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A Method for Determining the Photospheric 4He Abundance
Share, Gerald H.; Murphy, Ronald J.
The photospheric 4He/H ratio is not measured directly but is inferred from stellar evolution models, helioseismology, and coronal observations. We suggest a procedure for determining the photospheric ratio on the basis of solar wind isotopic He abundances and γ-ray line measurements. Recent Ulysses measurements of the 4He/
An Ultraviolet View of Massive Star Formation in Seyfert Host Galaxies.
O'Connell, Robert W.; Bohlin, Ralph C.; Smith, Andrew M. +5 more
We present deep vacuum ultraviolet (λλ 1200-3300 Å) imagery of four Seyfert galaxies observed by the Ultraviolet Imaging Telescope (UIT): NGC 1068, NGC 2992, NGC 4151, and Mrk 335. These data have a spatial resolution of ∼3" and a limiting surface brightness of ∼24.5 mag arcsec-2 The host galaxies display a diverse range in ultraviolet …
The HST Medium Deep Survey: Light Profiles and Redshifts for Field Galaxies with z<~0.6
Griffiths, R. E.; Windhorst, R. A.; Schmidtke, P. C. +3 more
High-resolution isophotal light profiles have been determined for 36 field galaxies in images taken for the Hubble Space Telescope Medium Deep Survey prior to HST's refurbishment mission. The images were obtained with the Wide Field Camera in "parallel mode" and deconvolved using the Lucy-Richardson image-restoration algorithm with a large library…
Three-dimensional nature of interaction regions: Pioneer, Voyager, and Ulysses solar cycle variations from 1 to 5 AU
Smith, Edward J.; González-Esparza, J. Américo
We combined in-ecliptic observations of interaction regions from 1 to 5 AU by four spacecraft that traveled to Jupiter at different phases of the solar cycle: Pioneer 11 (declining phase of cycle 20), Voyager 1 and 2 (ascending phase of cycle 21), and Ulysses (just after solar maximum 22). We used this set of 97 interaction regions to study two di…
A Laboratory for Magnetized Accretion Disk Model: Ultraviolet and X-Ray Emission from Cataclysmic Variable GK Persei
Kenyon, Scott J.; Yi, Insu
We analyze the ultraviolet spectrum of the cataclysmic variable GK Per at maximum light. The flat ultraviolet spectrum in this system requires a truncated inner accretion disk and an unusually flat radial temperature profile. This requirement is not satisfied by any nonmagnetic steady or nonsteady disk model.
We consider a magnetized accretio…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 …