Search Publications
Smoothness of Titan's Ontario Lacus: Constraints from Cassini RADAR specular reflection data
Lorenz, R. D.; Wye, L. C.; Zebker, H. A.
Cassini RADAR altimetry data collected on the 49th flyby of Titan (2008 December 21) over Ontario Lacus in Titan's south polar region provides strong evidence for an extremely smooth surface, with less than 3 mm rms surface height variation over the 100m-wide Fresnel zone. Histograms of the raw radar echoes imply a mirror-like specular reflection …
Spatial and alignment analyses for a field of small volcanic vents south of Pavonis Mons and implications for the Tharsis province, Mars
Greeley, Ronald; Williams, David A.; Glotch, Timothy D. +5 more
A field of small volcanic vents south of Pavonis Mons was mapped with each vent assigned a two-dimensional data point. Nearest neighbor and two-point azimuth analyses were applied to the resulting location data. Nearest neighbor results show that vents within this field are spatially random in a Poisson sense, suggesting that the vents formed inde…
Global Star Formation Rate Density over 0.7 < z < 1.9
Henry, Alaina; Shim, Hyunjin; Teplitz, Harry +4 more
We determine the global star formation rate (SFR) density at 0.7 < z < 1.9 using emission-line-selected galaxies identified in Hubble Space Telescope-Near Infrared Camera and Multi-Object Spectrograph (HST-NICMOS) grism spectroscopy observations. Observing in a pure parallel mode throughout HST Cycles 12 and 13, our survey covers ~104 arcmin…
Cassini detection of Enceladus' cold water-group plume ionosphere
Coates, A. J.; Thomsen, M. F.; Wilson, R. J. +6 more
This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the plume. The data …
Simultaneous Multiwavelength Observations of Markarian 421 During Outburst
Maraschi, L.; Covino, S.; Antonelli, L. A. +226 more
We report on the results of two coordinated multiwavelength campaigns that focused on the blazar Markarian 421 during its 2006 and 2008 outbursts. These campaigns obtained UV and X-ray data using the XMM-Newton satellite, while the gamma-ray data were obtained utilizing three imaging atmospheric Cerenkov telescopes, the Whipple 10 m telescope and …
Properties of WNh stars in the Small Magellanic Cloud: evidence for homogeneous evolution
Martins, F.; Hillier, D. J.; Foellmi, C. +4 more
Aims: We aim to assess the nature of three WNh stars in the SMC, to constrain stellar evolution beyond the main sequence at low metallicity, and to investigate the metallicity dependence of the clumping properties of massive stars.
Methods: We compute atmosphere models to derive the stellar and wind properties of the three WNh targets. A FUV/U…
The growth and assembly of a massive galaxy at z ~ 2
Röttgering, H. J. A.; Miley, G. K.; Overzier, R. A. +3 more
We study the stellar mass assembly of the Spiderweb galaxy (MRC1138-262), a massive z = 2.2 radio galaxy in a protocluster and the probable progenitor of a brightest cluster galaxy. Nearby protocluster galaxies are identified and their properties are determined by fitting stellar population models to their rest-frame ultraviolet to optical spectra…
Diurnal variations of Titan's ionosphere
Wahlund, J. -E.; Galand, M.; Waite, J. H. +7 more
We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator,…
The XMM Cluster Survey: forecasting cosmological and cluster scaling-relation parameter constraints
Hilton, Matt; West, Michael J.; Freeman, Peter E. +16 more
We forecast the constraints on the values of σ8,Ωm and cluster scaling-relation parameters which we expect to obtain from the XMM Cluster Survey (XCS). We assume a flat Λ cold dark matter Universe and perform a Monte Carlo Markov Chain analysis of the evolution of the number density of galaxy clusters that takes into account …
Evolution of Nuclear Star Clusters
Merritt, David
Two-body relaxation times of nuclear star clusters are short enough that gravitational encounters should substantially affect their structure in 10 Gyr or less. In nuclear star clusters without massive black holes, dynamical evolution is a competition between core collapse, which causes densities to increase, and heat input from the surrounding ga…