Search Publications
Self-gravity wakes in Saturn's A ring measured by stellar occultations from Cassini
Sremčević, M.; Colwell, J. E.; Esposito, L. W.
An azimuthal brightness asymmetry in Saturn's A ring is caused by ephemeral agglomerations that continually form under the mutual gravity of the ring particles only to be torn apart by Keplerian shear. We calculate the shape and spacing of the self-gravity wakes from Cassini stellar occultations. The wakes are highly flatttened structures, with he…
The vertical structure of Titan's upper atmosphere from Cassini Ion Neutral Mass Spectrometer measurements
Waite, J. H.; Kasprzak, W. T.; Müller-Wodarg, I. +4 more
Data acquired by the Ion Neutral Mass Spectrometer (INMS) on the Cassini spacecraft during its close encounter with Titan on 26 October 2004 reveal the structure of its upper atmosphere. Altitude profiles of N 2, CH 4, and H 2, inferred from INMS measurements, determine the temperature, vertical mixing rate, and es…
Discovery of Ultracompact Dwarf Galaxies in the Virgo Cluster
Drinkwater, M. J.; Jones, J. B.; Phillipps, S. +7 more
We have discovered nine ultracompact dwarf galaxies (UCDs) in the Virgo Cluster, extending samples of these objects outside the Fornax Cluster. Using the Two Degree Field (2dF) multifiber spectrograph on the Anglo-Australian Telescope, the new Virgo members were found among 1500 color-selected, starlike targets with 16.0<bj<20.2 i…
Determining Solar Abundances Using Helioseismology
Basu, Sarbani; Antia, H. M.
The recent downward revision of solar photospheric abundances of oxygen and other heavy elements has resulted in serious discrepancies between solar models and solar structure as determined through helioseismology. In this work we investigate the possibility of determining the solar heavy-element abundance without reference to spectroscopy by usin…
Stellar occultations at UV wavelengths by the SPICAM instrument: Retrieval and analysis of Martian haze profiles
Montmessin, F.; Korablev, O.; Bertaux, J. L. +3 more
Observations made by the SPICAM ultraviolet spectrometer on board the Mars Express orbiter are presented. We focus on several hundreds of atmospheric profiles which have been collected over 3/4 of a Martian year by making use of the stellar occultation technique. The typical structure of the Martian haze possesses at least one discrete layer (60% …
Fe K Emission and Absorption in the XMM-EPIC Spectrum of the Seyfert Galaxy IC 4329a
Reeves, J. N.; Braito, V.; Markowitz, A.
We present a detailed analysis of the XMM-Newton long-look of the Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two resolved peaks at 6.4 and 7.0 keV, consistent with neutral or near-neutral Fe Kα and Kβ emission. There is a prominent redward asymmetry in the 6.4 keV line, which could indicate emission from a Compton shoulder. Alterna…
Clathrate Hydrates of Oxidants in the Ice Shell of Europa
Hand, Kevin P.; Carlson, Robert W.; Cooper, John F. +1 more
Europa's icy surface is radiolytically modified by high-energy electrons and ions, and photolytically modified by solar ultraviolet photons. Observations from the Galileo Near Infrared Mapping Spectrometer, ground-based telescopes, the International Ultraviolet Explorer, and the Hubble Space Telescope, along with laboratory experiment results, ind…
Linking Stellar Mass and Star Formation in Spitzer MIPS 24 µm Galaxies
Le Floc'h, E.; Dole, H.; Lagache, G. +7 more
We present deep Ks<21.5 (Vega) identifications, redshifts, and stellar masses for most of the sources composing the bulk of the 24 µm background in the GOODS/CDFS. Our identified sample consists of 747 Spitzer MIPS 24 µm objects and includes ~94% of all the 24 µm sources in the GOODS-South field that have fluxes S
Composition of Titan's surface from Cassini VIMS
Sotin, C.; Brown, R. H.; Buratti, B. J. +15 more
Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the a…
An HST Study of the Supernovae Accompanying GRB 040924 and GRB 041006
Cenko, S. B.; Peterson, B. A.; Price, P. A. +23 more
We present the results from a Hubble Space Telescope ACS study of the supernovae (SNe) associated with gamma-ray bursts (GRBs) 040924 (z=0.86) and 041006 (z=0.71). We find evidence that both GRBs were associated with an SN 1998bw-like supernova dimmed by ~1.5 and ~0.3 mag, respectively, making GRB 040924 the faintest GRB-associated SN ever detecte…