Search Publications
HST NICMOS Imaging of z ~ 2, 24 µm-selected Ultraluminous Infrared Galaxies
Helou, George; Colbert, James; Surace, Jason +3 more
We present Hubble Space Telescope NICMOS H-band imaging of 33 ultraluminous infrared galaxies (ULIRGs) at z ~ 2 that were selected from the 24 µm catalog of the Spitzer Extragalactic First Look Survey. The images reveal that at least 17 of the 33 objects are associated with interactions. Up to one-fifth of the sources in our sample could be …
The Globular Cluster Systems around NGC 3311 and NGC 3309
Whitmore, Bradley C.; Rothberg, Barry; Harris, William E. +2 more
We present extensive new photometry in (g', i') of the large globular cluster (GC) system around NGC 3311, the central cD galaxy in the Hydra cluster. Our GMOS data cover a 5.5' field of view and reach a limiting magnitude i' simeq 26.0, about 0.5 mag fainter than the turnover point of the GC luminosity function. We find that NGC 3311 has a huge p…
The nature of the hard state of Cygnus X-3
Larsson, S.; Zdziarski, A. A.; Vilhu, O. +4 more
The X-ray binary Cygnus X-3 (Cyg X-3) is a highly variable X-ray source that displays a wide range of observed spectral states. One of the main states is significantly harder than the others, peaking at ~20 keV, with only a weak low-energy component. Due to the enigmatic nature of this object, hidden inside the strong stellar wind of its Wolf-Raye…
Probing the Ionization Structure of the Narrow-Line Region in the Seyfert 1 Galaxy NGC 4151
Kraemer, S. B.; Crenshaw, D. M.; Schmitt, H. R.
We present a study of the distribution of [O III] λ5007 and [O II] λ3727 emission in the narrow-line region (NLR) of the Seyfert 1 galaxy NGC 4151. While the NLR of NGC 4151 exhibits an overall structure consistent with the unified model of Seyfert galaxies, narrowband [O III] and [O II] images obtained with the Wide Field and Planetary Camera 2 a…
In-flight performance and calibration of SPICAV SOIR onboard Venus Express
Montmessin, Franck; Bertaux, Jean-Loup; Korablev, Oleg +13 more
Solar occultation in the infrared, part of the Spectoscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument onboard Venus Express, combines an echelle grating spectrometer with an acousto-optic tunable filter (AOTF). It performs solar occultation measurements in the IR region at high spectral resolution. The wave…
Relative age of interior layered deposits in southwest Candor Chasma based on high-resolution structural mapping
Kirk, Randolph L.; McEwen, Alfred S.; Okubo, Chris H. +1 more
High-resolution topography generated from stereo HiRISE (High-Resolution Imaging Science Experiment) imagery reveals the meter-scale structure of interior layered deposits (ILD) in southwest Candor Chasma. This study seeks to determine the age of the local ILD relative to any normal faults that can be attributed to chasma formation. The study area…
Constraints on the Emission and Viewing Geometry of the Transient Anomalous X-Ray Pulsar XTE J1810-197
Gotthelf, E. V.; Perna, Rosalba
The temporal decay of the flux components of the transient anomalous X-ray pulsar XTE J1810-197 following its 2002 outburst presents a unique opportunity to probe the emission geometry of a magnetar. Toward this goal, we model the magnitude of the pulsar's modulation in narrow spectral bands over time. Following previous work, we assume that the p…
The Ascraeus Mons fan-shaped deposit: Volcano ice interactions and the climatic implications of cold-based tropical mountain glaciation
Head, James W.; Kadish, Seth J.; Marchant, David R. +1 more
Amazonian-aged fan-shaped deposits extending to the northwest of each of the Tharsis Montes in the Tharsis region on Mars have been interpreted to have originated from mass-wasting, volcanic, tectonic and/or glacial processes. We use new data from MRO, MGS, and Odyssey to characterize these deposits. Building on recent evidence for cold-based glac…
Discovery of a Young, Energetic 70.5 ms Pulsar Associated with the TeV Gamma-Ray Source HESS J1837-069
Gotthelf, E. V.; Halpern, J. P.
We report the discovery of 70.5 ms pulsations from the X-ray source AX J1838.0-0655 using the Rossi X-Ray Timing Explorer ( RXTE). PSR J1838-0655 is a rotation-powered pulsar with spin-down luminosity Ė = 5.5 × 1036 ergs s-1, characteristic age τc ≡ P/2dot P = 23 kyr, and surface dipole magnetic field strength B
First identification of mirror mode waves in Venus' magnetosheath?
Zhang, T. L.; Glassmeier, K. -H.; Baumjohann, W. +3 more
In this paper first time observations of mirror mode like structures in Venus' magnetosheath are presented. Using magnetometer data from the Venus Express spacecraft it is shown that in two regions in the Venusian magnetosheath strong compressional waves exist, which propagate nearly perpendicular to the ambient magnetic field. They are most likel…