Search Publications
On the He II Emission in η Carinae and the Origin of Its Spectroscopic Events
Davidson, K.; Hillier, D. J.; Humphreys, Roberta M. +2 more
We describe and analyze Hubble Space Telescope (HST) observations of transient emission near 4680 Å in η Car, reported earlier by Steiner & Damineli. If, as seems probable, this is He II λ4687, then it is a unique clue to η Car's 5.5 yr cycle. According to our analysis, several aspects of this feature support a mass-ejection model of the obser…
Ion cyclotron waves in Saturn's E ring: Initial Cassini observations
Russell, C. T.; Dougherty, M. K.; Leisner, J. S. +3 more
The magnetometer onboard the Cassini spacecraft observes ion cyclotron waves produced by both water-group (O+, OH+, H2O+, or H3O+) and O2+ ions at nearly all radial distances and local times within the E ring. These left-hand elliptically polarized waves travel…
Trends in the Globular Cluster Luminosity Function of Early-Type Galaxies
Jordán, Andrés; Tonry, John L.; Côté, Patrick +8 more
We present results from a study of the globular cluster luminosity function (GCLF) in a sample of 89 early-type galaxies observed as part of the ACS Virgo Cluster Survey. Using a Gaussian parameterization of the GCLF, we find a highly significant correlation between the GCLF dispersion, σ, and the galaxy luminosity, MB,gal, in the sense…
Spitzer IRAC Images and Sample Spectra of Cassiopeia A's Explosion
Smith, J. D.; Reach, William T.; Rho, Jeonghee +5 more
We present Spitzer IRAC images and representative 5.27-38.5 µm IRS spectra of the Cas A SNR. We find that various IRAC channels are each most sensitive to a different spectral and physical component. Channel 1 (3.6 µm) provides an excellent match to the radio synchrotron images. Where channel 1 is strong with respect to the other IRAC …
Near-infrared spectra of the leading and trailing hemispheres of Enceladus
Smith, J. D.; Verbiscer, Anne J.; Skrutskie, Michael F. +5 more
We present individual spectra 0.8-2.5 µm of the leading and trailing hemispheres of Enceladus obtained with the CorMASS spectrograph on the 1.8 m Vatican Advanced Technology Telescope (VATT) at the Mount Graham International Observatory. While the absorption bands of water ice dominate the spectrum of both hemispheres, most of these bands ar…
Methane, ethane, and mixed clouds in Titan's atmosphere: Properties derived from microphysical modeling
Barth, Erika L.; Toon, Owen B.
Theoretical arguments point to and recent observations confirm the existence of clouds in Titan's atmosphere, yet we possess very little data on their particle size, composition and formation mechanism. A time-dependent microphysical model is used to study the evolution of ice clouds in Titan's atmosphere. The model simulates nucleation, condensat…
Comparing dynamical and photometric-stellar masses of early-type galaxies at z ~ 1
Cimatti, A.; Popesso, P.; Stern, D. +13 more
Aims.The purpose of this study is to explore the relationship between galaxy stellar masses, based on multiwavelength photometry spectral template fitting and dynamical masses based on published velocity dispersion measurements, for a sample of 48 early-type galaxies at z ∼ 1 with HST/ACS morphological information.
Methods: .We determine photo…
Hubble Space Telescope Near-Infrared Snapshot Survey of 3CR Radio Source Counterparts at Low Redshift
O'Dea, Christopher P.; Sparks, William B.; Baum, Stefi +9 more
We present newly acquired images of the near-infrared counterpart of 3CR radio sources. All the sources were selected to have a redshift of less than 0.3 to allow us to obtain the highest spatial resolution. The observations were carried out as a snapshot program using the Near-Infrared Camera and Multiobject Spectrograph (NICMOS) on-board the Hub…
Evidence for orbital motion of material close to the central black hole of Mrk 766
Turner, T. J.; Reeves, J. N.; George, I. M. +1 more
Time-resolved X-ray spectroscopy has been obtained for the narrow line Seyfert galaxy Mrk 766 from XMM-Newton observations. We present analysis in the energy-time plane of EPIC pn data in the 4-8 keV band with energy resolution R ≃ 50. A component of Fe Kα emission detected in the maps shows a variation of photon energy with time that appears both…
Dynamics of the Venus upper atmosphere: Outstanding problems and new constraints expected from Venus Express
Drossart, P.; Bougher, S. W.; Rafkin, S.
A consistent picture of the dynamics of the Venus upper atmosphere from ∼90 to 200 km has begun to emerge [e.g., Bougher, S.W., Alexander, M.J., Mayr, H.G., 1997. Upper Atmosphere Dynamics: Global Circulation and Gravity Waves. Venus II, CH. 2.4. University of Arizona Press, Tucson, pp. 259-292; Lellouch, E., Clancy, T., Crisp, D., Kliore, A., Tit…