Search Publications
Interplanetary and solar surface properties of coronal holes observed during solar maximum
Woch, J.; Solanki, S. K.; Forsyth, R. +2 more
Data from the Solar Wind Ion Composition Spectrometer (SWICS) on board the Ulysses spacecraft and synoptic maps from Kitt Peak are used to analyze the relatively short-lived coronal holes which exist during the maximum phase of the solar activity cycle 23. They are compared with the persistent polar coronal holes which prevail around solar minimum…
The X-Ray Properties of the Nearby Star-forming Galaxy IC 342: The XMM-Newton View
Bauer, F. E.; Brandt, W. N.; Lehmer, B.
We present results on the X-ray properties of IC 342 using a 10 ks XMM-Newton observation. Thirty-five sources are detected coincident with the disk of IC 342 (more than tripling the number known), of which ~31 are likely to be intrinsic to IC 342. This point-source population exhibits a diverse range of spectral properties and has an X-ray lumino…
Blue Horizontal-Branch Stars in Old, Metal-rich Stellar Systems
O'Connell, Robert W.; Dorman, Ben; Rood, Robert T. +5 more
Twenty years ago, Burstein et al. recognized that the metal-rich globular clusters in the Andromeda galaxy (M31) exhibited anomalously strong Balmer and CN lines compared to Milky Way clusters. They suggested that younger ages might be the cause, unless blue stars above the main-sequence turnoff or on the horizontal branch were uncommonly prominen…
The far-infrared/radio correlation in the ISO era. The warm and cold far-infrared/radio correlations
Völk, H. J.; Tuffs, R. J.; Pierini, D. +1 more
We present the correlation between the far-infrared (FIR) and radio emissions from a composite sample of 72 nearby normal galaxies observed with the ISOPHOT instrument on board the Infrared Space Observatory. The galaxies in the sample have measurements at three FIR wavelengths (60, 100 and 170 mu m), which allowed a direct determination of the wa…
Asteroid observations with the Hubble Space Telescope. II. Duplicity search and size measurements for 6 asteroids
Lattanzi, M.; Tanga, P.; Cellino, A. +3 more
We present the results of the observations of five Main Belt asteroids and one Trojan obtained using the Fine Guidance Sensors (FGS) of the Hubble Space Telescope. For each object, estimates of the spin axis orientation, angular size and overall shape, as well as possible indications of a binary structure, are derived. This enables the computation…
The Distance to the Large Magellanic Cloud Cluster NGC 1866 and the Surrounding Field
Salaris, M.; Walker, A. R.; Brocato, E. +2 more
We use the main-sequence stars in the LMC cluster NGC 1866 and red clump stars in the local field to obtain two independent estimates of the LMC distance. We apply an empirical main-sequence-fitting technique based on a large sample of subdwarfs with accurate Hipparcos parallaxes in order to estimate the cluster distance modulus, and the multicolo…
The ASCA X-Ray Spectrum of Arp 102B and Evaluation of Simple Models for Its Associated, Metastable Fe II Absorber
Charlton, Jane C.; Eracleous, Michael; Halpern, Jules P.
We have observed the broad-line radio galaxy Arp 102B with ASCA in order to determine the absorbing column density toward its X-ray source and measure its X-ray spectrum. The ultimate goal was to constrain the properties of the medium responsible for the metastable Fe II absorption lines observed in the ultraviolet spectrum of this object. The 0.5…
Nitrogen Overabundance: Globular Cluster and Halo Formation
Burstein, David; Li, Yong
Halo globular clusters pose four succinct issues that must be solved in any scenario of their formation: single-age, single-metallicity stellar populations; a lower limit ([Fe/H]~-2.5) to their average metallicity; comprising only 1% of the stellar halo mass; and being among the oldest stars in our Galaxy. New spectra are presented of Galactic sta…
First NACO observations of the Brown Dwarf LHS 2397aB
Bouy, H.; Brandner, W.; Lagrange, A. M. +3 more
Observations of the standard late type M8 star LHS 2397aA were obtained at the ESO-VLT 8 m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics facility. The observations were taken during the NACO commissioning, and the infrared standard star LHS 2397aA was observed in the H, and Ks broad band filters. In both bands the brown dwarf companion…
Mid-infrared imaging of the dust shell around the post-asymptotic giant branch star HD 161796
Gledhill, T. M.; Yates, J. A.
We present mid-infrared (IR) images of HD 161796 (IRAS 17436+5003), taken with the OSCIR imager on the Gemini North Telescope, that resolve for the first time the thermal emission structure of the dust shell around this post-asymptotic giant branch (AGB) star. As well as a basic axisymmetric structure, the observations show deviations from axisymm…