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Ultracompact Dwarf Candidates in the Hydra Cluster
Harris, William E.; Wehner, Elizabeth M. H.
NGC 3311, the giant cD galaxy in the Hydra Cluster (A1060), has one of the largest globular cluster systems known. We describe new Gemini GMOS (g', i') photometry of the NGC 3311 field which reveals that the red, metal-rich side of its globular cluster population extends smoothly upward into the mass range associated with the…
Dependence of Heliospheric Lyα Absorption on the Interstellar Magnetic Field
Wood, Brian E.; Linsky, Jeffrey L.; Izmodenov, Vladislav V. +1 more
We use newly developed three-dimensional kinetic MHD models of the heliosphere to predict heliospheric H I Lyα absorption for various lines of sight. These predictions are compared with actual Lyα spectra from the Hubble Space Telescope, many of which have yielded previous detections of heliospheric absorption. We find that the absorption predicte…
Multiobject Spectroscopy of Young Star Clusters in NGC 4676
Kewley, Lisa J.; Chambers, Kenneth C.; Barnes, Joshua E. +1 more
Galaxy interactions are known to trigger starbursts. The young star clusters formed in mergers may be young globular clusters. The ages of these young star clusters yield the timing of interaction-triggered star formation and provide an important way to reconstruct the history of merging galaxies. Here we present the first results from our investi…
Crater clusters on Mars: Shedding light on martian ejecta launch conditions
Richardson, Derek C.; Berman, Daniel C.; Popova, Olga P. +2 more
We have identified two classes of crater clusters on Mars. One class is "small clusters" (crater diameter D∼ tens m, spread over few hundred m), fitting our earlier calculations for the breakup of weak stone meteoroids in the martian atmosphere [Popova, O.P., Nemtchinov, I.V., Hartmann, W.K., 2003. Meteorit. Planet. Sci. 38, 905-925]. The second c…
Enceladus: Cassini observations and implications for the search for life
Hansen, C. J.; Tinetti, G.; Hartman, H. +5 more
Aims:The recent Cassini discovery of water vapor plumes ejected from the south pole of the Saturnian satellite, Enceladus, presents a unique window of opportunity for the detection of extant life in our solar system.
Methods: With its significant geothermal energy source propelling these plumes >80 km from the surface of the moon and the en…
A new constraint for gamma-ray burst progenitor mass
Fruchter, Andrew S.; Larsson, Josefin; Levan, Andrew J. +1 more
Recent comparative observations of long-duration gamma-ray bursts (LGRBs) and core collapse supernova (cc SN) host galaxies demonstrate that these two, highly energetic transient events are distributed very differently upon their hosts. LGRBs are much more concentrated on their host galaxy light than cc SN. Here we explore the suggestion that this…
Neutral cloud interaction with Saturn's main rings
Jurac, S.; Richardson, J. D.
The dense water cloud just outward of Saturn's main rings could strongly influence the surface composition of main ring constituents. Cassini pictures display brightening toward the outer edges of the main rings, suggesting that the outer edges have more icy material. We show that this enhanced brightening might not be a ring evolutionary feature,…
Magnetic fields and gas in the cluster-influenced spiral galaxy NGC 4254. I. Radio and X-rays observations
Ehle, M.; Beck, R.; Chyży, K. T.
Aims:Radio observations can show how cluster galaxies are affected by various environmental factors, that perturb their morphology, as well as modify properties of the interstellar medium (ISM), especially the characteristics of its magnetic field.
Methods: We made high-resolution and high-sensitivity radio-polarimetric VLA observations of NGC…
The D-CIXS X-ray spectrometer on the SMART-1 mission to the Moon—First results
Barabash, S.; Lundin, R.; Grande, M. +28 more
The SMART-1 mission has recently arrived at the Moon. Its payload includes D-CIXS, a compact X-ray spectrometer. SMART-1 is a technology evaluation mission, and D-CIXS is the first of a new generation of planetary X-ray spectrometers. Novel technologies enable new capabilities for measuring the fluorescent yield of a planetary surface or atmospher…
Are Moreton Waves Coronal Phenomena?
Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.
We report on permeability characteristics of the upper solar atmosphere due to the progression of a Moreton wave. An exceptional Moreton wave is tracked to cover most of the Sun, following an unusually large solar X-ray flare observed on 2003 October 29. Using Hα intensity and Doppler measurements, the Moreton wave is tracked for as long as 12 min…