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A photometric monitoring of bright high-amplitude delta Scuti stars. II. Period updates for seven stars

Derekas, A.; Mészáros, Sz.; Rodríguez, E. +10 more

We present new photometric data for seven high-amplitude delta Scuti stars. The observations were acquired between 1996 and 2002, mostly in the Johnson photometric system. For one star (GW UMa), our observations are the first since the discovery of its pulsational nature from the Hipparcos data. The primary goal of this project was to update our k…

Io's auroral limb glow: Hubble Space Telescope FUV observations

Moos, H. W.; Strobel, D. F.; Retherford, K. D.

Observations of Io's FUV aurora were obtained using the Space Telescope Imaging Spectrograph (STIS) on several occasions between 1997 and 2000. The STIS first-order long-slit spectroscopy mode and 2″ wide slit were used to produce nearly monochromatic images of Io. These images reveal several distinct auroral features, including limb brightened em…

An XMM-Newton observation of the galaxy group MKW 4

Read, A. M.; O'Sullivan, E.; Ponman, T. J. +2 more

We present an X-ray study of the galaxy group or poor cluster MKW 4. Working with XMM-Newton data we examine the distribution and properties of the hot gas which makes up the group halo. The inner halo shows some signs of structure, with circular or elliptical beta models providing a poor fit to the surface brightness profile. This may be evidence…

Chandra observations of the Mice

Read, Andrew M.

Presented here are high spatial and spectral resolution Chandra X-ray observations of the famous interacting galaxy pair, the Mice, a system similar to, though less evolved than, the well-known Antennae galaxies. Previously unpublished ROSAT High Resolution Imager data of the system are also presented.

Starburst-driven galactic winds outflowi…

Evidence for electrostatic decay in the solar wind at 5.2 AU

MacDowall, R. J.; Scime, E. E.; Thejappa, G. +1 more

The Unified Radio and Plasma wave Experiment (URAP) on the Ulysses spacecraft provides in situ observations of Langmuir waves and ion-acoustic waves in the solar wind. The observations presented in this paper were obtained at 5.2 AU from the Sun. Low-frequency (20-200 Hz in the spacecraft frame) electric field signals are observed coincident in ti…

A European Southern Observatory Very Large Telescope Survey of Near-Infrared (Z <= 25) Selected Galaxies at Redshifts 4.5 < z < 6: Constraining the Cosmic Star Formation Rate near the Reionization Epoch

Fontana, A.; Cristiani, S.; Giallongo, E. +4 more

We present the results of a Very Large Telescope (VLT) and Hubble Space Telescope imaging survey aimed at the identification of 4.5<z<6 galaxies. In the VLT data, a set of broadband and intermediate-band filters has been used to select 13 high-z candidates in a Z_AB<=25 mag catalog, over an area of about 30 arcmin². D…

Oscillations in the wings of sunspot transition region lines

Wilhelm, K.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more

We explore a new approach to the investigation of optically thin emission lines by comparing the intensity variations in opposite wings of the spectral lines and apply the method to investigate the oscillations above sunspots. The observations show that it is easier to detect the 3 min oscillations above sunspots in the short wavelength (``blue'')…

Submillimeter Wave Astronomy Satellite Mapping Observations of Water Vapor around Sagittarius B2

Bergin, Edwin A.; Neufeld, David A.; Goldsmith, Paul F. +1 more

Observations of the 1₁₀-1₀₁ 556.936 GHz transition of ortho-water with the Submillimeter Wave Astronomy Satellite have revealed the presence of widespread emission and absorption by water vapor around the strong submillimeter continuum source Sagittarius B2. An incompletely sampled spectral line map of a region of size 26

Composite Accretion Disk and White Dwarf Model Analyses of the Quiescence of Dwarf Novae: EM Cygni, CZ Orionis, and WW Ceti

Sion, Edward M.; Winter, Lisa

We explore the origin of the far-UV (FUV) spectra of three dwarf novae using combined high-gravity photosphere and accretion disk models. We have carried out an IUE archival comparative study of the three U Gem-type dwarf novae EM Cyg, CZ Ori, and WW Cet. For EM Cyg, the FUV spectrum during quiescence is dominated by an accretion disk with M=5×10<…

Lower hybrid cavities in the inner magnetosphere

André, M.; Eriksson, A. I.; Tjulin, A.

We present observations of lower hybrid cavities from altitudes above 10,000 km, using data from Viking and Cluster satellites. Lower hybrid cavities (LHCs) are narrow (ion gyroradius scale) density depletions with enhanced amplitude of waves in the lower hybrid frequency range, previously reported below 1750 km altitude by the Freja satellite and…