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A deep survey of brown dwarfs in Orion with Gemini
Tamura, M.; Lucas, P. W.; Roche, P. F.
We report the results of a deep near-infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26 arcmin2 area, including 138 brown dwarf candidates, defined as M < 0.075 Msolar for an assumed age of 1 Myr. Only 33 of the brown dwarf candidates are planeta…
Self-regulated active galactic nuclei heating in elliptical galaxies
Kawata, D.; Gibson, B. K.
We study the effect of active galactic nuclei (AGN) heating on the chemodynamical evolution of elliptical galaxies and their X-ray and optical properties using high-resolution Λ-dominated cold dark matter cosmological simulations. Our model considers an AGN as being `active' when a convergent gas inflow condition exists within the nucleus of a gal…
Two Pulsar Wind Nebulae: Chandra/XMM-Newton Imaging of GeV J1417-6100
Ng, C. -Y.; Romani, Roger W.; Roberts, Mallory S. E.
We report on Chandra ACIS and XMM-Newton MOS/pn imaging observations of two pulsar wind nebulae (K3/PSR J1420-6048 and G313.3+0.1, the ``Rabbit'') associated with the Galactic unidentified γ-ray source GeV J1417-6100. With excellent ACIS imaging the very energetic pulsar PSR J1420-6048 is separated from its surrounding nebula. This nebula has surp…
Abundance of Elements beyond the Iron Group in Cool DO White Dwarfs
Kruk, J. W.; Chayer, P.; Dupuis, J. +1 more
We report the presence of elements beyond the iron group in the atmospheres of the cool DO white dwarfs HD 149499 B and HZ 21. Photospheric lines of germanium (Z=32), arsenic (33), selenium (34), tin (50), tellurium (52), iodine (53), and perhaps bromine (35) are observed in ultraviolet spectra of HD 149499 B obtained with the Far Ultraviolet Spec…
Signature of Saturn's auroral cusp: Simultaneous Hubble Space Telescope FUV observations and upstream solar wind monitoring
Cowley, Stanley W. H.; Bunce, Emma J.; Clarke, John T. +3 more
Model simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the possibility that the FUV bright emissions sometimes observed near noon are associated with reconnection occurring at the dayside magnetopause, p…
Where are the X-ray quasi-periodic oscillations in active galaxies?
Vaughan, S.; Uttley, P.
In this paper, we address the question of whether existing X-ray observations of Seyfert galaxies are sufficiently sensitive to detect quasi-periodic oscillations (QPOs) similar to those observed in the X-ray variations of Galactic black holes (GBHs). We use data from XMM-Newton and simulated data based on the best Rossi X-ray Timing Explorer (RXT…
Probing the Intergalactic Medium-Galaxy Connection toward PKS 0405-123. II. A Cross-Correlation Study of Lyα Absorbers and Galaxies at z<0.5
Weiner, Benjamin J.; Chen, Hsiao-Wen; Mulchaey, John S. +2 more
We present a pilot study of the clustering properties of Lyα absorbers with respect to known galaxies based on 112 Lyα absorbers and 482 galaxies identified at z<0.5 along the sight line toward PKS 0405-123. The principal goal is to determine the origin of Lyα absorbers based on their cross-correlation amplitude with known galaxies and to inves…
Dynamics of cloud features on Uranus
Sromovsky, L. A.; Fry, P. M.
Near-infrared adaptive optics imaging of Uranus by the Keck 2 telescope during 2003 and 2004 has revealed numerous discrete cloud features, 70 of which were used to extend the zonal wind profile of Uranus up to 60° N. We confirmed the presence of a north-south asymmetry in the circulation [Karkoschka, E., 1998. Science 280, 570-572], and improved …
The X-ray emission properties and the dichotomy in the central stellar cusp shapes of early-type galaxies
Pellegrini, S.
The Hubble Space Telescope has revealed a dichotomy in the central surface brightness profiles of early-type galaxies, which have subsequently been grouped into two families: core, boxy, anisotropic systems; and cuspy (`power-law'), discy, rotating ones. Here we investigate whether a dichotomy is also present in the X-ray properties of the two fam…
No oceans on Titan from the absence of a near-infrared specular reflection
West, R. A.; Brown, M. E.; Roe, H. G. +2 more
With its substantial atmosphere of nitrogen, hydrocarbons and nitriles, Saturn's moon Titan is a unique planetary satellite. Photochemical processing of the gaseous constituents produces an extended haze that obscures the surface. Soon after the Voyager fly-bys in 1980 and 1981 photochemical models led to the conclusion that there should be enough…