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Outer Layers of a Carbon Star: The View from the Hubble Space Telescope

Brown, Alexander; Robinson, Richard D.; Linsky, Jeffrey L. +13 more

To advance our understanding of the relationship between stellar chromospheres and mass loss, which is a common property of carbon stars and other asymptotic giant branch stars, we have obtained ultraviolet spectra of the nearby N-type carbon star UU Aur using the Hubble Space Telescope (HST). In this paper we describe the HST observations, identi…

Non-LTE line formation for iron group elements. II. Fe VI.

Butler, K.; Becker, S. R.

A non-LTE line formation calculation for Fevi is presented. The data for radiative bound-bound transitions which have been derived as part of this work are described and their accuracy is evaluated. The theoretical non-LTE spectrum of Fevi is compared to an IUE spectrum of Feige 67. An iron abundance of approximately ten times the solar value is d…

Ulysses magnetic field observations of fluctuations within polar coronal flows.

Balogh, A.; Forsyth, R. J.; Smith, E. J. +1 more

The Ulysses spacecraft has gathered data from within flows from the Sun's southern polar coronal hole, the first in situ measurement of this region. We present a brief analysis of the heliospheric magnetic field data from this region, using a fractal method. As is the case near the ecliptic, estimated spectral exponents are near 5/3 on spacecraft …

GHRS Observations of Mass-loaded Flows in Abell 78

Borkowski, Kazimierz J.; Tsvetanov, Zlatan; Harrington, J. Patrick

Spectroscopic observations of the central star of the planetary nebula Abell 78 were obtained with the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope (HST) in the vicinity of the C IV lambda 1548.2, 1550.8 doublet. We find a series of narrow absorption features superposed on the broad, P Cygni stellar wind profile. …

The gamma-ray burst GB 920622.

Greiner, J.; Hurley, K.; Fishman, G. J. +12 more

We have analyzed the Ulysses, BATSE, and COMPTEL spectral data from the γ-ray burst of June 22, 1992 (GB 920622). COMPTEL data reveal a hard to soft evolution within the first pulse of the burst, while the mean hardness ratios of the three pulses are the same. Unlike the single instrument spectra, the composite spectrum of GB 920622 averaged over …

Evidence on sizes and fragmentation of the nuclei of comet Shoemaker-Levy 9 from Hubble Space Telescope images.

Sekanina, Z.

Digital maps of the central regions of 13 nuclear condensations of Comet Shoemaker-Levy 9, obtained with the Wide Field Planetary Camera-2 of the Hubble Space Telescope on January 24-25, March 28-30, and July 4, 1994, were analyzed with the aim to identify the presence of distinct, major fragments in each condensation, to deconvolve their contribu…

Detection of Hot Gas in the Interstellar Medium

Jenkins, Edward B.; Cowie, Lennox L.; Huang, Jia-Sheng +1 more

We present data on the C IV, Si IV, and N V absorption lines in eight disk stars observed by HST (Hubble Space Telescope) with the GHRS (Goddard High Resolution Spectrograph) at intermediate resolution. C IV and Si IV absorption lines are detected in seven target stars, while N V lines are detected in four distant stars and one nearby star. By fit…

Spectroscopic binary orbits from ultraviolet radial velocities. Paper 17: HD 206267

Stickland, D. J.

Low-Mass Binaries in the Hyades

Reid, I. Neill; Gizis, John

We have used the HST Planetary Camera to search for companions to a sample of low-mass (M_υ > 11.5) members of the Hyades cluster. Our observations, which extend in sensitivity beyond the hydrogen-burning limit, detect 5 companions amongst the 21 targets. One binary system appears to lie 70% beyond the Hyades, so the observed binary f…

A study of systematic positional errors in the SPM plates

Lindegren, L.; Crifo, F.; Platais, I. +4 more

The high-precision reference system defined by the Hipparcos 30-month solution is used to evaluate the presence of potential systematic errors in star positions on the Southern Proper Motion program (SPM) plates. The SPM plates modeled into the Hipparcos positions show a consistent magnitude equation which can be explained by lens decentering. Not…