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CCD Speckle Observations of Binary Stars from the Southern Hemisphere. III. Differential Photometry
Franz, Otto G.; Horch, Elliott; Ninkov, Zoran
Two hundred seventy-two magnitude difference measures of 135 double star systems are presented. The results are derived from speckle observations using the Bessel V and R passbands and a fast readout CCD camera. Observations were taken at two 60 cm telescopes, namely the Helen Sawyer Hogg Telescope, formerly at Las Campanas, Chile, and the Lowell-…
An Astrometric Study of the Triple Star ADS 48
Kiselev, A. A.; Kiyaeva, O. V.; Polyakov, E. V. +1 more
We analyze the series of relative positions of the hierarchical triple system ADS 48 ABF (AB = 6 arcsec, AF = 327 arcsec) obtained with the 26-inch Pulkovo refractor during 1961-1995 and measured with the Fantazia automated measuring system. A new relative orbit of pair AB is determined by the method of apparent-motion parameters using new observa…
Oxygen abundance in coronal streamers during solar minimum
Giordano, S.; Antonucci, E.; Marocchi, D.
We present a study of the oxygen abundance relative to hydrogen in the equatorial streamer belt of the solar corona during the recent period of activity minimum. The oxygen abundance is derived from the spectroscopic observations of the outer corona performed during 1996 with the Ultraviolet Coronagraph Spectrometer (SOHO) in the ultra-violet regi…
An ICME observed by Voyager 2 at 58 AU and by Ulysses at 5 AU
Wang, C.; Heber, B.; von Steiger, R. +1 more
Between days 175 and 180 (June 24 through 29) of 1999, the PLS instrument on Voyager 2 observed alpha particle enhancements with fractional percentages of alpha to proton number densities exceeding 10%. Ulysses (located at 5.3 AU) observed at least two candidate source features for these enhancements. To identify the correct source structure, a 1D…
UV observations of the galaxy cluster Abell 1795 with the optical monitor on XMM-Newton
Kaastra, J. S.; Fabian, A. C.; Mushotzky, R. F. +8 more
We present the results of an analysis of broad band UV observations of the central regions of Abell 1795 observed with the optical monitor on XMM-Newton. As have been found with other UV observations of the central regions of clusters of galaxies, we find evidence for star formation. However, we also find evidence for absorption in the cD galaxy o…
The LMC eclipsing binary HV 2274 revisited
Salaris, M.; Groenewegen, M. A. T.
We reanalyse the UV/optical spectrum and optical broad-band data of the eclipsing binary HV 2274 in the LMC, and derive its distance following the method given by Guinan et al. (\cite{Guinan98a},\cite{Guinan98b}) of fitting theoretical spectra to the stars' UV/optical spectrum plus optical photometry. We describe the method in detail, pointing out…
Constraints on thick disc and halo parameters from HST photometry of field stars in the Galaxy
Santiago, B. X.; Kerber, L. O.; Javiel, S. C.
We analyse a sample of over 1000 stars from 32 fields imaged in the V and I bands with the Wide Field and Planetary Camera, on board of the Hubble Space Telescope. The fields are located at Galactic latitudes | b | >= 15deg and in various directions on the sky. We consider models for the structure of the Galaxy with different choices…
RX J0848+4456: Disentangling a Moderate Redshift Cluster
Papovich, C.; Tozzi, P.; Rosati, P. +7 more
We present a multiwavelength study of RX J0848+4456, a cluster of galaxies discovered through X-ray emission in the ROSAT Deep Cluster Survey. Our observations consist of WFPC2 imaging, optical spectra, and X-ray data collected with the Chandra X-Ray Observatory. We find that RX J0848+4456 consists of an X-ray-emitting cluster of galaxies at a red…
Observations of the Interstellar Medium in the Magellanic Bridge
Sembach, K. R.; Dufton, P. L.; Keenan, F. P. +2 more
We present ultraviolet and optical spectra of DI 1388, a young star in the Magellanic Bridge, a region of gas between the Small and Large Magellanic Clouds. The data have signal-to-noise ratios of 20-45 and a spectral resolution of 6.5 km s-1. Interstellar absorption by the Magellanic Bridge at vLSR~200 km s-1 is v…
Deep Near-Infrared Luminosity Function of a Cluster of Galaxies at Z=0.3
Andreon, S.
The deep near-infrared luminosity function of AC 118, a cluster of galaxies at z=0.3, is presented. AC 118 is a bimodal cluster, as evidenced both by our near-infrared images of lensed galaxies, by public X-ray ROSAT images, and by the spatial distribution of bright galaxies. Taking advantage of the extension and depth of our data, which sample an…