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Observational Consequences of the Hypothesized Helium-rich Stellar Population in ω Centauri
Terndrup, D. M.; Newsham, G.
In response to the proposed high-helium content stars as an explanation for the double main sequence observed in ω Centauri, we investigated the consequences of such stars elsewhere on the color-magnitude diagram. We concentrated on the horizontal branch, where the effects of high helium are expected to show themselves more clearly. In the process…
Photometric Properties of the Most Massive High-Redshift Galaxies
Hernquist, Lars; Cox, Thomas J.; Hopkins, Philip F. +2 more
We calculate the observable properties of the most massive high-redshift galaxies in the hierarchical formation scenario where stellar spheroid and supermassive black hole growth are fueled by gas-rich mergers. Combining high-resolution hydrodynamical simulations of the hierarchical formation of a z~6 quasar, stellar population synthesis models, t…
The 1-200 keV X-Ray Spectrum of NGC 2992 and NGC 3081
Gehrels, N.; Beckmann, V.; Tueller, J.
The Seyfert 2 galaxies NGC 2992 and NGC 3081 have been observed by INTEGRAL and Swift. We report the results and a comparison of the spectrum above 10 keV based on INTEGRAL IBIS/ISGRI, Swift/BAT, and BeppoSAX/PDS. A spectrum can be extracted in the X-ray energy band ranging from 1 up to 200 keV. Although NGC 2992 shows a complex spectrum below 10 …
MOC observations of four Mars year variations in the south polar residual cap of Mars
Thomas, Peter C.; Wolff, Michael J.; James, Philip B. +1 more
The residual south polar cap of Mars (RSPC) is distinct from the residual north polar cap both in composition and in morphology. CO 2 frost in the RSPC is stabilized by its high albedo during southern spring and summer despite the relatively large insolation during that period. The morphology of the RSPC in summer displays a bewildering…
Infrared study of the southern Galactic star-forming region associated with IRAS 14416-5937
Ojha, D. K.; Vig, S.; Ghosh, S. K. +1 more
Aims:Our goal was to carry out an infrared study of the southern Galactic massive star-forming region associated with IRAS 14416-5937.
Methods: This star-forming region has been mapped simultaneously in two far infrared bands at ~150 and 210 µm, using the TIFR 1-m balloon borne telescope with ~1' angular resolution. We have used 2MASS JH…
Structure of the Near-Surface Layers of the Sun: Asphericity and Time Variation
Basu, Sarbani; Antia, H. M.; Bogart, Richard S.
We present results on the structure of the near-surface layers of the Sun obtained by inverting frequencies of high-degree solar modes from ``ring diagrams.'' We have results for eight epochs between 1996 June and 2003 October. The frequencies for each epoch were obtained from ring diagrams constructed from Michelson Doppler Imager (MDI) Dopplergr…
An XMM-Newton view of M101 - III. Diffuse X-ray emission
Read, A. M.; Warwick, R. S.; Roberts, T. P. +2 more
We present a study of the X-ray properties of the nearby face-on Scd spiral galaxy M101 based on recent XMM-Newton observations. In this third and final paper in the present series, we focus on the spatial and spectral properties of the residual emission, after excluding bright X-ray sources with LX > 1037ergs-1…
Magnetic Feature and Morphological Study of X-Ray Bright Points with Hinode
Golub, Leon; Sakao, Taro; Tsuneta, Saku +8 more
We observed X-ray bright points (XBPs) in a quiet region of the Sun with the X-Ray Telescope (XRT) aboard the Hinode satellite on 2006 December 19. XRT's high-resolution X-ray images revealed many XBPs with complicated structure and evolving dramatically with time. Almost all of the dynamic eruptions in the quiet region were composed of XBPs, and …
Particle Acceleration at the Earth's Bow Shock
Burgess, David
Shocks can be viewed as sites where upstream bulk flow energy is converted into downstream thermal energy. Collisionless shocks have the further property that they are sites of particle acceleration, as some fraction of the flow energy is diverted to a small number of energetic particles. Shocks are thus important in many astrophysical and solar e…
Scale sizes of intense auroral electric fields observed by Cluster
Nilsson, H.; Buchert, S.; Karlsson, T. +4 more
The scale sizes of intense (>0.15 V/m, mapped to the ionosphere), high-altitude (4-7 RE geocentric distance) auroral electric fields (measured by the Cluster EFW instrument) have been determined in a statistical study. Monopolar and bipolar electric fields, and converging and diverging events, are separated. The relations between the…