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The discovery of the ``21'' mu m and ``30'' mu m emission features in Planetary Nebulae with Wolf-Rayet central stars
Waters, L. B. F. M.; Hony, S.; Tielens, A. G. G. M.
We report the discovery of the ``21'' mu m and ``30'' mu m features in the planetary nebulae around the hydrogen-deficient stars HD 826 and HD 158269. The carriers of these features are known to be produced in outflows around carbon-rich stars. This discovery demonstrates that the bulk of the dust in these nebulae has been produced during a carbon…
Far Ultraviolet Spectroscopic Explorer Observations of Capella
Young, P. R.; Moos, H. W.; Linsky, J. L. +4 more
Far Ultraviolet Spectroscopic Explorer observations of the binary system Capella reveal a rich emission-line spectrum containing neutral and ionic species, among them H I, O I, C III, O VI, S VI, Ne V, and Ne VI. In addition, Fe XVIII λ974.85, formed at temperatures of ~6×106 K, is detected. Whereas the strong transition region lines pr…
Solar Internal Composition and Nuclear Reaction Rates in the Light of Helioseismology
Couvidat, S.; Turck-chièze, S.; Nghiem, P. +1 more
Acoustic modes are a suitable probe to check the internal solar composition and give constraints on regions of turbulence or mixing in stellar interiors. The recent results obtained with the SOHO satellite involve practically all the acoustic modes and are extremely useful to check theoretical assumptions. If turbulence is favoured to explain lith…
Multiwavelength Study of the Starburst Galaxy NGC 7714. II. The Balance between Young, Intermediate-Age, and Old Stars
Leitherer, Claus; Lançon, Ariane; González Delgado, Rosa M. +1 more
We combine existing multiwavelength data (including an HST/GHRS UV spectrum and a ground-based optical spectrum) with unpublished HST/WFPC2 images, near-IR photometry, and K-band spectroscopy. We use these data to constrain the young, the intermediate-age, and the old stellar populations in the central regions of the starburst galaxy NGC 7714. In …
High velocity structures in, and the X-ray emission from the LBV nebula around η Carinae
Weis, K.; Bomans, D. J.; Duschl, W. J.
The Luminous Blue Variable star eta Carinae is one of the most massive stars known. It underwent a giant eruption in 1843 in which the Homunculus nebula was created. ROSAT and ASCA data indicate the existence of a hard and a soft X-ray component which appear to be spatially distinct: a softer diffuse shell of the nebula around eta Carinae and a ha…
Resolving Sirius-like binaries with the Hubble Space Telescope
Bond, Howard E.; Barstow, M. A.; Holberg, J. B. +1 more
We present initial results from a Hubble Space Telescope ultraviolet imaging survey of stars known to have hot white dwarf companions which are unresolved from the ground. The hot companions, discovered through their EUV or UV emission, are hidden by the overwhelming brightnesses of the primary stars at visible wavelengths. Out of 17 targets obser…
The Red Stellar Population in NGC 1569
Leitherer, Claus; Greggio, L.; Tosi, M. +6 more
We present HST NICMOS photometry of the resolved stellar population in the dwarf irregular galaxy NGC 1569. The color-magnitude diagram (CMD) in the F110W and F160W photometric bands contains ~2400 stars with a formal photometric error <~0.1 mag down to mF110W~23.5 and mF160W~22.5. The fiducial photometry has a completenes…
Precise Masses for Wolf 1062 AB from Hubble Space Telescope Interferometric Astrometry and MCDonald Observatory Radial Velocities
McArthur, B. E.; Benedict, G. F.; Franz, O. G. +17 more
We present an analysis of astrometric data from Fine Guidance Sensor 3 (FGS 3), a white-light interferometer on HST, and of radial velocity data from two ground-based campaigns. We model the astrometric and radial velocity measurements simultaneously to obtain parallax, proper motion, and component masses for Wolf 1062 (Gl 748; M3.5 V). To derive …
Ultraviolet Spectropolarimetry of Narrow-Line Radio Galaxies
Dey, Arjun; Spinrad, Hyron; van Breugel, Wil +4 more
We present the results of UV spectropolarimetry (λrest~=2000-3000 Å) and far-UV spectroscopy (λrest~=1500-2000 Å) of two low-redshift narrow-line radio galaxies (NLRGs) taken with the Faint Object Spectrograph on board the Hubble Space Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the presence of bro…
NICMOS Coronagraphic Observations of 55 Cancri
Schneider, G.; Hines, D. C.; Becklin, E. E. +3 more
We present new near-infrared (1.1 µm) observations of the circumstellar environment of the planet-bearing star 55 Cancri. With these Hubble Space Telescope (HST) images we are unable to confirm the observation of bright scattered radiation at longer NIR wavelengths previously reported by Trilling and coworkers. NICMOS coronagraphic images wi…