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Observations of the SW Sextantis Star BH Lyncis in a High State
Szkody, Paula; Hoard, D. W.
We present time-resolved photometry and medium resolution (2 Å) spectroscopy of the SW Sextantis star BH Lyncis obtained during a high state of the system. Previous detailed observations have been obtained only during low and intermediate states. In addition, we present the first International Ultraviolet Explorer low-resolution (6 Å) spectrum of …
Red giants in the halo of the S0 galaxy NGC 3115: a distance and a bimodal metallicity distribution
Elson, Rebecca A. W.
Using the Hubble Space Telescope, we resolve the red giant branch in the halo of the S0 galaxy NGC 3115. We measure magnitudes and (V-I) colours for stars down to 1.5mag below the tip of the red giant branch. From the brightest stars we estimate a distance modulus (m-M)_0=30.21+/-0.30, corresponding to a distance of 11.0+/-1.5Mpc. This is in excel…
HST Observations of Host Galaxies in Three Radio-selected BL Lacertae Objects
Giavalisco, Mauro; Urry, C. Megan; Scarpa, Riccardo +3 more
We present high-resolution images of three BL Lac objects (0814+425, 1823+568, 2254+074) taken with the WFPC-2 camera on Hubble Space Telescope (HST) as part of a study of BL Lacs from a complete radio-selected sample. In two cases we clearly detect the host galaxies while the third BL Lac (0814+425) is unresolved. The host galaxy of 2254+074 is a…
Active Spacecraft Potential Control
Goldstein, R.; Schmidt, R.; Pedersen, A. +13 more
Barium stars, galactic populations and evolution.
Luri, X.; Figueras, F.; Torra, J. +4 more
In this paper HIPPARCOS astrometric and kinematical data together with radial velocities from other sources are used to calibrate both luminosity and kinematics parameters of Ba stars and to classify them. We confirm the results of our previous paper (where we used data from the HIPPARCOS Input Catalogue), and show that Ba stars are an inhomogeneo…
Do First Results from SOHO UVCS Indicate That the Solar Wind Is Accelerated by Solitary Waves?
Davila, J. M.; Ofman, L.
The Ultraviolet Coronagraph Spectrometer (UVCS) on board the recently launched US-European Solar and Heliospheric Observatory (SOHO) satellite has found O VI and H I emission lines with a broad component that corresponds to ~300 km s-1 unresolved motions at about 0.7 solar radii above the photosphere. These motions appear to be independ…
The luminosity function of the globular cluster NGC 6752 with the Hubble Space Telescope: evidence of mass segregation
Bragaglia, A.; Carretta, E.; Ferraro, F. R. +2 more
We present the luminosity function (LF) for the lower main sequence of the Galactic globular cluster NGC6752, as obtained from Hubble Space Telescope (HST) observations centred 2 arcmin from the cluster centre. We present data in the F814W and F555W filters. Our LF reaches down to M_I=11 or, translated to a mass function, to M~=0.12 Msolar. The LF…
Detailed Lensing Properties of the MS 2137-2353 Core and Reconstruction of Sources from Hubble Space Telescope Imagery
Le Fèvre, O.; Hammer, F.; Luppino, G. A. +3 more
A deep HST image of the core of the cluster of galaxies MS 2137-2353 has revealed detailed morphological structures in two arc systems, which are modeled and well reproduced. An analysis of the lensing properties of the dark matter component indicates that the cluster could have a mass distribution almost as simple as a single elliptical mass dist…
The Nuclear Ionized Gas in the Radio Galaxy M84 (NGC 4374)
Heckman, Timothy M.; Bower, Gary A.; Wilson, Andrew S. +1 more
We present optical images of the nucleus of the nearby radio galaxy M84 (NGC 4374 = 3C 272.1) obtained with the Wide Field/Planetary Camera 2 aboard the Hubble Space Telescope. Our three images cover the Hα + [N II] emission lines as well as the V and I continuum bands. Analysis of these images confirms that the Hα + [N II] emission in the central…
Fractionated stellar wind - the example of σ Orionis E.
Groote, D.; Hunger, K.
In main-sequence stars, at effective temperatures below =~20000K, radiation ceases to be able to drive a stellar wind. In a rather narrow transition regime, elemental segregation seems possible due to the decoupling of He and, under special circumstances, also of H from the absorbing metal ions in the wind. This effect may even be more pronounced,…