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Whisper, a Resonance Sounder and Wave Analyser: Performances and Perspectives for the Cluster Mission

Fergeau, P.; Décréau, P. M. E.; Canu, P. +7 more

The Morphology of Distant Cluster Galaxies. II. HST Observations of Four Rich Clusters at z ~= 0.4

Dressler, Alan; Oemler, Augustus, Jr.; Butcher, Harvey R.

We present Hubble Space Telescope (HST) WF/PC and WFPC2 observations of four rich clusters of galaxies at redshifts z ~ 0.4: CL 1447+2619, CL 0939+4713, CL 0024+1654, and Abell 370. Extensive ground-based observations have shown that all have substantial populations of blue, star-forming, and (in some cases) starbursting galaxies. We find the gala…

Infrared spectral energy distributions of the interacting galaxies ARP 244, NGC 6240, and ARP 220.

Schulz, B.; Klaas, U.; Heinrichsen, I. +1 more

For the luminous galaxies Arp 244, NGC 6240 and Arp 220 detailed infrared spectral energy distributions between 3 and 200µm obtained with ISOPHOT are presented. The maximum of the infrared energy distribution can now clearly be determined. The SEDs can be well represented by cold dust emission with temperatures of 30-50K which by far dominat…

A multiwavelength study of the Seyfert 1 galaxy MCG-6-30-15

Fabian, A. C.; Reynolds, C. S.; Celotti, A. +1 more

We present a multiwaveband spectroscopic study of the nearby Seyfert 1 galaxy MCG-6-30-15. New optical spectra from the Anglo-Australian Telescope are presented which clearly show the effects of dust extinction/reddening on both the emission-line spectrum and the non-stellar AGN continuum. The reddening is constrained to be in the range E(B-V)=0.6…

Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. V. Mass Dependence of Dredge-up and the Chemical History of the Large Magellanic Cloud

Ford, H. C.; Harrington, J. P.; Wood, P. R. +6 more

A photoionization analysis of Hubble Space Telescope UV and ground-based optical spectrophotometry is given for eight more planetary nebulae (PNs) in the Large Magellanic Cloud (LMC). This allows the central stars to be placed accurately on the H-R diagram and permits the determination of the He, C, N, O, Ne, S, and Ar abundances. In some cases, t…

In-Flight Performance of the Virgo Solar Irradiance Instruments on SOHO

Dewitte, Steven; Chevalier, André; Fröhlich, Claus +7 more

The in-flight performance of the total and spectral irradiance instruments within VIRGO (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (SOlar and Heliospheric Observatory) is in most aspects better than expected. The behaviour during the first year of operation of the two types of radiometers and the sunpho…

First Hubble Space Telescope Observations of Mira AB Wind-accreting Binary Systems

Raymond, John; Karovska, Margarita; Guinan, Edward +1 more

The Mira AB system belongs to a class of detached binaries in which a compact object accretes mass from the wind of a cool giant or supergiant. This system provides a unique laboratory for detailed study of the characteristics of the wind accretion processes because it can be spatially resolved with the Hubble Space Telescope (HST) and the compone…

The Evolution of the Final Helium Shell Flash Star V605 Aquilae From 1917 to 1997

De Marco, Orsola; Clayton, Geoffrey C.

Only three stars have been observed going through a final helium shell flash since the advent of modem instrumentation, FG Sagittae (in 1894), V605 Aquilae (in 1919), and Sakurai's Object (in 1996). In this paper, we present for the first time a spectrum taken of V605 Aql, while it was in its cool giant phase in 1921. This spectrum is identical to…

Hubble Space Telescope Observations of the Post-Core-Collapse Globular Cluster NGC 6752. II. A Large Main-Sequence Binary Population

Bailyn, Charles D.; Rubenstein, Eric P.

We present a color-magnitude diagram (CMD) of NGC 6752 based on post-refurbishment Planetary Camera 2 observations of its core. The main sequence is broadened and asymmetric, as would be expected if there were large numbers of binary stars. We use artificial star experiments to characterize the broadening of the main sequence that is expected, due…

The HIPPARCOS proper motion of the Magellanic Clouds

Kroupa, Pavel; Bastian, Ulrich

The proper motion of the Large (LMC) and Small (SMC) Magellanic Cloud using data acquired with the Hipparcos satellite is presented. Hipparcos measured 36 stars in the LMC and 11 stars in the SMC. A correctly weighted mean of the data yields the presently available most accurate values, µ_αcos( δ) = 1.94±0.29 mas/yr, µ_δ<…