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Wind variability in central stars of planetary nebulae. II.
Patriarchi, P.; Perinotto, M.
New high resolution IUE spectra of central stars of the planetary nebulae (CSPN) NGC 40, NGC 6543, NGC 6826, and BD +30 3639 have been obtained between August 1994 and September 1995 to explore the variability of their P Cygni profiles. The data have been analyzed together with previous observations of the same stars. Significant changes in the pr…
Detection of young stellar objects with ISO.
Felli, M.; Gilmore, G.; Omont, A. +4 more
Preliminary 15µm results obtained with ISOCAM are compared with deep K-band and H_2_O maser observations of a 0.244deg^2^ field in the galactic plane at I=+45^o^. A new maser source is found to be associated with the infrared source with the largest colour index, (m_K_-m_15µm_)>=10, most probably a young star in its earliest evoluti…
Observations of 3C273 with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. II.
Savage, B. D.; Ebbets, D. C.; Crenshaw, D. M. +19 more
Observations of the quasar 3C 273 taken with the Goddard High Resolution Spectrograph in November and December 1993 are presented here. We have included both the fully-reduced spectra, and spectra combined with our earlier (1991) observations. There are a total of 10 new medium resolution exposures covering four wavelength regions: 1164-1201 Angst…
Lateral Shock of the R Aquarii Jet
Hollis, J. M.; Pedelty, J. A.; Kafatos, M.
The R Aqr jet was observed with the VLA B-configuration at two epochs separated by ~13.2 yr. Comparison of the resulting 6 cm continuum images show that the radio jet has undergone a lateral counterclockwise rotation of ~6°-12° on the plane of the sky. The model of jet parcels on independent trajectories is difficult to reconcile with these observ…
Circumstellar Gas in the Wide Binary HD 188037
Jura, M.; Kahane, C.; Fischer, D. +1 more
We report radio, optical, and ultraviolet studies of the wide binary HD 188037 (=IRC +20439). We detect the CO (2-1) and (1-0) rotational lines from the circumstellar envelope in this system, which consists of a luminous (~7000 L⊙) mass-losing M-type star and, at a separation of 0.75", a main-sequence A-type star. The strong (2-1) line …
Ultraviolet observations of Chiron with the HST/FOS: Examining a Centaur's Gray Matter
Parker, Joel Wm.; Stern, S. Alan; A'Hearn, Michael F. +2 more
We present ultraviolet (UV) observations of Chiron during two epochs using the Hubble Space Telescope / Faint Object Spectrograph (HST/FOS). The first observations (1996 Jan 23-24 UT) were made 3 weeks before Chiron's perihelion, and include a series of seven spectra obtained over 3.9 hours. A single follow-up observation was made 3 months later (…
The vertical disc structure of U Geminorum in outburst
Naylor, T.; La Dous, C.
We have obtained phase-resolved UV spectroscopy from the International Ultraviolet Explorer, and V-band CCD photometry of U Gem in outburst. Our data show little or no orbital modulation outside eclipse, in contrast to the X-ray light curves during outburst, which show large dips. We find that a consistent model of the optical, UV and X-ray light …
The Trigonometric Parallax of the Hyades Cluster
van Altena, W. F.; Lee, J. T.; Hoffleit, E. D.
The recent completion of the Fourth Edition of the General Catalogue of Trigonometric Parallaxes (YPC) has enabled us to redetermine the trigonometric parallax of the Hyades Cluster based on individual measurements of the cluster member stars. Since the YPC has been carefully evaluated and corrected for systematic errors in both the absolute paral…
Searching for chromospheric Lyman-α emission in A-F stars from IUE high resolution spectra.
Talavera, A.; Freire Ferrero, R.; Bruhweiler, F. +3 more
With the aim of locating the boundary for the onset of chromospheric emission in the H-R diagram we have undertaken a spectroscopic study of the hydrogen Ly-α, using the IUE short wavelength spectrograph in the high resolution mode. We report here on the analysis of IUE spectra of 11 A-F type stars. We have detected Ly-α emission in stars as early…
Self-consistent and Time-dependent Solar Wind Models
Rosner, R.; Suess, S. T.; Musielak, Z. E. +2 more
We describe the first results from a self-consistent study of Alfvén waves for the time-dependent, single-fluid magnetohydrodynamic (MHD) solar wind equations, using a modified version of the ZEUS MHD code. The wind models we examine are radially symmetrical and magnetized; the initial outflow is described by the standard Parker wind solution. Our…