. We present the deepest spectra taken to date with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. We targeted two faint (…
Dust Environment Modelling of Comet 67P/Churyumov-Gerasimenko
Agarwal, Jessica; Grün, Eberhard; Müller, Michael
Dust is an important constituent of cometary emission; its analysis is one of the major objectives of ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko (C-G). Several instruments aboard Rosetta are dedicated to studying various aspects of dust in the cometary coma, all of which require a certain level of exposure to dust to achieve their go…
Local plasma processes and enhanced electron densities in the lower ionosphere in magnetic cusp regions on Mars
Gurnett, D. A.; Lundin, R.; Winningham, J. D. +11 more
Both the MARSIS ionospheric sounder and the charged particle instrument package ASPERA-3 are experiments on board the Mars Express spacecraft. Joint observations have shown that events of intense ionospheric electron density enhancements occur in the lower ionosphere of magnetic cusp regions, and that these enhancements are not associated with pre…
The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS
Bézard, Bruno; Vinatier, Sandrine; Nixon, Conor A.
We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyb…
The Chemical Distribution in a Subluminous Type Ia Supernova: Hubble Space Telescope Images of the SN 1885 Remnant
Wheeler, J. Craig; Fesen, Robert A.; Hamilton, Andrew J. S. +4 more
SN 1885 was a probable subluminous SN Ia that occurred in the bulge of the Andromeda galaxy, M31, at a projected location 16" from the nucleus. Here we present and analyze Hubble Space Telescope images of the SN 1885 remnant seen in absorption against the M31 bulge via the resonance lines of Ca I, Ca II, Fe I, and Fe II. Viewed in Ca II H and K li…
Divergence and Vorticity of Solar Subsurface Flows Derived from Ring-Diagram Analysis of MDI and GONG Data
Howe, R.; Komm, R.; Hill, F. +3 more
We measure the relation between divergence and vorticity of subsurface horizontal flows as a function of unsigned surface magnetic flux. Observations from the Michelson Doppler Imager (MDI) Dynamics Program and Global Oscillation Network Group (GONG) have been analyzed with a standard ring-diagram technique to measure subsurface horizontal flows f…